10 Years' Experience of Using Low-Field Intraoperative MRI in Transsphenoidal Surgery for Pituitary Adenoma: Results of the Swiss Pituitary Registry (SwissPit)

Abstract

For 20 years, several studies have reported intraoperative magnetic resonance imaging (iMRI) utility to achieve gross total resections in transsphenoidal pituitary adenoma surgery. Although few studies on low-field iMRI included >100 patients, data on hormonally active tumors remain scarce and follow-up times are <3 years. This is not sufficient to judge the long-term efficiency of the use of low-field iMRI. The aim of this retrospective study is to report the detailed outcome of iMRI-controlled transsphenoidal surgery in >200 patients during a follow-up exceeding 5 years. Patients undergoing surgery for pituitary adenoma by iMRI-controlled, endoscopically assisted transsphenoidal surgery at the authors' institution between 2006 and 2016 were eligible for inclusion. Data were collected in the Swiss Pituitary Registry. A Polestar 0.15T-scanner was used. A total of 231 patients had surgery for 160 nonfunctioning adenomas; 28 hGH-, 27 PRL-, 10 ACTH-secreting and 6 mixed adenomas and were followed for 62 months (9-178). Additional iMRI-guided resections were possible in 54% and increased the gross total resection rate by 4% (P= 0.004). Remission rates were as follows: nonfunctioning adenoma, 53%; acromegaly, 61%; prolactinoma, 50%; Cushing disease, 90%. Tumor regrowth and recurrence was detected at a mean time of 24 and 63 months, respectively. Recovery of deficient hormone axes was detected in 22% to 27%. The risk for new postoperative hormonal deficiencies was 15%. Postoperative relieve of visual field and visual acuity deficiencies was seen in 94 (86%) and 73 (81%) patients, respectively. Judged by long-term follow-ups of >200 nonfunctioning/functioning pituitary adenomas, the use of low-field iMRI in transsphenoidal surgery increases resection rates and sustainably influences outcomes.