The role of sonographic patterns during endobronchial ultrasound-transbronchial needle aspiration for lung cancer staging: a narrative review

In lung cancer accurate assessment of the mediastinal lymph node status is of paramount importance for the stage assignment as well as crucial for the therapeutic plan. TAC and positron emission tomography (PET) are valuable tools to achieve a preliminary picture of the mediastinal staging but Endobronchial ultrasound-transbronchial needle aspiration (EBUS-TBNA) is considered the first choice for investigating mediastinal lymph nodes as recommended by updated guide-lines. Despite the EBUS-TBNA sensitivity is satisfactory, it is not high enough to exclude mediastinal lymph node metastases; therefore devices and technologies were implemented to increase its sensitivity. The purpose of this narrative review is to describe the tools aimed at correctly interpreting sonographic patterns during EBUS and maximizing the diagnostic accuracy of TBNA. The bibliographic research identified 354 articles potentially related to the purpose of the current review and after accurate reading we selected 21 articles. Eight articles focused on the sonographic features of lymph nodes found during EBUS, 2 papers considered the Doppler patterns and, finally, 18 studies analyzed the advantages of ultrasound elastography. Sonographic features, vascular patterns and ultrasound elastography have proved to be helpful in directing the operator to biopsy the most suspect lymph node, especially in patients with CT-negative and/or PET-negative mediastinum.