The utility and safety of intraoperative MRI (iMRI) for resection of pituitary adenomas is not clearly established in the context of advances in endoscopic approaches. The goal in this study was to evaluate the safety and efficacy of iMRI for pituitary adenoma resection, with endoscopic transsphenoidal (ETS) versus microscopic transsphenoidal (MTS) approaches.
Radiographic and clinical outcomes of all pituitary adenomas resected using iMRI between 2008 and 2017 at a single institution were retrospectively evaluated.
Of 212 tumors treated, 131 (62%) underwent further resection based on iMRI findings, resulting in a significant increase in gross-total resection on postoperative MRI compared with iMRI (p = 0.0001) in both ETS and MTS groups. iMRI increased rates of gross-total resection for cavernous sinus invasion Knosp grades 1 and 2, but not in Knosp ≥ 3 across treatment groups (p < 0.0001). The extent of resection on postoperative MRI was significantly correlated with increased progression-free survival (p < 0.0001). Initial hormone remission off medical therapy was achieved in 64%, with a significantly higher rate of remission in tumors resected via the ETS approach (81%) compared with the MTS approach (55%) (p = 0.02). The rate of persistent new hormone deficit was low at 8%, including a 2.8% rate of permanent diabetes insipidus, and 45% of patients had improvement in preoperative hormone deficit following surgery. Serious postoperative complications including CSF leaks requiring reoperation were rare at 1%, with no postoperative infections.
These results suggest that iMRI is a safe and effective method of increasing the extent of resection for pituitary adenomas while preserving hormone function. When paired with the endoscope, iMRI may offer the ability to tailor more aggressive removal of tumors while optimizing pituitary function, resulting in high rates of secretory hormone remission. Secretory tumors and adenomas with Knosp grade < 3 cavernous sinus invasion may benefit most from the use of iMRI.