In Vivo Imaging of the Biliary (BD) and Pancreatic Duct (PD) with Optical Coherence Tomography (OCT) During ERCP

Abstract

Background: Pancreatic adenocarcinomas and cholangiocarcinomas likely arise from dysplastic PD and BD epithelium, respectively. Current imaging techniques are unable to detect these dysplastic lesions because these changes occur at the microscopic level. OCT has the potential to image cellular and subcellular structures. Aims: (1) to image the BD and PD in vivo with OCT in diseased and normal states and (2) to correlate high resolution endoscopic OCT imaging with histopathologic changes of the PD and BD epithelium. Methods: Patients age ≥18 years undergoing ERCP for the evaluation of biliary or pancreatic disease were eligible. After fluoroscopic evaluation of the BD or PD, but prior to any endoscopic stent placement, a 2.4 mm diameter radial scanning OCT probe was passed over a guidewire using a monorail type system. Digitized images of the entire OCT examination with a corresponding fluoroscopic image identifying the location of the OCT probe and the distance of the probe from the major papilla were recorded during probe withdrawal. Histologic analysis of brush cytology, biopsy, EUS-FNA, and/or surgical resection specimens from the corresponding area of interest in the BD or PD was reviewed in blinded fashion. OCT features characterized on the basis of our previous experience in dogs and reported in humans (reflectance pattern, intensity, and structural organization) were compared to the fluoroscopic and histologic features of normal epithelium, inflammation, dysplasia, and cancer. Results: 11 patients (6 men; 5 women; mean age 67, range 35-89) were enrolled with BD OCT imaging in 9 pts [2 normal and 7 strictures - 1 extrinsic Hodgkin's lymphoma, 2 pancreatic cancer, 2 benign PSC-dominant strictures, 1 autoimmune pancreatitis (AIP), and 1 cholangiocarcinoma] and PD OCT imaging in 2 pts [1 chronic pancreatitis stricture and 1 pancreatic cancer]. Average fluoro time for OCT imaging was 12 seconds (range 3-34). Low light scattering and loss of organizational structure on OCT correlated with dysplasia and cancer in all patients with cancer. In patients with inflammation, a heterogenous reflectance pattern and wall thickening was noted in 3 of 4 with a homogenous low reflectance pattern in the AIP patient. No complications occurred. Conclusions: In this pilot study, in vivo intraductal OCT of the BD and PD was both feasible and safe. Intraductal OCT appears to have the potential for identifying dysplastic cellular changes or cancer in the PD or BD epithelium during ERCP.