MRI appearances of bladder endometriosis

Endometriosis is characterized by endometrial tissue in ectopic foci outsid e the uterus. Involvement of the urinary tract is rare, with the bladder be ing most commonly affected in these cases. Radiologically these lesions, wh ich are usually small, may be difficult to distinguish from intrinsic bladd er neoplasia. Four cases of vesical endometriosis are presented with the MR I features that suggest the diagnosis.