High-Field Intraoperative Magnetic Resonance Imaging Increases Extent of Resection and Progression-Free Survival for Nonfunctioning Pituitary Adenomas

Abstract

The effect of intraoperative magnetic resonance imaging (iMRI) on tumor control during endoscopic transsphenoidal surgery (TSS) for nonfunctioning pituitary adenomas (NFPAs) has not yet been completely characterized. The present study assessed the effect of the iMRI findings on gross total resection (GTR) and progression-free survival at a mean follow-up of 62 ± 9.4 months. Retrospective analyses were performed on the data from 133 consecutive patients with NFPA who had undergone endoscopic TSS with iMRI using a 1.5T scanner. Compared with the first and final iMRI scans, the GTR rate increased from 42.9% to 63.9%. Multivariate logistic regression analysis revealed that a lower GTR rate was associated with a higher Knosp score (odds ratio [OR], 3.612; 95% confidence interval [CI], 1.568-8.321; P= 0.003), an increased tumor volume (OR, 0.926; 95% CI, 0.866-0.991; P= 0.025), and a history of surgery (OR, 0.376; 95% CI, 0.155-0.917; P= 0.031). During follow-up, 8 tumors (9.4%) recurred, and 29 remnants (60.4%) regenerated. The recurrence and regeneration rates were 0.019 and 0.121 patient/year, respectively. Kaplan-Meier analysis revealed that the tumor recurrence rates were lower for patients who had undergone GTR (P < 0.01) compared with those who had not. Univariate Cox regression analysis suggested that the presence of tumor remnants (hazard ratio, 1.546; 95% CI, 1.071-2.232; P= 0.02) was the influencing factor associated with tumor progression. High-field iMRI can increase the GTR rate in endoscopic TSS for NPFAs. The increased GTR rate was associated with longer progression-free survival. Cavernous sinus invasion, tumor size, and surgical history were important predictors of GTR in patients with NFPA.