- Assistant Professor, Optical Sciences
- Assistant Professor, Biomedical Engineering
- Assistant Professor, BIO5 Institute
- Ph.D. Mechanical Engineering
- Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea, Republic of
- Design, analysis and application of confocal self-interference microscopy
- M.S. Mechanical Engineering
- Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea, Republic of
- B.S. Mechanical Engineering
- Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea, Republic of
- Harvard Medical School and Massachusetts General Hospital (2016 - 2017)
- Harvard Medical School and Massachusetts General Hospital (2009 - 2016)
- Harvard Medical School and Massachusetts General Hospital (2007 - 2009)
- Korea Advanced Institute of Science and Technology (2006 - 2007)
- Clinical Research Day Award
- Massachusetts General Hospital, Fall 2018
- Mentor Award
- Harvard-MIT summer institute at MGH, Summer 2016
- Poster Exhibition Winner
- Dermatology Entrepreneurship Conference, Spring 2015
My research is focused on developing novel optical microscopy technologies and improving patient care using these technologies. My research area includes (1) lowcost smartphone in vivo microscopy, (2) high-speed comprehensive in vivo endomicroscopy, and (3) ultraminiature endomicroscopy.Low-cost smartphone in vivo microscopy: I am currently leading a NIH-sponsored research project for developing smartphone confocal microscope and diagnosing Kaposi's sarcoma in Uganda with the smartphone confocal microscope. I will further advance the smartphone microscopy technology and address other applications, including diagnosis of cervical and oral cancers in low-resource settings, large-population screening of skin cancers in the US, and aiding science and medical educations.High-speed comprehensive in vivo endomicroscopy: I have previously developed a high-speed confocal microscopy system and endoscopic imaging catheters and acquired largest in vivo confocal images of human organ reported. At the UA, I plan to further advance the technology by i) increasing the imaging speed by orders of magnitude and ii) incorporating fluorescence imaging modality.Ultraminiature endomicroscopy: In my previous research, I have developed miniature endoscopic catheters that can visualize internal organs in vivo through a needle-sized device. At the UA, I will develop microscopic imaging catheter with a extremely small diameter and utilize it for guiding cancer diagnosis and treatment.
Biomedical Optics; Biomedical instrumentation; Medical device development
Biomed Optics+BiphotonicBME 630 (Fall 2020)
Biomed Optics+BiphotonicOPTI 630 (Fall 2020)
Biomedical Engr SeminarBME 696A (Fall 2020)
Directed Graduate ResearchOPTI 792 (Fall 2020)
DissertationOPTI 920 (Fall 2020)
ThesisOPTI 910 (Fall 2020)
Biomedical InstrumentationBME 330 (Spring 2020)
Bme Student ForumBME 696C (Spring 2020)
DissertationOPTI 920 (Spring 2020)
Master's ReportOPTI 909 (Spring 2020)
ResearchOPTI 900 (Spring 2020)
ThesisOPTI 910 (Spring 2020)
Biomed Optics+BiphotonicOPTI 630 (Fall 2019)
Biomedical Engr SeminarBME 696A (Fall 2019)
DissertationOPTI 920 (Fall 2019)
ThesisOPTI 910 (Fall 2019)
Biomedical InstrumentationBME 330 (Spring 2019)
DissertationOPTI 920 (Spring 2019)
ThesisOPTI 910 (Spring 2019)
Biomed Optics+BiphotonicBME 630 (Fall 2018)
Biomed Optics+BiphotonicOPTI 630 (Fall 2018)
Independent StudyOPTI 599 (Fall 2018)
- Zhu, W., Gong, C., Kulkarni, N., Nguyen, C., & Kang, D. (2019). Smartphone based microscopes. In Smartphone based medical diagnostics.
- Do, D., Tearney, G. J., & Kang, D. (2017). Miniature confocal microscopy devices for imaging skin. In Reflectance confocal microscopy of cutaneous tumors.
- Woods, K., Kang, D., Neumann, H., Vieth, M., & Coron, E. (2014). Confocal Endomicroscopy. In Pathobiology of Human Disease.
- Gong, C., Kulkarni, N., Zhu, W., Nguyen, C. D., Curiel-Lewandrowski, C., & Kang, D. (2019). Low-cost, high-speed near infrared reflectance confocal microscope. Biomedical optics express, 10(7), 3497-3505.More infoWe have developed a low-cost, near-infrared (NIR) reflectance confocal microscope (RCM) to overcome challenges in the imaging depth and speed found in our previously-reported smartphone confocal microscope. In the new NIR RCM device, we have used 840 nm superluminescent LED (sLED) to increase the tissue imaging depth and speed. A new confocal detection optics has been developed to maintain high lateral resolution even when a relatively large slit width was used. The material cost of the NIR RCM device was still low, ~$5,200. The lateral resolution was 1.1 µm and 1.3 µm along the vertical and horizontal directions, respectively. Axial resolution was measured as 11.2 µm. confocal images of human forearm skin obtained at the imaging speed of 203 frames/sec clearly visualized characteristic epidermal and dermal cellular features of the human skin.
- Kang, D., Do, D., Ryu, J., Grant, C. N., Giddings, S. L., Rosenberg, M., Hesterberg, P. E., Yuan, Q., Garber, J. J., Katz, A. J., & Tearney, G. J. (2019). A miniaturized, tethered, spectrally-encoded confocal endomicroscopy capsule. Lasers in surgery and medicine.More infoThe tethered spectrally-encoded confocal endomicroscopy (SECM) capsule is an imaging device that once swallowed by an unsedated patient can visualize cellular morphologic changes associated with gastrointestinal (GI) tract diseases in vivo. Recently, we demonstrated a tethered SECM capsule for counting esophageal eosinophils in patients with eosinophilic esophagitis (EoE) in vivo. Yet, the current tethered SECM capsule is far too long to be widely utilized for imaging pediatric patients, who constitute a major portion of the EoE patient population. In this paper, we present a new tethered SECM capsule that is 33% shorter, has an easier and repeatable fabrication process, and produces images with reduced speckle noise.
- Zeidan, A., Do, D., Kang, D., Ikuta, M., Ryu, J., & Tearney, G. J. (2019). High-Resolution, Wide-Field, Forward-Viewing Spectrally Encoded Endoscope. Lasers in surgery and medicine, 51(9), 808-814.More infoSpectrally encoded endoscopy (SEE) is an optical imaging technology that uses spatial wavelength multiplexing to conduct endoscopy in miniature, small diameter probes. Contrary to the previous side-viewing SEE devices, forward-viewing SEE probes are advantageous as they provide a look ahead that facilitates navigation and surveillance. The objective of this work was to develop a miniature forward-viewing SEE probe with a wide field of view and a high spatial resolution.
- Freeman, E. E., Semeere, A., Osman, H., Peterson, G., Rajadhyaksha, M., González, S., Martin, J. N., Anderson, R. R., Tearney, G. J., & Kang, D. (2018). Smartphone confocal microscopy for imaging cellular structures in human skin. Biomedical optics express, 9(4), 1906-1915.More infoWe report development of a low-cost smartphone confocal microscope and its first demonstration of human skin imaging. The smartphone confocal microscope uses a slit aperture and diffraction grating to conduct two-dimensional confocal imaging without using any beam scanning devices. Lateral and axial resolutions of the smartphone confocal microscope were measured as 2 and 5 µm, respectively. confocal images of human skin revealed characteristic cellular structures, including spinous and basal keratinocytes and papillary dermis. Results suggest that the smartphone confocal microscope has a potential to examine cellular details and may help disease diagnosis in resource-poor settings, where conducting standard histopathologic analysis is challenging.
- Ikuta, M., Kang, D., Do, D., Zeidan, A., & Tearney, G. J. (2018). Single-beam spectrally encoded color imaging. Optics letters, 43(10), 2229-2232.More infoWe have developed, to the best of our knowledge, a new method of conducting spectrally encoded color imaging using a single light beam. In our method, a single broadband light beam was incident on a diffraction grating, where the overlapped third order of the red, fourth order of the green, and fifth order of the blue spectral bands were focused on a line illuminating tissue. This configuration enabled each point on the line to be illuminated by three distinctive wavelengths, corresponding to red, green, and blue. A custom grating was designed and fabricated to achieve high diffraction efficiencies for the wavelengths and diffraction orders used for color spectrally encoded imaging. A bench system was built to test the new spectrally encoded color imaging method. For a beam diameter of 174 μm, the bench system achieved 89,000 effective pixels over a 70° circular field. Spectrally encoded color images of excised swine tissue revealed blood vessels with a similar color appearance to those obtained via a conventional color camera. The results suggest that this single-beam spectrally encoded color method is feasible and can potentially simplify color spectrally encoded endoscopy probe designs.
- Tabatabaei, N., Kang, D., Kim, M., Wu, T., Grant, C. N., Rosenberg, M., Nishioka, N. S., Hesterberg, P. E., Garber, J., Yuan, Q., Katz, A. J., & Tearney, G. J. (2018). Clinical Translation of Tethered Confocal Microscopy Capsule for Unsedated Diagnosis of Eosinophilic Esophagitis. Scientific reports, 8(1), 2631.More infoEsophagogastroduodenoscopy (EGD) is a widely used procedure, posing significant financial burden on both healthcare systems and patients. Moreover, EGD is time consuming, sometimes difficult to tolerate, and suffers from an imperfect diagnostic yield as the limited number of collected biopsies does not represent the whole organ. In this paper, we report on technological and clinical feasibility of a swallowable tethered endomicroscopy capsule, which is administered without sedation, to image large regions of esophageal and gastric mucosa at the cellular level. To demonstrate imaging capabilities, we conducted a human pilot study (n = 17) on Eosinophilic Esophagitis (EoE) patients and healthy volunteers from which representative cases are presented and discussed. Results indicate that, compared to endoscopic biopsy, unsedated tethered capsule endomicroscopy obtains orders of magnitude more cellular information while successfully resolving characteristic tissue microscopic features such as stratified squamous epithelium, lamina propria papillae, intraepithelial eosinophils, and gastric cardia and body/fundic mucosa epithelia. Based on the major import of whole organ, cellular-level microscopy to obviate sampling error and the clear cost and convenience advantages of unsedated procedure, we believe that this tool has the potential to become a simpler and more effective device for diagnosing and monitoring the therapeutic response of EoE and other esophageal diseases.
- Tearney, G. J., & Kang, D. (2018). Introduction to biomedical optical imaging issue. Lasers in surgery and medicine, 50(3), 182.
- Kang, D., Schlachter, S. C., Carruth, R. W., Kim, M., Wu, T., Tabatabaei, N., Soomro, A. R., Grant, C. N., Rosenberg, M., Nishioka, N. S., & Tearney, G. J. (2017). Large-area spectrally encoded confocal endomicroscopy of the human esophagus in vivo. Lasers in surgery and medicine, 49(3), 233-239.More infoDiagnosis of esophageal diseases is often hampered by sampling errors that are inherent in endoscopic biopsy, the standard of care. Spectrally encoded confocal microscopy (SECM) is a high-speed reflectance confocal endomicroscopy technology that has the potential to visualize cellular features from large regions of the esophagus, greatly decreasing the likelihood of sampling error. In this paper, we report results from a pilot clinical study imaging the human esophagus in vivo with a prototype SECM endoscopic probe.
- Tearney, G. J., & Kang, D. (2017). Introduction to biomedical optical imaging. Lasers in surgery and medicine, 49(3), 214.
- Brachtel, E. F., Johnson, N. B., Huck, A. E., Rice-Stitt, T. L., Vangel, M. G., Smith, B. L., Tearney, G. J., & Kang, D. (2016). Spectrally encoded confocal microscopy for diagnosing breast cancer in excision and margin specimens. Laboratory investigation; a journal of technical methods and pathology, 96(4), 459-67.More infoA large percentage of breast cancer patients treated with breast conserving surgery need to undergo multiple surgeries due to positive margins found during post-operative margin assessment. Carcinomas could be removed completely during the initial surgery and additional surgery avoided if positive margins can be determined intraoperatively. Spectrally encoded confocal microscopy (SECM) is a high-speed reflectance confocal microscopy technology that has a potential to rapidly image the entire surgical margin at subcellular resolution and accurately determine margin status intraoperatively. In this study, in order to test the feasibility of using SECM for intraoperative margin assessment, we have evaluated the diagnostic accuracy of SECM for detecting various types of breast cancers. Forty-six surgically removed breast specimens were imaged with an SECM system. Side-by-side comparison between SECM and histologic images showed that SECM images can visualize key histomorphologic patterns of normal/benign and malignant breast tissues. Small (500 μm × 500 μm) spatially registered SECM and histologic images (n=124 for each) were diagnosed independently by three pathologists with expertise in breast pathology. Diagnostic accuracy of SECM for determining malignant tissues was high, average sensitivity of 0.91, specificity of 0.93, positive predictive value of 0.95, and negative predictive value of 0.87. Intra-observer agreement and inter-observer agreement for SECM were also high, 0.87 and 0.84, respectively. Results from this study suggest that SECM may be developed into an intraoperative margin assessment tool for guiding breast cancer excisions.
- Kang, D., Schlachter, S. C., Carruth, R. W., Kim, M., Wu, T., Tabatabaei, N., Vacas-Jacques, P., Shishkov, M., Woods, K., Sauk, J. S., Leung, J., Nishioka, N. S., & Tearney, G. J. (2014). Comprehensive confocal endomicroscopy of the esophagus in vivo. Endoscopy international open, 2(3), E135-40.More infoBiopsy sampling error can be a problem for the diagnosis of certain gastrointestinal tract diseases. Spectrally-encoded confocal microscopy (SECM) is a high-speed reflectance confocal microscopy technology that has the potential to overcome sampling error by imaging large regions of gastrointestinal tract tissues. The aim of this study was to test a recently developed SECM endoscopic probe for comprehensively imaging large segments of the esophagus at the microscopic level in vivo.
- Kim, M., Kang, D., Wu, T., Tabatabaei, N., Carruth, R. W., Martinez, R. V., Whitesides, G. M., Nakajima, Y., & Tearney, G. J. (2014). Miniature objective lens with variable focus for confocal endomicroscopy. Biomedical optics express, 5(12), 4350-61.More infoSpectrally encoded confocal microscopy (SECM) is a reflectance confocal microscopy technology that can rapidly image large areas of luminal organs at microscopic resolution. One of the main challenges for large-area SECM imaging in vivo is maintaining the same imaging depth within the tissue when patient motion and tissue surface irregularity are present. In this paper, we report the development of a miniature vari-focal objective lens that can be used in an SECM endoscopic probe to conduct adaptive focusing and to maintain the same imaging depth during in vivo imaging. The vari-focal objective lens is composed of an aspheric singlet with an NA of 0.5, a miniature water chamber, and a thin elastic membrane. The water volume within the chamber was changed to control curvature of the elastic membrane, which subsequently altered the position of the SECM focus. The vari-focal objective lens has a diameter of 5 mm and thickness of 4 mm. A vari-focal range of 240 μm was achieved while maintaining lateral resolution better than 2.6 μm and axial resolution better than 26 μm. Volumetric SECM images of swine esophageal tissues were obtained over the vari-focal range of 260 μm. SECM images clearly visualized cellular features of the swine esophagus at all focal depths, including basal cell nuclei, papillae, and lamina propria.
- Kang, D., Carruth, R. W., Kim, M., Schlachter, S. C., Shishkov, M., Woods, K., Tabatabaei, N., Wu, T., & Tearney, G. J. (2013). Endoscopic probe optics for spectrally encoded confocal microscopy. Biomedical optics express, 4(10), 1925-36.More infoSpectrally encoded confocal microscopy (SECM) is a form of reflectance confocal microscopy that can achieve high imaging speeds using relatively simple probe optics. Previously, the feasibility of conducting large-area SECM imaging of the esophagus in bench top setups has been demonstrated. Challenges remain, however, in translating SECM into a clinically-useable device; the tissue imaging performance should be improved, and the probe size needs to be significantly reduced so that it can fit into luminal organs of interest. In this paper, we report the development of new SECM endoscopic probe optics that addresses these challenges. A custom water-immersion aspheric singlet (NA = 0.5) was developed and used as the objective lens. The water-immersion condition was used to reduce the spherical aberrations and specular reflection from the tissue surface, which enables cellular imaging of the tissue deep below the surface. A custom collimation lens and a small-size grating were used along with the custom aspheric singlet to reduce the probe size. A dual-clad fiber was used to provide both the single- and multi- mode detection modes. The SECM probe optics was made to be 5.85 mm in diameter and 30 mm in length, which is small enough for safe and comfortable endoscopic imaging of the gastrointestinal tract. The lateral resolution was 1.8 and 2.3 µm for the single- and multi- mode detection modes, respectively, and the axial resolution 11 and 17 µm. SECM images of the swine esophageal tissue demonstrated the capability of this device to enable the visualization of characteristic cellular structural features, including basal cell nuclei and papillae, down to the imaging depth of 260 µm. These results suggest that the new SECM endoscopic probe optics will be useful for imaging large areas of the esophagus at the cellular scale in vivo.
- Kang, D., Martinez, R. V., Whitesides, G. M., & Tearney, G. J. (2013). Miniature grating for spectrally-encoded endoscopy. Lab on a chip, 13(9), 1810-6.More infoSpectrally-encoded endoscopy (SEE) is an ultraminiature endoscopy technology that acquires high-definition images of internal organs through a sub-mm endoscopic probe. In SEE, a grating at the tip of the imaging optics diffracts the broadband light into multiple beams, where each beam with a distinctive wavelength is illuminated on a unique transverse location of the tissue. By encoding one transverse coordinate with the wavelength, SEE can image a line of the tissue at a time without using any beam scanning devices. This feature of the SEE technology allows the SEE probe to be miniaturized to sub-mm dimensions. While previous studies have shown that SEE has the potential to be utilized for various clinical imaging applications, the translation of SEE for medicine has been hampered by challenges in fabricating the miniature grating inherent to SEE probes. This paper describes a new fabrication method for SEE probes. The new method uses a soft lithographic approach to pattern a high-aspect-ratio grating at the tip of the miniature imaging optics. Using this technique, we have constructed a 500 μm-diameter SEE probe. The miniature grating at the tip of the probe had a measured diffraction efficiency of 75%. The new SEE probe was used to image a human finger and formalin fixed mouse embryos, demonstrating the capability of this device to visualize key anatomic features of tissues with high image contrast. In addition to providing high quality imaging SEE optics, the soft lithography method allows cost-effective and reliable fabrication of these miniature endoscopes, which will facilitate the clinical translation of SEE technology.
- Schlachter, S. C., Kang, D., Gora, M. J., Vacas-Jacques, P., Wu, T., Carruth, R. W., Wilsterman, E. J., Bouma, B. E., Woods, K., & Tearney, G. J. (2013). Spectrally encoded confocal microscopy of esophageal tissues at 100 kHz line rate. Biomedical optics express, 4(9), 1636-45.More infoSpectrally encoded confocal microscopy (SECM) is a reflectance confocal microscopy technology that uses a diffraction grating to illuminate different locations on the sample with distinct wavelengths. SECM can obtain line images without any beam scanning devices, which opens up the possibility of high-speed imaging with relatively simple probe optics. This feature makes SECM a promising technology for rapid endoscopic imaging of internal organs, such as the esophagus, at microscopic resolution. SECM imaging of the esophagus has been previously demonstrated at relatively low line rates (5 kHz). In this paper, we demonstrate SECM imaging of large regions of esophageal tissues at a high line imaging rate of 100 kHz. The SECM system comprises a wavelength-swept source with a fast sweep rate (100 kHz), high output power (80 mW), and a detector unit with a large bandwidth (100 MHz). The sensitivity of the 100-kHz SECM system was measured to be 60 dB and the transverse resolution was 1.6 µm. Excised swine and human esophageal tissues were imaged with the 100-kHz SECM system at a rate of 6.6 mm(2)/sec. Architectural and cellular features of esophageal tissues could be clearly visualized in the SECM images, including papillae, glands, and nuclei. These results demonstrate that large-area SECM imaging of esophageal tissues can be successfully conducted at a high line imaging rate of 100 kHz, which will enable whole-organ SECM imaging in vivo.
- Tabatabaei, N., Kang, D., Wu, T., Kim, M., Carruth, R. W., Leung, J., Sauk, J. S., Shreffler, W., Yuan, Q., Katz, A., Nishioka, N. S., & Tearney, G. J. (2013). Tethered confocal endomicroscopy capsule for diagnosis and monitoring of eosinophilic esophagitis. Biomedical optics express, 5(1), 197-207.More infoEosinophilic esophagitis (EoE) is an allergic condition that is characterized by eosinophils infiltrating the esophageal wall. The treatment of the disease may require multiple follow up sedated endoscopies and biopsies to confirm elimination of eosinophils. These procedures are expensive, time consuming, and may be difficult for patients to tolerate. Here we report on the development of a confocal microscopy capsule for diagnosis and monitoring of EoE. The swallowable capsule implements a high-speed fiber-based reflectance confocal microscopy technique termed Spectrally Encoded Confocal Microscopy (SECM). SECM scans the sample in one dimension without moving parts by using wavelength swept source illumination and a diffraction grating at the back plane of the objective lens. As the wavelength of the source is tuned, the SECM optics within the 7 x 30 mm capsule are rotated using a driveshaft enclosed in a 0.8 mm flexible tether. A single rotation of the optics covered a field of view of 22 mm x 223 µm. The lateral and axial resolutions of the device were measured to be 2.1 and 14 µm, respectively. Images of Acetic Acid stained swine esophagus obtained with the capsule ex vivo and in vivo clearly showed squamous epithelial nuclei, which are smaller and less reflective than eosinophils. Imaging of esophageal biopsies from EoE patients ex vivo demonstrated the capability of this technology to visualize individual eosinophils. Based on the results of this study, we believe that this capsule will be a simpler and more effective device for diagnosing EoE and monitoring the therapeutic response of this disease.
- Unglert, C. I., Namati, E., Warger, W. C., Liu, L., Yoo, H., Kang, D., Bouma, B. E., & Tearney, G. J. (2012). Evaluation of optical reflectance techniques for imaging of alveolar structure. Journal of biomedical optics, 17(7), 071303.More infoThree-dimensional (3-D) visualization of the fine structures within the lung parenchyma could advance our understanding of alveolar physiology and pathophysiology. Current knowledge has been primarily based on histology, but it is a destructive two-dimensional (2-D) technique that is limited by tissue processing artifacts. Micro-CT provides high-resolution three-dimensional (3-D) imaging within a limited sample size, but is not applicable to intact lungs from larger animals or humans. Optical reflectance techniques offer the promise to visualize alveolar regions of the large animal or human lung with sub-cellular resolution in three dimensions. Here, we present the capabilities of three optical reflectance techniques, namely optical frequency domain imaging, spectrally encoded confocal microscopy, and full field optical coherence microscopy, to visualize both gross architecture as well as cellular detail in fixed, phosphate buffered saline-immersed rat lung tissue. Images from all techniques were correlated to each other and then to corresponding histology. Spatial and temporal resolution, imaging depth, and suitability for in vivo probe development were compared to highlight the merits and limitations of each technology for studying respiratory physiology at the alveolar level.
- Kang, D., Yoo, H., Jillella, P., Bouma, B. E., & Tearney, G. J. (2011). Comprehensive volumetric confocal microscopy with adaptive focusing. Biomedical optics express, 2(6), 1412-22.More infoComprehensive microscopy of distal esophagus could greatly improve the screening and surveillance of esophageal diseases such as Barrett's esophagus by providing histomorphologic information over the entire region at risk. Spectrally encoded confocal microscopy (SECM) is a high-speed reflectance confocal microscopy technology that can be configured to image the entire distal esophagus by helically scanning the beam using optics within a balloon-centering probe. It is challenging to image the human esophagus in vivo with balloon-based SECM, however, because patient motion and anatomic tissue surface irregularities decenter the optics, making it difficult to keep the focus at a predetermined location within the tissue as the beam is scanned. In this paper, we present a SECM probe equipped with an adaptive focusing mechanism that can compensate for tissue surface irregularity and dynamic focal variation. A tilted arrangement of the objective lens is employed in the SECM probe to provide feedback signals to an adaptive focusing mechanism. The tilted configuration also allows the probe to obtain reflectance confocal data from multiple depth levels, enabling the acquisition of three-dimensional volumetric data during a single scan of the probe. A tissue phantom with a surface area of 12.6 cm(2) was imaged using the new SECM probe, and 8 large-area reflectance confocal microscopy images were acquired over the depth range of 56 μm in 20 minutes. Large-area SECM images of excised swine small intestine tissue were also acquired, enabling the visualization of villous architecture, epithelium, and lamina propria. The adaptive focusing mechanism was demonstrated to enable acquisition of in-focus images even when the probe was not centered and the tissue surface was irregular.
- Yoo, H., Kang, D., Katz, A. J., Lauwers, G. Y., Nishioka, N. S., Yagi, Y., Tanpowpong, P., Namati, J., Bouma, B. E., & Tearney, G. J. (2011). Reflectance confocal microscopy for the diagnosis of eosinophilic esophagitis: a pilot study conducted on biopsy specimens. Gastrointestinal endoscopy, 74(5), 992-1000.More infoDiagnosis of eosinophilic esophagitis (EoE) currently requires endoscopic biopsy and histopathologic analysis of the biopsy specimens to count intraepithelial eosinophils. Reflectance confocal microscopy (RCM) is an endomicroscopy technology that is capable of obtaining high-resolution, optically sectioned images of esophageal mucosa without the administration of exogenous contrast.
- Kang, D., Suter, M. J., Boudoux, C., Yoo, H., Yachimski, P. S., Puricelli, W. P., Nishioka, N. S., Mino-Kenudson, M., Lauwers, G. Y., Bouma, B. E., & Tearney, G. J. (2010). Comprehensive imaging of gastroesophageal biopsy samples by spectrally encoded confocal microscopy. Gastrointestinal endoscopy, 71(1), 35-43.More infoSpectrally encoded confocal microscopy (SECM) is a high-speed reflectance confocal microscopy technique that has the potential to be used for acquiring comprehensive images of the entire distal esophagus endoscopically with subcellular resolution.
- Kang, D., Yelin, D., Bouma, B. E., & Tearney, G. J. (2009). Spectrally-encoded color imaging. Optics express, 17(17), 15239-47.More infoSpectrally-encoded endoscopy (SEE) is a technique for ultraminiature endoscopy that encodes each spatial location on the sample with a different wavelength. One limitation of previous incarnations of SEE is that it inherently creates monochromatic images, since the spectral bandwidth is expended in the spatial encoding process. Here we present a spectrally-encoded imaging system that has color imaging capability. The new imaging system utilizes three distinct red, green, and blue spectral bands that are configured to illuminate the grating at different incident angles. By careful selection of the incident angles, the three spectral bands can be made to overlap on the sample. To demonstrate the method, a bench-top system was built, comprising a 2400-lpmm grating illuminated by three 525-microm-diameter beams with three different spectral bands. Each spectral band had a bandwidth of 75 nm, producing 189 resolvable points. A resolution target, color phantoms, and excised swine small intestine were imaged to validate the system's performance. The color SEE system showed qualitatively and quantitatively similar color imaging performance to that of a conventional digital camera.
- Kim, J., Kang, D., & Gweon, D. (2006). Spectrally encoded slit confocal microscopy. Optics letters, 31(11), 1687-9.More infoA simple and cost-effective method for real-time imaging in confocal microscopy is proposed. Spectrally encoded slit confocal microscopy (SESCoM) uses a spectral encoding technique together with a confocal slit aperture to achieve two-dimensional images. Simulation and experimental results of the SESCoM's axial and lateral performances are presented. The measured FWHM of the axial response is 1.15 mum when an objective with a NA of 0.95 is used. FWHMs of the lateral line spread functions are measured to be 236 and 244 nm along the x and y directions, respectively. Both the axial and the lateral experimental results agree well with the simulation results.
- Kang, D., & Gweon, D. (2005). Image of a straight edge in confocal self-interference microscopy. Optics letters, 30(13), 1650-2.More infoAn image of a straight edge in confocal self-interference microscopy (CSIM) is analyzed. Simulations of edge images based on a two-dimensional imaging equation are presented that show a 103% increase in edge gradient and a 43.1% decrease in the 10-90% width. The first experimental results, to our knowledge, for CSIM are presented and show good agreement with the simulation results and a 23% decrease in the 10-90% width.
- Kang, D., & Gweon, D. (2005). Two-dimensional imaging theory of confocal self-interference microscopy. Journal of the Optical Society of America. A, Optics, image science, and vision, 22(12), 2737-45.More infoA two-dimensional coherent imaging equation is derived for confocal self-interference microscopy (CSIM), which uses a birefringent material to generate an interference pattern in the detection optics. This interference pattern, called a self-interference pattern, sharpens the point-spread function (PSF) along the lateral direction. To derive the imaging equation, an equation for the self-interference pattern is derived. Numerical simulation results based on the imaging equation are presented. One-point response results show a 42.8% reduction in the FWHM of the lateral PSF. Two-point response results show a nearly twofold improvement in two-point resolution.
- Kang, D., & Gweon, D. (2003). Enhancement of lateral resolution in confocal self-interference microscopy. Optics letters, 28(24), 2470-2.More infoWe describe confocal self-interference microscopy with enhanced lateral resolution. A uniaxial anisotropic crystal is used to cause interference between two linearly polarized beams that are reflected from the same pointlike object in the focal plane of the objective lens. Theory and the optimal design that maximizes the sensitivity of the interference signal are presented. A numerical experiment shows a 38% decrease in the lateral FWHM for simple confocal self-interference microscopy.
- Kang, D. (2019, April). Light sheet microscopy of human skin in vivo. OSA Biophotonics Congress.
- Kang, D. (2019, April). Low-cost, high-speed near-infrared confocal microscope. OSA Biophotonics Congress.
- Kang, D. (2019, February). Artifact correction and automated eosinophil counting for SECM tethered capsule endomicroscopy. Photonics West.
- Kang, D. (2019, February). Evaluating fibrin polymerization dynamics in three dimensions peri-operatively in cardiac surgical patients using spectrally encoded confocal microscopy (SECM). Photonics West.
- Kang, D. (2019, February). High-speed spectrally encoded confocal microscopy (SECM) using 100-kHz swept source laser. Photonics West.
- Kang, D. (2019, February). Implementation of a Portable Confocal Microscope to Diagnose Kaposi’s Sarcoma: The Challenge of Point-of-Care Diagnostics for Skin of Color in Low Resource Settings. Skin of Color Society (SOCS) 15th Annual Scientific Symposium.
- Kang, D. (2019, February). Low-cost, smartphone confocal microscope. Photonics West.
- Kang, D. (2019, February). Preclinical swine joint imaging using forward-viewing spectrally encoded endoscopy. Photonics West.
- Kang, D. (2019, February). Probe-based video-rate color forward-view spectrally encoded endoscopy,. Photonics West.
- Kang, D. (2019, February). Smartphone confocal microscopy for imaging Kaposi’s sarcoma in low-resource settings. Photonics West.
- Kang, D. (2019, June). NOVEL POINT OF CARE DIAGNOSTIC STRATEGIES FOR SKIN DISEASE IN LOW RESOURCE SETTINGS: PORTABLE CONFOCAL MICROSCOPY FOR KAPOSI’S SARCOMA. 24th World Congress of Dermatology.
- Kang, D. (2019, May). AUTOMATED DIAGNOSIS OF EOSINOPHILIC ESOPHAGITIS FROM LARGE IMAGES OBTAINED BY SPECTRALLY-ENCODED TETHERED CAPSULE REFLECTANCE ENDOMICROSCOPY. Digestive Diseases Week.
- Kang, D. (2019, September). High-speed blood flow imaging with scanless confocal microscope. IEEE Photonics Conference 2019.
- Freeman, E. E., Semeere, A., Namaganda, P., Martin, J., Gonzalez, S., Peterson, G., Rajadhyaksha, M., Anderson, R. R., Tearney, G. J., & Kang, D. (2018, January). Smartphone confocal microscopy of human skin in vivo. Photonics West.
- Kang, D. (2018, January). Spectrally encoded confocal microscopy for comprehensive and low-cost in vivo cellular imaging. BME seminar.
- Kang, D. (2018, January). Spectrally encoded confocal microscopy for comprehensive and low-cost in vivo cellular imaging. OSC Colloquium.
- Kang, D., Do, D., Grant, C. N., Giddings, S. L., Rosenberg, M., Hesterberg, P. E., Yuan, Q., Garber, J. J., Katz, A. J., & Tearney, G. J. (2018, January). Small SECM endoscopic capsule for imaging human esophagus in vivo. Photonics West.
- Zeidan, A., Do, D., Kang, D., Ikuta, M., & Tearney, G. J. (2018, January). Forward-viewing spectrally encoded endoscopy with angled detection optics. Photonics West.
- Do, D., Kang, D., Ikuta, M., Hyun, C., & Tearney, G. J. (2017, January). Forward-viewing spectrally encoded endoscopy. Photonics West.
- Ikuta, M., Kang, D., Do, D., & Tearney, G. J. (2017, January). Single-fiber approach for color spectrally encoded endoscopy. Photonics West.
- Kang, D. (2017, May). In vivo Cellular Imaging with Spectrally Encoded Confocal Microscopy. Conference on Lasers and Electro-Optics (CLEO).
- Kang, D., Kim, M., Do, D., Grant, C. N., Rosenberg, M., Nishioka, N. S., & Tearney, G. J. (2017, January). In vivo imaging of human esophagus with SECM half-inch tethered endoscopic capsule. Photonics West.
- Kang, D., Tabatabaei, N., Do, D., & Tearney, G. J. (2017, January). Clinical experience with spectrally encoded confocal microscopy for imaging human esophagus in vivo. Photonics West.
- Kang, D. (2019, November). Low-cost confocal microscopy for point-of-care cellular morphologic imaging in vivo. NIH-IEEE Health Innovations Point-of-care Technology.
- Freeman, E. E., Semeere, A., Namaganda, P., Laker-Oketta, M., Lukande, R., Tearney, G. J., Gonzalez, S., Rajadhyaksha, M., Anderson, R. R., Martin, J., & Kang, D. (2017, July). Portable Confocal Microscopy as a Diagnostic Tool for Kaposi’s Sarcoma in Africa. International Conference on Malignancies in HIV/AIDS (ICMH).