BI-RADS MRI enhancement characteristics of ductal carcinoma in situ.

To identify the Breast Imaging Reporting and Data System magnetic resonance imaging (MRI) enhancement characteristics of ductal carcinoma in situ (DCIS). A retrospective review of consecutive patients who underwent breast MRI for newly diagnosed breast carcinoma prior to surgery was conducted. This yielded 381 lesions in 361 patients with pathologic confirmation of either DCIS alone, invasive carcinoma alone, or mixed invasive and in-situ disease. Presence or absence of a MRI lesion at the site of the documented carcinoma was recorded, and for all identified MRI lesions the Breast Imaging Reporting and Data System morphology patterns were recorded. MRI features of the different malignancy types were compared utilizing Fisher's exact tests; 64/381 (16.8%) lesions had DCIS, 101/381 (26.5%) had invasive carcinoma, and 216/381 (56.7%) had mixed invasive/in situ carcinoma. A MRI lesion corresponding to the known cancer was identified in 55/64 (85.9%) cases of DCIS, 98/101 (97.0%) cases of invasive carcinoma, and 212/216 (98.1%) cases of mixed invasive and in-situ carcinoma. For pure DCIS lesions, 38/64 (59.4%) exhibited nonmass-like enhancement (NMLE), 9/64 (14.1%) were masses, and 8/64 (12.5%) were a focus. For pure invasive carcinomas 79/101(78.2%) were masses, 16/101 (15.8%) were NMLE, and 3/101 (3.0%) were a focus. For mixed lesions 163/216 (75.5%) were masses, 44/216 (20.4%) demonstrated NMLE, and 5/216 (2.3%) were a focus. The most common NMLE patterns of pure DCIS were segmental distribution and clumped internal enhancement. Although there is overlap in the MRI morphology and enhancement pattern of in situ and invasive breast carcinoma, DCIS more frequently manifests as NMLE than does invasive carcinoma.