BI-RADS 3 lesions on MRI

Abstract

Probably benign (BI-RADS 3) lesions on MRI are an empirically assigned category that lack specific criteria that could be used for an objective diagnosis. In this chapter, we describe the probably benign BI-RADS 3 category on MRI and report frequency and malignancy rates. The rate of malignancy in BI-RADS 3 lesions on MRI is below 2 % in the majority of studies. It is lowest in foci (0.9 %) and highest in non-mass enhancements (4 %). Malignant BI-RADS 3 lesions diagnosed by immediate MR-directed ultrasound or a single MRI follow-up in 6-12 months (in case a lesion is not visible by MR-directed ultrasound or MR-directed ultrasound was not performed) support the recommendation of these two management approaches. Finally, in accordance with published data we discuss imaging criteria for those breast lesions that might or might not be appropriately be assigned BI-RADS 3 on MRI.