Feature Of The Week 03/08/2015: Endoscopic Optical Coherence Angiography Enables Three Dimensional Visualization of Subsurface Microvasculature
Endoscopic imaging technologies such as confocal laser endomicroscopy (CLE) and narrowband imaging (NBI) have been used to investigate vascular changes as hallmarks of early cancer in the GI tract. However, the limited frame rate and field of view make CLE imaging sensitive to motion artifacts, whereas NBI has limited resolution and visualizes only the surface vascular pattern. Endoscopic optical coherence tomography (OCT) enables high speed volumetric imaging of subsurface features at near-microscopic resolution, and can image microvasculature without exogenous contrast agents such as fluorescein, which obliterates the image in areas of bleeding, or after biopsies and resections. OCT has been demonstrated for visualizing microvasculature in small animal models and larger vasculature in swine, however, the speed, resolution, and stability of previous systems were not sufficient for 3D visualization of microvasculature in endoscopic clinical applications. In this study, we developed an ultrahigh speed endoscopic OCT imaging system for clinical gastroenterology using a high speed swept source and a micromotor imaging catheter, and performed endoscopic OCT imaging in the human GI tract with a 10-fold higher imaging speed and dramatically improved scanning stability compared to commercially available endoscopic OCT systems. The system achieved a 600 kHz axial scan rate and 8 μm axial resolution in tissue. High imaging speed and stable distal scanning provide dense sampling with wide coverage, enabling OCT angiography in the human GI tract. Endoscopic OCT angiography of normal esophagus, non-dysplastic Barrett’s esophagus (BE) and normal recto-anal junction are demonstrated.
1. Tsai, et al., “Endoscopic Optical Coherence Angiography Enables Three Dimensional Visualization of Subsurface Microvasculature” Gastroenterology 147 (6), 1219-1221 (2014).
2. Ahsen, et al., “Correction of Rotational Distortion for Catheter Based en face OCT and OCT Angiography” Optics Letter 39 (20), 5973-5976 (2014).
3. Tsai, et al., “Ultrahigh Speed Endoscopic Optical Coherence Tomography for Gastroenterology,” Biomedical Optics Express 5 (12), 4387-4404 (2014).
Courtesy of Tsung-Han Tsal and James Fujimoto and from Massachusetts Institute of Technology.