Dongkyun Kang
Assistant Professor, BIO5 Institute
Assistant Professor, Biomedical Engineering
Assistant Professor, Optical Sciences
Primary Department
(520) 621-6997
Work Summary
We are developing low-cost in vivo microscopy devices that can visualize cellular details of human tissues in vivo and help disease diagnosis and treatment in low-resource settings, high-speed tissue microscopy technologies that can examine entire organ under risk of having malignant diseases and detect small, early-stage lesions, and miniature microscopy devices that have the potential to examine anatomically-challenging human organs and facilitate integration of microscopic imaging with other imaging modalities.
Research Interest
My research is focused on developing novel optical microscopy technologies and improving patient care using these technologies. My research area includes (1) low-cost smartphone in vivo microscopy, (2) high-speed comprehensive in vivo endomicroscopy, and (3) ultraminiature endomicroscopy. (1) 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. (2) 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. (3) 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.

Publications

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.

Biopsy 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.

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.

Spectrally 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.

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.

Three-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.

Ikuta, M., Kang, D., Do, D., Zeidan, A., & Tearney, G. J. (2018). Spectrally encoded color imaging with a single light beam. Optics Letters.
Kang, D., & Gweon, D. (2003). Enhancement of lateral resolution in confocal self-interference microscopy. Optics letters, 28(24), 2470-2.

We 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.