Narrow-Band Imaging Evaluation of Bladder Tumors

Abstract

Narrow-band imaging (NBI) is a novel optical method designed to enhance visual detection of bladder tumors over conventional white-light imaging (WLI) cystoscopy. Current experience with NBI cystoscopy in evaluating and treating non-muscle-invasive bladder tumors is reviewed. A comprehensive literature search was conducted including all published studies and abstracts investigating NBI cystoscopy in patients with bladder cancer. Comprehensive cystoscopic images are provided to illustrate differences between NBI and WLI cystoscopy. Early experience suggests that NBI cystoscopy detects more bladder tumors than does WLI cystoscopy, and NBI-assisted fulguration and transurethral resection (TUR) appear to result in fewer tumor recurrences. Questions remain, however, such as the following: Does NBI cystoscopy detect high-grade tumors, such as carcinoma in situ, that are missed by WLI cystoscopy? Would false positives lead to an unaccepted number of negative biopsies? And how might observer bias skew results? In addition, a major drawback of current studies is that the quality of cystoscopy and TUR by individual surgeons has not been addressed. Although clinical trials are just beginning, NBI cystoscopy holds promise that this new optical method may improve visualization of bladder tumors over conventional WLI cystoscopy. Further prospective and comparative trials are required to determine whether NBI will play a role in evaluating and treating urothelial tumors in individual patients.