Ultrasonography of the Mediastinum: Techniques, Current Practice, and Future Directions

In the everyday practice of respiratory physicians, ultrasound techniques play a key role by enabling several diagnostic and interventional procedures. The application of ultrasound to endoscopic procedures allows both a visualization and a guided sampling of mediastinal and hilar lymph nodes. Endobronchial ultrasound can be combined with transbronchial needle aspiration, and, similarly, endoscopic ultrasound can be combined with fine-needle aspiration to sample virtually all mediastinal nodal stations from the airways and the esophagus. Endobronchial ultrasound-transbronchial needle aspiration and endoscopic ultrasound-fine needle aspiration showed a complementary diagnostic yield, and, recently, endoscopic ultrasound with bronchoscope was introduced in clinical practice to perform a transesophageal needle aspiration by using an ultrasound bronchoscope. This technique allows a single operator to perform both transbronchial and transesophageal needle sampling with the same instrument during a single bronchoscopic procedure. Mediastinal staging impacts the management of patients affected by lung cancer, and the most recent guidelines clearly state that endobronchial ultrasound and endoscopic ultrasound should be the initial tissue sampling procedure over surgical staging. In addition, endoscopic ultrasound techniques demonstrated an excellent yield in diagnosing lymphoma and benign diseases, for example, sarcoidosis. The aim of this review was to discuss the current role and future perspectives of endosonography techniques available for the evaluation of the mediastinum. Special emphasis was placed on equipment and technical aspects, the diagnostic role, and future directions of development.