Catheter-based intraluminal optical coherence tomography (OCT) of the ureter: ex-vivo correlation with histology in porcine specimens

Intraluminal optical coherence tomography (OCT) applies coherent light to provide cross-sectional images with a spatial resolution of 10–25 μm. We compared OCT and matching whole-mount histology microscopy sections of porcine upper ureters ex vivo for visualization and delineation of different tissue layers of the ureteral wall. Porcine ureters (six specimens, 24 quadrants) were flushed with normal saline solution prior to insertion of the OCT catheter (diameter, 0.014 inch, OCT wavelength, 1,300±20 nm). Cross-sectional OCT images were obtained in marked locations before specimens were fixed in 4% formalin, cut at marked locations, whole-mounted, and stained with hematoxilin and eosin. Visualization and delineation of different tissue layers of the ureteral wall by OCT was compared with matching histology by two independent observers (O1,O2). OCT distinguished tissue layers of the ureteral wall in all quadrants. In OCT images, O1/O2 delineated urothelium and lamina propria in 23/24 quadrants, lamina propria and muscle layer in 19/16 quadrants, inner and outer muscle layer in 13/0 quadrants, and urothelial cell layers in 13/2 quadrants, respectively. Intraluminal OCT provides histology-like images of the ureter in porcine specimens ex vivo and reliably distinguishes between urothelium and deeper tissue layers of the ureteral wall.