Volumetric Laser Endomicroscopy for Barrett's Esophagus - Looking at the Fine Print

Barrett's esophagus (BE) is a premalignant condition. The incidence of adenocarcinoma in BE has been reported to be between 0.1-3%. Dysplasia in BE is patchy and extensive biopsy sampling is labor intensive, low yield and does not eliminate the sampling error completely. Volumetric laser endomicroscopy (VLE) is expected to enable endoscopists to do targeted biopsy of dysplastic/cancerous lesions (not visible on white light endoscopy) among patients with BE. We reviewed 7 studies with a total of 62 subjects who had undergone VLE. Of 34 patients with available data, VLE correlated with histology in 17 subjects (50%). It missed the underlying diagnosis in one subject (2.9%). VLE led to inadvertent biopsy in 16 patients (47.1%), and led or would have led to upstaging of disease in 11 subjects (32.4%). In the entire cohort, the sensitivity, specificity, positive predictive value and negative predictive value (NPV) of VLE for diagnosis of dysplasia, buried Barrett's or intramucosal carcinoma was 92.3%, 23.8%, 42.9% and 83.3%, respectively. High sensitivity and NPV can potentially help space out the surveillance intervals. Low specificity does lead to a high number of biopsies, which are likely less than non targeted biopsies. Volumetric laser endomicroscopy is a safe and sensitive test to identify mucosal lesions in patients with BE which are invisible under standard white light endoscopy.