Figure 4b. Oligodendroglioma. (a) Axial CT image shows a hypoattenuating mass (arrow) in the cortex and subcortical white matter of the right frontal lobe. (b) Axial T1-weighted magnetic resonance (MR) image shows low signal intensity of the mass, which spares the extreme perimeter of the cortical gray matter. (c) Axial T2-weighted MR image shows high signal intensity of the mass. (d) Axial apparent diffusion coefficient (ADC) MR image shows mild high signal intensity of the mass, a finding that indicates absence of restricted water diffusion. (e) Axial contrast-enhanced T1-weighted MR image shows no enhancement of the mass, a finding typical of this tumor. (f ) Photograph of the gross specimen shows expanded gyri, which are a result of neoplastic involvement. Scale is in centimeters.