MRI of the Breast as Part of the Assessment in Population-Based Mammography Screening

Purpose: To evaluate the indications and impact of MRI of the breast as an assessment modality in population-based mammography screening. Materials and Methods: 135 consecutive contrast-enhanced MRI exams of the breast, which were performed between April 2007 and October 2012 as part of the assessment at one mammography screening unit before issuance of a final management recommendation (e. g. definitely benign or malignant), were retrospectively reviewed. Overall, the cases with an MRI exam of the breast during assessment represent less than 2 % of all assessment cases at this screening unit. All MRI exams were performed as part of the routine clinical care on a 1.5 T or 3 T whole-body magnet using a standard dynamic breast MRI protocol. Results: In the 135 study patients, a total of 30 malignancies in 28 patients were found, including two bilateral cancers. One patient was diagnosed with a non-Hodgkin lymphoma, and of the remaining 29 malignant lesions, 3 (10 %) were in-situ cancers (DCIS) and 26 (90 %) were invasive breast cancers including 3 multifocal or multicentric cancers. All 26 detected invasive cancers were lymph-node negative and 25/29 (86 %) of the detected breast cancer were early stage cancers (stage 0 or 1). 53 of the 135 MRI exams (39.3 %) were suspicious for malignancy (BIRADS 4 or 5) with no cancer missed by MRI. The sensitivity, specificity, positive predictive value, and negative predictive value of the MRI on a per patient basis were 100 %, 77 %, 0.53, and 1, respectively. Conclusion: MRI is a useful problem-solving tool in mammography screening assessment with a high sensitivity and an acceptable positive predictive value.