The Impact of Iomri on Glioblastoma Resection and Clinical Outcomes in a Modern Real-world Scenario

Introduction: Intraoperative magnetic resonance imaging (ioMRI) helps increase extent of resection (EOR) to achieve gross total resection (GTR) in patients with glioblastoma multiforme (GBM). Despite randomized data on safety and feasibility, ioMRI’s actual impact in a modern neurosurgical setting has not been investigated. We analyze effects on progression-free survival (PFS) of patients with GBM and its correlation with postoperative performance status based on real-world data from a single high-volume center.

Methods: We included patients undergoing ioMRI for tumor resection between March 2018 and June 2020. Volumetric analysis was implemented to calculate EOR and categorize cases as GTR or subtotal resection (STR). Logistic regression was applied in cases of GTR at postoperative MRI to identify factors leading to STR at ioMRI. Progression-free survival (PFS) was analyzed through regression analyses. Correlation analysis was conducted to identify factors affecting postoperative Karnofsky performance status (KPS) on the fifth day (POD5) and in the third month (POM3).

Results: We enrolled 172 patients with confirmed GBM. Mean EOR increased from 93.9% to 98.3% (p < 0.0001) with the use of ioMRI, with GTR rates increasing from 78.5% to 93.0% (p=0.0002). Residual tumor volume decreased from 1.3±4.2cm3 to 0.6±2.5cm3 (p=0.0037). Logistic regression revealed recurrent GBM (odds ratio [OR]=3.047, 95% confidence interval 1.165–7.974, p=0.023) and tumor volumes less than 15cm3 (OR=3.031, 1.062–8.651, p=0.038) were risk factors leading to STR. Multivariate Cox regression analysis revealed worse preoperative KPS (hazard ratio [HR]=0.983, 0.967–0.998, p=0.031), lower EOR (HR=0.110, 0.014–0.885, p=0.038), and no adjuvant therapy before progression (HR=0.421, 0.236–0.751, p=0.0034) were independent risk factors for progression. Additional resection after ioMRI (HR=0.898, 0.543–1.483, p=0.67) did not affect PFS.

Conclusion : Implementing ioMRI in GBM resection can clearly decrease residual tumor volume and significantly improve EOR and GTR. However, additional resection after ioMRI did not improve PFS of patients with GBM in this large series.