Intraoperative MRI Volumetrics Predict Survival in Lower-Grade Glioma, Especially IDH-Mutant Tumours
A retrospective single-institution study of 90 lower-grade glioma patients found that greater extent of resection and smaller residual T2/FLAIR volumes on intraoperative MRI predict longer progression-free and overall survival, with FLAIR-based metrics independently predictive in IDH-mutant tumours. Additional resection prompted by iMRI occurred in 56% of cases but did not independently improve survival. Relevant for neuropathology labs performing IDH mutation testing as part of integrated molecular-radiological prognostication.
The original study
Lower-grade glioma imaging volumes and survival: a single-institution analysis of 90 patients after resection using intraoperative MRI.
- Authors
- Nadel JL, Gamboa NT, Botros D, Crabb BT, Kendall N, Findlay MC, et al.
- Journal
- Journal of neuro-oncology
- PMID
- 41854942
Original abstract
PURPOSE: Extent of resection (EOR) and residual tumor volume (RTV) are key prognostic factors in lower-grade gliomas (LGGs). Intraoperative magnetic resonance imaging (iMRI) enables real-time assessment of tumor removal, but the survival relevance of sequential volumetric measures remains incompletely defined. This study evaluated the relationship between T2- and FLAIR-based imaging volumes, EOR, and survival in patients undergoing LGG resection with iMRI with long-term radiographic and clinical follow-up. METHODS: We retrospectively reviewed 90 patients with WHO Grade 2-3 LGGs who underwent iMRI-guided resection between 2011 and 2023 at a single institution. Radiographic and clinical follow-up was tracked through 2025. Volumetric analyses were performed on preoperative, intraoperative, immediate postoperative, and three-month postoperative T2-weighted and FLAIR sequences. Associations between imaging volumes, EOR, and progression-free (PFS), malignant progression-free (mPFS), and overall (OS) survival were assessed using log-rank and multivariable Cox regression analyses, including subgroup analysis by isocitrate dehydrogenase (IDH) mutation status. RESULTS: Median clinical and radiographic follow-up was 94.5 ± 34.8 months. Greater EOR correlated with longer survival across all metrics. In IDH-mutant tumors, FLAIR-based EOR was independently predictive of PFS (p ≤ 0.03), mPFS (p ≤ 0.02), and OS (p ≤ 0.02) on multivariable analysis. Additional resection after iMRI occurred in 55.6% of patients, with 90% yielding positive tumor margins, but did not independently improve survival. CONCLUSION: In LGG surgery accompanied by iMRI, greater EOR and smaller residual T2/FLAIR volumes predict longer survival, particularly among IDH-mutant tumors. The use of iMRI facilitates maximal safe resection.