Figure 11a. Cortical gyral enhancement. (a) Diagram illustrates gyral enhancement that is localized to the superficial gray matter of the cerebral cortex. There is no enhancement of the arachnoid, and none in the subarachnoid space or sulci. (b) Coronal gadolinium-enhanced T1-weighted MR image in a case of herpes encephalitis shows multifocal, intraaxial, curvilinear, cortical gyri-form enhancement that involves both temporal lobes. The enhancement is most prominent on the right but is also seen in the left insular region (arrows) as well as in the medial frontal lobes and cingulate gyrus (arrowhead).