Sharon L Shin MD, Presenter: Nothing to Disclose

Hemi Dua MD, Abstract Co-Author: Nothing to Disclose

Franklin Goldberg MD, Abstract Co-Author: Nothing to Disclose

Derek Muradali MD, Abstract Co-Author: Nothing to Disclose

Nodal status is a major prognostic indicator in breast cancer patients. Despite reported value of diffusion weighted MR imaging (DWI) in assessing primary breast lesions, little is known regarding DWI of axillary lymph nodes. The objective of this two-part study is to determine the ability of DWI of the axilla in breast cancer patients to: Part I: differentiate metastatic from benign lymph nodes, and Part II: assess axillary response to treatment in those patients receiving neoadjuvant chemotherapy (NAC).

Part I: This retrospective study included 116 patients (mean age 50.6 ± 13.0 years): 36 patients with primary invasive breast cancer (IBC) and metastatic axillary lymph nodes, 34 patients with IBC and negative nodal status, and 48 patients with no history of malignancy and normal nodes on clinical exam. IBC nodal status was determined by axillary lymph node dissection, sentinel lymph node biopsy, core biopsy or fine needle aspiration. Diffusion-weighted MRI at 1.5T was acquired at b values of 0 and 1000 s/mm2. The apparent diffusion coefficient (ADC) of the most suspicious axillary lymph node based on morphology and size was measured. Part II: 6 patients with axillary lymph node metastases receiving NAC underwent followup MR imaging, and nodal response to treatment was assessed.

Part I: Mean ADC for axillary lymph nodes in patients with IBC and metastatic nodes, 0.79 ± 0.16 x 10-3 mm2/s, was lower compared to patients with IBC and negative nodes, 1.13 ± 0.31 x 10-3 mm2/s, and patients with no history of breast cancer and benign nodes, 1.06 ± 0.24 x 10-3 mm2/s (p<0.001). ADC cutoff of 0.93 x 10-3 mm2/s to determine metastatic lymph node involvement correlated with sensitivity, specificity, positive predictive value, and accuracy of 81%, 71%, 74%, and 76%. Part II: For the six patients with axillary metastatic lymphadenopathy receiving NAC and subsequent MR imaging, mean ADC rose from 0.77± 0.13 x 10-3 mm2/s pre-NAC to 1.26 ± 0.30 x 10-3 mm2/s post-NAC (p=0.031).

Diffusion-weighted imaging shows potential in assessing for axillary lymph node metastases in breast cancer patients. In addition, a rise in ADC is seen with treatment response to NAC in metastatic axillary lymph nodes.

DWI is a promising diagnostic tool in the MR evaluation of axillary lymph node status in breast cancer, as well as in monitoring nodal response to neoadjuvant chemotherapy.

Shin, S, Dua, H, Goldberg, F, Muradali, D, Diffusion-weighted MR Imaging in Predicting Breast Cancer Metastases in Axillary Lymph Nodes and Assessing Nodal Response to Neoadjuvant Chemotherapy.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034405.html