Three-Dimensional Optical Coherence Tomography on Endoscopic Mucosal Resection Specimens Confirms Identification of Malignant From Metaplastic Lesions in Patients With Barrett's Esophagus

Abstract

BACKGROUND/AIMS: Endoscopic mucosal resection (EMR) has been an effective method to assess patients with esophageal nodules arising in Barrett's esophagus (BE). Optical Coherence Tomography (OCT) enables real-time, three-dimensional (3D) imaging of tissue microstructure, with resolution approaching histology and can be used to evaluate pathological features both In Vivo and within EMR specimens. In comparison, the latter is difficult to assess on confocal endoscopy which depends on In Vivo fluorescein to achieve optimal images . METHODS: A prototype OCT imaging system was developed in collaboration with the LightLab imaging Inc., providing images with an axial resolution of ~5um in tissue and ~15um along the transverse dimension. The OCT system has an axial scanning rate of ~59kHz and the system sensitivity is 103dB. The in-house developed fiberoptic imaging probe (2.5mm in diameter) can pass through the working channel of the endoscope. A 3DOCT dataset covering an imaging area of 20 mm x 8 mm x 2 mm can be acquired in 20s. Standard EMR was performed on 12 patients using Duette (Cook Medical, Inc.). Twentyfour EMR specimens, including 9 benign, 6 BE, 2 BE with low-grade dysplasia, 1 BE with high grade dysplasia, and 6 early adenocarcinomas, were subsequently imaged with 3DOCT and sent for standard H&E histology. Imaging features identified in the OCT images were then compared with matching histology. RESULTS: Cross-sectional and en face images could be reconstructed from the 3D-OCT dataset. Cross-sectional OCT image showed features matching with the corresponding histology. BE glands were observed at regions over the lamina propria layer while both the lamina propria layer and the muscular mucosa were preserved in 87% of OCT imaging dataset. En face OCT highlighted the distribution of the glandular structures in Barrett's esophagus and allowed quantification of BE gland density. In lesions with intramucosal and invasive adenocarcinoma, the muscular mucosa layer was less distinct or lost in the OCT images. This may be due to the destruction of tissue architecture or the thickened mucosa from the tumor. No lamina propria layer is identified in the datasets of 6 early adenocarcinomas. In addition, the shape and the distribution of the glandular structures were irregular compared to those of the BE glands. These distinctive patterns associated with adenocarcinoma were observed in both cross-sectional and en face OCT images. CONCLUSIONS: We demonstrated 3D-OCT images of EMR specimens of human esophagus ranging from benign nodules, BE with LGD, BE with HGD to adenocarcinoma. These studies comparing 3D-OCT images with histology are promising in improving In Vivo evaluation of esophageal nodules in the future. ACKNOWLEDGEMENT: NIH 5R01CA075289-14 and AFOSR FA9550-07-1-0101.