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Recently, the functional extension of optical coherence tomography (OCT) with OCT angiography (OCTA) allows volumetric imaging of the subsurface microvasculature without requiring exogenous contrast agents like conventional angiography techniques. However, performing OCTA requires intensive computation to extract the changes of OCT signal due to moving red blood cells in the microvascular network. In this study, we have developed a graphic processing unit (GPU)-accelerated framework to realize high speed OCTA imaging and the visualization of the microvascular network after the data acquisition. In addition, we investigate the feasibility of providing real-time microvascular imaging leveraging dynamic scattering OCT and GPU.

Oral cancer was ranked as the fifth most common cancers in both sexes in Taiwan in 2014. For patients diagnosed with the advanced or late stage of oral SCC, the five-year survival rate is reported to be ~ 33% suggesting the importance of the early detection of oral cancer. There have been various studies of investigating the clinical utility of OCT for the early detection of oral precancerous lesions with 1300 nm OCT technology. In this study, we have developed a long-wavelength, multiscale OCT imaging system enabling multiscale imaging of the ex vivo oral precancerous tissue with an increased imaging depth. Objectives with two different magnifications are mounted to a power turret, enabling seamless change of the OCT imaging resolution via the software control. OCT imaging over a variety of oral precancer pathologies will be demonstrated with above OCT system.

Endoscopic optical coherence tomography (OCT) angiography enables volumetric coregistered architectural and microvasculature imaging of the human gastrointestinal tract in vivo. In this talk, we will discuss technical advances and clinical gastroenterology applications with the endoscopic OCT angiography technique.

Miniaturization and cost reduction of OCT systems are important for enabling many new clinical applications as well as accelerating the development of existing applications. Silicon photonics is an important low-cost, high-volume, multi-functional platform for integrated optics because it can benefit from existing semiconductor fabrication techniques to integrate many advanced optical functions onto a single microchip. We present a miniaturized silicon photonic integrated swept source OCT receiver, measuring 3×4mm2, with advanced functionalities including dual polarization, dual balanced, in-phase and quadrature detection, essentially enabling the detection of the full vector field (amplitude, phase, and polarization) of the optical signal. With this integrated receiver, we demonstrate full-range OCT for complex conjugate artifact suppression, polarization diversity detection for removing polarization fading artifact, and polarization sensitive OCT for tissue birefringence imaging. The silicon photonic integrated receiver is a key advance towards developing a miniaturized, multi-functional swept source OCT system.

We developed an ultrahigh speed endoscopic swept source optical coherence tomography (OCT) system for clinical gastroenterology using a vertical-cavity surface-emitting laser (VCSEL) and micromotor based imaging catheter, which provided an imaging speed of 600 kHz axial scan rate and 8 μm axial resolution in tissue. The micromotor catheter was 3.2 mm in diameter and could be introduced through the 3.7 mm accessory port of an endoscope. Imaging was performed at 400 frames per second with an 8 μm spot size using a pullback to generate volumetric data over 16 mm with a pixel spacing of 5 μm in the longitudinal direction. Three-dimensional OCT (3D-OCT) imaging was performed in patients with a cross section of pathologies undergoing standard upper and lower endoscopy at the Veterans Affairs Boston Healthcare System (VABHS). Patients with Barrett’s esophagus, dysplasia, and inflammatory bowel disease were imaged. The use of distally actuated imaging catheters allowed OCT imaging with more flexibility such as volumetric imaging in the terminal ileum and the assessment of the hiatal hernia using retroflex imaging. The high rotational stability of the micromotor enabled 3D volumetric imaging with micron scale volumetric accuracy for both en face and cross-sectional imaging. The ability to perform 3D OCT imaging in the GI tract with microscopic accuracy should enable a wide range of studies to investigate the ability of OCT to detect pathology as well as assess treatment response.

Excisional biopsy is the current gold standard for disease diagnosis; however, it requires a relatively long processing time and it may also suffer from unacceptable false negative rates due to sampling errors. Optical coherence tomography (OCT) is a promising imaging technique that provide real-time, high resolution and three-dimensional (3D) images of tissue morphology. Optical coherence microscopy (OCM) is an extension of OCT, combining both the coherence gating and the confocal gating techniques. OCM imaging achieves cellular resolution with deeper imaging depth compared to confocal microscopy. An integrated OCT/OCM imaging system can provide co-registered multiscale imaging of tissue morphology. 3D-OCT provides architectural information with a large field of view and can be used to find regions of interest; while OCM provides high magnification to enable cellular imaging. The integrated OCT/OCM system has an axial resolution of

Barrett's esophagus (BE) with high-grade dysplasia is generally treated by endoscopic mucosal resection or esophagectomy. Radiofrequency ablation (RFA) is a recent treatment that allows broad and superficial ablation for BE. Endoscopic three-dimensional optical coherence tomography (3D-OCT) is a volumetric imaging technique that is uniquely suited for follow-up surveillance of RFA treatment. 3D-OCT uses a thin fiberoptic imaging catheter placed down the working channel of a conventional endoscope. 3D-OCT enables en face and cross-sectional evaluation of the esophagus for detection of residual BE, neo-squamous mucosa, or buried BE glands. Patients who had undergone RFA treatment with the BARRX HALO90 system were recruited and imaged with endoscopic 3D-OCT before and after (3-25 months) RFA treatment. 3D-OCT findings were compared to pinch biopsy to confirm the presence or absence of squamous epithelium or buried BE glands following RFA. Gastric, BE, and squamous epithelium were readily distinguished from 3D-OCT over a large volumetric field of view (8mmx20mmx1.6 mm) with ~5μm axial resolution. In all patients, neosquamous epithelium (NSE) was observed in regions previously treated with RFA. A small number of isolated glands were found buried beneath the regenerated NSE and lamina propria. NSE is a marker of successful ablative therapy, while buried glands may have malignant potential and are difficult to detect using conventional video endoscopy and random biopsy. Buried glands were not observed with pinch biopsy due to their extremely sparse distribution. These results indicate a potential benefit of endoscopic 3D-OCT for follow-up assessment of ablative treatments for BE.