ITVT-08. Combined use of awake surgery and intraoperative MRI augments extent of resection in eloquent gliomas without neurological impairment

Abstract

Abstract Maximizing the extent of resection (EOR) while preserving functional integrity is a mainstay of glioma surgery. Intraoperative MRI (iMRI) helps to augment the EOR. However, in eloquently located gliomas the significance of iMRI is controversial since the EOR is limited by functional rather than image-based boundaries. Thus, we sought to determine the impact of iMRI in our institutional series of awake glioma resections within or adjacent to eloquent (language, motor, sensory) areas since the implementation of a 1.5 Tesla iMRI in 2009. Tumor- and procedure-related data and functional outcome were assessed through medical charts review. The EOR was determined volumetrically on pre-, intra- and postoperative T1 contrast-enhanced (CE) and FLAIR MR images. 131 of 166 awake surgeries (79%) were performed under iMRI-guidance with concurrent language (n=72) and/or motor (n=50) mapping. iMRI was done when functional boundaries were reached (62%), for resection control (28%) or for other reasons (10%). Additional resection after iMRI (AR) was performed in 63 cases (73%); otherwise resection was terminated because the targeted EOR or functional boundaries were reached. New or deteriorated neurological deficits occurred in 20 patients prior and 15 patients post iMRI; however, all but 3 resolved within 6 months. Median EOR significantly increased after AR from 92.6% to 98.4% (∆5.8%; p<0.0001) in CE tumors and from 64.5% to 85.8% (∆21.3%; p<0.0001) in non-enhancing tumors. Remarkably, the reason to perform iMRI (resection control or functional limitations), did not affect the frequency of AR, deficits acquired post iMRI or the increase in EOR after AR. In conclusion, iMRI is a valuable adjunct to maximize the EOR in awake glioma resections without increasing the risk for functional impairment, particularly in non-enhancing tumors. Importantly, iMRI contributes to a maximized EOR even in cases where the resection had to be stopped because functional boundaries were reached.