Computer-Aided Volumetric Analysis as a Sensitive Tool for the Management of Incidental Meningiomas

Background: Meningiomas, which are typically slow growing lesions that depend on location, can be relatively benign. Knowing their exact rate of growth can be helpful in determining whether surgery is necessary.

Objective: In this study, we retrospectively reviewed the meningioma practices of the two senior authors (JR, MR). Our goal was to measure meningioma growth using a variety of methods (linear, using diameters, and volumetric, using the computer-aided perimeter and cross-sectional diameter methods) to compare rates of growth among the methods.

Methods: Of 295 meningioma patients seen over an 8-year period, we identified a cohort of 31 patients with at least 30 months of follow-up. Volumes were calculated using medical imaging software with T1 post-contrast magnetic resonance imaging. Doubling times and growth rates were calculated.

Results: Of the 31 patients, 26 (84%) were shown to have growing meningiomas. The perimeter methodology measured higher growth rates than the diameter method for both doubling times as well as percentage annual growth (P < 0.01). The mean doubling time was 13.4 years (range, 2.1–72.8 years) and 17.9 years (range, 4–92.3 years) comparing perimeter and diameter methods, respectively. The mean percentage of annual growth was 15.2% (range, 1.8–61.7%) and 5.6% (range, 0.7–12.2%) comparing perimeter and diameter methods, respectively. Linear growth was calculated at 0.7 mm/year.

Conclusion: Overall, the methods traditionally used to track meningiomas using cross-sections underestimated the amount of tumor progression compared with volumes calculated using computer-aided perimeter methods.