Intraoperative ultrasonography with intraoperative MRI confirmation in glioma surgery: Evaluating a combined resection strategy

Background: Various intraoperative imaging adjuncts help detect residual tumor and maximize the extent of resection (EOR) in glioma surgery. Intraoperative magnetic resonance imaging (IOMRI) and intraoperative ultrasonography (IOUS) are potent technologies used to guide resection. The primary objective of this study was to effectively combine these two modalities for glioma resection, compare them for residual tumor detection, and examine their respective advantages. Methods: A prospective observational study was conducted over 2 years, and patients with glioma involving eloquent or near-eloquent regions were included. They underwent surgical resections guided by combining IOUS and IOMRI. IOUS was done preresection and also used to monitor resection. IOMRI was done at the end of the intended tumor resection. Basic patient characteristics, IOUS and IOMRI findings, and surgical outcomes were evaluated. Results: Thirty-four patients were included in the study. The mean age was 39.47 ± 11.04 years; 41.2% of the tumors were insular gliomas, and 61.8% were high-grade gliomas (grade 3 or 4). The median EOR was 91.42% (80.47–99.44%), and the median residual tumor volume was 4.46 cc (0.22–8.30 cc). 29.4% (10/34) of patients underwent further resection after IOMRI, resulting in a 10% increase in median EOR; nine of these were insular gliomas. The estimates of the EOR on IOUS and IOMRI were concordant in 64.7% of cases and discordant in 35.3% of cases. IOUS had a sensitivity of 85% and a specificity of 100% to detect residual tumor compared to IOMRI. Conclusion: A combined strategy using IOUS for intraoperative guidance and IOMRI as final confirmation yielded favorable surgical outcomes. IOUS, although comparable to IOMRI in detecting residual tumor, IOMRI proved beneficial, especially in insular gliomas.