Cystoscopy results improved with narrow-band imaging

August 1, 2010

Urologists using flexible cystoscopy with narrow-band imaging find more new nonmuscle-invasive bladder cancers than with flexible cystoscopy using white light.

San Francisco-Urologists using flexible cystoscopy with narrow-band imaging (NBI) find more new nonmuscle-invasive bladder cancers than with flexible cystoscopy using white light, research shows. The findings in bladder cancer echo similar comparisons for gastrointestinal cancers that NBI is superior, said researcher Yijun Shen, MD, of Fudan University Hospital, Shanghai, China.

NBI uses specific wavelengths of light to enhance the visual contrast between mucosal surfaces and microvascular structures without the use of dyes or contrast agents, Dr. Shen said. Endoscopic NBI, he added, is routinely used around the world to assess gastrointestinal abnormalities.

"What we found was that anyone, even residents, can use NBI efficiently and effectively in detecting bladder cancer after a short learning curve," Dr. Shen told Urology Times. "NBI is not difficult to master."

The ongoing debate over white light cystoscopy versus NBI comes down to observer bias, Dr. Shen said. Most prior studies in nonmuscle-invasive bladder cancer have used the same urologist viewing the same images under white light and NBI. That raises questions of reliability and utility in the broader urologist population. Dr. Shen used a randomized sequence of images taken using white light and NBI to compare detection rates of new nonmuscle-invasive bladder cancer under the different illumination sources. He presented the results at the AUA annual meeting in San Francisco.

The study used the same Lucera sequential endoscopy system (Olympus, Center Valley, PA) to image 45 bladders with suspected new nonmuscle-invasive bladder cancer using both NBI and white light imaging. All 45 patients were examined between February 2009 and October 2009. Images were shown to observers in a predetermined, random order for a set length of time to eliminate any potential observer bias.

A total of 110 biopsies were performed based on white light findings and 142 biopsies based on NBI findings. Biopsies obtained by both white light and NBI were examined separately by an experienced pathologist. After cystoscopy and biopsy, all 45 patients had a standard transurethral resection with tissue samples examined to confirm the presence of tumors.

Of the 45 patients in the study, 41 (91.1%) had nonmuscle-invasive bladder cancer confirmed by pathology following TUR. Of the patients with tumors, 33 were detected by both white light and NBI. None of the tumors were seen only by white light, seven were seen only by NBI, and one was missed by both white light and NBI.

NBI more sensitive, specific

Of the 110 biopsies identified under white light, 89 showed signs of cancer. Of the 142 biopsies identified under NBI, 113 showed signs of cancer. The sensitivity of white light imaging was 80.5% compared to 97.6% for NBI (p<.05), the specificity was 50% and 75%, respectively (p<.05), and accuracy was 77.8% and 95.6%, respectively (p<.05).

Dr. Shen reported that five T1 cancers were found on TUR. All five were identified on NBI while white light imaging missed two T1 cancers. NBI also detected 24 cancerous lesions in 15 patients that were missed by white light imaging.

"NBI is clearly more effective to detect new nonmuscle-invasive bladder cancer than white light, just like it is in gastrointestinal use," Dr. Shen said. "It only takes 20 or 30 images for a new user to become proficient in this new technique."