Sampling Instruments for the Transbronchial Approach to Peripheral Pulmonary Lesions

摘要

Since the advent of the flexible bronchoscope, the ability to sample a peripheral pulmonary nodule through the bronchial tree has been a constant challenge for pulmonologists. Over the years, there have been numerous publications on this topic, highlighting a variety of different guidance techniques. In the last decades, new technologies (electromagnetic navigation, virtual bronchoscopy, ultrasound miniprobe, cone beam computed tomography, robotic bronchoscopy) have been added to the traditional fluoroscopy, in an attempt to improve lesion centering and to increase the diagnostic yield. Even if, from meta-analysis and systematic reviews,1 the newer technologies seem to provide better results in comparison with fluoroscopy, especially for small nodules (<2 cm), it is surprising that prospective randomized trials comparing the new systems of guidance to fluoroscopy on large series of patients are still lacking. However, from the several papers on the transbronchial approach to peripheral nodules, we can extrapolate some evidence: the results of the different trials are characterized by a large variability and, in any case, sensitivity is never higher than 70% to 75% in the majority of the studies.1 The major factor that limits diagnostic outcome is that not all the nodules have a relationship with the bronchial tree and, consequently, in some cases, there is no way to reach the target. In fact, for this reason, in the majority of the studies, the presence of a bronchus sign is a predictor for a positive result, irrespective of which guidance system is used. Variations in diagnostic yield depend on several other factors: size and location of the lesion, guidance systems used, operator's experience, and sampling instruments used. In this issue of JOBIP, Gildea et al2 publish an interesting study that is a post hoc analysis of patients previously included in the Navigate trial, a multicenter cohort study that prospectively evaluated the diagnostic yield of electromagnetic navigation bronchoscopy on 1215 patients with pulmonary nodules (median size=2 cm), observed at 29 US sites.3 The aim of this post hoc analysis is to retrospectively evaluate the impact, the safety, and the relative accuracy of biopsy tool strategies. 416 patients with a true-positive malignant diagnosis were divided into those who underwent a more restricted biopsy strategy (biopsy forceps, brush, BAL/washing) and those receiving an extensive biopsy strategy including more tools (biopsy forceps, brush, transbronchial needle, triple needle cytology brush, needle brush, GeneCut biopsy system, BAL). The results allow the authors to conclude that the extensive biopsy strategy, including transbronchial needle (TBNA), provides higher true-positive rates without increasing complications. 86.8% of the malignant diagnoses in the Navigate study were obtained using the extensive strategy, whereas only 13.2% of true-positive diagnoses were obtained with a restricted number of biopsy tools. It is interesting to note that, among the different biopsy tools, the biopsy forceps and the transbronchial needle had the highest positivity rate and the greatest impact on outcome, increasing the true-positive results, respectively, by 9.3% and by 5.8%. Very few cases were missed by biopsy forceps and by needle and diagnosed by other tools (5 cases by brush alone, 1 case by triple needle brush alone, 3 cases by needle brush, 2 by core biopsy system, and 2 by washing alone). This study confirms 2 evidences that were already known from previous studies: (1) the sensitivity for malignancy significantly increases when >1 sampling instrument is used4,5 and (2) the transbronchial needle has a high diagnostic rate. In fact, several studies and also a meta-analysis4–7 showed that the transbronchial needle is the sampling tool with the highest diagnostic yield in the transbronchial approach to peripheral pulmonary lesions and it is the single best contributor to the success of bronchoscopy in the