Intraoperative MRI in pediatric brain tumor surgery: Optimizing surgical decision-making and extent of resection.

OBJECTIVE: To assess the impact of intraoperative MRI (ioMRI) on the extent of resection (EoR) in pediatric brain tumor surgery and evaluate the benefits and limitations of its routine implementation. METHODS: Observational single-center study, including prospectively collected data of 118 ioMRI-guided intracranial tumor resections in 108 children that were performed at the University Hospital Zurich between May 2013 and October 2022. EoR was graded as gross total (GTR; no residual tumor), sub-total (STR; > 90% tumor resection), and partial resection (PR; < 90% tumor resection). RESULTS: A total of 118 ioMRI-guided interventions were performed in 108 individual children aged ≤ 18 years. The intended EoR determined pre-operatively was GTR in 81 cases (68.6%), STR in 24 (20.3%), and PR in 13 (11.0%). IoMRI confirmed the intended EoR achieved in 78/118 procedures (66.1%), demonstrating GTR in 48 cases (40.7%), STR in 50 (42.4%), and PR in 20 (16.9%). In 48 cases (40.7%), ioMRI findings prompted further intraoperative evaluation; additional tumor resection was performed in 45 cases (93.8%), resulting in improved EoR. The final EoR distribution after ioMRI-guidance was 80 GTR (67.8%), 25 STR (21.2%), and 13 PR (11.0%), resulting in a rate of achieving the intended EoR in 99.2% of cases (117/118). Surgical site infections (SSI) occurred in 4 cases (3.4%). CONCLUSIONS: This study highlights the substantial impact of ioMRI in pediatric brain tumor surgery, demonstrating a high rate of surgical site reopening for residual tumor resection, which substantially improved the EoR and minimized the need for a second operation - without increasing SSI incidence.