Imaging-Based Score for Predicting Higher-Grade Meningiomas

Introduction: Predicting whether an intracranial meningioma will be higher grade based on preoperative imaging studies remains challenging. While various imaging characteristics have been previously found in the literature to correlate with higher grade lesions, such as presence of edema, heterogeneous enhancement, and shape irregularity, no single finding has been shown to have a high positive predictive value for higher grade meningiomas.

Materials and Methods: After IRB approval we retrospectively reviewed all patients operated on at a single academic institution for intracranial meningiomas between 2014 and 2018. Patient demographics, preoperative laboratories, and imaging were reviewed. One point was assigned for each of the following imaging characteristics: presence of parenchymal edema, heterogeneous enhancement, irregular borders, presence of calcifications, and volume over 40 mL. The Imaging Score (IS) was calculated by adding up the points, with the total score ranging from 0 to 5. Predictive ability of the score to identify meningiomas with grade higher versus WHO grade 1 lesions was evaluated.

Results: Eighty-seven patients who underwent surgery for intracranial meningiomas from 2014 to 2018 who had appropriate imaging, demographic information, and pathological results available were included in the analysis. Nine lesions were infratentorial and 78 were supratentorial. Fifty-two percent were WHO grade 1 tumors and 48% were WHO grade 2 tumors. A total of 70% of the patients were male and 30% were female. There was no significant difference in age between patients with WHO grade 1 and tumors. Individual imaging characteristics of the tumor were analyzed and compared between WHO grades 1 and 2. WHO grade 2 meningiomas were more likely to be larger in size and more likely to demonstrate inhomogeneous enhancement and irregular contours. Interestingly, calcifications were more likely in grade 2 tumors, although the difference was not statistically significant. Using the Imaging Score, the probability of having a WHO Grade 2 meningioma was 0% with the score of 0, 33.3% for those with the score of 1, 35.7% with score of 2, 66.7% with score of 3, 76.2% with score of 4, and 100% with score of 5 ([Table 1]).

Conclusion: The current population of patients studied has a significantly higher rate of WHO grade 2 meningiomas than that which has been previously reported. The Imaging Score presented combines various imaging characteristics and shows a good positive predictive value in this patient cohort for identifying a WHO grade 2 or higher lesion. Further studies to validate this scoring system on a wider cohort of patients are necessary ([Table 2]).