Postoperative MRI appearance after transsphenoidal pituitary tumor resection

BACKGROUND Knowledge of the magnetic resonance imaging (MRI) appearance of the pituita ry fossa following transsphenoidal resection of a pituitary adenoma, in the early and late postoperative period, is important for detecting complicati ons and for assessing extent of tumor excision. Few prospective studies hav e addressed this issue. METHODS Fourteen patients with pituitary macroadenomas were prospectively studied w ith MRI. Maximal tumor resection was accomplished in each patient, and the postoperative histological diagnoses included non-secreting adenoma in 11 p atients, prolactinoma in 2 and necrosis in one. Early postoperative scans w ere obtained within 14 days after surgery, and late studies between 3 and 4 months, in all patients. Four patients also had delayed scans between 8 mo nths and a year. The maximum coronal dimension (MCTD) of the sellar and sup rasellar contents was measured on T1-weighted contrast enhanced scans. RESULTS All patients had normal or improved visual examinations and normal or impro ved hormonal function postoperatively. The preoperative MCTD ranged from 11 mm to 59 mm in height (mean 30.3 mm). There was little change in MCTD on t he early postoperative MRI scans (range 7-49 mm, mean 23.5 mm). However, in all patients the MCTD decreased in height by 4 months (range 2-35 mm, mean 12.7 mm). This change represented a 58% mean reduction in size compared to the preoperative measurements. CONCLUSIONS We conclude that the appearance of the sellar contents on early postoperati ve MRI may appear remarkably similar to that seen before surgery, even afte r technically adequate resection. The postoperative mass may represent a co mbination of residual tumor, edema, postoperative hemorrhage and hemostatic material. Routine follow-up MRI after transsphenoidal resection of pituita ry tumors may be delayed until at least 4 months after surgery in patients who are clinically stable. (C) 1999 by Elsevier Science Inc.