When a radiologist reviewed Deirdre Hall’s mammogram images last summer, everything seemed fine. There were no shadows or lumps or irregular patches that could signal cancer. The doctor gave it a second look for one reason: artificial intelligence software had drawn a circle around an area in the upper part of her left breast that it found suspicious. Because the AI software had put up that red flag, Hall, 55, got an order for an ultrasound that led to a biopsy.