The role of diffusion tensor imaging and dynamic susceptibility perfusion MRI in the evaluation of meningioma grade and subtype.

Purpose: We prospectively investigated the relationship between diffusion tensor imaging (DTI), dynamic susceptibility perfusion (DSP) MRI metrics and grade, subtype and Ki-67 labelling index of meningiomas. MATERIALS AND ΜETHODS: Thirty-nine patients operated for meningioma were included in the study. DTI and DSP were performed within a week prior to surgical excision. Lesion/normal (L/N) tissue ratios and peritumoral area/normal tissue (P/N) ratios were calculated for the apparent diffusion coefficient (ADC), fractional anisotropy (FA) and relative cerebral blood volume (rCBV). In the tumor specimens Ki-67 antigen expression was evaluated by the MIB-1 immunostaining method.

Results: There were 31 grade I, 7 grade II and one grade III meningiomas. Grade I meningiomas had a significantly lower L/N rCBV ratios than grade II/III meningiomas (median 5.1 vs 6.4, p=0.031). Grade I meningiomas revealed significantly lower P/N rCBV ratios than grade II/III meningiomas (median 0.78 vs 1.1, p=0.0077). Grade I meningiomas had significantly higher FA ratios than grade II/III meningiomas (median 0.5 vs 0.31, p=0.012). Meningiomas of meningothelial type had a significantly higher L/N rCBV ratio than other grade I meningiomas (median 5.4 vs 3.8, p=0.0136). There was no significant correlation between rCBV, ADC, FA and Ki-67 index.

Conclusion: Dynamic susceptibility perfusion indexes in lesion/normal and peritumoral/normal tissue ratios are useful for the differentiation grade I from grade II/III menigiomas. Meningothelial meningiomas showed higher lesion/normal tissue rCBV ratios from the other benign meningioma subtypes.