Intraoperative MRI for Brain Tumors: A 15-year Retrospective Review at a Single Australian Institution

Introduction:

Background: Maximal safe resection is the objective of most neuro-oncological operations. Intraoperative magnetic resonance imaging (iMRI) may guide the surgeon to improve the extent of safe resection. There is limited evidence investigating the impact of iMRI on intraoperative decision-making. Our study aims to investigate the impact of iMRI on the rate of further resection following visualization of residual tumor.

Methods:

Methods: A retrospective cohort study identified all intracranial tumor operations performed in the 1.5T iMRI machine of a single center (2007–2023). Patients were identified using SurgiNet and were grouped according to their histopathological diagnosis in accordance with the WHO 2021 classification. The primary outcome was the rate of reoperation due to iMRI visualization of residual tumor.

Results: A total of 574 cases were identified, including 152 low-grade gliomas (LGG), 108 high-grade gliomas (HGG), 194 pituitary adenomas, 15 metastases, and six meningiomas. Further resection following iMRI visualization occurred in 45% of LGG cases, 47% of HGG cases, 29% of pituitary cases, and in no meningioma or metastasis cases. Chi-square analysis showed that the rate of further resection after iMRI use across 2018-2023 was significantly higher than that across 2007-2012 (46% versus 33%, p=0.036).

Conclusion : Intraoperative MRI for guiding further resection was most useful in cases of LGG and HGG, possibly reflecting the difficulty of differentiating these tumor types from normal brain tissue. In addition, there was increased reliance on iMRI over time which may represent our surgeons becoming accustomed to its use.