Background: Knowledge of the magnetic resonance imaging (MRI) appearance of the pituitary fossa following transsphenoidal resection of a pituitary adenoma, in the early and late postoperative period, is important for detecting complications and for assessing extent of tumor excision. Few prospective studies have addressed this issue.
Methods: Fourteen patients with pituitary macroadenomas were prospectively studied with MRI. Maximal tumor resection was accomplished in each patient, and the postoperative histological diagnoses included non-secreting adenoma in 11 patients, prolactinoma in 2 and necrosis in one. Early postoperative scans were 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 months and a year. The maximum coronal dimension (MCTD) of the sellar and suprasellar contents was measured on T1-weighted contrast enhanced scans.
Results: All patients had normal or improved visual examinations and normal or improved 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 the 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 postoperative MRI may appear remarkably similar to that seen before surgery, even after technically adequate resection. The postoperative mass may represent a combination of residual tumor, edema, postoperative hemorrhage and hemostatic material. Routine follow-up MRI after transsphenoidal resection of pituitary tumors may be delayed until at least 4 months after surgery in patients who are clinically stable.