Role of Contrast-Enhanced Sonography in the Evaluation of Axillary Lymph Nodes in Breast Carcinoma

Objectives-To evaluate the diagnostic performance of contrast-enhanced sonography for characterization of the lymph node status (metastatic or not) in patients with breast carcinomas by comparison with sentinel lymph node biopsy. Methods-From January to August 2015, 50 female patients with a histologic diagnosis of invasive breast carcinoma were prospectively examined by ipsilateral axillary contrast-enhanced sonography. The test was performed by a single radiologist using an ultrasound system with a broadband 8-12-MHz, 38-mm high-resolution linear transducer. For the target lymph node, we chose a node with a sonographic pattern that was suspicious for malignancy: ie, a longitudinal-to-transverse diameter ratio of less than 2, absence of a central hyperechogenic hilum, or both. In cases with a lack of sonographic signs of malignancy, we evaluated the node with the maximal transverse diameter. Nodes were considered malignant in cases with total absence of contrast enhancement and in those with enhancement alterations. Within 1 week, all patients underwent sentinel lymph node biopsy, followed by a histologic test. Results-The histologic test showed benignity in 22 of 50 sentinel lymph nodes, whereas 28 were metastatic. Among the 22 patients with negative biopsy results, contrast-enhanced sonography showed 18 concordances and 4 false-positives results; among the 28 with positive biopsy results, contrast-enhanced sonography obtained 100% correct characterizations of the axillary status. The sensitivity, specificity, and accuracy were 100%, 82%, and 92%, respectively. Conclusions-Contrast-enhanced sonography appears to be a method with high accuracy for characterization of axillary lymph nodes, very close to the reference-standard sentinel lymph node biopsy. This technique seems to have overall high sensitivity.