I had DCIS 4 years ago in rt. breast and now have enlarged ducts in left breast. The radiologist suggested possilby getting an MRI and/or biopsy. Does an MRI identify the type of cells that are in the duct or is biopsy the only way to know for sure? I don't want added medical expense if they are going to recommend a biopsy later, anyway. Also, what do they usually do about debris in the ducts?