Dongkyun Kang

Dongkyun Kang

Assistant Professor, BIO5 Institute
Assistant Professor, Biomedical Engineering
Assistant Professor, Optical Sciences
Primary Department
Contact
(520) 621-6997

Work Summary

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

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

Tearney, G. J., & Kang, D. (2017). Introduction to biomedical optical imaging. Lasers in surgery and medicine, 49(3), 214.
Kim, J., Kang, D., & Gweon, D. (2006). Spectrally encoded slit confocal microscopy. Optics letters, 31(11), 1687-9.

A 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.

An 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.

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.

Eosinophilic 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.

Kang, D., Yelin, D., Bouma, B. E., & Tearney, G. J. (2009). Spectrally-encoded color imaging. Optics express, 17(17), 15239-47.

Spectrally-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.