Comparative Study of Intraoperative MRI Versus Conventional Surgery for Non-Enhancing Brain Tumors

Introduction: Intraoperative MRI (ioMRI) is increasingly utilized in the resection of non-enhancing brain tumors, but its impact on extent of resection (EOR) and overall survival (OS) remains uncertain. This study aims to evaluate the effects of ioMRI on EOR and OS in patients undergoing resection of non-enhancing brain tumors.

Methods: This is an IRB-approved single institution retrospective study of patients with non-enhancing gliomas, glioneuronal, neuronal, and ependymal tumors who underwent surgical resection between 2010 and 2023. Variables collected included demographic data, tumor characteristics, volumetric analyses, surgical details, and OS. Statistical analyses included univariable and multivariable Cox regression for OS and linear regression for EOR.

Results: A total of 613 patients were analyzed, with 357 (58.2%) being male and a mean age of 41.1 (± 13.7) years. The sample comprised 200 (32.6%) oligodendrogliomas, 144 (23.5%) low-grade gliomas, 153 (25.0%) high-grade gliomas, and 16 (2.6%) glioneuronal/neuronal tumors. ioMRI was employed in 310 (50.1%) patients. Baseline characteristics, including age, gender, tumor histology, IDH mutation status, and MGMT promoter methylation, were comparable between ioMRI and non-ioMRI groups. Gross total resection was achieved in 59.3% of ioMRI cases versus 44.3% in non-ioMRI cases (p=0.002). The ioMRI group demonstrated a significantly higher mean EOR on T2-FLAIR MRI (78.5%) compared to the non-ioMRI group (69.9%, p< 0.001). Median OS was 143 (95% Confidence Interval [CI] 131-172) months. On multivariate Cox regression, ioMRI was a significant predictor of extended OS (hazard ratio [HR]: 1.47; 95% CI 1.03–2.12; p=0.035). Other predictors of improved OS included younger age, preoperative KPS ≥ 90, absence of ventricular opening during surgery, smaller preoperative and postoperative tumor volume on T2-FLAIR MRI, and higher EOR.

Conclusion : ioMRI significantly increased EOR and independently predicted improved OS in patients with non-enhancing brain tumors. These findings underscore the utility of ioMRI in optimizing surgical outcomes and prolonging survival in this patient population.