Computer-aided volumetric analysis as a sensitive tool for the management of incidental meningiomas

Meningiomas are typically slow-growing lesions that, depending on the location, can be relatively benign. Knowing their exact rate of growth can be helpful in determining whether surgery is necessary. 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. 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. 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. Overall, we found that computer-aided perimeter methods showed a more accurate picture of tumor progression than traditional methods, which generally underestimated growth.