I had a CT scan of the abdomen after receiving an abnormal ultrasound with the following impression
Dear madam, I think that everything is said. It can be only calcification which means nothing. But it can also be a stone.  You didn't mentioned the exact symptoms which led you to these diagnostic tests, but if it is a stone lodged in sphincter of Odd you would have typical biliary comics or even jaundice from time to time. So I recommend you if u have these symptoms u should do cholecystectomy, if not u can do i too, or you can wait for symptoms to appear. Dilatation of duct goes with biliary obstruction due to stones or tumors. Wish you good health.