Urs Utzinger

Interests

Research

Microscopy, Optical Spectroscopy, Signal and Data Analysis, Optical Imaging

Teaching

Instrumentation, Biomedical Optics, Signal and Data Analysis, Mechatronics & Robotics, Device Design

Courses

Scholarly Contributions

Books

• Barton, J. K., Utzinger, U., & Tumlinson, A. R. (2015). Combined Endoscopic Optical Coherence Tomography and Laser Induced Fluorescence in Optical Coherence Tomography: Technology and Applications , Drexler and Fujimoto. Springer.
• Utzinger, U. (2014). Fiber Optic Probe Design in Second Edition Biomedical Photonics Handbook, voDinh. CRC Press.

Journals/Publications

• Larson, M., Gmitro, A. F., Utzinger, U., Rouse, A. R., Woodhead, G. J., Carlson, Q., Hennemeyer, C. T., & Barton, J. K. (2021). Using FDA-approved drugs as off-label fluorescent dyes for optical biopsies: from in silico design to ex vivo proof-of-concept. Methods and Applications in Fluorescence.
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  AbstractOptical biopsies bring the microscope to the patient rather than the tissue to the microscope, and may complement or replace the tissue-harvesting component of the traditional biopsy process with its associated risks. In general, optical biopsies are limited by the lack of endogenous tissue contrast and the small number of clinically approved in vivo dyes. This study tests multiple FDA-approved drugs that have structural similarity to research dyes as off-label in situ fluorescent alternatives to standard ex vivo hematoxylin & eosin tissue stain. Numerous drug-dye combinations shown here may facilitate relatively safe and fast in situ or possibly in vivo staining of tissue, enabling real-time optical biopsies and other advanced microscopy technologies, which have implications for the speed and performance of tissue- and cellular-level diagnostics.
• Bal, U., Utzinger, U., Bal, A., & Moral, O. T. (2020). The Determination of Absorption and Reduced Scattering Coefficients of Optical Phantoms Using a Frequency-Domain Multi-Distance Method in a Non-contact Manner. ADVANCES IN ELECTRICAL AND COMPUTER ENGINEERING, 20(2), 3-10.
• Gutruf, P., Utzinger, U., & Subbian, V. (2020). Moving from Pedagogy to Andragogy in Biomedical Engineering Design: Strategies for Lab-at-Home and Distance Learning. Biomedical Engineering Education.
• Behkam, R., Kollech, H. G., Jana, A., Hill, A., Danford, F., Howerton, S., Ram, S., Rodríguez, J. J., Utzinger, U., & Girkin, C. A. (2019). Racioethnic Differences in the Biomechanical Response of the Lamina Cribrosa. Acta biomaterialia.
• Geest, J., Kollech, H. G., Behkam, R., Jana, A., Utzinger, U., & Girkin, C. A. (2019). Biomechanical Response of the Lamina Cribrosa in Glaucomatous and Non glaucomatous samples. Investigative Ophthalmology \& Visual Science, 60(9), 6189--6189.
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  ARVO Meeting Abstract
• Black, J. F., & Barton, J. K. (2017). Ultraminiature optical design for multispectral fluorescence imaging endoscopes. Journal of Biomedical Optics, 22(3), 036013-22-10. doi:http://dx.doi.org/10.1117/1.JBO.22.3.036013
• Keenan, M., Tate, T. H., Kieu, K., Black, J. F., Utzinger, U., & Barton, J. K. (2017). Design and characterization of a combined OCT and wide field imaging falloposcope for ovarian cancer detection. Biomedical Optics Express, 8(1), 124--136.
• Pacheco, S., Wang, C., Chawla, M. K., Nguyen, M., Baggett, B. K., Utzinger, U., Barnes, C. A., & Liang, R. (2017). High resolution, high speed, long working distance, large field of view confocal fluorescence microscope. Scientific Reports, 7(1), 13349.
• Dean, Z. S., Elias, P., Jamilpour, N., Utzinger, U., & Wong, P. K. (2016). Probing 3D Collective Cancer Invasion Using Double-Stranded Locked Nucleic Acid Biosensors. Analytical Chemistry, 88(17), 8902--8907.
• Tate, T. H., Baggett, B., Rice, P. F., Koevary, J. W., Orsinger, G. V., Nymeyer, A. C., Welge, W. A., Saboda, K., Roe, D. J., Hatch, K. D., & others, . (2016). Multispectral fluorescence imaging of human ovarian and fallopian tube tissue for early-stage cancer detection. Journal of biomedical optics, 21(5), 056005--056005.
• Vande Geest, J. P., Haskett, D. G., McIntyre, J. O., Maestas, D., Howerton, S., Mcgrath, D. V., Smith, T., Utzinger, U., Ardilia, C., Doetschman, T. C., Ardilia, C., Doetschman, T. C., Smith, T., Utzinger, U., Howerton, S., McGgrath, D. V., Maestas, D., McIntyre, J. O., Haskett, D. G., & Vande Geest, J. P. (2016). 2-Photon characterization of optical proteolytic beacons for imaging changes in MMP activity in a mouse model of aneurysm. Microscopy and Microanalysis, 22, 349-360. doi:http://dx.doi.org/10.1017/S1431927616000088
• Bal, U., Engin, M., & Utzinger, U. (2015). A multiresolution approach for enhancement and denoising of microscopy images. SIGNAL IMAGE AND VIDEO PROCESSING, 9(4), 787-799.
• Carbary-Ganz, J. L., Welge, W. A., Barton, J. K., & Utzinger, U. (2015). In vivo molecular imaging of colorectal cancer using quantum dots targeted to vascular endothelial growth factor receptor 2 and optical coherence tomography/laser-induced fluorescence dual-modality imaging. Journal of Biomedical Optics, 20, 096015.
• Utzinger, U., Baggett, B., Weiss, J., Hoying, J., & Edgar, L. (2015). Large-scale time series microscopy of neovessel growth during angiogenesis. Angiogenesis, 1-14.
• Carbary-Ganz, J. L., Barton, J. K., & Utzinger, U. (2014). Quantum dots targeted to vascular endothelial growth factor receptor 2 as a contrast agent for the detection of colorectal cancer. Journal of biomedical optics, 19(8), 086003.
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  We successfully labeled colorectal cancer in vivo using quantum dots targeted to vascular endothelial growth factor receptor 2 (VEGFR2). Quantum dots with emission centered at 655 nm were bioconjugated to anti-VEGFR2 antibodies through streptavidin/biotin linking. The resulting QD655-VEGFR2 contrast agent was applied in vivo to the colon of azoxymethane (AOM) treated mice via lavage and allowed to incubate. The colons were then excised, cut longitudinally, opened to expose the lumen, and imaged en face using a fluorescence stereoscope. The QD655-VEGFR2 contrast agent produced a significant increase in contrast between diseased and undiseased tissues, allowing for fluorescence-based visualization of the diseased areas of the colon. Specificity was assessed by observing insignificant contrast increase when labeling colons of AOM-treated mice with quantum dots bioconjugated to isotype control antibodies, and by labeling the colons of saline-treated control mice. This contrast agent has a great potential for in vivo imaging of the colon through endoscopy.
• Edgar, L. T., Hoying, J. B., Utzinger, U., Underwood, C. J., Krishnan, L., Baggett, B. K., Maas, S. A., Guilkey, J. E., & Weiss, J. A. (2014). Mechanical interaction of angiogenic microvessels with the extracellular matrix. Journal of biomechanical engineering, 136(2), 021001.
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  Angiogenesis is the process by which new blood vessels sprout from existing blood vessels, enabling new vascular elements to be added to an existing vasculature. This review discusses our investigations into the role of cell-matrix mechanics in the mechanical regulation of angiogenesis. The experimental aspects of the research are based on in vitro experiments using an organ culture model of sprouting angiogenesis with the goal of developing new treatments and techniques to either promote or inhibit angiogenic outgrowth, depending on the application. Computational simulations were performed to simulate angiogenic growth coupled to matrix deformation, and live two-photon microscopy was used to obtain insight into the dynamic mechanical interaction between angiogenic neovessels and the extracellular matrix. In these studies, we characterized how angiogenic neovessels remodel the extracellular matrix (ECM) and how properties of the matrix such as density and boundary conditions influence vascular growth and alignment. Angiogenic neovessels extensively deform and remodel the matrix through a combination of applied traction, proteolytic activity, and generation of new cell-matrix adhesions. The angiogenic phenotype within endothelial cells is promoted by ECM deformation and remodeling. Sensitivity analysis using our finite element model of angiogenesis suggests that cell-generated traction during growth is the most important parameter controlling the deformation of the matrix and, therefore, angiogenic growth and remodeling. Live two-photon imaging has also revealed numerous neovessel behaviors during angiogenesis that are poorly understood such as episodic growth/regression, neovessel colocation, and anastomosis. Our research demonstrates that the topology of a resulting vascular network can be manipulated directly by modifying the mechanical interaction between angiogenic neovessels and the matrix.
• Geest, J. P., Tong, J., Danford, F., Ayyalasomayajula, A., & Utzinger, U. (2014). Quantification of the pressure dependent anterior microstructure of the lamina cribrosa using multiphoton microscopy. Investigative Ophthalmology \& Visual Science, 55, 4248--4248.
• Hoying, J. B., Utzinger, U., & Weiss, J. A. (2014). Formation of microvascular networks: role of stromal interactions directing angiogenic growth. Microcirculation (New York, N.Y. : 1994), 21(4), 278-89.
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  In the adult, angiogenesis leads to an expanded microvascular network as new vessel segments are added to an existing microcirculation. Necessarily, growing neovessels must navigate through tissue stroma as they locate and grow toward other vessel elements. We have a growing body of evidence demonstrating that angiogenic neovessels reciprocally interact with the interstitial matrix of the stroma resulting in directed neovascular growth during angiogenesis. Given the compliance and the viscoelastic properties of collagen, neovessel guidance by the stroma is likely due to compressive strain transverse to the direction of primary tensile forces present during active tissue deformation. Similar stromal strains control the final network topology of the new microcirculation, including the distribution of arterioles, capillaries, and venules. In this case, stromal-derived stimuli must be present during the post-angiogenesis remodeling and maturation phases of neovascularization to have this effect. Interestingly, the preexisting organization of vessels prior to the start of angiogenesis has no lasting influence on the final, new network architecture. Combined, the evidence describes interplay between angiogenic neovessels and stroma that is important in directed neovessel growth and invasion. This dynamic is also likely a mechanism by which global tissue forces influence vascular form and function.
• Watson, J. M., Marion, S. L., Rice, P. F., Bentley, D. L., Besselsen, D. G., Utzinger, U., Hoyer, P. B., & Barton, J. K. (2014). In vivo time-serial multi-modality optical imaging in a mouse model of ovarian tumorigenesis. Cancer Biology and Therapy, 15(1), 42-60.
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  Abstract: Identification of the early microscopic changes associated with ovarian cancer may lead to development of a diagnostic test for high-risk women. In this study we use optical coherence tomography (OCT) and multiphoton microscopy (MPM) (collecting both two photon excited fluorescence [TPEF] and second harmonic generation [SH G]) to image mouse ovaries in vivo at multiple time points. We demonstrate the feasibility of imaging mouse ovaries in vivo during a longterm survival study and identify microscopic changes associated with early tumor development. These changes include alterations in tissue microstructure, as seen by OCT, alterations in cellular fluorescence and morphology, as seen by TPEF, and remodeling of collagen structure, as seen by SH G. These results suggest that a combined OCT-MPM system may be useful for early detection of ovarian cancer. © 2014 Landes Bioscience.
• Williams, M. J., Utzinger, U., Barkmeier-Kraemer, J. M., & Vande Geest, J. P. (2014). Differences in the microstructure and biomechanical properties of the recurrent laryngeal nerve as a function of age and location. Journal of biomechanical engineering, 136(8).
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  Idiopathic onset of unilateral vocal fold paralysis (UVP) is caused by damage to the recurrent laryngeal nerve (RLN) and results in difficulty speaking, breathing, and swallowing. This damage may occur in this nerve as it loops around the aortic arch, which is in a dynamic biomechanical environment. The goal of this study is to determine if the location-dependent biomechanical and microstructural properties of the RLN are different in piglets versus adolescent pigs. The neck/distal and thoracic/proximal (near the aortic arch) regions of the RLN from eight adolescent pigs and six piglets were isolated and mechanically assessed in uni-axial tension. Two-photon imaging (second harmonic) data were collected at 5%, 10%, and 15% strain during the mechanical test. The tangential modulus (TM) and the strain energy density (W) were determined at each level of strain. The mean mode of the preferred fiber angle and the full width at half maximum (FWHM, a measure of fiber splay) were calculated from the imaging data. We found significantly larger values of TM, W, and FWHM in the proximal segments of the left RLN when compared to the distal segments (18.51 MPa ± 1.22 versus 10.78 MPa ± 1.22, p < 0.001 for TM, 0.046 MPa ± 0.01 versus 0.026 MPa ± 0.01, p < 0.003 for W, 15.52 deg ± 1.00 versus 12.98 deg ± 1.00, p < 0.001 for FWHM). TM and W were larger in the left segments than the right (15.32 MPa ± 1.20 versus 11.80 MPa ± 1.20, p < 0.002 for TM, 0.038 MPa ± 0.01 versus 0.028 MPa ± 0.01, p < 0.0001 for W). W was larger in piglets when compared to adolescent pigs (0.042 MPa ± 0.01 versus 0.025 MPa ± 0.01, p < 0.04). The proximal region of the left porcine RLN is more stiff than the distal region and has a higher degree of fiber splay. The left RLN of the adolescent pigs also displayed a higher degree of strain stiffening than the right. These differences may develop as a result of the more dynamic environment the left RLN is in as it loops around the aortic arch.
• Bal, U., Andresen, V., Baggett, B., & Utzinger, U. (2013). Intravital confocal and two-photon imaging of dual-color cells and extracellular matrix mimics. Microscopy and Microanalysis, 19(1), 201-212.
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  PMID: 23380006;PMCID: PMC3992248;Abstract: Abstract We report our efforts in identifying optimal scanning laser microscope parameters to study cells in three-dimensional culture. For this purpose we studied contrast of extracellular matrix (ECM) mimics, as well as signal attenuation, and bleaching of red and green fluorescent protein labeled cells. Confocal backscattering, second harmonic generation (SHG), and autofluorescence were sources of contrast in ECM mimics. All common ECM mimics exhibit contrast observable with confocal reflectance microscopy. SHG imaging on collagen I based hydrogels provides high contrast and good optical penetration depth. Agarose is a useful embedding medium because it allows for large optical penetration and exhibits minimal autofluorescence. We labeled breast cancer cells' outline with DsRed2 and nucleus with enhanced green fluorescent protein (eGFP). We observed significant difference both for the bleaching rates of eGFP and DsRed2 where bleaching is strongest during two-photon excitation (TPE) and smallest during confocal imaging. But for eGFP the bleaching rate difference is smaller than for DsRed2. After a few hundred microns depth in a collagen I hydrogel, TPE fluorescence of DsRed2 becomes twice as strong compared to confocal imaging. In fibrin and agarose gels, the imaging depth will need to be beyond 1 mm to notice a TPE advantage. Copyright © Microscopy Society of America 2013.
• Bal, U., Engin, M., & Utzinger, U. (2013). A multiresolution approach for enhancement and denoising of microscopy images. Signal, Image and Video Processing, 1-13.
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  Abstract: In order to overcome blurring due to microscope optics in fluorescence microscopy, we propose a wavelet transform-based non-iterative blind deconvolution method. In our proposed deconvolution algorithm, we used wavelet-based denoising algorithms. We compared discrete wavelet transform (DWT) and wavelet packet transform (WPT) structures as denoising algorithms. WPT-based algorithm resulted in less error than the DWT-based algorithm. Minimum error was obtained for coif5 wavelet type. We compared our denoising methods with several standard denoising methods. Also, we compared our proposed deconvolution algorithm with several standard deconvolution methods. Our proposed wavelet transform-based deconvolution method resulted in the least error compared to other methods. To test the efficacy of our deconvolution method on cell images, we proposed a wavelet entropy-based non-reference image quality (contrast enhancement) metric. We tested our proposed metric by increasing blurring ratio both for noiseless and noisy images. Our metric is useful for evaluating image quality in terms of deblurring. © 2013 Springer-Verlag London.
• Banerjee, B., Rial, N. S., Renkoski, T., Graves, L. R., Reid, S. A., Chengcheng, H. u., Tsikitis, V. L., Nfonsom, V., Pugh, J., & Utzinger, U. (2013). Enhanced visibility of colonic neoplasms using formulaic ratio imaging of native fluorescence. Lasers in Surgery and Medicine, 45(9), 573-581.
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  PMID: 24114774;Abstract: Background and Objectives Colonoscopy is the preferred method for colon cancer screening, but can miss polyps and flat neoplasms with low color contrast. The objective was to develop a new autofluorescence method that improves image contrast of colonic neoplasms. Study Design/Materials and Methods We selected the three strongest native fluorescence signals and developed a novel method where fluorescence images are processed in a ratiometric formula to represent the likely cellular and structural changes associated with neoplasia. Native fluorescence images of fresh surgical specimens of the colon containing normal mucosa, polypoid and flat adenomas as well as adenocarcinoma were recorded using a prototype multi-spectral imager. Sixteen patients, with a mean age of 62 years (range 28-81) undergoing elective resection for colonic neoplasms were enrolled. High contrast images were seen with fluorescence from tryptophan (Tryp), flavin adenine dinucleotide (FAD) and collagen. Results When the image intensity of Tryp was divided pixel by pixel, by the intensities of FAD and collagen, the resulting formulaic ratio (FR) images were of exceptionally high contrast. The FR images of adenomas and adenocarcinomas had increased Weber contrast. Conclusions FR imaging is a novel imaging process that represents the likely metabolic and structural changes in colonic neoplasia that produces images with remarkably high contrast. Lasers Surg. Med. 45:573-581, 2013. © 2013 Wiley Periodicals, Inc.
• Renkoski, T. E., Banerjee, B., Graves, L. R., Rial, N. S., A., S., Tsikitis, V. L., Nfonsam, V. N., Tiwari, P., Gavini, H., & Utzinger, U. (2013). Ratio images and ultraviolet C excitation in autofluorescence imaging of neoplasms of the human colon. Journal of Biomedical Optics, 18(1).
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  PMID: 23291657;PMCID: PMC3537599;Abstract: The accepted screening technique for colon cancer is white light endoscopy. While most abnormal growths (lesions) are detected by this method, a significant number are missed during colonoscopy, potentially resulting in advanced disease. Missed lesions are often flat and inconspicuous in color. A prototype ultraviolet spectral imager measuring autofluorescence (AF) and reflectance has been developed and applied in a study of 21 fresh human colon surgical specimens. Six excitation wavelengths from 280 to 440 nm and formulaic ratio imaging were utilized to increase lesion contrast and cause neoplasms to appear bright compared to normal tissue. It was found that in the subset of lesions which were most difficult to visualize in standard color photographs [low contrast lesions, (LCLs)] a ratio image (F340/F440) of AF images excited at 340 and 440 nm produced extraordinary images and was effective in about 70% of these difficult cases. Contrast may be due to increased levels of reduced nicotinamide adenine dinucleotide, increased hemoglobin absorption, and reduced signal from submucosal collagen. A second successful ratio image (R480/R555) combined two reflectance images to produce exceptional images especially in particular LCLs where F340/F440 was ineffective. The newly discovered ratio images can potentially improve detection rate in screening with a novel AF colonoscope. © 2013 Society of Photo-Optical Instrumentation Engineers.
• Utzinger, U., Banerjee, B., Rial, N. S., Renkoski, T., Graves, L. R., Reid, S. A., Hu, C., Tsikitis, V. L., Nfonsom, V., Pugh, J., & Utzinger, U. -. (2013). Enhanced visibility of colonic neoplasms using formulaic ratio imaging of native fluorescence. Lasers in surgery and medicine, 45(9).
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  Colonoscopy is the preferred method for colon cancer screening, but can miss polyps and flat neoplasms with low color contrast. The objective was to develop a new autofluorescence method that improves image contrast of colonic neoplasms.
• Utzinger, U., Renkoski, T. E., Banerjee, B., Graves, L. R., Rial, N. S., Reid, S. A., Tsikitis, V. L., Nfonsam, V. N., Tiwari, P., Gavini, H., & Utzinger, U. -. (2013). Ratio images and ultraviolet C excitation in autofluorescence imaging of neoplasms of the human colon. Journal of biomedical optics, 18(1).
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  The accepted screening technique for colon cancer is white light endoscopy. While most abnormal growths (lesions) are detected by this method, a significant number are missed during colonoscopy, potentially resulting in advanced disease. Missed lesions are often flat and inconspicuous in color. A prototype ultraviolet spectral imager measuring autofluorescence (AF) and reflectance has been developed and applied in a study of 21 fresh human colon surgical specimens. Six excitation wavelengths from 280 to 440 nm and formulaic ratio imaging were utilized to increase lesion contrast and cause neoplasms to appear bright compared to normal tissue. It was found that in the subset of lesions which were most difficult to visualize in standard color photographs [low contrast lesions, (LCLs)] a ratio image (F340/F440) of AF images excited at 340 and 440 nm produced extraordinary images and was effective in about 70% of these difficult cases. Contrast may be due to increased levels of reduced nicotinamide adenine dinucleotide, increased hemoglobin absorption, and reduced signal from submucosal collagen. A second successful ratio image (R480/R555) combined two reflectance images to produce exceptional images especially in particular LCLs where F340/F440 was ineffective. The newly discovered ratio images can potentially improve detection rate in screening with a novel AF colonoscope.
• Utzinger, U., Utzinger, U. -., George, R., Chandrasekaran, A., Brewer, M. A., & Hatch, K. D. (2010). Clinical research device for ovarian cancer detection by optical spectroscopy in the ultraviolet C-visible. Journal of biomedical optics, 15(5), 057009.
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  Early detection of ovarian cancer could greatly increase the likelihood of successful treatment. However, present detection techniques are not very effective, and symptoms are more commonly seen in later stage disease. Amino acids, structural proteins, and enzymatic cofactors have endogenous optical properties influenced by precancerous changes and tumor growth. We present the technical details of an optical spectroscopy system used to quantify these properties. A fiber optic probe excites the surface epithelium (origin of 90% of cases) over 270 to 580 nm and collects fluorescence and reflectance at 300 to 800 nm with four or greater orders of magnitude instrument to background suppression. Up to four sites per ovary are investigated on patients giving consent to oophorectomy and the system's in vivo optical evaluation. Data acquisition is completed within 20 s per site. We illustrate design, selection, and development of the components used in the system. Concerns relating to clinical use, performance, calibration, and quality control are addressed. In the future, spectroscopic data will be compared with histological biopsies from the corresponding tissue sites. If proven effective, this technique can be useful in screening women at high risk of developing ovarian cancer to determine whether oophorectomy is necessary.
• Watson, J. M., Marion, S. L., Rice, P. F., Bentley, D. L., Besselsen, D., Utzinger, U., Hoyer, P. B., & Barton, J. K. (2013). In vivo three-dimensional optical coherence tomography and multiphoton microscopy in a mouse model of ovarian neoplasia. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 8577.
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  Abstract: Our goal is to use optical coherence tomography (OCT) and multiphoton microscopy (MPM) to detect early tumor development in a mouse model of ovarian neoplasia. We hope to use information regarding early tumor development to create a diagnostic test for high-risk patients. In this study we collect in vivo images using OCT, second harmonic generation and two-photon excited fluorescence from non-vinylcyclohexene diepoxide (VCD)-dosed and VCD-dosed mice. VCD causes follicular apoptosis (simulating menopause) and leads to tumor development. Using OCT and MPM we visualized the ovarian microstructure and were able to see differences between non-VCD-dosed and VCD-dosed animals. This leads us to believe that OCT and MPM may be useful for detecting changes due to early tumor development. © 2013 Copyright SPIE.
• Watson, J. M., Marion, S. L., Rice, P. F., Utzinger, U., Brewer, M. A., Hoyer, P. B., & Barton, J. K. (2013). Two-photon excited fluorescence imaging of endogenous contrast in a mouse model of ovarian cancer. Lasers in Surgery and Medicine, 45(3), 155-166.
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  PMID: 23362124;Abstract: Background and Objective Ovarian cancer has an extremely high mortality rate resulting from poor understanding of the disease. In order to aid understanding of disease etiology and progression, we identify the endogenous fluorophores present in a mouse model of ovarian cancer and describe changes in fluorophore abundance and distribution with age and disease. Study Design/Materials and Methods A mouse model of ovarian cancer was created by dosing with 4-vinylcyclohexene diepoxide, which induces follicular apoptosis (simulating menopause), and 7,12-dimethylbenz[a]anthracene, a known carcinogen. Imaging of ovarian tissue was completed ex vivo with a multiphoton microscope using excitation wavelength of 780 nm and emission collection from 405 to 505 nm. Two-photon excited fluorescence images and corresponding histologic sections with selective stains were used to identify endogenous fluorophores. Results The majority of collected fluorescence emission was attributed to NADH and lipofuscin, with additional contributions from collagen and elastin. Dim cellular fluorescence from NADH did not show observable changes with age. Changes in ovarian morphology with disease development frequently caused increased fluorescence contributions from collagen and adipose tissue-associated NADH. Lipofuscin fluorescence was much brighter than NADH fluorescence and increased as a function of both age and disease. Conclusions Our finding of NADH fluorescence patterns similar to that seen previously in human ovary, combined with the observation of lipofuscin accumulation with age and disease also seen in human organs, suggests that the findings from this model may be relevant to human ovarian disease. Increased lipofuscin fluorescence might be used as an indicator of disease in the ovary and this finding warrants further study. © 2013 Wiley Periodicals, Inc.
• Banerjee, B., Graves, L. R., & Utzinger, U. (2012). Tryptophan fluorescence of cells and tissue in esophageal carcinoma. IEEE Sensors Journal, 12(11), 3273-3274.
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  Abstract: Cancer is a cellular process. The emission spectrum of tryptophan, which produces the strongest fluorescence in cells, was investigated in cells and tissues of a normal and malignant esophagus. Estimated fluorescence intensity per cell was about three times greater in cancerous cells than in normal cells. The fluorescence was also greater in cancerous tissue but the difference was attenuated, probably because of absorption and scattering. Cellular fluorescence from tryptophan may be useful for the detection of cancer in esophageal cells and tissues. © 2012 IEEE.
• Banerjee, B., Renkoski, T., Graves, L. R., Rial, N. S., Tsikitis, V. L., Nfonsam, V., Pugh, J., Tiwari, P., Gavini, H., & Utzinger, U. (2012). Tryptophan autofluorescence imaging of neoplasms of the human colon. Journal of Biomedical Optics, 17(1).
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  PMID: 22352653;Abstract: Detection of flat neoplasia is a major challenge in colorectal cancer screening, as missed lesions can lead to the development of an unexpected 'incident' cancer prior to the subsequent endoscopy. The use of a tryptophanrelated autofluorescence has been reported to be increased in murine intestinal dysplasia. The emission spectra of cells isolated from human adenocarcinoma and normal mucosa of the colon were studied and showed markedly greater emission intensity from cancerous cells compared to cells obtained from the surrounding normal mucosa. A proto-type multispectral imaging system optimized for ultraviolet macroscopic imaging of tissue was used to obtain autofluorescence images of surgical specimens of colonic neoplasms and normal mucosa after resection. Fluorescence images did not display the expected greater emission from the tumor as compared to the normal mucosa, most probably due to increased optical absorption and scattering in the tumors. Increased fluorescence intensity in neoplasms was observed however, once fluorescence images were corrected using reflectance images. Tryptophan fluorescence alone may be useful in differentiating normal and cancerous cells, while in tissues its autofluorescence image divided by green reflectance may be useful in displaying neoplasms. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).
• Gainer, C. F., Utzinger, U., & Romanowski, M. (2012). Scanning two-photon microscopy with upconverting lanthanide nanoparticles via Richardson-Lucy deconvolution. Journal of Biomedical Optics, 17(7).
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  PMID: 22894486;PMCID: PMC3389607;Abstract: The use of upconverting lanthanide nanoparticles in fast-scanning microscopy is hindered by a long luminescence decay time, which greatly blurs images acquired in a nondescanned mode. We demonstrate herein an image processing method based on Richardson-Lucy deconvolution that mitigates the detrimental effects of their luminescence lifetime. This technique generates images with lateral resolution on par with the system's performance, ∼1.2 μm, while maintaining an axial resolution of 5 μm or better at a scan rate comparable with traditional two-photon microscopy. Remarkably, this can be accomplished with near infrared excitation power densities of 850 W/cm 2, several orders of magnitude below those used in two-photon imaging with molecular fluorophores. By way of illustration, we introduce the use of lipids to coat and functionalize these nanoparticles, rendering them water dispersible and readily conjugated to biologically relevant ligands, in this case epidermal growth factor receptor antibody. This deconvolution technique combined with the functionalized nanoparticles will enable three-dimensional functional tissue imaging at exceptionally low excitation power densities. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).
• Mir, S. M., Baggett, B., & Utzinger, U. (2012). The efficacy of image correlation spectroscopy for characterization of the extracellular matrix. Biomedical Optics Express, 3(2), 215-224.
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  PMID: 22312576;PMCID: PMC3269840;Abstract: Image correlation spectroscopy (ICS) is known to be a useful tool for the evaluation of fiber width in the extracellular matrix. Here we evaluate a more general from of ICS fit parameters for fiber networks and arrive at a means of quantifying the fiber density, pore size and length which facilitates the characterization of the extracellular matrix. A simulation package was made to create images with different structural properties of fiber networks such as fiber orientation, width, fiber density and length. A pore finding algorithm was developed which determines the distribution of circular voids in the image. Collagen I hydrogels were prepared under different polymerization conditions for validation of our pore size algorithm with microscopy data. ICS parameters included amplitude, standard deviation and ellipticity and are shown to predict the structural properties of fiber networks in a quantitative manner. While the fiber width is related to the ICS sigma; the fiber density relates to the pore size distribution which correlates with the ICS amplitude in thresholded images. Fiber length is related to ICS ellipticity if the fibers have a preferred orientation. Findings from ICS and pore distribution algorithms were verified for both simulated and microscopy data. Based on these findings, we conclude that ICS can be used in the assessment of the extracellular matrix and the prediction of fiber orientation, width, density, length and matrix pore size. © 2012 Optical Society of America.
• Renkoski, T. E., Hatch, K. D., & Utzinger, U. (2012). Wide-field spectral imaging of human ovary autofluorescence and oncologic diagnosis via previously collected probe data. Journal of Biomedical Optics, 17(3).
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  PMID: 22502561;PMCID: PMC3380934;Abstract: With no sufficient screening test for ovarian cancer, a method to evaluate the ovarian disease state quickly and nondestructively is needed. The authors have applied a wide-field spectral imager to freshly resected ovaries of 30 human patients in a study believed to be the first of its magnitude. Endogenous fluorescence was excited with 365-nm light and imaged in eight emission bands collectively covering the 400- to 640-nm range. Linear discriminant analysis was used to classify all image pixels and generate diagnostic maps of the ovaries. Training the classifier with previously collected single-point autofluorescence measurements of a spectroscopic probe enabled this novel classification. The process by which probe-collected spectra were transformed for comparison with imager spectra is described. Sensitivity of 100% and specificity of 51% were obtained in classifying normal and cancerous ovaries using autofluorescence data alone. Specificity increased to 69% when autofluorescence data were divided by green reflectance data to correct for spatial variation in tissue absorption properties. Benign neoplasm ovaries were also found to classify as nonmalignant using the same algorithm. Although applied ex vivo, the method described here appears useful for quick assessment of cancer presence in the human ovary. © 2012 society of Photo-Optical Instrumentation Engineers (SPIB).
• Utzinger, U., George, R., Michaelides, M., Brewer, M. A., & Utzinger, U. -. (2012). Parallel factor analysis of ovarian autofluorescence as a cancer diagnostic. Lasers in surgery and medicine, 44(4).
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  Endogenous fluorescence from certain amino acids, structural proteins, and enzymatic co-factors in tissue is altered by carcinogenesis. We evaluate the potential of these changes in fluorescence to predict a diagnosis of malignancy and to estimate the risk of developing ovarian cancer.
• Watson, J. M., Rice, P. F., Marion, S. L., Brewer, M. A., Davis, J. R., Rodriguez, J. J., Utzinger, U., Hoyer, P. B., & Barton, J. K. (2012). Analysis of Second-Harmonic Generation Microscopy in a Mouse Model of Ovarian Carcinoma. Journal of Biomedical Optics, 17(7), 076002-1 to 076002-9. doi:10.1117/1.JBO.17.7.076002
• Watson, J. M., Rice, P. F., Marion, S. L., Brewer, M. A., Davis, J. R., Rodriguez, J. J., Utzinger, U., Hoyer, P. B., & Bartona, J. K. (2012). Analysis of second-harmonic-generation microscopy in a mouse model of ovarian carcinoma. Journal of Biomedical Optics, 17(7).
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  PMID: 22894485;PMCID: PMC3389559;Abstract: Second-harmonic-generation (SHG) imaging of mouse ovaries ex vivo was used to detect collagen structure changes accompanying ovarian cancer development. Dosing with 4-vinylcyclohexene diepoxide and 7,12-dimethylbenz[a]anthracene resulted in histologically confirmed cases of normal, benign abnormality, dysplasia, and carcinoma. Parameters for each SHG image were calculated using the Fourier transform matrix and gray-level co-occurrence matrix (GLCM). Cancer versus normal and cancer versus all other diagnoses showed the greatest separation using the parameters derived from power in the highest-frequency region and GLCM energy. Mixed effects models showed that these parameters were significantly different between cancer and normal (P > 0.008). Images were classified with a support vector machine, using 25% of the data for training and 75% for testing. Utilizing all images with signal greater than the noise level, cancer versus not-cancer specimens were classified with 81.2% sensitivity and 80.0% specificity, and cancer versus normal specimens were classified with 77.8% sensitivity and 79.3% specificity. Utilizing only images with greater than of 75% of the field of view containing signal improved sensitivity and specificity for cancer versus normal to 81.5% and 81.1%. These results suggest that using SHG to visualize collagen structure in ovaries could help with early cancer detection. ©2012 Society of Photo-Optical Instrumentation Engineers (SPIE).
• Kyrish, M., Utzinger, U., Descour, M. R., Baggett, B. K., & Tkaczy, T. S. (2011). Ultra-slim plastic endomicroscope objective for non-linear microscopy. Optics Express, 19(8), 7603-7615.
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  PMID: 21503069;PMCID: PMC3097473;Abstract: Non-linear microscopy has the potential to provide clinically useful information on the structure of biological tissue in vivo via an endomicroscope. The ability to use plastic as the optical material in a multiphoton objective was evaluated based on several criteria including autofluorescence, injection molding induced birefringence, and pulse broadening due to group velocity dispersion. An all-plastic, refractive ultraslim endoscope objective was built with design specifications of NA = 0.4, FOV = 250 μm, 1.27 mm outer diameter, and 0.8 mm clear aperture. Initial images of second-harmonic generation signal (illumination at 780 nm) in collagen fibers and two-photon excited fluorescence (illumination at 920 nm) of Convallaria rhizome are reported. © 2011 Optical Society of America.
• Watson, J. M., Rice, P. F., Marion, S. L., Bentley, D. L., Brewer, M. A., Utzinger, U., Hoyer, P. B., & Barton, J. K. (2011). Multi-modality optical imaging of ovarian cancer in a post-menopausal mouse model. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 7890.
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  Abstract: Our goal is to use optical imaging to detect cancer development on the sub cellular scale. By determining the microscopic changes that precede ovarian cancer we hope to develop a minimally invasive screening test for high risk patients. A mouse ovarian cancer model has been developed by treating mice with 4-Vinylcyclohexene Diepoxide to induce ovarian failure and 7, 12-Dimethylbenz[a]anthracene (DMBA) to induce ovarian cancer. Using optical coherence tomography (OCT) and multiphoton microscopy (MPM) we have obtained co-registered en face images of sixty-seven mouse ovaries ex vivo and forty-two ovaries in vivo. Preliminary analysis indicates that OCT and MPM can visualize ovarian microstructure. During the next year we will be completing a long term survival study using post-menopausal mice that have been treated with DMBA to induce cancer and imaged in vivo at time points before and after treatment. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
• Yan, D., McPheeters, S., Johnson, G., Utzinger, U., & P., J. (2011). Microstructural differences in the human posterior sclera as a function of age and race. Investigative Ophthalmology and Visual Science, 52(2), 821-829.
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  PMID: 21051726;PMCID: PMC3262314;Abstract: Purpose. The purpose of this study was to quantify the age and race-related differences in the microstructural organization of the human posterior sclera. Such differences may contribute to the predisposition of primary open-angle glaucoma in various high-risk populations. Methods. Posterior-temporal scleras from 75 right eyes were procured at an average distance of 35 mm from the center of the optic nerve head (ONH). A light-scattering device was used to investigate the matrix organization of posterior scleral fibers around the ONH. In addition to the degree of alignment (via eccentricity), the percentage occurrence of fiber angles within equatorial and meridionally aligned bins was quantified as a function of depth, sex, age, and race. There were 20 African Americans, 55 Caucasians, 49 males, 26 females, in this study, all falling within three age groups (60 years, n = 34). Three scleral layers, normalized for depth, were examined. Results. For all ages and both races, fibers were preferentially oriented equatorially at all layers (P < 0.001). The African Americans had a significantly higher percentage of occurrence of meridional fibers than did the Caucasians (P < 0.001). The percentage occurrence of meridional fibers decreased significantly from the inner to the outer layers of the posterior sclera (P < 0.001). Conclusions. Statistically significant microstructural differences were found in the posterior sclera between African American and Caucasian donors. Ongoing work is focused on identifying whether such microstructural differences play a role in the higher prevalence of glaucoma in African American populations. © 2011 The Association for Research in Vision and Ophthalmology, Inc.
• Edgar, L. T., Guilkey, J. E., Underwood, C. J., Baggett, B., Utzinger, U., & Weiss, J. A. (2010). Three-dimensional simulation of in vitro angiogenesis: Effects of extracellular matrix structure and density. ASME 2010 Summer Bioengineering Conference, SBC 2010, 931-932.
• Utzinger, U., & Richards-Kortum, R. R. (2010). Fibre Optic Probes in Optical Spectroscopy, Clinical Applications. Encyclopedia of Spectroscopy and Spectrometry, 573-588.
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  Abstract: In the clinical environment, optical techniques have been used for decades (microscope, colposcope, ophthalmoscope, endoscope, laparascope). Integration of spectroscopic devices into existing procedures is an obvious task. Fibre optic cables provide a flexible solution for adequate optical interfacing between the optical and spectroscopic device and the sample to be interrogated in situ. This article outlines fibre optic solutions for fluorescence and both elastic and inelastic scattering detection. After describing the fibre optic interface, probes for fluorescence spectroscopy followed by probes for reflectance measurements and side looking are presented. Finally, diffuser tips, refocusing and designs for Raman spectroscopy are discussed. © 1999 Elsevier Ltd All rights reserved.
• Krishnan, L., Utzinger, U., Maas, S., Reese, S., Weiss, J. A., Williams, S. K., & Hoying, J. B. (2009). Extracellular matrix stiffness modulates microvascular morphology during early sprouting angiogenesis in vitro. Proceedings of the ASME Summer Bioengineering Conference 2009, SBC2009, 1289-1290.
• Black, K. C., Kirkpatrick, N. D., Troutman, T. S., Liping, X. u., Vagner, J., Gillies, R. J., Barton, J. K., Utzinger, U., & Romanowski, M. (2008). Gold nanorods targeted to delta opioid receptor: Plasmon-resonant contrast and photothermal agents. Molecular Imaging, 7(1), 50-57.
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  PMID: 18384724;Abstract: Molecularly targeted gold nanorods were investigated for applications in both diagnostic imaging and disease treatment with cellular resolution. The nanorods were tested in two genetically engineered cell lines derived from the human colon carcinoma HCT-116, a model for studying ligand-receptor interactions. One of these lines was modified to express delta opioid receptor (δOR) and green fluorescent protein, whereas the other was receptor free and expressed a red fluorescent protein, to serve as the control. Deltorphin, a high-affinity ligand for δOR, was stably attached to the gold nanorods through a thiol-terminated linker. In a mixed population of cells, we demonstrated selective imaging and destruction of receptor-expressing cells while sparing those cells that did not express the receptor. The molecularly targeted nanorods can be used as an in vitro ligand-binding and cytotoxic treatment assay platform and could potentially be applied in vivo for diagnostic and therapeutic purposes with endoscopic technology. © 2008 BC Decker Inc.
• Udovich, J. A., Kirkpatrick, N. D., Kano, A., Tanbakuchi, A., Utzinger, U., & Gmitro, A. F. (2008). Spectral background and transmission characteristics of fiber optic imaging bundles. Applied Optics, 47(25), 4560-4568.
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  PMID: 18758526;Abstract: The emission and transmission properties of three commercially produced coherent fiber optic imaging bundles were evaluated. Full fluorescence excitation versus emission data were collected from 250 to 650 nm excitation for high-resolution Sumitomo, Fujikura, and Schott fiber bundles. The results generated show regions of autofluorescence and inelastic Raman scattering in the imaging bundles that represent a wavelength-dependent background signal when these fibers are used for imaging applications. The high-resolution fiber bundles also exhibit significant variation in transmission with the angle of illumination, which affects the overall coupling and transmission efficiency. Knowledge of these properties allows users of high-resolution imaging bundles to optimally design systems that utilize such bundles. ©2008 Optical Society of America.
• Hariri, L. P., Tumlinson, A. R., Wade, N. H., Besselsen, D. G., Utzinger, U., Gerner, E. W., & Barton, J. K. (2007). Ex vivo optical coherence tomography and laser-induced fluorescence spectroscopy imaging of murine gastrointestinal tract. Comparative Medicine, 57(2), 175-185.
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  PMID: 17536618;Abstract: Optical coherence tomography (OCT) and laser-induced fluorescence (LIF) spectroscopy each have clinical potential in identifying human gastrointestinal (GI) pathologies, yet their diagnostic capability in mouse models is unknown. In this study, we combined the 2 modalities to survey the GI tract of a variety of mouse strains and ages and to sample dysplasias and inflammatory bowel disease (IBD) of the intestines. Segments (length, 2.5 cm) of duodenum and lower colon and the entire esophagus were imaged ex-vivo with combined OCT and LIF. We evaluated 30 normal mice (A/J and 10- and 21-wk-old and retired breeder C57BL/6J) and 10 mice each of 2 strains modeling colon cancer and IBD (Apc Min and IL2-deficient mice, respectively). Histology was used to classify tissue regions as normal, Peyer patch, dysplasia, adenoma, or IBD. Features in corresponding OCT images were analyzed. Spectra from each category were averaged and compared via Student t tests. OCT provided structural information that led to identification of the imaging characteristics of healthy mouse GI. With histology as the 'gold standard,' we developed preliminary image criteria for early disease in the form of adenomas, dysplasias, and IBD. LIF characterized the endogenous fluorescence of mouse GI tract, with spectral features corresponding to collagen, NADH, and hemoglobin. In the IBD sample, LIF emission spectra displayed potentially diagnostic peaks at 635 and 670 nm, which we attributed to increased porphyrin production by bacteria associated with IBD. OCT and LIF appear to be useful and complementary modalities for ex vivo imaging of mouse GI tissues. Copyright 2007 by the American Association for Laboratory Animal Science.
• Kirkpatrick, N. D., Brewer, M. A., & Utzinger, U. (2007). Endogenous optical biomarkers of ovarian cancer evaluated with multiphoton microscopy. Cancer Epidemiology Biomarkers and Prevention, 16(10), 2048-2057.
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  PMID: 17932352;Abstract: Purpose: Among gynecologic cancers, ovarian cancer is the second most common and has the highest mortality. Currently, there is no accurate early diagnostic technique for ovarian cancer. Furthermore, little is understood regarding the early progression of this disease. We have imaged multiphoton interactions of endogenous tissue constituents from normal and abnormal ovarian biopsies that were kept viable during transport from the operating room and microscopy. Experimental Design: The ovarian surface and underlying stroma were assessed with two-photon excited fluorescence (2PEF) and second harmonic generation (SHG). High-resolution, optically sectioned images were analyzed for epithelial morphology based on 2PEF and collagen density and structural integrity based on SHG. Additionally, multiwavelength 2PEF provided an estimation of the cellular redox ratio of epithelial cells. Results: Normal tissue exhibited a uniform epithelial layer with highly structured collagen in the stroma, whereas abnormal tissue exhibited varied epithelium with large cells and substantial quantitative changes to the collagen structure. Samples from patients at high risk for developing ovarian cancer (based on their personal/family history of cancer) exhibited highly variable cellular redox ratios and changes in collagen structure that trended toward cancer samples. Conclusion: This study highlights differences in endogenous signals in viable ovarian biopsies based on quantitative collagen structural changes and redox ratio estimates that may lead to improved detection and further insights in ovarian cancer, particularly in the early stages of the disease. Copyright © 2007 American Association for Cancer Research.
• Utzinger, U., Kirkpatrick, N. D., Andreou, S., Hoying, J. B., & Utzinger, U. -. (2007). Live imaging of collagen remodeling during angiogenesis. American journal of physiology. Heart and circulatory physiology, 292(6).
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  To better understand interstitial matrix remodeling during angiogenesis, we probed endogenous optical signatures of collagen fibrils and cells with multiphoton microscopy to noninvasively visualize, in real-time, changes to fibril organization around angiogenic sprouts and growing neovessels. From analyses of the second-harmonic generation signal from fibrillar collagen and two-photon excited fluorescence, as well as coherent transmitted light from vascular cells, we found that microvessel fragments interacting with the collagen matrix exhibited two key features: a strong association of fibrillar collagen around the parent vessel fragment during vessel construct reconstitution and a substantial collagen fibril reorganization by sprout and neovessel tips. Results indicate that angiogenic sprouts and growing neovessels actively and differentially remodel existing collagen fibrils. This imaging approach to assess local changes in matrix organization may have a broader impact on tissue biology and mechanics during angiogenesis and allow for new insights in cardiovascular, diabetes, and cancer research.
• Brewer, M., Kirkpatrick, N. D., Wharton, J. T., Wang, J., Hatch, K., Auersperg, N., Utzinger, U., Gershenson, D., Bast, R., & Zou, C. (2006). 4-HPR modulates gene expression in ovarian cells. International Journal of Cancer, 119(5), 1005-1013.
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  PMID: 16570282;Abstract: Ovarian cancer has a high rate of recurrence and subsequent mortality following chemotherapy despite intense efforts to improve treatment outcomes. Recent trials have suggested that retinoids, especially 4-(N-hydroxyphenyl) retinamide (4-HPR), play an important role as a chemopreventive agent and are currently being used in clinical trials for ovarian cancer chemoprevention as well as treatment. This study examines the mechanism of its activity in premalignant and cancer cells. We investigated the modulation of gene expression by 4-HPR in immortalized ovarian surface epithelial (IOSE) cells and ovarian cancer (OVCA433) cells with DNA microarray. Real time RT-PCR and western blotting were used to confirm the microarray results and metabolic changes were examined with optical fluorescence spectroscopy. 4-HPR resulted in an up-regulation of expression of proapoptotic genes and mitochondrial uncoupling protein in OVCA433 cells and modulation of the RXR receptors in IOSE cells, and down-regulation of mutant BRCA genes in both IOSE and OVCA433 cells. 4-HPR had a larger effect on the redox in the 433 cells compared to IOSE. These findings suggest that 4-HPR acts through different mechanisms in premalignant ovarian surface cells and cancer cells, with a preventive effect in premalignant cells and a treatment effect in cancer cells. © 2006 Wiley-Liss, Inc.
• Hariri, L. P., Tumlinson, A. R., Besselsen, D. G., Utzinger, U., Gerner, E. W., & Barton, J. K. (2006). Endoscopic optical coherence tomography and laser-induced fluorescence spectroscopy in a murine colon cancer model. Lasers in Surgery and Medicine, 38(4), 305-313.
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  PMID: 16596657;Abstract: Background and Objectives: The diagnostic feasibility of optical coherence tomography (OCT) and laser-induced fluorescence (LIF) have been evaluated for human colorectal cancer. This study applies these technologies to a murine model of colorectal adenoma. Study Design/Materials and Methods: The lower colon of 10 ApcMin and two C57BL/6J mice was surveyed over five 4-week intervals using a prototype 2.0 mm diameter OCT-LIF endoscope-based system. Four categories were histologically classified: control C57BL/6J, adenomatous, non-diseased regions of adenomatous, and non-diseased ApcMin. OCT images were compared to histology. Spectra from the four categories were compared via the Student's t-test. Results: Three ApcMin and two control mice completed the study. One adenoma was histologically identified; OCT visualized mucosal thickening/abnormal mass development over the imaging timepoints. LIF spectral comparisons revealed decreased 405 nm intensity and the presence of a peak at 680 nm in the adenomatous ApcMin. Conclusions: These preliminary data indicate endoscopic OCT-LIF has the potential to identify colorectal adenomas in murine models. © 2006 Wiley-Liss, Inc.
• Kirkpatrick, N. D., Hoying, J. B., Botting, S. K., Weiss, J. A., & Utzinger, U. (2006). In vitro model for endogenous optical signatures of collagen. Journal of Biomedical Optics, 11(5).
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  PMID: 17092170;Abstract: Type I collagen is a major component of the extracellular matrix as well as many tissue engineered models. To understand changes in collagen related models over time, it is important to evaluate collagen dynamics with noninvasive techniques. Fluorescence spectroscopy provides a method to noninvasively measure endogenous collagen fluorescence. Additionally, second harmonic generation (SHG) imaging of collagen produces high resolution images of the fibrils. In this study, a novel in vitro collagen measurement chamber was developed for measurement in standard spectroscopic cuvette chambers and microscopic imaging. The fluorescence of polymerized collagen was found to be highly variable, primarily depending on incubation time after polymerization. Changes in fluorescence over time were consistent with increases at UVA excitation wavelengths (λex=360 nm) and decreases at UVC excitation wavelengths (λex = 270 nm), suggesting changes in nonenzymatic association of the collagen fibrils. SHG imaging of the collagen suggested that a stable network formed during polymerization. Unlike the fluorescence emission, SHG images from the gels varied little with time suggesting that SHG is not as sensitive to cross-linking or fibril-fibril associated changes. The developed measurement system will allow further studies on the effect of enzymatic cleavages and structural alterations on collagen fluorescence and SHG. © 2006 Society of Photo-Optical Instrumentation Engineers.
• McNally, J. B., Kirkpatrick, N. D., Hariri, L. P., Tumlinson, A. R., Besselsen, D. G., Gerner, E. W., Utzinger, U., & Barton, J. K. (2006). Task-based imaging of colon cancer in theApc^Min/+ mouse model. Applied Optics, 45(13), 3049-3062.
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  PMID: 16639453;Abstract: Optical coherence tomography (OCT), laser-induced fluorescence (LIF), and laser-scanning confocal microscopy (LSCM) were used for the task of multimodal study of healthy and adenomatous mouse colon. The results from each modality were compared with histology, which served as the gold standard. The Apc Min/+ genetic mouse model of colon cancer was compared with wild-type mice. In addition, a special diet was used for the task of studying the origins of a 680 nm autofluorescent signal that was previously observed in colon. The study found close agreement among each of the modalities and with histology. All four modalities were capable of identifying diseased tissue accurately. The OCT and LSCM images provided complementary structural information about the tissue, while the autofluorescence signal measured by LIF and LSCM provided biochemical information. OCT and LIF were performed in vivo and nondestructively, while the LSCM and histology required extraction of the tissue. The magnitude of the 680 nm signal correlates with chlorophyll content in the mouse diet, suggesting that the autofluorescent compound is a dietary metabolite. © 2006 Optical Society of America.
• Sun, J., Kun, F. u., Wang, A., W., A., Utzinger, U., & Drezek, R. (2006). Influence of fiber optic probe geometry on the applicability of inverse models of tissue reflectance spectroscopy: Computational models and experimental measurements. Applied Optics, 45(31), 8152-8162.
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  PMID: 17068558;Abstract: Accurate recovery of tissue optical properties from in vivo spectral measurements is crucial for improving the clinical utility of optical spectroscopic techniques. The performance of inversion algorithms can be optimized for the specific fiber optic probe illumination-collection geometry. A diffusion-theory-based inversion method has been developed for the extraction of tissue optical properties from the shape of normalized tissue diffusion reflectance spectra, specifically tuned for a fiber probe that comprises seven hexagonally close-packed fibers. The central fiber of the probe goes to the spectrometer as the detecting fiber, and the surrounding six outer fibers are connected to the white-light source as illumination fibers. The accuracy of the diffusion-based inversion algorithm has been systematically assessed against Monte Carlo (MC) simulation as a function of probe geometry and tissue optical property combinations. By use of this algorithm, the spectral absorption and scattering coefficients of normal and cancerous tissue are efficiently retrieved. Although there are significant differences between the diffusion approximation and the MC simulation at short source-detector (SD) separations, we show that with our algorithm the tissue optical properties are well retrieved within the SD separation of 0.5-3 mm that is compatible with endoscopie specifications. The presented inversion method is computationally efficient for eventual real-time in vivo tissue diagnostics application. © 2006 Optical Society of America.
• Hariri, L., Tumlinson, A. R., Wade, N., Besselsen, D., Utzinger, U., Gerner, E., & Barton, J. (2005). Ex vivo optical coherence tomography and laser induced fluorescence spectroscopy imaging of murine gastrointestinal tract. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 5692, 295-306.
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  Abstract: Optical Coherence Tomography (OCT) and Laser Induced Fluorescence Spectroscopy (LIF) have separately been found to have clinical potential in identifying human gastrointestinal (GI) pathologies, yet their diagnostic capability in mouse models of human disease is unknown. We combine the two modalities to survey the GI tract of a variety of mouse strains and sample dysplasias and inflammatory bowel disease (IBD) of the small and large intestine. Segments of duodenum and lower colon 2.5 cm in length and the entire esophagus from 10 mice each of two colon cancer models (ApcMin and AOM treated A/J) and two IBD models (Il-2 and Il-10) and 5 mice each of their respective controls were excised. OCT images and LIF spectra were obtained simultaneously from each tissue sample within 1 hour of extraction. Histology was used to classify tissue regions as normal, Peyer's patch, dysplasia, adenoma, or IBD. Features in corresponding regions of OCT images were analyzed. Spectra from each of these categories were averaged and compared via the student's t-test. Features in OCT images correlated to histology in both normal and diseased tissue samples. In the diseased samples, OCT was able to identify early stages of mild colitis and dysplasia. In the sample of IBD, the LIF spectra displayed unique peaks at 635nm and 670nm, which were attributed to increased porphyrin production in the proliferating bacteria of the disease. These peaks have the potential to act as a diagnostic for IBD. OCT and LIF appear to be useful and complementary modalities for imaging mouse models.
• Hsu, K. M., Brewer, M. A., Utzinger, U., & Drezek, R. A. (2005). Biophysical modeling to extract tissue properties from fluorescence spectra. Proceedings of the 2005 Summer Bioengineering Conference, 2005, 1214-1215.
• Kirkpatrick, N. D., Brands, W. R., Zou, C., Brewer, M. A., & Utzinger, U. (2005). Intrinsic fluorescence biomarkers in cells treated with chemopreventive drugs. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 5699, 255-262.
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  Abstract: Non-invasive monitoring of cellular metabolism offers promising insights into areas ranging from biomarkers for drug activity to cancer diagnosis. Fluorescence spectroscopy can be utilized in order to exploit endogenous fluorophores, typically metabolic co-factors nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), and estimate the redox status of the sample. Fluorescence spectroscopy was applied to follow metabolic changes in epithelial ovarian cells as well as bladder epithelial cancer cells during treatment with a chemopreventive drug that initiates cellular quiescence. Fluorescence signals consistent with NADH, FAD, and tryptophan were measured to monitor cellular activity, redox status, and protein content. Cells were treated with varying concentrations of N-4-(hydroxyphenyl) retinamide (4-HPR) and measured in a stable environment with a sensitive fluorescence spectrometer. A subset of measurements was completed on a low concentration of cells to demonstrate feasibility for medical application such as in bladder or ovary washes. Results suggest that all of the cells responded with similar dose dependence but started at different estimated redox ratio baseline levels correlating with cell cycle, growth inhibition, and apoptosis assays. NADH and tryptophan related fluorescence changed significantly while FAD related fluorescence remained unaltered. Fluorescence data collected from approximately 1000 - 2000 cells, comparable to a bladder or ovary wash, was measurable and useful for future experiments. This study suggests that future intrinsic biomarker measurements may need to be most sensitive to changes in NADH and tryptophan related fluorescence while using FAD related fluorescence to help estimate the baseline redox ratio and predict response to chemopreventive agents.
• Kirkpatrick, N. D., Brewer, M. A., & Utzinger, U. (2005). Multiphoton imaging of an in vitro ovarian tissue model. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 5860, 1-8.
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  Abstract: In order to understand the distribution of endogenous fluorescence in the ovary, ovarian biopsies were maintained with a viable tissue imaging system and characterized with multiphoton imaging. It was imperative to maintain a stable in vitro environment so that tissue images could provide accurate correlative data for in vivo spectroscopic measurements. Evaluating tissue viability in real time poses a difficult task given that viability assays are tailored for cell culture. The focus of this study was to design a robust in vitro imaging chamber for assessment of ovarian autofluorescence and simple, reliable viability assays for tissue status monitoring. © 2005 SPIE and OSA.
• Kirkpatrick, N. D., Zou, C., Brewer, M. A., Brands, W. R., Drezek, R. A., & Utzinger, U. (2005). Endogenous fluorescence spectroscopy of cell suspensions for chemopreventive drug monitoring. Photochemistry and Photobiology, 81(1), 125-134.
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  PMID: 15535738;Abstract: Cancer chemopreventive agents such as N-4-(hydroxyphenyl)-retinamide (4HPR) are thought to prevent cancers by suppressing growth or inducing apoptosis in precancerous cells. Mechanisms by which these drugs affect cells are often not known, and the means to monitor their effects is not available. In this study endogenous fluorescence spectroscopy was used to measure metabolic changes in response to treatment with 4HFR in ovarian and bladder cancer cell lines. Fluorescence signals consistent with nicotinamide adenine dinucleotide (NADH), flavin adenine dinucleotide (FAD) and tryptophan were measured to monitor cellular activity through redox status and protein content. Cells were treated with varying concentrations of 4HPR and measured in a stable environment with a sensitive fluorescence spectrometer. Results suggest that redox signal of all cells changed in a similar dose-dependant manner but started at different baseline levels. Redox signal changes depended primarily on changes consistent with NADH fluorescence, whereas the FAD fluorescence remained relatively constant. Similarly, tryptophan fluorescence decreased with increased drug treatment, suggesting a decrease in protein production. Given that each cell line has been shown to have a different apoptotic response to 4HPR, fluorescence redox values along with changes in tryptophan fluorescence may be a response as well as an endpoint marker for chemopreventive drugs. © 2005 American Society for Photobiology.
• Ming, A., Bender, J. E., Pfefer, J., Utzinger, U., & Drezek, R. A. (2005). Depth-sensitive reflectance measurements using obliquely oriented fiber probes. Journal of Biomedical Optics, 10(4).
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  PMID: 16178650;Abstract: Computer simulation is used to facilitate the design of fiberprobe geometries that enable enhanced detection of optical signals, arising from specific tissue depths. Obtaining understanding of the relationship between fiber-probe design and tissue interrogation is critical when developing strategies for optical detection of epithelial precancers that originate at known depths from the tissue surface. The accuracy of spectroscopic diagnostics may be enhanced by discretely probing the optical properties of epithelium and underlying stroma, within which the morphological and biochemical features vary as a function of depth. While previous studies have investigated controlling tissue-probing depth for fluorescence-based modalities, in this study we focus on the detection of reflected light scattered by tissue. We investigate how the depth of optical interrogation may be controlled through combinations of collection angles, source-detector separations, and numerical apertures. We find that increasing the obliquity of collection fibers at a given source-detector separation can effectively enhance the detection of superficially scattered signals. Fiber numerical aperture provides additional depth selectivity; however, the perturbations in sampling depth achieved through this means are modest relative to the changes generated by modifying the angle of collection and source-detection separation. © 2005 Society of Photo-Optical Instrumentation Engineers.
• Utzinger, U., Kirkpatrick, N. D., Drezek, R. A., & Brewer, M. A. (2005). Endogenous fluorescence emission of the ovary. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 5702, 92-96.
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  Abstract: Epithelial ovarian cancer has the highest mortality rate among the gynecologic cancers. Early detection would significantly improve survival and quality of life of women at increased risk to develop ovarian cancer. We have constructed a device to investigate endogenous signals of the ovarian tissue surface in the UV C to visible range and describe our initial investigation of the use of optical spectroscopy to characterize the condition of the ovary. We have acquired data from more than 33 patients. A table top spectroscopy system was used to collect endogenous fluorescence with a fiberoptic probe that is compatible with endoscopic techniques. Samples were broken into five groups: Normal-Low Risk (for developing ovarian cancer) Normal-High Risk, Benign, and Cancer. Rigorous statistical analysis was applied to the data using variance tests for direct intensity versus diagnostic group comparisons and principal component analysis (PCA) to study the variance of the whole data set. We conclude that the diagnostically most useful excitation wavelengths are located in the UV. Furthermore, our results indicate that UV B and C are most useful. A safety analysis indicates that UV-C imaging can be conducted at exposure levels below safety thresholds. We found that fluorescence excited in the UV-C and UV-B range increases from benign to normal to cancerous tissues. This is in contrast to the emission created with UV-A excitation which decreased in the same order. We hypothesize that an increase of protein production and a decrease of fluorescence contributions of the extracellular matrix could explain this behavior. Variance analysis also identified fluctuation of fluorescence at 320/380 which is associated with collagen cross link residues. Small differences were observed between the group at high risk and normal risk for ovarian cancer. High risk samples deviated towards the cancer group and low risk samples towards benign group.
• Wang, A., Bender, J., Pfefer, J., Utzinger, U., & Drezek, R. (2005). Depth-sensitive reflectance measurements using obliquely oriented fiber probes. Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 5691, 54-65.
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  Abstract: Computer simulation was used to facilitate the design of fiber-probe geometries which enable enhanced detection of optical signals arising from specific tissue depths. Obtaining understanding of the relationship between fiber-probe design and tissue interrogation is critical when developing strategies for optical detection of epithelial pre-cancers which originate at known depths from the tissue surface. We investigated how the depth of optical interrogation may be controlled through combinations of collection angles, source-detector separations and numerical apertures. We found that increasing the obliquity of collection fibers at a given source-detector separation can effectively enhance the detection of superficially scattered signals. Fiber numerical aperture provides additional depth selectivity; however, the perturbations in sampling depth achieved through this means are modest relative to the changes generated by modifying the angle of collection and source-detection separation.
• Brewer, M. A., Utzinger, U., Barton, J. K., Hoying, J. B., Kirkpatrick, N. D., Brands, W. R., Davis, J. R., Hunt, K., Stevens, S. J., & Gmitro, A. F. (2004). Imaging of the ovary. Technology in Cancer Research and Treatment, 3(6), 617-627.
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  PMID: 15560720;Abstract: Epithelial ovarian cancer has the highest mortality rate among the gynecologic cancers and spreads beyond the ovary in 90% of the women diagnosed with ovarian cancer. Detection before the disease has spread beyond the ovary would significantly improve the survival from ovarian cancer, which is currently only 30% over 5 years, despite extensive efforts to improve the survival. This study describes initial investigation of the use of optical technologies to improve the outcome for this disease by detecting cancers at an earlier and more treatable stage. Women undergoing oophorectomy were recruited for this study. Ovaries were harvested for fluorescence spectroscopy, confocal microscopy, and optical coherence tomography. Fluorescence spectroscopy showed large diagnostic differences between normal and abnormal tissue at 270 and 340 nm excitation. Optical coherence tomography was able to image up to 2mm deep into the ovary with particular patterns of backscattered intensity observed in normal versus abnormal tissue. Fluorescence confocal microscopy was able to visualize sub-cellular structures of the surface epithelium and underlying cell layers. Optical imaging and/or spectroscopy has the potential to improve the diagnostic capability in the ovary, but extended systematic investigations are needed to identify the unique signatures of disease. The combination of optical technologies supported by modern molecular biology may lead to an instrument that can accurately detect early carcinogenesis.
• Tumlinson, A. R., Hariri, L. P., Utzinger, U., & Barton, J. K. (2004). Miniature endoscope for simultaneous optical coherence tomography and laser-induced fluorescence measurement. Applied Optics, 43(1), 113-121.
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  PMID: 14714651;Abstract: We have designed a multimodality system that combines optical coherence tomography (OCT) and laser-induced fluorescence (LIF) in a 2.0-mm-diameter endoscopic package. OCT provides ∼18-μm resolution cross-sectional structural information over a 6-mm field. LIF spectra are collected sequentially at submillimeter resolution across the same field and provide histochemical information about the tissue. We present the use of a rod prism to reduce the asymmetry in the OCT beam caused by a cylindrical window. The endoscope has been applied to investigate mouse colon cancer in vivo.
• Brookner, C., Utzinger, U., Follen, M., Richards-Kortum, R., Cox, D., & Atkinson, E. N. (2003). Effects of biographical variables on cervical fluorescence emission spectra. Journal of Biomedical Optics, 8(3), 479-483.
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  PMID: 12880354;Abstract: Diagnostic algorithms can classify tissue samples as diseased or nondiseased based on fluorescence emission collected from the intact cervix. Such algorithms can distinguish high-grade squamous intraepithelial lesions from low-grade squamous intraepithelial lesions. An understanding of the effects of the values of biographical covariates, such as age, race, smoking, or menopausal status on the emission spectra for each patient could improve diagnostic efficiency. The analysis described was performed using data collected from two previously published clinical trials; one study measured spectra from 395 sites in 95 patients referred to a colposcopy clinic with abnormal Pap smears, and the second study measured spectra from 204 sites in 54 patients self-referred for screening and expected to have a normal Pap smear. For this analysis, data about age, race, menstrual cycle, and smoking were collected. The principal components from normalized data were compared. There are clear intensity differences observed with age and menopausal status; postmenopausal patients exhibit higher emission intensities. Differences associated with biographical variables need to be tested in larger studies, which stratify adequately for these variables. The addition of these biographical variables in the preprocessing of data could dramatically improve algorithm performance and applicability. ©2003 Society of Photo-Optical Instrumentation Engineers.
• Cox, D. D., Chang, S. K., Dawood, M. Y., Staerkel, G., Utzinger, U., Richards-Kortum, R. R., & Follen, M. (2003). Detecting the signal of the menstrual cycle in fluorescence spectroscopy of the cervix. Applied Spectroscopy, 57(1), 67-72.
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  PMID: 14610938;Abstract: Fluorescence spectroscopy of the cervix has been shown to be an effective noninvasive diagnostic tool for cervical intraepithelial neoplasia (precancer). To assess the effect of the menstrual cycle on fluorescence spectroscopy, daily measurements were made on ten subjects for the length of their cycle. These measurements were analyzed to determine if there was a statistically significant signal associated with the menstrual cycle. A signal was found for emission wavelengths between 425 and 445 nm inclusive-near the main hemoglobin absorption band, the Soret band, at 420 nm. We suspect that the slight displacement of the Soret band is due to the nearby dominant NAD(P)H peak, which increases the signal-to-noise ratio and affects statistical significance. The signal consists of a reduction in fluorescence intensity for the first few days of the cycle. This analysis indicates that hemoglobin absorption is the main menstrualcycle effect on the use of fluorescence spectroscopy on the cervix. The effect is confined to a small set of excitation/emission wavelengths and to approximately the first 8 days of the cycle. This suggests that any problems from the menstrual cycle can be avoided with a simple requirement that the device not be used during the period of menstrual bleeding.
• Utzinger, U., & Richards-Kortum, R. R. (2003). Fiber optic probes for biomedical optical spectroscopy. Journal of Biomedical Optics, 8(1), 121-147.
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  PMID: 12542388;Abstract: Fiber optic probes are a key element for biomedical spectroscopic sensing. We review the use of fiber optic probes for optical spectroscopy, focusing on applications in turbid media, such as tissue. The design of probes for reflectance, polarized reflectance, fluorescence, and Raman spectroscopy is illustrated. We cover universal design principles as well as technologies for beam deflecting and reshaping.
• Utzinger, U., Bueeler, M., Sanghoon, O. h., Heintzelman, D. L., Svistun, E. S., Abd-El-Barr, M., Gillenwater, A., & Richards-Kortum, R. (2003). Optimal visual perception and detection of oral cavity neoplasia. IEEE Transactions on Biomedical Engineering, 50(3), 396-399.
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  PMID: 12669997;Abstract: The most common way to detect disease is by visual inspection of the suspect tissue. However, the human eye is not optimized for this task because the perceived spectrum of light is divided into three channels, all of which have overlapping spectral sensitivity curves. Here, we present new methods to optimize visually perceived contrast based on spectral differences between normal and abnormal tissue. We apply these methods to the perception of fluorescence emission from the oral cavity. Abnormalities in the oral cavity are optimally perceived when the excitation is between 420-440 nm. To optimally visualize fluorescence at 340-nm excitation, the emission should be observed through a blue bandpass filter transmitting light at 430 nm.
• Brewer, M., Utzinger, U., Yang, L. i., Atkinson, E. N., Satterfield, W., Auersperg, N., Richards-Kortum, R., Follen, M., & Bast, R. (2002). Fluorescence spectroscopy as a biomarker in a cell culture and in a nonhuman primate model for ovarian cancer chemopreventive agents. Journal of Biomedical Optics, 7(1), 20-26.
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  PMID: 11818008;Abstract: Objective: The objective of this study was to compare the effects of chemopreventive agents on natural fluorescence emission of ovarian cells in a cell culture and in a primate model as a feasibility trial to monitor drug activity. Methods: Fluorescence emission spectra were collected from normal (NOE) and immortalized ovarian surface epithelial cells at 290, 360, and 450 nm excitation. Redox potentials were calculated and compared to % apoptosis and cell survival. Fluorescence emission spectra were collected from 18 female rhesus macaques receiving fenretinide [N-(-hydroxyphenyl)retinamide (4-HPR)] orally and/or oral contraceptive pills (OCP) or no medication. Fluorescence intensities and redox ratios were compared using a two-tailed Student's t test. Results: Apoptosis and cell survival correlated with fluorescence emission consistent with metabolically active proteins [flavin adenine dinucleotide (FAD) and nicotinamide adenine dinucleotide (NAD(P)H)] and the resulting redox ratio in cells grown with 4-HPR. The 4-HPR consistently inhibited cell survival in a dose dependent manner. Degree of correlation varied between different cell lines. In primates receiving 4-HPR, fluorescence emission was increased at 450 nm excitation, 550 nm emission consistent with FAD presence, whereas those receiving OCP showed decreased emission at 350 nm excitation, 450 nm emission consistent with decreased NAD(P)H presence. Redox ratios were increased by both drugs. Conclusions: Fluorescence intensity and redox ratio appear to be altered by 4-HPR treatment in vivo and in cell culture and by OCP in vivo. Fluorescence intensity may be useful to monitor chemopreventive agents in clinical trials. © 2002 Society of Photo-Optical Instrumentation Engineers.
• Chang, S. K., Dawood, M. Y., Staerkel, G., Utzinger, U., Atkinson, E. N., Richards-Kortum, R. R., & Follen, M. (2002). Fluorescence spectroscopy for cervical precancer detection: Is there variance across the menstrual cycle?. Journal of Biomedical Optics, 7(4), 595-602.
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  PMID: 12421126;Abstract: This study assesses one possible cause of inter-patient variation in fluorescence spectroscopy of the cervix: the menstrual cycle. Ten patients with no history of an abnormal Pap smear were seen daily throughout 30 consecutive days of their cycle. Fluorescence excitation-emission matrices were measured from three cervical sites on each patient. Principal component analysis was used to determine which spectral regions varied with the day of the cycle. Classification was performed to assess the influence of menstrual cycle on precancer diagnosis. Variations in the principal component scores and the redox ratio values show that the fluorescence emission spectra at 340-380 nm excitation appear to correlate with the cell metabolism of the cervical epithelium throughout the menstrual cycle; these changes do not affect diagnostic classification. The menstrual cycle affects intra-patient variation but does not appear to cause a significant level of inter-patient variation. It does not need to be controlled for in optical detection strategies based on fluorescence spectroscopy. © 2002 Society of Photo-Optical Instrumentation Engineers.
• Chang, S. K., Follen, M., Malpica, A., Utzinger, U., Staerkel, G., Cox, D., Atkinson, E. N., MacAulay, C., & Richards-Kortum, R. (2002). Optimal excitation wavelengths for discrimination of cervical neoplasia. IEEE Transactions on Biomedical Engineering, 49(10), 1102-1111.
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  PMID: 12374334;Abstract: Fluorescence spectroscopy has shown promise for the in vivo, real-time detection of cervical neoplasia. However, selection of excitation wavelength has in the past been based on in vitro studies and the availability of light sources. The goal of this study was to determine optimal excitation wavelengths for in vivo detection of cervical neoplasia. Fluorescence excitation-emission matrices (EEMs) were measured in vivo from 351 sites in 146 patients. Data were analyzed in pairs of diagnostic classes to determine which combination of excitation wavelengths yields classification algorithms with the greatest sensitivity and specificity. We find that 330-340-, 350-380-, and 400-450-nm excitation yield the best performance. The sensitivity and specificity for discrimination of squamous normal tissue and high-grade squamous intraepithelial lesion (HGSIL) were 71% and 77% on cross validation using three excitation wavelengths. These results are comparable with those found in earlier in vivo studies; however, in this study we find that the proportion of samples which are HGSIL influences performance. Furthermore stratification of samples within low-grade squamous intraepithelial lesion and HGSIL also appears to influence diagnostic performance. Future diagnostic studies should be carried out at these excitation wavelengths in larger groups so that data can be stratified by diagnostic subcategory, age and menopausal status. Similarly, large studies should be done in screening populations.
• MacAulay, C., Richards-Kortum, R., Utzinger, U., Fedyk, A., Atkinson, E. N., Cox, D., & Follen, M. (2002). Variation of fluorescence spectroscopy during the menstrual cycle. Optics Express, 10(12), 493-504.
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  PMID: 19436387;Abstract: Cervical autofluorescence has been demonstrated to have potential for real-time diagnosis. Inter-patient and intra-patient variations in fluorescence intensity have been measured. Inter-patient measurements may vary by a factor of ten, while intra-patient measurements may vary by a factor of two. Age and menopausal status have been demonstrated to account for some of the variations, while race and smoking have not. In order to explore in detail the role of the menstrual cycle in intra-patient variation, a study was designed to measure fluorescence excitation emission matrices (EEMs) in patients daily throughout one cycle. Ten patients with a history of normal menstrual cycles and normal Papanicolaou smears underwent daily measurements of fluorescence EEMs from three colposcopically normal sites throughout one menstrual cycle. Changes in signals from porphyrin, NADH, and FAD fluorescence and blood absorption were noted when the data was viewed in a graphical format. Visually interpreted features of the EEMs in this graphical format did not appear to correlate with the day of the menstrual cycle with the exception that blood absorption features were more prominent during the menstrual phase (during which bleeding occurs), suggesting that measurements during the menstrual phase should be avoided. Variations in cycle date likely do not account for inter- or intra-patient variations. © 2002 Optical Society of America.
• Myakov, A., Nieman, L., Wicky, L., Utzinger, U., Richards-Kortum, R., & Sokolov, K. (2002). Fiber optic probe for polarized reflectance spectroscopy in vivo: Design and performance. Journal of Biomedical Optics, 7(3), 388-397.
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  PMID: 12175288;Abstract: We present the design and construction of a fiber optic probe for elastic light scattering spectroscopy in vivo with polarized excitation and polarization sensitive detection. The performance of the fiber probe is evaluated using a suspension of polystyrene spheres placed atop a diffusely scattering substrate, and it demonstrates that the size-dependent characteristics of the scatterers can be extracted in the presence of a highly diffusely scattering background using a linear combination of forward and backward Mie scattering components of the scatterers. Subsequently, Mie theory calculations are performed over a broad range of diagnostically relevant parameters of nuclei-mean diameter, size distribution, and relative refractive index-to understand how the polarized reflectance measurements with the fiber probe can be used to extract morphological information about epithelial tissue. Finally, the feasibility of in vivo measurements with the fiber optic based polarization sensitive light scattering spectroscopy is demonstrated. © 2002 Society of Photo-Optical Instrumentation Engineers.
• Brewer, M., Baze, W., Hill, L., Utzinger, U., Wharton, J. T., Follen, M., Khan-Dawood, F., & Satterfield, W. (2001). Rhesus macaque model for ovarian cancer chemoprevention. Comparative Medicine, 51(5), 424-429.
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  PMID: 11924802;Abstract: Purpose: The objective of the study reported here was to explore whether a nonhuman primate model could be developed for chemoprevention of ovarian cancer. Methods: An initial feasibility trial was done with three monkeys to determine tolerance for these drugs and for acquisition of surgical ovarian biopsy specimens. In the study, 19 female adult Macacca mulatta (rhesus macaques) were given fenretinide (4HPR) oral contraceptive (OCP), the combination of 4HPR+OCP, or no medication for three months. Laparotomy was performed before and after drug administration, and ovarian biopsy specimens were obtained to evaluate the potential for this animal as a model for ovarian cancer chemoprevention, as well as evaluating fluorescence spectroscopy and other potential biomarkers for ovarian cancer prevention studies. Results: The monkeys tolerated the drugs, surgeries, and acquisition of multiple ovarian biopsy specimens with resultant minimal morbidity. On initial data analysis, fluorescence spectroscopy was the marker that appeared the most promising. Conclusions: On the basis of results of this study, this model merits further investigation. The rhesus monkey is an excellent candidate for a nonhuman primate model for ovarian cancer chemoprevention.
• Brewer, M., Utzinger, U., Satterfield, W., Hill, L., Gershenson, D., Bast, R., Wharton, J. T., Richards-Kortum, R., & Follen, M. (2001). Biomarker modulation in a nonhuman rhesus primate model for ovarian cancer chemoprevention. Cancer Epidemiology Biomarkers and Prevention, 10(8), 889-893.
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  PMID: 11489756;Abstract: Objective: The objective of this study was to explore whether a nonhuman primate model could be developed to test drugs for the prevention of ovarian cancer. Methods: Nineteen adult female Rhesus macaques were given fenretinide (4HPR), oral contraceptives (OCP), the combination (4HPR + OCP), or no medication for 3 months. Exploratory laparotomy was done pre- and postdrug to assess intermediary biomarkers of neoplastic phenotype, proliferation, response pathways, and growth-regulatory and metabolic markers. Fluorescence emission spectra were plotted for each group pre- and postdrug and means were overlaid on these plots and normalized. Fluorescence intensities were compared using the 2-tailed Student t test, (P = 0.1-0.01). Results: All monkeys tolerated drugs and surgeries without difficulty. Histochemical markers showed no significant trend. However, fluorescence spectroscopy showed increased intensity at 450 nm excitation, 550 nm emission correlating with increased FAD presence. The 4HPR group (P = 0.01) showed higher intensity than the OCP group (P = 0.05-0.07) when compared with the controls. Decreased emission was seen at 350 nm excitation, 450 nm emission correlating with decreased NAD(P)H presence. The OCP group showed the largest change (P < 0.01), and the control group showed the smallest change. Conclusions: The nonhuman primate is an excellent model to test drug effect on the ovarian surface epithelium and merits additional study. Fluorescence spectroscopy was the most sensitive marker for drug activity and the apparent increase in NAD and FAD in the 4HPR group is consistent with the effect of 4HPR observed in cell culture. The differences between the OCP and the 4HPR groups suggest a different mechanism of activity of these drugs.
• Brewer, M., Utzinger, U., Silva, E., Gershenson, D., Bast Jr., R. C., Follen, M., & Richards-Kortum, R. (2001). Fluorescence spectroscopy for in vivo characterization of ovarian tissue. Lasers in Surgery and Medicine, 29(2), 128-135.
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  PMID: 11553899;Abstract: Background and Objective: The objective of this study was to explore whether fluorescence spectroscopy signatures differed between normal variations within the ovary, benign neoplasms, and ovarian cancer. Study Design/Materials and Methods: Ovarian tissue fluorescence emission spectra were collected sequentially at 18 excitation wavelengths ranging from 330 to 500 nm from 11 patients undergoing oophorectomy and assembled into fluorescence excitation emission matrices (EEMs); biopsies corresponded to the area interrogated. Spectral areas that could differentiate normal ovary, benign neoplasms, and cancers were evaluated, using histopathology as the reference standard. Results: The most promising measurements are (1) the integrated fluorescence intensity from 400 to 430 nm excitation at 460 nm emission, and (2) the ratios of fluorescence intensities at 330 nm excitation, 385 and 500 nm emission, and at 375 and 415 nm excitation, 460 nm emission. Simple systems to visualize these optical signatures at laparoscopy could be designed. Conclusion: Fluorescence spectroscopy may have the ability to distinguish ovarian cancers from normal ovarian structures and benign neoplasms, as well as differentiate between normal variations and metaplastic structures and should be further explored as a device for the early detection of ovarian cancers. © 2001 Wiley-Liss, Inc.
• Coghlan, L., Utzinger, U., Richards-Kortum, R., Brookner, C., Zuluaga, A., Gimenez-Conti, I., & Follen, M. (2001). Fluorescence spectroscopy of epithelial tissue throughout the dysplasia-carcinoma sequence in an animal model: Spectroscopic changes precede morphologic changes. Lasers in Surgery and Medicine, 29(1), 1-10.
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  PMID: 11500855;Abstract: Background and Objective: The hamster cheek pouch carcinogenesis model, using chronic treatments of dimethylbenz[α]anthracene (DMBA) was used as a model system to investigate changes in epithelial tissue autofluorescence throughout the dysplasia-carcinoma sequence. Study Design/Materials and Methods: Fluorescence emission spectra were measured weekly from 42 DMBA-treated animals and 20 control animals at 337, 380, and 460 nm excitation. A subset of data in which histopathology was available was used to develop diagnostic algorithms to separate neoplastic and non-neoplastic tissue. The change in fluorescence intensity over time was examined in all samples at excitation-emission wavelength pairs identified as diagnostically useful. Results: Algorithms based on autofluorescence can separate neoplastic and non-neoplastic tissue with 95% sensitivity and 93% specificity. Greatest contributions to diagnostic algorithms are obtained at 380 nm excitation, and 430, 470, and 600 nm emission. Changes in fluorescence intensity are apparent as early as 3 weeks after initial treatment with DMBA, whereas morphologic changes associated with dysplasia occur on average at 7.5-12.5 weeks after initial treatment. Conclusions: Fluorescence spectroscopy provides a potential tool to identify biochemical changes associated with dysplasia and hyperplasia, which precede morphologic changes observed in histologically stained sections. © 2001 Wiley-Liss, Inc.
• Drezek, R., Sokolov, K., Utzinger, U., Boiko, I., Malpica, A., Follen, M., & Richards-Kortum, R. (2001). Understanding the contributions of NADH and collagen to cervical tissue fluorescence spectra: Modeling, measurements, and implications. Journal of Biomedical Optics, 6(4), 385-396.
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  PMID: 11728196;Abstract: Objective: At 380 nm excitation, cervical tissue fluorescence spectra demonstrate characteristic changes with both patient age and the presence of dysplasia. A Monte Carlo model was developed in order to quantitatively examine how intrinsic NADH and collagen fluorescence, in combination with tissue scattering and absorption properties, yield measured tissue spectra. Methods: Excitation-emission matrices were measured for live cervical cells and collagen gel phantoms. Fluorescence microscopy of fresh tissue sections was performed to obtain the location and density of fluorophores as a function of patient age and the presence of dysplasia. A Monte Carlo model was developed which incorporated measurements of fluorophore line shapes and spatial distributions. Results: Modeled spectra were consistent with clinical measurements and indicate that an increase in NADH fluorescence and decrease in collagen fluorescence create clinically observed differences between normal and dysplastic tissue spectra. Model predictions were most sensitive to patient age and epithelial thickness. Conclusions: Monte Carlo techniques provide an important means to investigate the combined contributions of multiple fluorophores to measured emission spectra. The approach will prove increasingly valuable as a more sophisticated understanding of in vivo optical properties is developed. © 2001 Society of Photo-Optical Instrumentation Engineers.
• Utzinger, U., Brewer, M., Silva, E., Gershenson, D., Blast Jr., R. C., Follen, M., & Richards-Kortum, R. (2001). Reflectance spectroscopy for in vivo characterization of ovarian tissue. Lasers in Surgery and Medicine, 28(1), 56-66.
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  PMID: 11430444;Abstract: Background and Objective: To explore whether reflectance spectroscopy can differentiate normal ovary, benign neoplasms, and ovarian cancer. Study Design/Materials and Methods: Reflectance spectra (390-600 nm) were measured at three source-detector separations (SDS) in vivo at 64 sites in 16 patients undergoing oophorectomy. Parameters with largest statistical differences were identified. Based on these parameters algorithms were developed and evaluated. Results: Promising parameters were the reflectance intensity from 540 to 580 nm (SDS, 1.1 mm), the slope of the reflectance spectrum from 490 to 520 nm (SDS, 1.1 mm), the slope from 510 to 530 nm (SDS, 2.1 mm), and the slope from 510 to 530 (SDS, 3 mm). Average sensitivity and specificity were 86 ± 6% and 79 ± 5% to separate normal ovary from benign neoplasms and cancers. Average sensitivity and specificity were 86 ± 4% and 80 ± 8% to separate ovarian cancers from benign neoplasms and normal ovary. Conclusion: Reflectance spectroscopy should be further investigated for ovarian cancer screening. 2001 Wiley-Liss, Inc.
• Utzinger, U., Bueeler, M., Heintzelman, D. L., Gillenwater, A., & Richards-Kortum, R. (2001). Cancer screening through the use of enhanced visual systems. Proceedings of SPIE - The International Society for Optical Engineering, 4259, 22-23.
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  Abstract: The human eyes are not made to detect disease, however visual perception is the most common screening method for early cancer detection. With optimal illumination and observation configuration there is significant improvement of optical contrast between normal and pre-cancerous tissue in the oral cavity, both for reflected or fluorescent light.
• Utzinger, U., Heintzelman, D. L., Mahadevan-Jansen, A., Malpica, A., Follen, M., & Richards-Kortum, R. (2001). Near-infrared Raman spectroscopy for in vivo detection of cervical precancers. Applied Spectroscopy, 55(8), 955-959.
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  Abstract: This study evaluates the potential of near-infrared Raman spectroscopy for in vivo detection of squamous dysplasia, a precursor to cervical cancer. A pilot clinical trial was carried out at three clinical sites. Raman spectra were measured from one colposcopically normal and one abnormal area of the cervix. These sites were then biopsied and submitted for routine histologic analysis. Twenty-four evaluable measurements were made in vivo in 13 patients. Cervical tissue Raman spectra contain peaks in the vicinity of 1070, 1180, 1195, 1210, 1245, 1330, 1400, 1454, 1505, 1555, 1656, and 1760 cm-1. The ratio of intensities at 1454 to 1656 cm-1 is greater for squamous dysplasia than all other tissue types, while the ratio of intensities at 1330 to 1454 cm-1 is lower for samples with squamous dysplasia than all other tissue types. A simple algorithm based on these two intensity ratios separates high-grade squamous dysplasia from all others, misclassifying only one sample. Spectra measured in vivo resemble those measured in vitro. Cervical epithelial cells may contribute to tissue spectra at 1330 cm-1, a region associated with DNA. In contrast, epithelial cells probably do not contribute to tissue spectra at 1454 cm-1, a region associated with collagen and phospholipids.
• Coghlan, L., Utzinger, U., Drezek, R., Heintzelman, D., Zuluaga, A., Brookner, C., Richards-Kortum, R., Gimenez-Conti, I., & Follen, M. (2000). Optimal fluorescence excitation wavelengths for detection of squamous intra-epithelial neoplasia: Results from an animal model. Optics Express, 7(12), 436-446.
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  PMID: 19407895;Abstract: Using the hamster cheek pouch carcinogenesis model, we explore which fluorescence excitation wavelengths are useful for the detection of neoplasia. 42 hamsters were treated with DMBA to induce carcinogenesis, and 20 control animals were treated only with mineral oil. Fluorescence excitation emission matrices were measured from the cheek pouches of the hamsters weekly. Results showed increased fluorescence near 350-370 nm and 410 nm excitation and decreased fluorescence near 450-470 nm excitation with neoplasia. The optimal diagnostic excitation wavelengths identified using this model - 350-370 nm excitation and 400-450 nm excitation - are similar to those identified for detection of human oral cavity neoplasia. © 2000 Optical Society of America.
• Heintzelman, D. L., Utzinger, U., Fuchs, H., Zuluaga, A., Gossage, K., Gillenwater, A. M., Jacob, R., Kemp, B., & Richards-Kortum, R. R. (2000). Optimal excitation wavelengths for in vivo detection of oral neoplasia using fluorescence spectroscopy. Photochemistry and Photobiology, 72(1), 103-113.
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  PMID: 10911734;Abstract: There is no satisfactory mechanism to detect premalignant lesions in the upper aero-digestive tract. Fluorescence spectroscopy has potential to bridge the gap between clinical examination and invasive biopsy; however, optimal excitation wavelengths have not yet been determined. The goals of this study were to determine optimal excitation-emission wavelength combinations to discriminate normal and precancerous/cancerous tissue, and estimate the performance of algorithms based on fluorescence. Fluorescence excitation-emission matrices (EEM) were measured in vivo from 62 sites in nine normal volunteers and 11 patients with a known or suspected premalignant or malignant oral cavity lesion. Using these data as a training set, algorithms were developed based on combinations of emission spectra at various excitation wavelengths to determine which excitation wavelengths contained the most diagnostic information. A second validation set of fluorescence EEM was measured in vivo from 281 sites in 56 normal volunteers and three patients with a known or suspected premalignant or malignant oral cavity lesion. Algorithms developed in the training set were applied without change to data from the validation set to obtain an unbiased estimate of algorithm performance. Optimal excitation wavelengths for detection of oral neoplasia were 350, 380 and 400 nm. Using only a single emission wavelength of 472 nm, and 350 and 400 nm excitation, algorithm performance in the training set was 90% sensitivity and 88% specificity and in the validation set was 100% sensitivity, 98% specificity. These results suggest that fluorescence spectroscopy can provide a simple, objective tool to improve in vivo identification of oral cavity neoplasia.
• Agrawal, A., Utzinger, U., Brookner, C., Pitris, C., Mitchell, M. F., & Richards-Kortum, R. (1999). Fluorescence spectroscopy of the cervix: Influence of acetic acid, cervical mucus, and vaginal medications. Lasers in Surgery and Medicine, 25(3), 237-249.
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  PMID: 10495301;Abstract: Background and Objective: Fluorescence spectroscopy has been shown to provide information useful in the detection of cervical dysplasia. The goal of this study was to determine if substances found on the cervix such as acetic acid, mucus, and vaginal medications can influence the fluorescence in the spectral region useful for discriminating normal cervical tissue from abnormal tissue. Study Design/Materials and Methods: Fluorescence spectra were collected at 337 nm excitation from the cervix in vivo both before and after application of acetic acid; the data were analyzed to identify the effects of the acetic acid on the spectra. Cervical mucus was acquired from patients referred for colposcopy and frozen until measurements were taken. Fluorescence excitation-emission matrices (EEMs) were measured for the mucus samples. Additionally, the transmission spectra of mucus were measured to determine if its absorption could influence the fluorescence signal measured from the tissue. EEMs were measured for samples of commonly prescribed vaginal medications. All EEMs were compared to those of cervical biopsies. Results: Acetic acid introduces changes in both the lineshape and intensity of the spectra. On average, the changes are more significant in spectra of abnormal tissue. Cervical mucus was found to have no significant absorption bands, but the measured fluorescence was approximately the same order of magnitude as that measured from the cervix in vitro. Most medications exhibited significant fluorescence in the spectral region of diagnostic interest for the cervix. Conclusions: Acetic acid appears to increase the differences in fluorescence emission spectra of normal and pre-cancerous cervical tissues; thus, its use is beneficial. The presence of cervical mucus can possibly interfere with the collection of fluorescence spectra for tissue classification. Patients should not use vaginal preparations during the 48 hours prior to tissue fluorescence measurements.
• Brookner, C. K., Utzinger, U., Staerkel, G., Richards-Kortum, R., & Mitchell, M. F. (1999). Cervical fluorescence of normal women. Lasers in Surgery and Medicine, 24(1), 29-37.
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  PMID: 10037349;Abstract: Background and Objective: Cervical tissue fluorescence spectra have previously been measured in vivo in women with a recent abnormal Papanicolaou smear. Diagnostic algorithms have been developed to diagnose squamous intraepithelial lesions (SILs) based on these fluorescence emission spectra. However, algorithms have not been tested in women with no history of cervical neoplasia. Study Design/Materials and Methods: Cervical fluorescence was measured from 54 women with no history of cervical dysplasia, and the spectra were compared to those from colposcopically normal sites in women with suspected dysplasia. Representative spectra from each group were compared and a two-sided, unpaired Student's t-test was performed to compare mean principal component scores used in previously published diagnostic algorithms. The ability of previously reported diagnostic algorithms to classify these samples as normal tissue was also assessed. Results: At the 0.05 level of significance, the mean scores of 4 of the 7 important principal components were statistically different for the two populations. However, when the data collected from volunteers in this study were preprocessed in the appropriate manner and the algorithms were applied, more normal samples were correctly classified than in the previous clinical study in which these algorithms were developed. Conclusion: Previously reported algorithms can accurately classify tissue type based on spectra from women with and without a history of cervical neoplasia.
• Mitchell, M. F., Cantor, S. B., Brookner, C., Utzinger, U., Schottenfeld, D., & Richards-Kortum, R. (1999). Screening for squamous intraepithelial lesions with fluorescence spectroscopy. Obstetrics and Gynecology, 94(5 SUPPL. 1), 889-896.
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  PMID: 10546779;Abstract: Objective: To evaluate the accuracy of fluorescence spectroscopy in screening for squamous intraepithelial lesions (SILs) and to compare its performance with that of Papanicolaou smear screening, colposcopy, cervicoscopy, cervicography, and human papillomavirus (HPV) testing.Data Sources: Receiver operating characteristic (ROC) curve analysis was used to analyze performance by fluorescence spectroscopy (primary data) and other methods (secondary data).Methods of Study Selection: In our search, 275 articles were identified in MEDLINE (1966-1996). Articles were included if the investigators had studied a population in whom low disease prevalence was expected; used either Papanicolaou smear screening and colposcopy or colposcopically directed biopsy as a standard against which the screening technique was measured, and included enough data for recalculation of reported sensitivities and specificities.Tabulation, Integration, and Results: Receiver operating characteristic curves for fluorescence spectroscopy were calculated using a Bayesian algorithm, and ROC curves for the other screening methods were constructed using meta-analytic techniques. Areas under the ROC curves and Q points were calculated. Screening colposcopy had the highest area under the curve (0.95), followed by screening cervicography (0.90), HPV testing (0.88), cervicoscopy (0.85), fluorescence spectroscopy (0.76), and Papanicolaou smear screening (0.70).Conclusion: In terms of screening for SILs, fluorescence spectroscopy performed better than the standard technique, Papanicolaou smear screening, and less well than screening colposcopy, cervicography, HPV testing, and cervicoscopy. The promise of this research technique warrants further investigation. Copyright (C) 1999 The American College of Obstetricians and Gynecologists.
• Utzinger, U., Trujillo, E. V., Atkinson, E. N., Mitchell, M. F., Cantor, S. B., & Richards-Kortum, R. (1999). Performance estimation of diagnostic tests for cervical precancer based on fluorescence spectroscopy: Effects of tissue type, sample size, population, and signal-to-noise ratio. IEEE Transactions on Biomedical Engineering, 46(11), 1293-1303.
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  PMID: 10582414;Abstract: Fluorescence spectroscopy may provide a cost-effective tool to improve precancer detection. We describe a method to estimate the diagnostic performance of classifiers based on optical spectra, and to explore the sensitivity of these estimations to factors affecting spectrometer cost. Fluorescence spectra were obtained at three excitation wavelengths in 92 patients with an abnormal Papanicolaou smear and 51 patients with no history of an abnormal smear. Bayesian classification rules were developed and evaluated at multiple misclassification costs. We explored the sensitivity of classifier performance to variations in tissue type, sample size, tested population, signal to noise ratio (SNR), and number of excitation and emission wavelengths. Sensitivity and specificity could be evaluated within ±7%. Minimal decrease in diagnostic performance is observed as SNR is reduced to 15, the number of excitation-emission wavelength combinations is reduced to 15 or the number of excitation wavelengths is reduced to one. Diagnostic performance is compromised when ultraviolet excitation is not included. Significant spectrometer cost reduction is possible without compromising diagnostic ability. Decision-analytic methods can be used to rate designs based on incremental cost-effectiveness.
• Zuluaga, A. F., Utzinger, U., Durkin, A., Fuchs, H., Gillenwater, A., Jacob, R., Kemp, B., Fan, J., & Richards-Kortum, R. (1999). Fluorescence excitation emission matrices of human tissue: a system for in vivo measurement and method of data analysis. Applied Spectroscopy, 53(3), 302-311.
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  Abstract: We describe a system capable of measuring spatially resolved reflectance spectra from 380 to 950 nm and fluorescence excitation emission matrices from 330 to 500 nm excitation and 380 to 700 nm emission in vivo. System performance was compared to that of a standard scanning spectrofluorimeter. This 'FastEEM' system was used to interrogate human normal and neoplastic oral cavity mucosa in vivo. Measurements were made through a fiber-optic probe and require 4 min total measurement time. We present a method based on autocorrelation vectors to identify excitation and emission wavelengths where the spectra of normal and pathologic tissues differ most. The FastEEM system provides a tool with which to study the relative diagnostic ability of changes in absorption, scattering, and fluorescence properties of tissue.
• Fuchs, H., Utzinger, U., Zuluaga, A. F., Gillenwater, A., Jacob, R., Kemp, B., & Richards-Kortum, R. (1998). Combined fluorescence and reflectance spectroscopy: in vivo assessment of oral cavity epithelial neoplasia. Conference on Lasers and Electro-Optics Europe - Technical Digest, 306-307.
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  Abstract: A system was designed to collect autofluorescence emission spectra at 18 different excitation wavelengths (330 to 500 nm). These spectra were assembled into excitation emission matrices (EEM). In vivo fluorescence EEMs and reflectance spectra of normal and neoplastic oral mucosa were obtained.
• Mahadevan-Jansen, A., Mitchell, M. F., Ramanujam, N., Malpica, A., Thomsen, S., Utzinger, U., & Richards-Kortum, R. (1998). Near-Infrared Raman Spectroscopy for In Vitro Detection of Cervical Precancers. Photochemistry and Photobiology, 68(1), 123-132.
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  PMID: 9679458;Abstract: In this study, we investigate the potential of near-infrared Raman spectroscopy to differentiate cervical precancers from normal tissues, inflammation and metaplasia and to differentially diagnose low-grade and high-grade precancers. Near infrared Raman spectra were measured from 36 biopsies from 18 patients in vitro. Detection algorithms were developed and evaluated relative to histopathologic examination. Algorithms based on empirically selected peak intensities, ratios of peak intensities and a combination of principal component analysis for data reduction and Fisher discriminant analysis for classification were investigated. Spectral peaks were tentatively identified from measured spectra of potential chromophores. Empirically selected normalized intensities can differentiate precancers from other tissues with an average sensitivity and specificity of 88 ±4% and 92 ±4%. Ratios of unnormalized intensities can differentiate precancers from other tissues with a sensitivity and specificity of 82% and 88% and high-grade from low-grade lesions with a sensitivity and specificity of 100%. Using multivariate methods, intensities at eight frequencies can be used to differentiate precancers from all other tissues with a sensitivity and specificity of 82% and 92% in an unbiased test. Raman algorithms can potentially separate benign abnormalities such as inflammation and metaplasia from precancers. Comparison of tissue spectra to published and measured chromophore spectra indicate that the most likely primary contributors to the tissue spectra are collagen, nucleic acids, phospholipids and glucose 1-phosphate. These results suggest that near-infrared Raman spectroscopy can be used for cervical precancer diagnosis and may be able to accurately separate samples with inflammation and metaplasia from precancer.
• Mahadevan-Jansen, A., Mitchell, M. F., Ramanujam, N., Utzinger, U., & Richards-Kortum, R. (1998). Development of a Fiber Optic Probe to Measure NIR Raman Spectra of Cervical Tissue in Vivo. Photochemistry and Photobiology, 68(3), 427-431.
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  PMID: 9747597;Abstract: The goal of this study was to develop a compact fiber optic probe to measure near infrared Raman spectra of human cervical tissue in vivo for the clinical diagnosis of cervical precancers. A Raman spectrometer and fiber optic probe were designed, constructed and tested. The probe was first tested using standards with known Raman spectra, and then the probe was used to acquire Raman spectra from normal and precancerous cervical tissue in vivo. Raman spectra of cervical tissue could be acquired in vivo in 90 s using incident powers comparable to the threshold limit values for laser exposure of the skin. Although some silica signal obscured tissue Raman bands below 900 cm -1, Raman features from cervical tissue could clearly be discerned with an acceptable signal-to-noise ratio above 900 cm -1. The success of the Raman probe described here indicates that near infrared Raman spectra can be measured in vivo from cervical tissues. Increasing the power of the excitation source could reduce the integration time to below 20 s.
• Strebel, R. T., Utzinger, U., Peltola, M., Schneider, J., Niederer, P. F., & Hess, O. M. (1998). Excimer laser spectroscopy: Influence of tissue ablation on vessel wall fluorescence. Journal of Laser Applications, 10(1), 34-40.
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  PMID: 10177221;Abstract: Limited steerability and injury to the normal vessel wall are major drawbacks of laser coronary angioplasty. To overcome these limitations a new generation of laser systems has been developed which allows not only to eliminate the atherosclerotic plaque but to guide the laser beam by analyzing the laser induced tissue fluorescence (=spectroscopy) for the treatment of the atherosclerotic vessel. An excimer laser (MAX 10 LP, 308 nm, Technolas, Munich, Germany) was used with an emitting (Ø 1070 μm) and a detecting (Ø 130 μm) optical fiber to induce tissue fluorescence which was analyzed quantitatively by a computerized system. Specimens from the descending (thoracic) aorta were obtained from 24 patients (mean age 68.1 years, range 44-92). Tissue fluorescence was induced with ablating (26-30 mJ/mm2) and nonablating (3 mJ/cm2) laser activations. The emitted fluorescence (range 380-575 nm) was normalized to a wavelength of 380 nm; as a measure of tissue fluorescence the intensity ratio at 500 nm divided by 400 nm was calculated in normal (n=78), mildly atherosclerotic (n=40), and severely atherosclerotic (n =48) tissue samples. Repeated laser activations were carried out and tissue fluorescence was checked until the fluorescence spectrum was normalized. All tissue samples were analyzed histologically by a semiquantitative score. Normal tissue samples showed the highest intensity ratios (5.9±3.4), whereas mildly (2.9±1.3) and severely atherosclerotic (2.1±1.0) samples elicited a significantly reduced fluorescence. Repeated tissue ablations were associated with a normalization of fluorescence intensity ratios in the mildly (7.0) as well as in the severely diseased (4.9) vessels. A curvilinear relationship between intensity ratio and the semiquantitative score was observed (r =0.66) as well as between intensity ratio and intimal wall thickness (r=0.62). No gender related differences were found but there was an inverse relationship between fluorescence intensity ratio and age (r=0.56) as well as between intimai thickness and age (r=0.41). Excimer laser spectroscopy allows reliable detection of atherosclerotic vessel alterations. Fluorescence intensity ratio is inversely proportional to the intimal wall thickness and the severity of the histologic alterations. There is an age dependency of fluorescence intensity ratio which can be explained by an increase in intimai wall thickness. Successful tissue ablation can be obtained by laser angioplasty and allows determination of the optimal point where complete tissue ablation is achieved by laser activation. Thus, excimer laser spectroscopy is an effective method for selective tissue ablation by laser angioplasty. © 1998 Laser Institute of America.
• Trujillo, E. V., Sandison, D. R., Utzinger, U., Ramanujam, N., Mitchell, M. F., & Richards-Kortum, R. (1998). Method to determine tissue fluorescence efficiency in vivo and predict signal-to-noise ratio for spectrometers. Applied Spectroscopy, 52(7), 943-951.
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  Abstract: Recent clinical trials have demonstrated the potential of fluorescence spectroscopy for in vivo diagnosis of pathology. There is significant potential to reduce the cost and complexity of instrumentation to measure tissue spectra; however, careful analysis is required to maximize performance and minimize cost. One measure of performance is the signal-to-noise ratio (SNR) of the resulting data. This paper describes a method to predict the SNR of a given optical design for a particular tissue application. In order to calculate the expected SNR, two pieces of information are required: (1) the throughput and inherent noise of the system and (2) a quantitative relationship between the illumination energy and the resulting tissue fluorescence available for collection, which we define as the tissue fluorescence efficiency (FE). We present a method to calculate the fluorescence efficiency of tissue from in vivo measurements of tissue fluorescence. We report FE measurements of the normal and precancerous human cervix in vivo at 337, 380, and 460 nm excitation. We also present and evaluate a method to estimate the throughput and noise of various spectrometers and predict the expected SNR for tissue spectra by using the measured tissue FE. For squamous cervical tissue, as the degree of the disease increases, FE decreases, and as the excitation wavelength increases, FE decreases. Cervical tissue FE varies more than two orders of magnitude, depending on the tissue type and on the excitation wavelength used. Our SNR calculations, based on measured values of tissue FE, demonstrate agreement within a factor of 1.3 of the measured SNR on average. This method can be used to estimate the performance of different spectrometer designs for clinical use.
• Muser, M. H., Krabbel, G., Utzinger, U., Prescher, V., Frei, P., Walz, F., Niederer, P., & Kaeser, R. (1996). Optimised restraint systems for low mass vehicles. SAE Technical Papers.
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  Abstract: In a collision of a low mass vehicle (600 kg) against a typical compact car (1200 kg), both vehicles cruising at 50 km/h, the LMV will experience a Δv of 20 m/s and a mean deceleration level of 45 - 50 g, approximately. The restraint systems of such vehicles must be adapted to this specific situation in order to guarantee a level of passive safety equal to current standards. The purpose of this study is to show that, in sled tests, FMVSS 208 and European occupant protection criteria can be met under the conditions encountered in a LMV, utilizing restraint system components which are appropriately adapted and optimised with respect to the severity of the crash situation under consideration. © Copyright 1996 Society of Automotive Engineers, Inc.
• Muser, M. H., Krabbel, G., Utzinger, U., Prescher, V., Frei, P., Walz, F., Niederer, P., & Kaeser, R. (1996). Optimised restraint systems for low mass vehicles. Stapp Car Crash Conference Proceedings, 345-355.
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  Abstract: Mathematical modeling has been used to find optimal combinations of the properties of the different restraint system components (e.g. belt system, airbag, set, steering wheel and column). A test rig that allows for an implementation of the driver side car interior has been built, and various sled tests have been performed. The results of the tests as well as comparison with the computer model are presented. The results clearly indicate the feasibility of the procedure, in that the envisaged protection criteria could be met.
• Kaufmann, P., Vassalli, G., Utzinger, U., & Hess, O. M. (1995). Coronary vasomotion during dynamic exercise: Influence of intravenous and intracoronary nicardipine. Journal of the American College of Cardiology, 26(3), 624-631.
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  PMID: 7642851;Abstract: Objectives. Our aim was to evaluate the influence of a calcium channel blocking agent of the dihydropyridine group (nicardipine) on coronary vasomotion during dynamic exercise. Background. Coronary vasomotion plays an important role in the pathophysiology of myocardial ischemia. Methods. Twenty-nine patients with coronary artery disease were studied at rest and during bicycle exercise with the use of biplane quantitative coronary angiography. Twelve patients without pretreatment (group 1) served as control subjects. Seventeen patients (group 2) received nicardipine, either 9.2 mg by intracoronary injection (n = 9) or 2.5 mg intravenously (n = 8) before exercise. Results. In the control group there was exercise-induced vasoconstriction (-29%, p < 0.001) of the stenotic segment but coronary vasodilation (+22%, p < 0.05) of the normal vessel segment. In group 2, nicardipine induced coronary vasodilation of both the normal (+16%, P < 0.001) and the stenotic vessel segment (+35%). During subsequent exercise there was some additional vasodilation of normal (+4%, p = NS) and stenotic arteries (+5%, p = NS). There was no difference between either intracoronary or intravenous nicardipine with regard to vasodilation. Application of sublingual nitroglycerin was associated with significant vasodilation of the normal vessel segment in groups 1 (+18%, p < 0.05) and 2 (+15%, p < 0.001). The stenotic vessels showed a significant increase in percent cross-sectional area after nitroglycerin in groups 1 (+12%, p = NS) and 2 (+51%, p < 0.001). Exertional angina pectoris occurred less frequently in group 2 (18%) than in group 1 (67% [p < 0.005 vs. group 2]); group 2 also had a smaller increase in mean pulmonary artery pressure (+14 vs. +21 mm Hg, p < 0.05). Conclusions. Exercise induces vasoconstriction of stenotic, but vasodilation of normal, coronary vessel segments. Intravenous and intracoronary nicardipine prevent vasoconstriction of stenotic coronary arteries during exercise and exert a significant anti-ischemic effect. The combination of two anti-ischemic drugs, nitroglycerin and nicardipine, has an additive effect on coronary vasomotion that is seen only in the stenotic vessel segment. Thus, the anti-ischemic action of nicardipine is mainly due to a primary effect on coronary vasomotor response rather than to secondary effects such as changes in loading conditions.
• Mayer, I. V., Lazarov, M. P., Utzinger, U., Freiburghaus, A. U., & Hess, O. M. (1995). Sonicated X-ray contrast agents for quantitative myocardial contrast echocardiography - a critical approach. Heart and Vessels, 10(2), 96-105.
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  PMID: 7782270;Abstract: Contrast echocardiography with sonicated radiographic contrast agents has been used for the qualitative and quantitative determination of myocardial blood flow. One major problem has been the size of the microbubbles since only bubbles smaller than 8 μm are expected to pass the capillary bed and larger bubbles may obstruct the capillaries and, thus, alter myocardial blood flow. These techniques have been used for several years, but their reliability has not yet been assessed accurately. Five different methods for the production of sonicated radiographic contrast agents (methods 1-3 from the literature, and 4 and 5 from our laboratory; M1-5) were evaluated for their use in quantitative contrast echocardiography. The sonication of non-ionic X-ray contrast media was performed with a standard titanium probe (20 kHz) for methods 1-4, with variation in the sonication time and the number of sonication jets used for each method. In M5, we used bubbles that were produced by the insufflation of oxygen in the X-ray contrast agent; large (>8 μm) bubbles were destroyed by sonication at 380kHz (resonance method). Mean bubble size was determined by computerized videomicroscopy. The effect of bubble size on the backscatter of the ultrasonic signal was calculated for each method. Mean bubble size (±1 SD) ranged between 11.5 ± 4μm and 16.1 ± 14 μm for M1-M5. The best values, i.e., the smallest bubbles, were found with M4 (prepressurized contrast medium). Assuming capillary passage for bubbles smaller than 8 μm, only 14%-48% of the bubbles were smaller than 8 μm (M1-M5). The best results with regard to bubble size (≤8 μm) were observed with M5 (48% ≤8 μm). In regard to the influence of bubble size on the backscatter of the ultrasonic signal, 56%-98.5% of the signal was produced by bubbles larger than 15 μm (M1-5) but the best results were obtained with M4. It is concluded that capillary-passage of sonicated microbubbles (≤8 μm) can be expected in only 14%-48% of the bubbles for the five different sonication techniques. More than 50% of all microbubbles produced by these techniques are larger than the expected 8 μm. These large bubbles are responsible for the backscatter of the ultrasonic signal in the vast majority of cases. Thus, the sonication of radiographic contrast agents appears to be inappropriate for the production of uniformly small microbubbles and, thus, this method is not suitable for quantitative measurements of coronary blood flow. © 1995 Springer-Verlag.
• Rol, P. O., Utzinger, U., Beck, D., & Niederer, P. (1995). Fiber beam shaping and ophthalmic applications. Proceedings of SPIE - The International Society for Optical Engineering, 2330, 56-62.
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  Abstract: In recent years laser technology has undergone a tremendous development in the field of ophthalmology. New laser sources such as solid state (Er:YAG, Ho:YAG) and diode lasers have become available and exhibit promising characteristics in view of routine therapeutic procedures. Therapeutic effects are now attempted to be obtained inside the eye by making use of optical fibers having a plane distal end surface. Under these conditions the laser beam emitted from the fiber diverges according to the numerical aperture of the fiber (typically from 0.2 to 0.4). Because the therapeutic effect obtained depends primarily on the power density on the tissue to be treated, optical components can be utilized for refocusing the laser beam. For this purpose, small reshaping micro optics set at the distal end of the fiber have been extensively presented. So far, they have been developed to fit the diameter of endoscopic working channels, i.e., typically about 2.2 mm. However, this diameter should be further reduced for intraocular applications because standardized surgical ports are only 0.9 mm in diameter (20 gauge). After a short review of axial systems based on the refocusing of the beam transmitted from the fiber, a more extended presentation of systems capable of deflecting this beam is given. Designs have been evaluated with ray patterns, spot dimensions, and irradiance distribution. Ray patterns have been computed using ray-tracing algorithms on the basis of the Snell's law of refraction while irradiances have been derived with the 3D optical analysis program ASAP (BRO, USA). Rays were homogeneously distributed, spatially across the fiber core as well as angularly across its numerical aperture. Foci have been defined as the location where the cross-section of the beam is the smallest: all the rays are taken into account regardless of their intensity, so that no irradiation of the targeted tissue occurs outside this area.
• Bosshart, F., Utzinger, U., Hess, O. M., Wyser, J., Mueller, A., Schneider, J., Niederer, P., Anliker, M., & Krayenbuehl, H. P. (1992). Fluorescence spectroscopy for identification of atherosclerotic tissue. Cardiovascular Research, 26(6), 620-625.
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  PMID: 1451142;Abstract: Objective: Vessel perforation and limited steerability of the laser light are the major limitations of laser angioplasty. To improve steerability fluoresence spectroscopy has been proposed for identification of atherosclerotic plaques. The aim was to investigate this. Methods: Fluorescence spectroscopy with three different excitation wavelengths (325 nm, 380 nm, 450 nm) was tested in an emission range of 400 nm to 600 nm. Intensity ratios at 480/420 nm were determined in different types of blood vessels. Necropsy material from 40 patients (punch biopsies of 4 mm diameter from the coronary and carotid artery as well as from the ascending and descending aorta) was studied spectroscopically. Histological alterations of the vessel wall were assessed by a semiquantitative score (0 to 10 points): (a) normal tissue, 0 to 2 points (mean=0.25; n=38); (b) mild atherosclerotic lesions, 3 to 5 points (mean=3.35; n=39); (c) severe atherosclerotic lesions, ≥ 6 points (mean=6.75; n=43). Results: Best spectroscopic results were obtained with an excitation wavelength of 325 nm. In samples with severe atherosclerotic lesions the fluoresence spectra showed a significant reduction of the emitted wavelength intensities when compared to normal tissue. There was a clear separation of the fluorescence spectra between normal and mild as well as between normal and severe atherosclerotic lesions; normal tissue showed an increased intensity in the range from 420 nm to 540 nm, whereas atherosclerotic lesions had no or only a small peak at 480 nm. There was a significant correlation between the semiquantitative score (n=120) and the fluorescence ratio at 480/420 nm (excitation wavelength 325 nm) with a correlation coefficient of 0.87. The spectroscopic results showed no differences between the samples taken from different types of vessels. Conclusions: Fluorescence spectroscopy allows a reliable identification of normal and atherosclerotic lesions. The close correlation between the emitted light intensity ratio at 480/420 nm and the histological alterations of the vessel wall suggests a relationship between vessel wall fluorescence and the atherosclerotic alterations of the wall.
• Dillier, N., Senn, C., Schlatter, T., Stockli, M., & Utzinger, U. (1990). Wearable digital speech processor for cochlear implants using a TMS320C25. Acta Oto-Laryngologica, Supplement, 120-127.
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  PMID: 2356719;Abstract: Based on a single-chip DSP (TMS320C25, Texas Instruments) a programmable battery-operated sound processor with a digital encoder interface for the Nucleus-22 cochlear implant (CI) was built. The number of quasi-simultaneously adressed electrodes is only limited by the selected pulse width and the maximum rate of stimulation and can be as high as 10 electrodes at 300 Hz repetition rate. Implementation of various processing strategies (formant or channel vocoder, filtebank, zero crossings, etc.) is possible as well as sophisticated adaptive noise reduction. Programs and stimulation parameters are stored in electrically erasable memory and may be updated via a host computer. The built-in analog output may be used for single-channel stimulation or acoustic verifications of the sound processed algorithms. The power consumption with current 16K word data memory and at amximum stimulation rate is about 1 Watt, which necessitates recharging of batteries after 11 h.

Proceedings Publications

• Keenan, M., Tate, T. H., Black, J. F., Utzinger, U., & Barton, J. K. (2018, January). Performance of combined OCT/MFI microendoscope for ovarian cancer detection. In SPIE Photonics West; Endoscopic Microscopy XI; and Optical Techniques in Pulmonary Medicine III, 9691, 96910D.
• Keenan, M., Howard, C., Tate, T., McGuiness, I., Sauer-Budge, A., Black, J., Utzinger, U., & Barton, J. K. (2016, March). Design of an everting balloon to deploy a microendoscope to the fallopian tubes. In Proc. SPIE, 9689, 968944-968944-6.
• Wang, C., Pacheco, S., Baggett, B., Chawla, M., Gray, D., Utzinger, U., Barnes, C., & Liang, R. (2016). Whole brain imaging with a scalable microscope. In Clinical and Translational Biophotonics.
• Black, J. F., Tate, T., Keenan, M., Swan, E., Utzinger, U., & Barton, J. (2015, Spring). A six-color four-laser mobile platform for multi-spectral fluorescence imaging endoscopy. In SPIE BiOS, 93040T--93040T.
• Swan, E., Tate, T., Keenan, M., Black, J. F., Utzinger, U., & Barton, J. (2015, March). Stray light mitigation in a novel endoscope for fallopian tubes. In SPIE BiOS, 93041O--93041O.
• Tate, T., Baggett, B., Rice, P., Watson, J., Orsinger, G., Nymeyer, A. C., Welge, W. A., Keenan, M., Saboda, K., Roe, D. J., & others, . (2015, Spring). Multispectral fluorescence imaging of human ovarian and Fallopian tube tissue for early stage cancer detection. In SPIE BiOS, 93130L--93130L.
• Tate, T., Keenan, M., Swan, E., Black, J., Utzinger, U., Barton, J., Figueiro, M., Lerner, S., Muschaweck, J., & Rogers, J. (2014, December). Optical design of an optical coherence tomography and multispectral fluorescence imaging endoscope to detect early stage ovarian cancer. In INTERNATIONAL OPTICAL DESIGN CONFERENCE 2014, 9293.
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  The five year survival rate for ovarian cancer is over 90% if early detection occurs, yet no effective early screening method exists. We have designed and are constructing a dual modality Optical Coherence Tomography (OCT) and Multispectral Fluorescence Imaging (MFI) endoscope to optically screen the Fallopian tube and ovary for early stage cancer. The endoscope reaches the ovary via the natural pathway of the vagina, cervix, uterus and Fallopian tube. In order to navigate the Fallopian tube the endoscope must have an outer diameter of 600 lam, be highly flexible, steerable, tracking and non-perforating. The imaging systems consists of six optical subsystems, two from OCT and four from MFI. The optical subsystems have independent and interrelated design criteria. The endoscope will be tested on realistic tissue models and ex vivo tissue to prove feasibility of future human trials. Ultimately the project aims to provide women the first effective ovarian cancer screening technique.
• George, R., Krishnamurthy, R., Lovisa, B., Krikpatrick, N. D., & Utzinger, U. (2006, January). Clinical device for early detection of ovarian cancer using optical spectroscopy. In Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 6091, xiii.
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  Abstract: A comprehensive, state-of-the-art, fully automated mobile optical spectroscopy system is designed using custom selected, low autofluorescence components to measure calibrated fluorescence and reflection spectra; primarily to determine the correlation between the etiology of ovarian cancer and endogenous optical signals. A series of experimental protocols have been built into the instrument. Nine tissue excitation bands cover 270nm to 580nm and autofluorescence is measured for five emission positions from 300nm to 800nm, with OD5 or better excitation suppression, within 30 seconds. UV exposure at 270nm is at a factor often or better below the TLV set for UV radiation by ACGIH. Tissue reflection measurements are performed above 320nm for assessing absorption and scattering. An SNR of 200 and above is achieved at all excitation conditions. Key emphasis is laid on reproducibility and long-term stability by integrating positive and negative standards that cover the system spectral range. Each measurement consists of background subtracted data collection, and continuous power monitoring. Light is well coupled to the tissue with a probe from a multi-leg fiber bundle with four excitation fibers, and three emission fibers that route the optical signals to the spectrometer. Patients undergoing oophorectomy are measured during surgery in vivo. Histological diagnosis of the biopsies from the probed area are obtained and compared with spectroscopic data. Preliminary results suggest differences in the UV excitation range consistent with tryptophan, collagen, NADH and FAD related endogenous fluorescence. Additionally, stratifying patients by menopausal status results in more sensitive discriminations between diseased and normal tissue.

Presentations

• Keenan, M., Tate, T., Swan, E. J., Black, J. F., Utzinger, U., & Barton, J. K. (2015, Spring). Dual-modal optical imaging microendoscope for ovarian cancer detection. BIOS Photonics West. San Francisco.
• Utzinger, U. (2015, September). Imaging Tissue with UV light. Biomedical Engineering Seminar. Texas A&M University, College Station: https://engineering.tamu.edu/biomedical.
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  • Seminar TitleImaging Tissue with UV light.• Brief Bio I received an engineering degree (M.S. 1989, mechanical engineering) and a Ph.D. (Ph.D. 1995, technical sciences) from the Swiss Federal Institute of Technology (ETH), Zürich Switzerland. I worked at The University of Texas in Austin as post-doctoral fellow. In 2001, I became faculty at the University of Arizona where I am currently an Associate Professor and Associate Department Head in Biomedical Engineering. I am also holding appointments in Obstetrics and Gynecology, Optical Sciences, Electrical and Computer Engineering, and the BIO5 Institute. From 2012 until end of 2014 I served as interim Department Head in Biomedical Engineering when our program grew from 40 to 200 undergraduate students and the first two class graduated from the program.I develop clinical imaging instrumentation to evaluate gynecological and gastrointestinal cancer. Using microscopy techniques I also study the extra cellular matrix and angiogenesis.• AbstractFluorescence imaging with UV radiation has been used in research settings for the last two decades. It was conceived as a tool sensitive to alteration in metabolism, protein synthesis and extracellular matrix remodeling. Initially we proposed to detect atherosclerotic plaques, and then built clinical devices for instantaneous cervical diagnosis and later for laparoscopic ovarian cancer evaluation and now endoscopy in the fallopian tubes. Recently we adapted the technology to create high contrast images through simple combination of multiple images for colonic lesion detection. In the past, the performance of many optical diagnostic imaging systems has been evaluated through sensitivity and specificity assessment of a standalone system. However, there are visual detection tasks where high contrast images of difficult-to-observe lesions could become an integral role in meeting detection rate targets for physicians.
• Keenan, M., Tate, T., Swan, E., Black, J., Utzinger, U., & Barton, J. (2014, January). Optical Imaging Falloposcope for Minimally Invasive Ovarian Cancer Detection. Journal of Minimally Invasive Gynecology.
• Keenan, M., Tate, T., Swan, E., Black, J., Utzinger, U., & Barton, J. K. (2014, October). Optical Coherence Tomography and Multispectral Fluorescence Imaging Falloposcope. Frontiers in OpticsOptical Society of America.
• Utzinger, U. (2014, June). Imaging tissue with UV light, is it worth it?. BC Cancer Research Seminar Series. Vancouver, CA: BC Cancer Agency.

Poster Presentations

• Ram, S., Howerton, S. J., Danford, F. L., Utzinger, U., Rodriguez, J. J., & Vande Geest, J. (2016, May 1-5). Racioethnic Differences in Biomechanical Environment of the Lamina Cribrosa. ARVO 2016 Annual Meeting. Seattle, WA: Assn. for Research in Vision and Ophthalmology.