Role of ADC values and ratios of MRI scan in differentiating typical from atypical/anaplastic meningiomas

: Atypical/anaplastic meningiomas are prone to aggressive behaviour which affects treatment planning and prognostication. Our aim was to assess the role of Apparent Diffusion Coefficient (ADC) values of MRI brain in differentiating typical from atypical/anaplastic meningioma. We reviewed 84 typical and 37 atypical/anaplastic meningiomas and compared mean ADC values and ADC ratios of their preoperative MRI brain. At 3 Tesla, mean ADC value for typical meningioma was1.03±0.10x10-3 and 0.63±0.05x10-3 for atypical/anaplastic meningioma. At 1.5 Tesla, mean ADC value for typical meningioma was 1.05±0.11x10-3 and atypical/ anaplastic meningioma was 0.70 ± 0.04x10-3. The mean ADC ratios were 1.08 ± 0.17 and 0.85 ± 0.15 for typical and atypical/anaplastic meningomas respectively. Mean ADC ratios and the mean ADC values of typical and atypical/anaplastic meningiomas were significantly different (p< 0.001). ADC values and ADC ratios have important role in differentiating typical from atypical/anaplastic meningioma and it must be part of the routine preoperative MRI reporting.