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The radiologists' role in axillary imaging in the setting of a suspicious breast mass is evolving in light of the Z0011 trial leading to expected practice variation. The purpose of our project was to generate a standardized algorithm guiding the utilization of axillary ultrasound in the setting of a highly suggestive or highly suspicious breast mass (BI-RADS 4C or 5) without a known cancer diagnosis. The algorithm was created with Z0011 practices in mind while reflecting the clinical preferences of our radiology and surgical teams. The four breast surgeons at our academic institution were individually queried regarding their preferred axillary imaging and biopsy approach. The best practices for axillary imaging were then developed in a breast imaging intradepartmental meeting. There was agreement among the surgical group that the presence of suspicious axillary lymph node (s) on ultrasound could be used for treatment planning and patient discussion but would not be used for surgical planning in most cases. They also agreed that an ultrasound-guided core needle biopsy of a suspicious axillary lymph node should be deferred until after surgical consultation. Discussion among our breast radiologists resulted in the consensus that axillary ultrasound in the setting of a BIRADS 4 or 5 mass should be deferred at its initial presentation unless there is palpable lymphadenopathy, suspicious lymph node on mammography, or a tumor is at least stage T3, presumably excluding them from Z0011 criteria. The decision was also made to defer biopsies of suspicious axillary lymph nodes without prior surgical consultation/discussion.

To investigate the ability of diffusion weighted images (DWI) to differentiate between metastatic and nonmetastatic axillary lymph nodes (LNs) in patients with newly diagnosed breast cancer.From January 2010 to February 2012, DWI was performed at b values of 0 and 800 for 16 metastatic LNs from 16 patients with breast cancer, and 20 nonmetastatic LNs from 20 women without breast cancer. The metastatic LNs were proven by ultrasound (US) guided core biopsy and the same LNs were identified on MRI by comparing the US images with MR images. Nonmetastatic LNs were verified by the stability in size and shape for at least 2 years on MRI. The apparent diffusion coefficient (ADC) value of the metastatic and nonmetastatic axillary LNs was compared. Receiver-operating-characteristics (ROC) analysis was performed to evaluate the diagnostic performance of the ADC value in differentiating between metastatic and nonmetastatic axillary LNs.The mean ADC value was 0.746 × 10(-3) for metastatic LNs and 1.033 × 10(-3) for nonmetastatic LNs (P 0.001). The area under the ROC curve was 0.884. The sensitivity and specificity for differentiating metastatic from nonmetastatic axillary LNs using a cutoff ADC value of 0.852 were 85% and 81%, respectively.There is a statistically significant difference between the ADC values of pathologically proven metastatic LNs and nonmetastatic LNs. DWI and ADC values are a useful tool for differentiating metastatic from nonmetastatic axillary LNs.

To compare magnetic resonance imaging (MRI) and ultrasound (US) for axillary lymph node (LN) staging in breast cancer patients in an observer-performance study.An observer-performance study was conducted with five breast radiologists reviewing 50 consecutive patients of newly diagnosed invasive breast cancer with the use of ipsilateral axillary MRI and US. LN status was pathologically proved in all patients. Each observer reviewed the images in two separate sessions: one for MRI and the other for US. Observers were asked to indicate their confidence of the presence of at least one ipsilateral metastatic LN on a quasi-continuous rating scale and whether they recommend percutaneous biopsy preoperatively. Receiver operating characteristic (ROC) analysis and area under the ROC curve were used to characterize diagnostic performance. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated from whether observers recommended biopsy.There were no statistically significant differences in each observer's performance between MRI and US, or in the performance of all observers as a group, in terms of ROC analysis. There were no statistically significant differences in sensitivity, specificity, PPV, or NPV between MRI and US, but there were statistically significant improvements in specificity and PPV from either MRI or US alone to MRI and US combined.Observer performance on MRI and US are comparable for axillary LN staging. When US and MRI are concordant for positive findings, higher specificity and PPV can be obtained.