Endosonographic elastography in the diagnosis of mediastinal lymph nodes

Background and study aims: Ultrasonographic elastography is a new technique for describing the mechanical properties of tissue during real-time ultrasonography. The aim of this study was to test the feasibility of this method in endosonography (EUS) of the dorsal mediastinum, and to compare the elastographic patterns of lymph nodes with results from EUS-guided fine-needle aspiration biopsy (FNAB). Patients and methods: 50 consecutive patients undergoing EUS-guided FNAB of at least one paraesophageal lymph node were included. Each of these targeted lymph nodes was examined also elastographically. The elastographic patterns were described and compared with the histologic results by a first examiner. The elastographic classification was subsequently further tested by two blinded reviewers. Results: In total, 66 lymph nodes were examined; 37 lymph nodes revealed benign and 29 malignant tissue at the histologic evaluation. Good elastographic records were obtained for all lymph nodes. Of the 37 benign lymph nodes, 31 showed a homogeneous pattern of intermediate elasticity, whereas a dominance of hard tissue with variable patterns was found in 23 of 29 malignant lymph nodes. Applying these criteria, the accuracy range among the three examiners was between 81.8% and 87.9% for benign lymph nodes and between 84.6% and 86.4% for malignant ones. The interobserver agreement was excellent (kappa = 0.84). Conclusion: EUS elastography of mediastinal lymph nodes can be performed reliably. The results are good for a noninvasive technique, but they remain inferior to the success rate of EUSguided FNAB. The method might occasionally be useful for targeting the most suitable lymph nodes for FNAB.