Assessment of the accuracy of ultrasound compared to magnetic resonance imaging in the ability to detect metastatic breast cancer to the axilla

Sentinel lymph node biopsy (SLNB) is routinely used in the staging of invasive breast cancer. The aim of this study was to investigate the diagnostic accuracy of ultrasonography (US) compared to magnetic resonance imaging (MRI) in the pre-operative assessment of metastatic disease to the axilla in breast cancer patients at our community hospital. We retrospectively reviewed a prospectively collected database of 277 patients seen at our breast center from 2009 to 2010. Patients with invasive breast cancer were then evaluated for axillary metastasis. Lymph nodes were sampled using fine needle aspiration (FNAB) or core biopsy. Histopathology of the sentinel lymph nodes (SLN) or results of the axillary dissection were compared to US or MRI results. A total of 228 patients had invasive breast cancer. In these patients, 122 lymph nodes were sampled. Pathology proven metastases to axillary lymph nodes were found in 76 cases. Accuracy and sensitivity were higher in US than MRI in detecting metastatic disease to the axilla (70.2%, 84.6%, P<0.001 and 60.0%, 52.6%, P <0.1, respectively). US was more accurate than MRI at detecting metastatic breast cancer in the axilla in our community hospital. Axillary US should be a routine part of assessment of breast cancer patients.