Discussion
atelectasis, TBLC, peripheral lesion, pneumothorax
ATELECTASIS, PNEUMOTHORAX
This prospective randomized monocentric trial aimed to investigate the added value of performing ENB procedure under CBCT guidance rather than in a standard endoscopy suite. Our results confirmed this benefit as the diagnostic yield almost double when ENB was performed under CBCT guidance (80% instead of 42%). Also, the diagnostic accuracy was higher under CBCT guidance (87% instead of 54%), a difference remaining significant in the sensitivity analysis. This high diagnostic yield and accuracy is in line with previously published data (ranging from 75 to 83%) for ENB procedures performed under CBCT guidance for small-sized nodule (less than 2 cm) [The high diagnostic yield observed under CBCT guidance in our study was obtained by the combined use of both forceps TBB and TBLC, each of them increasing the diagnostic yield equally (± 15%). Of note, the diagnostic yield of 42% obtained in the endoscopy suite under fluoroscopic guidance only appeared lower than previously reported [CBCT scans also provided interesting information regarding the distance of the nodule from the chest wall that could differ from pre-procedural chest CT scan due to lower level of pulmonary inflation and the development of atelectasis under general anesthesia. Accordingly, if peripheral lesion appeared closer than expected to the pleura during CBCT acquisition, TBLC were not performed if the diagnosis could be reached with TBB only (forceps located inside or in front of the lesion on CBCT acquisition). Theoretically, this could possibly reduce the risk of pneumothorax following TBLC when performed under CBCT guidance than under standard X-ray fluoroscopy. However, according to the low number of pneumothorax in our study (The added value of CBCT guidance in addition to ENB to reach targeted lesions was somewhat counterbalanced by a mild increase in the duration of the procedure as observed in our study. In addition, the accessibility to such hybrid room and the cost related to the combined used of CBCT and ENB could be another limitation in some centers. Also, higher ionizing radiation exposure compared to X-ray fluoroscopy could represent another disadvantage of CBCT guidance. Unfortunately, our study cannot evaluate this latter point as we did not systematically record this exposure for ENB performed in the endoscopy suite under standard X-ray fluoroscopy guidance. However, the radiation exposure observed in the CBCT group (5,6 mSv/patient), which is in line to the exposure reported in a similar study using ENB under CBCT guidance [Our study presents several limitations. It is a single-center (monocentric) and unblinded study. The number of subjects did not allow to perform accurate subgroups analysis such as correlations between nodules characteristics (size, presence of a bronchus sign, visibility on standard fluoroscopy) and the diagnostic yield or to demonstrate an added value to use the CrossCountry technique. For example, in the CBCT group, three patients had a surprising negative rEBUS whereas all of them had pathological diagnosis following biopsies. At the opposite, the diagnostic yield was only 76% when rEBUS was positive. However, no conclusion on the benefit to perform or not rEBUS when ENB is performed under CBCT guidance could be made according to the low number of patients in this subgroup analysis. Similarly, nodule size was previously shown as a factor influencing the diagnostic yield [Also, Medtronic developed in the meantime a new ENB platform called illumisite™. This platform uses tomosynthesis to correct the virtual target reducing the discrepancy between the static CT scan and the dynamic breathing lung, enhancing the visibility of the nodule on X-ray fluoroscopy, and allowing to locally register the nodule and adjust alignment during the procedure [In conclusion, we showed that the use of CBCT guidance during ENB procedure for nodule of a mean size less than 2 cm significantly increases the diagnostic yield of the technique. Even more than 90% of the lesion could be reached by the biopsy tools, opening new perspectives for future therapeutic approach of these nodules as bronchoscopy-guided ablation.