In a prospective study of 45 patients, 35 of whom were node-positive, there was no association between posttreatment axillary MRI findings and surgical pathology; MRI had a high false negative rate (46%), low sensitivity (55%), and specificity (63%) [114]. MRI Breast Without IV Contrast There is no relevant literature to support the use of MRI breast without IV contrast in the imaging of known axillary lymph node-positive breast cancer after completion of NAC. US Axilla If the axilla is imaged after NAC, US is the most useful imaging modality, although it only demonstrates moderate sensitivity (53%-86%) and specificity (78%) for detecting residual disease [112,124]. Therefore, surgical sampling of axillary lymph nodes after therapy remains the standard of care. US permits image-guided localization of the clipped metastatic axillary lymph node if the patient is undergoing sentinel node biopsy with surgical excision of the clipped node. The axilla is most commonly imaged after NAC in patients with a clinically positive axilla before therapy [4]. In a retrospective study of 408 clinically node-positive breast cancer patients treated with NAC, the strongest predictor of residual axillary disease was posttreatment US showing axillary lymphadenopathy, defined as axial cortical thickness >3.5 mm or loss of the hilum [125]. The prospective clinical Z1071 trial included 611 patients with US after NAC, 238 of whom had axillary CR. US features associated with residual disease included increased cortical thickness (mean 3.5 mm), absent hilum, and longer lymph node diameter [126]. Monitoring Response to Neoadjuvant Chemotherapy US Breast There is no relevant literature to support the use of breast US alone in the evaluation of known axillary lymph node- positive disease after completion of NAC. However, some studies have shown a correlation between pCR in the breast and the axilla [136].
Monitoring Response to Neoadjuvant Systemic Therapy for Breast Cancer. In a prospective study of 45 patients, 35 of whom were node-positive, there was no association between posttreatment axillary MRI findings and surgical pathology; MRI had a high false negative rate (46%), low sensitivity (55%), and specificity (63%) [114]. MRI Breast Without IV Contrast There is no relevant literature to support the use of MRI breast without IV contrast in the imaging of known axillary lymph node-positive breast cancer after completion of NAC. US Axilla If the axilla is imaged after NAC, US is the most useful imaging modality, although it only demonstrates moderate sensitivity (53%-86%) and specificity (78%) for detecting residual disease [112,124]. Therefore, surgical sampling of axillary lymph nodes after therapy remains the standard of care. US permits image-guided localization of the clipped metastatic axillary lymph node if the patient is undergoing sentinel node biopsy with surgical excision of the clipped node. The axilla is most commonly imaged after NAC in patients with a clinically positive axilla before therapy [4]. In a retrospective study of 408 clinically node-positive breast cancer patients treated with NAC, the strongest predictor of residual axillary disease was posttreatment US showing axillary lymphadenopathy, defined as axial cortical thickness >3.5 mm or loss of the hilum [125]. The prospective clinical Z1071 trial included 611 patients with US after NAC, 238 of whom had axillary CR. US features associated with residual disease included increased cortical thickness (mean 3.5 mm), absent hilum, and longer lymph node diameter [126]. Monitoring Response to Neoadjuvant Chemotherapy US Breast There is no relevant literature to support the use of breast US alone in the evaluation of known axillary lymph node- positive disease after completion of NAC. However, some studies have shown a correlation between pCR in the breast and the axilla [136].