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.