DETECTION WITH MR-IMAGING OF RESIDUAL TUMOR IN THE BREAST SOON AFTER SURGERY

OBJECTIVE. Difficulties in the preoperative assessment of tumor size a nd extent result in a positive pathologic margin in up to 70% of patie nts undergoing breast conservation surgery. Although positive margins usually require reexcision, the location and extent of surgery require d are often difficult to establish by current imaging techniques. We i nvestigated the accuracy of three-dimensional rotating delivery of exc itation off resonance (3D RODEO) MR imaging of the breast in revealing the presence and extent of residual tumor within the breast soon afte r 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 t hat 3D RODEO MR imaging accurately revealed the presence or absence an d the location and extent of recurrent tumor in 15 of the 18 patients who had pathologic confirmation. Of the three MR imaging-pathology mis matches, 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 exami nation. Our 19th patient showed no evidence of recurrent tumor on MR i maging 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 i n 84% of patients who had recently undergone breast surgery.