Volumetric Laser Endomicroscopy for Barrett’s Esophagus – Looking at the Fine Print

Abstract

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.Abbreviations: BE: Barrett’s Esophagus; BB: Buried Barrett’s; EAC: Esophageal adenocarcinoma; EDS: Evans Dysplasia Score; EMR: Endoscopic Mucosal Resection; GERD: Gastro-esophageal reflux disease; HGD: High grade dysplasia; IMC: Intra-mucosal adenocarcinoma; LGD: Low grade dysplasia; NBI: Narrow Band Imaging; OCT-SI: Optical Coherence Tomography Scoring Index; RFA: Radiofrequency ablation; SGS: Sub-squamous glandular structures; VLE: Volumetric Laser Endomicroscopy; WLE: White Light Endoscopy.

Barrett's esophagus: The pathomorphological and molecular genetic keystones of neoplastic progression

“… 16 That is why a lot of different endoscopy modalities and techniques were tried for visualization of dysplasia and precise biopsy, among them narrow‐band imaging (NBI), 50 , 51 , 52 acetic acid chromoendoscopy (AAC), 53 , 54 , 55 , 56 autofluorescence imaging (AFI), 57 , 58 confocal laser endomicroscopy (CLE) 59 , 60 , 61 , 62 , 63 and volumetric laser endomicroscopy (VLE). 64 , 65 , 66 Although some studies demonstrated different imaging modalities to be efficient, in other studies the use of these techniques did not report benefits in dysplasia detection rate. 67 , 68 , 69 , 70 Sensitivity of standard protocol with 4‐quadrant biopsy ranged from 28% to 85% in different studies and specificity varied from 56% to 100%, this led American Society for Gastrointestinal Endoscopy to set thresholds for any Preservation and Incorporation of Valuable endoscopic Innovations (PIVI) 71 : an imaging technology with targeted biopsies should have a per‐patient sensitivity of 90% or greater, negative predictive value (NPV) of 98% or greater for detecting HGD or early EAC and specificity of at least 80% to allow a reduction in the number of biopsies compared to standard protocol.…”

Barrett’s esophagus: novel strategies for screening and surveillance

“…74 VLE is sensitive in identifying mucosal lesions that are invisible under standard WLE, thus allowing targeted biopsy of dysplastic/cancerous lesions. 75 The novel VLE laser marking system further enables direct in vivo marking of suspicious areas for targeted biopsy. 76 Imaging features of VLE found to be independently predictive of BE neoplasia included lack of layering, higher surface than subsurface signaling, and irregularly dilated glands/ ducts.…”