The aging brain is characterized on CT or MRI as demonstrating volume increases in both cortical sulci and ventricles (Fig. 6-96). T2-weighted MR images also frequently display small areas of hyperintense signal along the anterolateral margins of the anterior horns of the lateral ventricles. These changes may or may not be associated with neurologic findings.
FIGURE 6-96. A case of cortical atrophy of aging as seen by CT. Enlargement of cortical sulci and sylvian fissures (arrows) with ex vacuo ventricular dilatation (arrowheads).
Patients with Alzheimer’s disease (AD) and other dementing disorders consistently show these age changes, but because many normal elderly do also, these changes cannot be used to diagnose AD. However, the absence of these findings typically excludes AD. Findings more specifically related to AD are those involving the temporal lobe. The earliest findings in AD involve atrophy of the temporal lobe with dilation of the temporal horn of the lateral ventricle, as well as dilation of the choroidal and hippocampal fissures caused by atrophy of the hippocampus, subiculum, and parahippocampal gyrus (89).