Direct endoscopic visualization of small peripheral lung nodules using a miniaturized videoendoscopy probe

摘要

In the past two decades, advanced bronchoscopy techniques have been developed for the diagnosis of peripheral lung nodules. Technologies such as ultrathin bronchoscopy, radial-endobronchial ultrasound (r-EBUS), electromagnetic and non-electromagnetic navigation and more recently robotic bronchoscopy have improved the ability to reach the lung target. However, these procedures provide a diagnostic yield that plateaus at about 70%, with a significant gap between navigational yield (the possibility to reach the target) and the diagnostic yield provided by sampling. To date, only r-EBUS can confirm, in real time, that a peripheral lesion has been reached.1 The main limits of r-EBUS to visualize the nodule are the size of the nodule, the nature of the nodule such as ground-glass opacities (GGOs) and the presence of atelectesia which could mimick a lung lesion.2, 3 Recently, a reusable miniaturized videoendoscopy probe of 1.3 mm (4 Fr), using CMOS technology with a definition of 160,000 pixels (400 × 400) (Iriscope® probe Lys Medical, Charleroy, Belgium) has been developed, and is so far the thinnest videoendoscopy probe available. The probe has been used in association with the navigational endoscopic technique to describe one case of emphysema,4 showing distorted alveolar structures. Here, we report the use of the technique for direct endoscopic visualization of small peripheral lung nodules. This retrospective study included all consecutive patients who had r-EBUS + Iriscope® exploration in our centre for the diagnosis of peripheral nodules from January to February 2024. The study was approved by the Institutional Review Board (agreement number E2024-10) with oral informed consent obtained in each case. The r-EBUS procedure was conducted as previously described1: the procedure was performed without navigation system or fluoroscopy, using a virtual bronchoscopy software planner to identify the optimal bronchial path to the lesion (LungPoint® planner, Broncus Medical Inc., San Jose, CA, USA), and a r-EBUS probe (1.4 mm UM-S20-17S probe, Olympus, Tokyo Japan) in a guide sheath (1.9-mm-diameter guide catheter, K401, Olympus) as described elsewhere.5, 6 R-EBUS nodule views were characterized as ‘centred’, when the radial probe image appeared within and completely surrounded by the lesion, and ‘tangential’ when the probe was adjacent to the lesion. Once a ultrasound (US) signal characteristic to the nodule was obtained, the r-EBUS probe was removed. Then, the Iriscope® probe was inserted within the lesion through the guide sheath for direct endoscopic visualization of the peripheral tumour. Secretions were cleared from the guide sheath using a small amount of saline before and during Iriscope® imaging. The technique also allowed the adjustment of the guide sheath within the tumour. The Iriscope® images were recorded for further analysis. After removing the Iriscope® probe, sampling, including cytological brush and forceps biopsies, was performed through the guide sheath. Incidentally, the Iriscope® probe was pushed into the normal part of the lung in some cases, providing visualization of non-tumoural parts of the distal lung. Chest radiographs after the procedure were not systematically performed. Specimens were considered diagnostic when a cytological, histological or microbiological diagnosis was confirmed and consistent with the clinical presentation. The images from Iriscope® were analysed after the procedure, blindly from the diagnosis and the patient's chart, by one endoscopist who did not perform the procedure (LT), and classified the images into ‘tumoural’ (visualization of tumoural tissue), suspicious (stenosis), non-specific (inflammation, secretion and haemorrhage), or normal (Table 1). A total of 23 procedures were performed. The median diameter of the lesion measured on CT was 15 mm in long axis (IQR = 6–35 mm) and 11 mm in short axis (IQR = 5–25 mm). All nodules had a solid appearance on CT. Twelve nodules measured less