Probably benign lesions detected on breast MR imaging.

The MR imaging BI-RADS atlas includes a category for probably benign findings, and many radiologists recommend short-term interval follow-up for breast MR imaging lesions. However, the characteristics of those MR imaging findings that could appropriately be considered probably benign are not well defined. This article reviews the published retrospective and prospective data regarding the use and cancer yield of the BI-RADS 3 assessment category as well as the morphology and kinetics of lesions that may be considered suitable for short-term follow-up. Consideration is also given to how the costs, clinical indication for the examination, experience of the reader, and availability of comparisons may affect the use of the BI-RADS 3 category. Based on the evidence that is available, an algorithm is offered with imaging examples as a guide for determining if lesions are appropriate for short-term follow-up. Additional research is needed to fully clarify the distinct morphologic and kinetic characteristics that allow patients to safely avoid biopsy without changing prognosis if malignancy is present.