Figure 13e. Anaplastic oligoastrocytoma. (a) Axial CT image shows a hypoattenuating mass (arrow) in the posterior portion of the right temporal lobe. The mass produces mild calvarial erosion. (b) Axial T1-weighted MR image shows low signal intensity of the mass. (c) Axial T2-weighted MR image shows mild heterogeneity of the mass. (d) Axial contrast-enhanced T1-weighted MR image shows no enhancement of the mass. (e) Intraoperative photograph shows exophytic extension of the mass beyond the normal cortical margin.