MKI67 and meningioma: In a retrospective study comparing the Ki-67 proliferation index and perfusion MRI features in high-grade meningiomas, although the mean Ki-67 value in G2 meningiomas (14.5%, range = 2%–28%) was lower than in G3 meningiomas (19.0%, range = 3%–38%), the difference was not statistically significant (P = 0.61) (18).