Diagnostic Value and Safety of Endobronchial Ultrasound-guided Transbronchial Mediastinal Cryobiopsy Versus Transbronchial Needle Aspiration in the Diagnosis of Lymphoma: a Randomized Controlled Trial

After the target lymph nodes are determined and the safety of needle aspiration is ensured, a 19-G needle will be placed in the working channel of the EBUS scope. The tip of the sheath of the needle will be visible on the endobronchial view, and the needle will then be allowed to pierce the airway wall and enter the lymph node using the jabbing technique under direct ultrasound guidance. A 50-mL syringe will be used to collect 20 mL of aspirates, which will be maintained for 20 s. Each lymph node will be sampled five times to optimize the diagnostic yield. Five passes per node are planned. The samples will not be evaluated on site.

After the target lymph node is located (vascular structures will be excluded via the Doppler function), a tunnel will be made between the target lymph node and the airway wall using a 19-G needle. Subsequently, a 1.1-mm cryoprobe (Erbe 20 402-401, ERBE, Tübingen, Germany) will be inserted through the tunnel and positioned within the target lymph node under EBUS monitoring. The distance between the cryoprobe tip and the lymph node edge will be confirmed to be \>5 mm in all four directions. Afterward, the probe will be cooled in liquid carbon dioxide for 5-9 s. A total of three passes will be performed.