BI-RADS category 3, 4, and 5 lesions identified at preoperative breast MRI in patients with breast cancer: implications for management.

• 1.4% (3/213) of BI-RADS 3 lesions were malignant including 2 delayed diagnoses after 13.2 months and 33.2 months, and 17.8% (38/214) of BI-RADS 4 lesions and 50% (1/2) of BI-RADS 5 lesions were malignant. • The incidence of delayed diagnosis from additional MRI-detected lesions was very low (0.7%, 2/306) during follow-up, which were all T1N0 contralateral cancer. • Annual follow-up might be adequate for preoperative MRI-detected BI-RADS 3 lesions and BI-RADS 4 lesions followed up after benign-concordant biopsy.