High-field intraoperative MRI in glioma surgery: A prospective study with volumetric analysis of extent of resection and functional outcome

Background

High-field intraoperative MRI (IoMRI) is a useful tool to improve the extent of glioma resection (EOR).

Objective

To compare the interest of 1.5 T IoMRI in glioma surgery between enhancing and non-enhancing tumors, based on volumetric analysis.

Methods

A prospective single-center study included consecutive adult patients undergoing glioma surgery with IoMRI. Volumetric evaluation was based on FLAIR hypersignal after gadolinium injection in non-enhancing tumors and T1 hypersignal after gadolinium injection in enhancing tumors. Endpoints comprised: residual tumor volume (RTV), EOR, workflow and clinical outcome on Karnofsky performance score (KPS).

Results

Fifty-three surgeries were performed from July 2014 to January 2016. Thirty-four patients underwent one IoMRI, and 19 two IoMRIs. In non-enhancing tumors, intraoperative RTV on 1st IoMRI T2/FLAIR was higher than in enhancing tumors on T1 sequences (7.25 cm³ vs. 0.74 cm³, respectively; P = 0.008), whereas the RTV on 2nd IoMRIs and final RTV were no longer significantly different. After IoMRI, 72% of patients underwent additional resection. In non-enhancing tumors, EOR increased from 77.3% on 1st IoMRI to 97.4% on last MRI (P < 0.001). Taking all tumors together, final RTV values were: median = 0 cm³, mean = 3.9 cm³. Mean final EOR was 94%. In 25% of patients, KPS was reduced during early postoperative course; at 3 and 6 months postoperatively, median KPS was 90.

Conclusion

Intraoperative MRI guidance significantly enhanced the extent of glioma resection, especially for non- or minimally enhancing tumors, while preserving patient autonomy.