MR imaging of residual tumor tissue after transsphenoidal surgery of hormone-inactive pituitary macroadenomas: a prospective study.

22 patients were examined by magnetic resonance (MR) imaging before and after transsphenoidal surgery of hormone-inactive pituitary macroadenomas to evaluate for tumor removal. MR imaging was performed without and with gadolinium-DTPA before the operation and 3 months after. In all cases a suprasellar tumor extension was found preoperatively, in 9 cases with an additional parasellar, in 2 cases with an additional retrosellar extension (average diameter 2.5 cm). In 7 cases complete tumor removal was shown by postoperative MR, but in 11 cases residual tumor tissue was found (4 x suprasellar, 5 x parasellar, 2 x retrosellar). In 4 patients postoperative MR could not clearly differentiate residual tumor from scar formation. Although in cases of residual tumor follow-up MR imaging was performed over a period of two years, residual tumor volumes did not appear to change. This study demonstrates that MR imaging is highly sensitive for evaluating residual tumor tissue after transsphenoidal surgery of hormone-inactive macroadenomas.