IDH1 and astrocytic tumor: The duration of the progression-free interval correlated with the mean rCBV in IDH wild-type astrocytic tumors (r = 0.48, p = 0.04), but not in IDH-mutant astrocytic tumors (r = − 0.05, p = 0.89) and oligodendrogliomas (r = − 0.16, p = 0.63).