Analysis Of Magnetic Resonance Imaging (Mri) In The Detection Of Mammographically Occult Breast Carcinoma

603 Background: Breast MRI may be useful for detecting mammographically occult ipsilateral carcinoma in newly diagnosed breast cancer. Our initial experience with breast MRI, demonstrated 16% of patients to have additional breast disease detected only by preoperative MRI. We further analyzed our findings to identify an association between patient factors and MRI detected disease. Methods: Preoperative MRI scans of 390 women with newly diagnosed breast cancer were reviewed. Using only patients with pathologic verification, the incidence of mammographically occult ipsilateral cancer was determined. Patient and tumor characteristics were further analyzed to identify factors which may predict pathologically positive MRI findings. Results: Of the 390 women undergoing preoperative MRI, 120 (31%) had ipsilateral findings requiring biopsy. Pathologically verified additional ipsilateral cancer was detected in 62 (16%). Multicentric disease was detected in 32 (52%) and multifocal or more extensive local disease in 30 (48%). The median age of all patients was 62 (27% premenopausal) whereas the median age of those with MRI detected additional carcinoma was 55 (44% premenopausal). Of those with additional disease detected by MRI, 74% had index lesions =1 cm and 63% node negative. The most common histology of the index lesion was infiltrating ductal carcinoma in 64%. In the 62 patients found to have additional disease by MRI the most common histology included infiltrating ductal carcinoma (58%), ductal carcinoma-in-situ (34%) and infiltrating lobular (8%). The histology of the MRI detected additional disease was identical to the index lesion in 71%. Conclusions: In women with newly diagnosed breast cancer, there was a 16% incidence of pathologically proven, mammographically occult ipsilateral disease detected by MRI. Patients found to have additional disease tended to be younger, premenopausal or have index tumors =1cm. The contribution of preoperative MRI in breast cancer management continues to evolve. A lower threshold for obtaining breast MRI may be appropriate in selected subsets of breast cancer patients. No significant financial relationships to disclose.