An evaluation of a videobronchoscopy-based autofluorescence system in lung cancer

Abstract

To the Editors: Autofluorescence (AF) has improved the sensitivity of bronchoscopy for pre-invasive cancer but has reduced specificity. Whether this applies to videobronchoscopy systems or depends on operator experience is unknown. We used a novel “slide-bank” model in order to evaluate the diagnostic performance of a video/AF bronchoscopy (AFI) system in lung cancer (refer to online supplementary material). AF bronchoscopy systems are designed to enhance the detection of pre-invasive lesions. Abnormal bronchial epithelium fluoresces at an altered wavelength when illuminated by blue light. AF systems process and display these changes visually, revealing occult pre-invasive lesions. Previously, the accuracy of AF systems in detecting pre-invasive lesions and cancer has been compared with white-light (WL) bronchoscopy 1, 2. However, increases in sensitivity have been offset by reduced specificity, i.e. false positives. Furthermore, bronchoscopy and AF may be subject to significant, unreported, inter-operator variation. We evaluated an AFI system with experienced and inexperienced bronchoscopists to assess sensitivity/specificity, negative predictive value/positive predictive value (NPV/PPV) and inter-observer agreement. Patients undergoing investigation for haemoptysis/lung cancer underwent bronchoscopy. Those with an established diagnosis of lung cancer involving the central airways were excluded. The study was approved by the local research ethics committee (Royal Brompton and Harefield Hospital, London, UK). All eligible patients who provided written informed consent underwent bronchoscopy performed by a single experienced operator (P.L. Shah) using the AFI system, under local anaesthetic with or without conscious sedation. The endobronchial tree was systematically examined under WL and then AF. The appearances were classified by the operator as normal, inflammatory, suspicious or definite malignancy. The still images of the endobronchial tree under both modes were captured and saved. We tested the AFI videobronchoscopy system (Olympus Medical Systems Corporation, Tokyo, Japan). This displays a high-quality WL image and can switch to AF mode by pressing a …