Use of Narrow Band Imaging (NBI) in Photodynamic Therapy (PDT) for Barrettʼs High Grade Dysplasia (BE+HGD) and Mucosal Carcinoma (IMC)

Abstract

Purpose: Endoscopic ablation using techniques such as porfimer sodium photodynamic therapy are increasingly used to treat patients with Barrett's dysplasia and mucosal carcinoma. However, PDT is associated with the risk of stricture in areas of overlapping light exposure. Use of fiber centering balloons has been promoted to improve light distribution. Narrow Band Imaging (NBI) uses spectrally narrowed optical filters and a monochromatic CCD to view the mucosal microvasculature. We hypothesized that NBI might permit improved visualization of the laser light fiber during PDT procedures and thereby improve the accuracy of light application. The aim of this study was to evaluate laser light application during PDT procedures using NBI and then compare the rates of stricture formation with previous PDT procedures performed using conventional white light endoscopy. Methods: After IRB approval, consecutive patients undergoing endoscopic ablation treatment with Ps-PDT for BE+HGD or IMC were compared for visualization and determination of laser fiber and mucosal location using standard definition white light endoscopy (Olympus GIF-Q180), high definition white light endoscopy (Olympus XGIF-H160Y2), and HD-NBI (Olympus XGIF-H160Y2, 415 and 540 nm). The incidence of post-Ps-PDT stricture formation (dysphagia associated with mucosal scarring or narrowing) was compared with historical controls. Results: Narrow Band Imaging used to guide porfimer sodium photodynamic therapy in 15 patients (9 BE+HGD pts, 6 IMC pts). All patients were men; mean age 67 yrs, range 59–76 yrs. The mean BE segment was 4 cm; range 1–10 cm. In all cases using a standard white-light endoscope, PDT laser light (630nm, Diomed Inc.) induced CCD video chip “white out” preventing direct visualization and positioning of the laser fiber. HD white light endoscopes (without NBI mode activated) visualized the light fiber position but not mucosal location. In each case, the use of HD NBI permitted real-time, continuous determination of the laser light fiber position and mucosal location. Strictures occurred in 2/15 patients (13%) after NBI Ps-PDT compared with 22–25% stricture rate in historical controls. Conclusions: The use of Narrow Band Imaging during PDT for Barrett's high grade dysplasia or mucosal carcinoma permitted the continuous determination of laser fiber position and mucosal location without the need for a fiber-centering balloon device and may reduce the rate of post ablation stricture.