Electrical impedance scanning of lymph nodes: Initial clinical and technical findings

PURPOSE: The sonographic differentiation between inflammatory and malignant lymph node enlargement remains imprecise. Electrical impedance scanning (EIS) is of more value in malignant breast lesions, and this study was undertaken to determine if it was of use in differentiating nodal enlargement. MATERIALS AND METHODS: Two hundred and thirty-six sonographically suspicious lymph nodes (146 patients) of mean size 18 x 11 x 11 mm mean depth 9 mm were examined using a commercially available electrical impedance imaging system. The following locations of lymph nodes were included in the study: cervical, axillary, inguinal, supraclavicular and chest/abdominal wall. The EIS results were compared to histopathological, serological or follow up findings. RESULTS: Using EIS 105/115 malignant nodes were correctly diagnosed, while 70/121 inflammatory or benign lymph nodes were correctly identified as benign by EIS (10 false-negative, 51 false-positive). Sensitivity (91.3%) and specificity (57.9%) were obtained. Corresponding negative and positive predictive values were 87.5% and 67.3%, respectively. CONCLUSIONS: Results from this initial study suggest potential value for EIS as an imaging adjunct in the differentiation of sonographically equivocal lesions. Best accuracy was achieved at chest/abdominal wall and inguinal locations. Due to technical restrictions with the present system, the examination of inframandibular and para-aortal lymph nodes should be limited to special cases. Malich, A. (2002)