Linear Endobronchial Ultrasound

Abstract

Linear endobronchial ultrasound (EBUS) also known as the convex probe endobronchial ultrasound (CP-EBUS) is a flexible bronchoscope with a linear ultrasound probe on the tip. It allows real-time EBUS-guided transbronchial needle aspiration (EBUS-TBNA) of mediastinal and hilar structures under ultrasound control. A dedicated 21- or 22-gauge needle is used for EBUS-TBNA. This minimally invasive procedure is an evolving diagnostic tool which allows the bronchoscopists to see beyond the airway and at the same time perform diagnostics. Clinical applications of EBUS-TBNA includes (a) lymph node staging in lung cancer patients, (b) diagnosis of intrapulmonary tumors, (c) diagnosis of unknown hilar and/or mediastinal lymphadenopathy, and (d) diagnosis of mediastinal tumors. The reach of EBUS-TBNA is comparable to mediastinoscopy which is still considered to be the “gold standard” of mediastinal staging but also extends to the hilar lymph nodes. High diagnostic yield has been achieved with EBUS-TBNA for lymph node staging in lung cancer. Data show that it is less invasive, safer than, and as accurate as surgical staging in lung cancer patients with discrete mediastinal lymph node enlargement. The diagnosis of mediastinal/hilar adenopathy of unknown origin may sometimes be challenging due to the limitation of the size of the needles available for EBUS-TBNA. Rapid on-site cytological evaluation is not always necessary during EBUS-TBNA, but it allows determination of whether sampling of the target has been achieved. More importantly, it allows triage of aspirate materials to secondary investigations (culture for granulomatous disease, flow cytometry for lymphoma). EBUS-TBNA is a novel approach which can be safely performed in an ambulatory setting with a high diagnostic yield.