MR imaging of pituitary tumors before and after surgical and/or medical treatment.

Four hundred fifteen cases of suspected pituitary tumors were examined by CT and magnetic resonance (MR). Forty-one microadenomas and 26 large sellar-suprasellar pituitary tumors were diagnosed and surgically removed (61 cases) or treated with bromocriptine (six cases). The present study demonstrated that (a) in cases of microadenomas, MR was more accurate than CT in three cases, as accurate as CT in 33 cases, but missed six cases diagnosed on CT, when MR images were suboptimal (thicker than 5 mm); (b) when the sellar-suprasellar mass was markedly constricted at the diaphragma sellae on MR sagittal slices (16 cases), transsphenoidal surgical approach was not only insufficient for total removal but could be dangerous, as the remaining suprasellar portion may rapidly increase in size following surgery from postoperative hemorrhage and/or acute edema with severe obstructive hydrocephalus (three cases) and/or acute blindness (two cases); (c) hemorrhage in pituitary tumors was easily seen on MR and missed on CT; (d) coronal MR slices visualized the carotid siphon obviating the need for angiography to rule out intrasellar aneurysm, which can mimic pituitary tumor on contrast CT; (e) postoperative MR was needed before considering radiotherapy to visualize accurately the relation of the optic chiasm to the residual tumor and to follow up its gradual change in size; (f) finally, in cases treated with bromocriptine, MR was more accurate than CT in following the gradual decrease of pituitary tumor.