Fractional anisotropy, perfusion, and metabolic correlates of peritumoural brain oedema in meningiomas: a cross-sectional observational multiparametric MRI study

OBJECTIVE: To evaluate perfusion, diffusion tensor, and spectroscopy correlates of peritumoural brain oedema (PTBO) in intracranial meningiomas and identify imaging parameters associated with PTBO volume using multiparametric Magnetic Resonance Imaging (MRI). METHODS: In this cross-sectional study of 66 adults, PTBO presence was defined as a T2-hyperintense peritumoural volume ≥ 10 mL (n = 26) and absence as ≤ 1 mL (n = 35); intermediate volumes were excluded (n = 5). Preoperative 1.5T MRI assessed relative cerebral blood volume (rCBV), apparent diffusion coefficient (ADC), fractional anisotropy (FA), and magnetic resonance spectroscopy (MRS). Independent predictors were identified via multivariable logistic regression. Diagnostic performance (Area Under the Curve, AUC) was estimated using 5-fold cross-validation. RESULTS: PTBO-associated tumours demonstrated significantly larger volumes, more frequent intratumoural necrosis, higher rCBV, elevated ADC, and increased choline ratios (p < 0.001 for all). Multivariable regression identified FA, rCBV, and tumour volume as independent predictors of PTBO presence. FA demonstrated superior discrimination (cross-validated AUC = 0.96; 95% CI 0.92-0.99) compared to rCBV (cross-validated AUC = 0.82) and tumour volume (cross-validated AUC = 0.78). CONCLUSION: Multiparametric MRI correlates significantly with PTBO. FA shows the strongest independent association with the presence of PTBO. Elevated rCBV/ADC, reduced FA, and higher choline ratios characterise oedema-forming meningiomas. All proposed FA thresholds (including values around 0.45) are exploratory, cohort-derived, and require external validation before clinical use.