Feasibility of a Modified Bronchoscopic Transparenchymal Nodule Access Technique (“Essen Tunnel”) for Improving the Diagnosis of Intraparenchymal Pulmonary Lesions

<bold>Background:</bold> Intraparenchymal lesions without airway access are a diagnostic challenge even in times of modern navigational bronchoscopy. Bronchoscopic transparenchymal nodule access(BTPNA) has seen limited clinical adoption for accessing those lesions. The “Essen tunnel” is a sheathless modified BTPNA(mBTPNA) aiming to improve endosonographic lesion detection and diagnostic yield. <bold>Methods:</bold> All patients undergoing virtual bronchoscopic navigation (VBN) incorporating the mBTPNA technique at our center from December 2019 to March 2024 were analysed. The tunnel entrance has been created towards the virtual target by using an 18/19-gauge needle in the central airway closest to the lesion after adjacent vessels have been excluded by rEBUS. If necessary, the ballon dilation of the tunnel was performed, allowing the insertion of an ultrathin bronchoscope(UTB) or a radial endobronchial ultrasound(rEBUS) probe to reach intraparenchymal lesions. <bold>Results:</bold> Among 266 lesions targeted via VBN, mBTPNA has been applied in 37(14%) lesions (12.7±4.1 mm). The tunnel was successfully created in 97.3% with UTB and r-EBUS intubation in 51.4% and 83.8% of cases, respectively. Semicircular to circular rEBUS pattern(SCP) were detected in 19.4% before and 61.3% after tunnel creation(p<0.01). SCP on rEBUS following mBTPNA was associated with a diagnostic yield of 66.7%, which was comparable to the yield in non-tunnel lesions with a bronchus sign (72.9%). No severe complications were observed. <bold>Interpretation:</bold> mBTPNA is a feasible and safe method to improve rEBUS detection and diagnostic yield of intraparenchymal lesions without airway access in VBN.