Yang VXD et al. (2005) Endoscopic Doppler optical coherence tomography in the human GI tract: initial experience. Gastrointest Endosc 61: 879–890

Optical coherence tomography (OCT) is an emerging endoscopic imaging technique that can visualize mucosal and submucosal microstructure. Functional OCT has also been developed with the addition of Doppler measurements, which could enable the detection and monitoring of changes in microvasculature and the assessment of vascular disease progression. Yang et al. performed a pilot trial in 22 patients undergoing routine esophagogastroduodenoscopy or flexible sigmoidoscopy, to evaluate the clinical feasibility of endoscopic Doppler (ED)OCT in normal and diseased conditions of the gastrointestinal tract.

The study found that the subsurface microstructure and microcirculation EDOCT images varied in vessel diameter, distribution, density and blood flow, for the different pathological gastrointestinal tissues and normal tissues.

There were no medical complications during the procedures and EDOCT was compatible with clinical endoscopic equipment. EDOCT imaging extended the endoscopy session by 10–20 min. In the Doppler mode, the apparatus achieved a velocity resolution that was 10-fold to 100-fold higher than Doppler endoscopic ultrasound. Limitations of EDOCT included 'Doppler shadows' below the vessels, lack of pressure sensors in the apparatus, and no standard comparable images for in vivo microcirculation visualization.

The authors conclude that EDOCT imaging is feasible in the gastrointestinal tract during endoscopy; however, the results of the trial are preliminary and further rigorous trials are required to determine whether EDOCT can be used to distinguish between healthy and diseased tissues, and between different pathologies.