High-spatial-resolution MRI of non-masslike breast lesions: interpretation model based on BI-RADS MRI descriptors.

OBJECTIVE: The purpose of this study was to assess an interpretation model based on BI-RADS MRI descriptors and high-spatial-resolution MR images in lesions showing non-masslike enhancement.
MATERIALS AND METHODS: Retrospective review was performed of 30 consecutive lesions showing non-masslike enhancement. MRI was performed on a 1.5-T scanner using the volumetric interpolated breath-hold examination sequence. The distribution patterns were classified into three categories: single quadrant/solitary lesion (linear), single quadrant/grouped lesion (focal, regional, segmental), and multiquadrant lesion (multiple regions, diffuse). The presence of a ductal pattern was assessed in the enhancing lesions after the tumor distribution had been decided. In addition to the BI-RADS MRI descriptors, the presence of clustered ring enhancement was also assessed in heterogeneous enhancing lesions.
RESULTS: The most frequent morphologic finding among the benign lesions was a linear pattern (50%) followed by homogeneous internal enhancement (42%), whereas a segmental pattern (56%) (p = 0.003), heterogeneous internal enhancement (44%), and clustered ring enhancement (44%) (p = 0.01) were the most frequent findings in malignant lesions. The features with the highest positive predictive value for carcinoma were a segmental distribution (100%), a clustered ring enhancement (100%), and a clumped internal architecture (88%). Using this interpretation model, the positive predictive value for carcinoma was 94%.
CONCLUSION: A combination of BI-RADS MRI descriptors and clustered ring enhancement criteria is useful for the differential diagnosis of lesions showing non-masslike enhancement.