IDH1 and diffuse astrocytoma: However, the presence of visible fluorescence did not correlate with age at diagnosis (p = 0.47), the pattern of CE on MRI (p = 0.32), extent of resection (p = 0.25) and histological subtype (diffuse astrocytoma IDH-mutant vs. oligodendroglioma IDH-mutant; p = 0.88).