Introduction
Bronchoscopy is one of the most important diagnostic procedures in lung cancer. This procedure not only aims to obtain a diagnosis but also renders important anatomical information. Furthermore, subtle changes in the airway epithelium and vascular patterns of the bronchial tree are clues to guide the endoscopist to the site of biopsy, help to determine resectability or local treatment in case of centrally located lung cancer and is the only tool to detect multifocal premalignant disease.
Three meta-analyses showed diagnostic superiority of autofluorescence bronchoscopy (AFB) over routine white light bronchoscopy (WLB) in detecting premalignant lesions.1–3 The superiority of AFB over WLB is especially significant in older studies using fiberoptic endoscopes. The use of video-endoscopes further improved detection in the AFB setting.4–6 Yet AFB is not widely used and is available in a few specialised centres only. In the most recent guideline of the American College of Chest Physicians, the use of AFB is recommended ‘when available’.7 Uncertainty on the natural history and the risk of progression from premalignant lesions to invasive carcinoma and the high rate of false positive AFB findings further question its use.7 However, AFB surveillance in a high-risk group appeared to significantly contribute in detecting new tumours in high-risk patients with known preinvasive lesions where 62% of the lung cancers were detected by AFB compared with 38% by CT.8 In a time where endo-bronchial ultrasound (EBUS) often is being used as the first and sole diagnostic procedure in patients with suspected lung cancer, this finding may support the need for systematic bronchoscopic evaluation in all cases.
Alternatively, the use of filters transmitting only part of the white light (narrow band imaging (NBI)) has been shown to be of additional value to detect angiogenic squamous dysplasia (as a precursor for invasive tumours)9–11 and was reported to be approximately equal to (video-)AFB in terms of sensitivity and had slightly better specificity.12 13 The type of vascular pattern was also related to histological subtype; dotted vessels correlated to adenocarcinoma (AC) and abrupt vessel endings to squamous-cell carcinoma (SqCC).13
Through technological improvement, new imaging techniques have become available in the form of high-definition (HD+) bronchoscopy. In combination with an improved video processor, this HD+ bronchoscope offers postprocessing real-time image enhancement (i-scan technology).14 In different settings, per pixel real-time adjustments can be made improving visualisation of minute changes in the epithelial layer (surface enhancement (SE)) and modify the colour spectrum (tone enhancement (TE)). In an earlier exploratory study, we found that HD+ bronchoscopy with i-scan image enhancement detected significantly more sites with abnormal and suspicious vascular patterns compared with routine WLB, AFB and HD+ bronchoscopy.15 In the evaluation of the gastrointestinal tract, real-time image enhancement has been shown to improve diagnostic yield.16 What the impact is of this i-scan technique with HD+ videobronchoscopy on the diagnostic performance is unknown. We hypothesise that image enhancement technology increases detection rate of synchronous lesions.
In this prospective investigator-initiated multicentre study, we therefore aim to investigate the diagnostic performance in daily clinical use of HD+ bronchoscopy, with or without SE or TE and relate visual imaging to biopsy outcome of all detected sites with abnormal and/or suspicious vascular patterns in patients with suspected lung cancer. Furthermore, this study aims to determine if these findings as a result of systematic evaluation of the central airways influence clinical work-up or choice of treatment.