MR imaging of the breast in patients with occult primary breast carcinoma

PURPOSE: To evaluate the utility of contrast material-enhanced magnetic resonance (MR) imaging of the breast for localization of the site of primary breast carcinoma in patients with isolated ipsilateral axillary metastasis, without other focal findings at physical examination or mammography. MATERIALS AND METHODS: Twelve women with biopsy-proved metastatic adenocarcinoma to axillary lymph nodes and occult primary tumor underwent MR imaging at 1.5 T with a three-dimensional spoiled gradient-echo pulse sequence before and after administration of gadopentetate dimeglumine. Enhancing areas were correlated with histopathologic findings at mastectomy (n = 8) or breast-conserving treatment (n = 4). RESULTS: In nine (75%) of the 12 patients, enhancement was seen on MR images that represented the site of the primary tumor at surgery. Eight had focal masses, and one had an area of regional enhancement. Two patients had negative MR findings, and no tumor was found at mastectomy One patient with regional enhancement on MR images had no corresponding tumor at surgery. CONCLUSION: Breast MR imaging enables identification of the site of primary tumor in most patients suspected of having occult primary breast cancer, and MR findings can influence surgical treatment.