Catheter-based intraluminal optical coherence tomography of the normal human upper urinary tract in vivo: proof of concept and comparison with an ex-vivo porcine model

Abstract

Objective: Single-slice, cross-sectional, intraluminal optical-coherence-tomography (OCT) is a new destruction-free optical imaging method that could be applied clinically to examine the upper urinary tract from within. In-vivo access to the human upper urinary tract (UUT) was attempted. Similar performance statistics as in ex-vivo porcine UUT were expected for delineation of different wall layers by in-vivo OCT of human UUTs.

MATERIALS AND METHODS: Institutional ethics committee approved OCT in a volunteer sample of 15 patients suspected of having UUT pathology (urolithiasis, strictures, urothelial carcinoma (UC)). Commercially available, catheter-mounted 400-μm-OCT-probes (lateral resolution, < 20 µm) were introduced through a rigid cystoscope and urinary catheter or a rigid ureteroscope. Delineations of different UUT wall layers were recorded for quadrants of OCT images. Continuity-corrected-chi-square-statistics were considered to be significant for P < 0.05.

RESULTS: OCT was technically successful in all patients. Among quadrants of OCT images of normal UUT in vivo (n = 532) and ex vivo (n = 248), respectively, two observers in consensus found that any tissue layers delineated in 454 (85%) and 223 (90%, P = 0.089), urothelium-lamina propria in 362 (68%) and 193 (78%, P = 0.006), lamina propria-muscle layer in 445 (84%) and 200 (81%, P = 0.352), different muscle layers in 191 (36%) and 207 (84%, P < 0.001), and different urothelial cell layers in 17 (3%) and 172 (69%, P < 0.001). Histopathology-confirmed non-invasive superficial UC showed intraluminal, papillary urothelial protrusions with undistorted lamina propria in three patients.

CONCLUSIONS: In-vivo OCT is technically feasible in the human UUT and may demonstrate urothelium, lamina propria, and muscle layer, and recognize non-invasive UC.