Fig. 9
From: Manifestations of pilocytic astrocytoma: a pictorial review
Focal midbrain glioma, a histopathologically proven pilocytic astrocytoma in an 11-year-old boy. Sagittal (a) and axial (b) T2-weighted images show an exophytic, sharply marginated, hyperintense mass involving the right cerebral peduncle. No surrounding oedema is identified. On this T1-weighted image (c), the mass is isointense compared with grey matter. The mass is isointense on diffusion-weighted imaging (d). An axial post-contrast image (e) shows heterogeneous enhancement of the tumour. Proton MRS with TE 144-ms (f, g) revealed high choline/Cr (2.46) and NAA/Cr ratios (1.27)