Usefulness of shear-wave elastography for detection of lymph node metastasis in esophageal and gastric cancer.

[BACKGROUND] Tissue hardness is closely related to disease pathophysiology. Shear-wave elastography (SWE) is a simple and noninvasive ultrasound technique that has been used to evaluate the presence of lymph node metastases and differentiate between benign and malignant tumors.

[AIM] To investigate SWE usefulness in measuring lymph node hardness to predict metastasis presence or absence in surgically removed lymph nodes.

[METHODS] This observational study obtained data from patients who underwent surgery for esophageal or gastric cancer at Nippon Medical School Hospital. The hardness of the surgically removed lymph nodes was measured using SWE. The lymph nodes with hardness values ≥ 2.2 m/s were considered clinically positive for metastasis, whereas those with lower hardness values were considered clinically negative. The lymph nodes subsequently underwent pathological examination to determine the presence of metastasis, and the SWE results and pathological assessments were compared.

[RESULTS] A total of 1077 lymph nodes were evaluated; 18 and 15 cases of esophageal and gastric cancer were identified, respectively. The optimal cutoff value for lymph node size was calculated to be 5.1 mm, and the area under the curve value was 0.74 (95% confidence interval: 0.69-0.84). When limited to a lymph node larger than the cut off value, the SWE sensitivity and specificity for metastasis identification were 0.76 and 0.82, respectively.

[CONCLUSION] SWE was useful in detecting lymph node metastases in the upper gastrointestinal tract.