Endobronchial ultrasound elastography strain ratio for mediastinal lymph node diagnosis
Background and Objective:
Ultrasound elastography is an imaging procedure that can assess the biomechanical characteristics of different tissues.
The aim of this study was to define the diagnostic value of the EBUS elastography strain ratio of mediastinal lymph nodes in patients with a suspicion of lung cancer. The diagnostic values of the strain ratios were compared with the EBUS B-mode features of selected mediastinal lymph nodes and with their cytological diagnoses.
Patients and methods:
This prospective, single-centre study enrolled patients with an indication for biopsy and mediastinal staging after a non-invasive diagnostic workup of a lung tumour. EBUS with standard B-mode evaluation and elastography with strain ratio measurement were performed before EBUS-TBNA.
Thirty-three patients with 80 suspicious mediastinal lymph nodes were included. Malignant infiltration was confirmed in 34 (42.5%) lymph nodes. The area under the receiver operating characteristic curve for the strain ratio was 0.87 (p < 0.0001). At a strain ratio ≥ 8, the accuracy for malignancy prediction was 86.25% (sens. 88.24%, spec. 84.78%, PPV 81.08%, NPV 90.70%). The strain ratio is more accurate than conventional B-mode EBUS modalities for differentiating between malignant and benign lymph nodes.
EBUS-guided elastography with strain ratio assessment can distinguish malignant from benign mediastinal lymph nodes with greater accuracy than conventional EBUS modalities. This new method may reduce the number of mediastinal EBUS-TBNAs and thus reduce the invasiveness and expense of mediastinal staging in patients with NSCLC.