Detection with MR imaging of residual tumor in the breast soon after surgery

OBJECTIVE. Difficulties in the preoperative assessment of tumor size and extent result in a positive pathologic margin in up to 70% of patients undergoing breast conservation surgery. Although positive margins usually require reexcision, the location and extent of surgery required are often difficult to establish by current imaging techniques. We investigated the accuracy of three-dimensional rotating delivery of excitation off resonance (3D RODEO) MR imaging of the breast in revealing the presence and extent of residual tumor within the breast soon after surgery. MATERIALS AND METHODS. Nineteen patients who had undergone lumpectomy or excisional biopsy were evaluated with contrast-enhanced 3D RODEO MR imaging of the breast within 10 months after surgery. The MR imaging results were correlated with serial-sectioned mastectomy or partial mastectomy specimens from 18 patients and with a clinical and mammographic follow-up examination in one patient. RESULTS. We found that 3D RODEO MR imaging accurately revealed the presence or absence and the location and extent of recurrent tumor in 15 of the 18 patients who had pathologic confirmation. Of the three MR imaging-pathology mismatches, two had irregular or nodular enhancement that corresponded to microabscesses. The third mismatch showed multicentric disease on MR imaging but only single-quadrant lobular carcinoma at pathologic examination. Our 19th patient showed no evidence of recurrent tumor on MR imaging or at 2-year follow-up clinical and mammographic examinations. CONCLUSION. MR imaging with 3D RODEO technique correctly revealed the presence or absence, the location, and the extent of recurrent tumor in 84% of patients who had recently undergone breast surgery.