Endobronchial Ultrasonography: Current Status and Future Directions

Endobronchial ultrasonography (EBUS) has emerged as a new diagnostic tool that allows the bronchoscopist to see beyond the airway. The radial probe EBUS was first introduced to evaluate the airway structure, which has been shown to be useful for identifying the extent of tumor invasion in the central airway. With advance in technology, smaller radial probes are now available that are capable of visualizing peripheral lung nodules. EBUS is also used as a tool to assist in a biopsy in respiratory diseases. The radial probe EBUS–guided transbronchial needle aspiration (TBNA) increases the yield of TBNA of mediastinal processes. By the use of the ultra-miniature probe EBUS along with the guide sheath, peripheral lung lesions can be accessed without the exposure to radiation. However, it is still not a real-time procedure with target visualization. The newest development is the convex probe EBUS (CP-EBUS) with a curvilinear electronic transducer on the tip of a flexible bronchovideoscope. CP-EBUS allows real-time EBUS-guided TBNA. Although the main indication for EBUS-TBNA is lymph node staging, it can also be used for diagnosis of intrapulmonary tumors, of unknown hilar and/or mediastinal lymphadenopathy, and of mediastinal tumors. To date, there are no reports of complications related to EBUS-guided TBNA. It is a novel approach that has a good diagnostic yield with excellent potential in assisting safe and accurate diagnostic interventional bronchoscopy. The aim of this review is to highlight the current status of the different EBUS techniques available and to discuss the future direction of EBUS.