Radiographic Comparison of Secretory Meningiomas and WHO Grade 2 Meningiomas: A Retrospective Cohort Analysis

Introduction: Secretory meningioma (SM) is a rare benign subtype of World Health Organization (WHO) Grade I meningioma associated with significant peritumoral brain edema (PTBE). WHO Grade II (G2) meningiomas are also associated with increased PTBE in comparison to WHO Grade I meningiomas, and preoperative radiographic differentiation of SM and G2 meningiomas may be difficult. Our aim was to compare SM and G2 patients and determine predictive radiographic features to differentiate these two preoperatively.

Methods: A retrospective review was conducted of all patients with confirmed pathology of intracranial SM and G2 who underwent surgery at a single institution between 2000 and 2019. Age, sex, tumor location, tumor volume, T2 edema grade, fluid-attenuated inversion recovery sequence (FLAIR) intensity, irregular margins, cystic component, and normalized apparent diffusion of coefficient (nADC) value were obtained. PTBE on FLAIR was classified into two groups: grades 0 (minimal/no edema) and 1 (edema of equal/smaller size than tumor), or grades 2 (significant edema greater than tumor size) and 3 (hemispheric edema). A nADC value was calculated by dividing the mean tumor ADC by the contralateral parenchymal ADC value. Univariate logistic regression models were constructed to explore the association between predictors and meningioma type (SM vs. G2). Subsequently, a bidirectional stepwise variable elimination process was performed to construct a multivariable logistic regression model to identify independent predictors of SM. The significance level for entry into and exit from the model was 0.15. p-Values were two-sided, with a significance threshold of 0.05.

Results: There were 56 patients with SM and 225 patients with G2 with available preoperative imaging. There was no statistically significant difference in age between cohorts. A bidirectional step-wise variable elimination process selected sex, tumor volume, T2 edema, FLAIR intensity, irregular margins, cystic component, and nADC for inclusion in a multivariable logistic regression model. While on univariate analysis there was greater female predominance in the SM cohort (p < 0.001), on multivariable analysis sex was not a statistically significant predictor. On multivariable analysis, larger tumor volumes were significantly associated with G2 meningiomas after controlling for confounders (OR: 0.56 per 10 cc increase in volume, p < 0.001). The presence of significant T2 edema strongly indicated 4.44 times greater odds of SM (p = 0.01). Tumor FLAIR hyperintensity was a very strong predictor of a tumor being a SM (OR: 7.80, p = 0.002), whereas cystic component suggests greater odds of G2 (OR: 0.08, p = 0.007). In addition, for every 0.1 increase in nADC value, a tumor is 1.54 times more likely to be SM (p < 0.001), possibly a reflection of differences in cellularity. Irregular margins were not associated with tumor type.

Conclusion: On preoperative imaging of patients with intracranial meningiomas, tumor FLAIR hyperintensity, greater PTBE, and higher ADC values were more likely to be SM. Larger tumors and presence of a cystic component were more predictive of G2 meningiomas.

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Artikel online veröffentlicht:
15. Februar 2022