Diagnostic accuracy of probe-based confocal laser endomicroscopy in detecting residual colorectal neoplasia after EMR: A prospective study

Background: Residual neoplasia after EMR of colorectal lesions is common. There is a critical need for imaging methods to accurately diagnose residual disease and to guide retreatment in real time. Objective: The aim was to estimate and compare the accuracy of virtual chromoendoscopy (VCE) and probe-based confocal laser endomicroscopy (pCLE) for detection of residual neoplastic tissue at the site of prior EMR. Design: Prospective, blind, pilot comparison of advanced endoscopic imaging (VCE and pCLE) by using matching histology as reference standard. Setting: Three tertiary-care referral hospitals. Patients: This study involved 92 participants who underwent follow-up colonoscopies for the evaluation of prior EMR sites within 1 year. Intervention: The EMR scars were assessed during follow-up high-resolution colonoscopy by using VCE (narrow-band imaging/Fujinon Intelligent Color Enhancement [FICE]), and pCLE. Confocal videos of EMR scars were interpreted in real time and were also stored and reviewed offline, blinded to histopathology and endoscopic appearance. Tissue confirmation by biopsies or polypectomy/repeat EMR was performed in all cases. Main Outcome Measurements: Sensitivity, specificity, and accuracy for VCE and pCLE alone and in combination against histopathology as the standard reference standard. Results: Among 129 EMR scars, residual neoplasia was confirmed by histology in 29 sites (22%). For VCE, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were 72%, 77%, 49%, 91%, and 77%, respectively, and were 97%, 77%, 55%, 99%, and 81% for pCLE (P =.045 for sensitivity). When only EMR scars for which VCE and pCLE agreed on the diagnosis were analyzed (95/129 scars), the accuracy, sensitivity, specificity, PPV, and NPV of pCLE and VCE were 90%, 100%, 87%, 67%, and 100%, respectively. Limitations: Small sample size, lack of power, involvement of highly experienced pCLE experts. Conclusion: Confocal endomicroscopy significantly increases the sensitivity for detecting residual neoplasia after colorectal EMR compared with endoscopy alone. When confocal endomicroscopy is used in combination with VCE, the accuracy is extremely high, and sensitivity approaches that of histopathology. Together, they may reduce the need for histologic examination and allow a highly accurate on-table decision to treat again or not, thus avoiding unnecessary repeat procedures. (Clinical trial registration number: 00874263.)