Intraoperative MRI in transsphenoidal resection of invasive pituitary macroadenomas

The use of intraoperative MRI (iMRI) increases extent of resection in transsphenoidal pituitary surgery. Microsurgical and endoscopic techniques have been established as equal and standard surgical methods. The object of the current study was to evaluate the additional value of iMRI for resection of invasive pituitary adenomas. We conducted a retrospective monocenter study of all consecutive patients treated with invasive pituitary adenomas graded as Knosp III-IV at our department after the introduction of iMRI in 2008. Out of 315 transsphenoidal surgeries for pituitary adenomas, 111 met the criteria for analysis. Patients treated with endoscopic or microsurgical technique were included. iMRI was performed at surgeons’ discretion, when maximal safe resection was assumed. Detailed volumetric tumor analysis using semiautomatic segmentation software (Brainlab Elements) before surgery, during surgery, and after surgery was performed. Additionally, demographic data, additional resection, endocrinological outcome as well as complications were evaluated. Postoperative tumor volume as measured in the follow-up MRI 3 months after surgery was significantly lower compared with intraoperative tumor volume ( p