Dynamic contrast enhanced MRI of the axilla in women with breast cancer: comparison with pathology of excised nodes

Axillary lymph node status is the most important prognostic factor in breast cancer patients and is currently determined by surgical dissection. This study was performed to assess whether dynamic gadopentetate dimeglumine (Gd) enhanced MRI is an accurate method for noninvasive staging of the axilla. 47 women with a new primary breast cancer underwent preoperative dynamic Gd enhanced MRI of the ipsilateral axilla. Lymph node enhancement was quantitatively analysed using a region of interest method. Enhancement indices and nodal area were compared with histopathology of excised nodes using a receiver operating characteristic (ROC) curve approach. 10 patients had axillary metastases pathologically and all had greater than or equal to 1 lymph node with an enhancement index of >21% and a nodal area of >0.4 cm(2). 37 patients had negative axillary nodes pathologically. 20 of these had enhancement indices <21% and nodal areas <0.4 cm(2). Using this method, a sensitivity of 100%, a specificity of 56%, a positive predictive value of 38% and a negative predictive value of 100% could be achieved. Using this method of quantitative assessment, dynamic Gd enhanced MRI may be a reliable method of predicting absence of axillary nodal metastases in women with breast cancer, thereby avoiding axillary surgery in women with a negative MRI study.