Don’t be afraid. They mark everything as birad4 as long as they are not almost 100% sure. MRI is too sensitive that it constantly pick up the wrong thing. Last Dec my MRI picked up a 15cm long band on my lung. Contrast CD scan two weeks later found nothing; the same MRI also found suspicious area and from the description really sounded like cancer on another breast. I ended up going through ultrasound and mammogram and its calcifications. However Radiologist still sent me to biopsy and also put a birad 4 on my radiologist report. The biopsy said I had ADH and needed to be removed since ADH will gradually increase the chance of getting breast cancer. I ended up having another mastectomy and the surgical pathology report didn’t find ADH at all. It’s all benign!