Prediction of brain invasion in patients with meningiomas using preoperative magnetic resonance imaging

Abstract

Brain invasion (BI) in meningiomas impacts WHO grading and therefore adjuvant treatment. However, BI is rare and neurosurgical sampling and neuropathological analyses are not standardised. Moreover, associations with imaging findings are sparsely known. Associations between BI and findings on preoperative MRI were investigated in 617 meningioma patients. BI was strongly correlated with other high-grade criteria (p<.001). Presence of a contrast enhancing tumour capsule, disruption of the arachnoid layer, intratumoural calcifications and T2-intensity were not related to high-grade histology or BI (p>.05, each). High-grade histology (p=.033) but not BI (p=.354) was associated with tumour location. Irregular tumour shape (OR: 3.33, 95%CI 1.33-8.30; p=.007), heterogeneous contrast enhancement (OR: 2.82, 95%CI 1.19-6.70; p=.015) and peritumoural edema (OR: 1.005 per ccm, 95%CI 1.001-1.008); p=.011) were associated with BI. Multivariable analyses identified only increasing edema volume (OR: 1.005 per ccm, 95%CI 1.002-1.009; p=.010) as a predictor for BI, independent of other histopathological high-grade criteria. We finally provide a new model to estimate the risk of BI using routine preoperative MRI. Several imaging characteristics were identified as predictors for BI. Consideration in clinical routine can increase the accuracy of the detection in neuropathological analyses.

Keywords: brain invasion; grading; magnetic resonance imaging; meningioma; radiology.

Figure 1. Boxpots visualizing the degree of association between peritumoural edema (PTBE) volume and histopathological findings

High-grade histology was associated with increased PTBE volume (left, p=.002) and PTBE volumes were larger in invasive than in non-invasive meningiomas (p<.001, right). However, no association was found between edema volume and other histopathological grading criteria (p=.117). The boxes indicate upper and lower 25% quartile, the whiskers the minimum/maximum value within 1.5 IQR of the lower/upper quartile, the dots the outliers, the asterisks the extreme values, and the heavy horizontal line indicates the median (ccm=cubic centimeter, *high-grade=grade II and III meningiomas.).

Figure 2. Prediction of brain invasion using findings on preoperative MRI

Predicted probability of brain invasive growth depending on PTBE volume in females (A) and males (B) according to the final multivariable model (Table 2).

Figure 3. Illustrative examples of the analyzed MRI variables

In (A), axial T2-weighted MRI shows cerebrospinal fluid at the brain/meningioma border (arrow), indicating a distinct tumour surface with an intact arachnoid layer. In (B and C), sagittal T1-weighted images show a contrast-enhancing tumour capsule (B, arrow), a heterogeneous gadolinium enhancement (C) and an irregular tumour shape with mushroom-like growth (C).