Figure 6b. Atypical appearance of a supratentorial pilocytic astrocytoma with prominent vasogenic edema. (a) Sagittal T1-weighted image shows a large supratentorial mass with a soft-tissue component (s) in the region of the lateral ventricle trigone and cystlike regions (c) located more superiorly and anteriorly. (b) Axial T2-weighted image demonstrates extreme hyperintensity of the cystlike portions (c) and more mild hyperintensity of the soft-tissue mass (s) within the lateral ventricle. Note vasogenic edema around the mass (arrows). Vasogenic edema is not a common feature of pilocytic astrocytomas. (c) Contrast-enhanced axial T1-weighted image reveals intense enhancement of the soft-tissue portion and lack of enhancement of the cystic portion.