PET images demonstrate asymmetrically (right greater than left) decreased glucose metabolism in the anterior frontal lobes. Corresponding CT images show atrophy of frontal lobe gyri, with resulting dilation of frontal lobe sulci and frontal horns of lateral ventricles. There is atrophy and hypometabolism of the caudate heads, with the right slightly more affected than left.

This patient was diagnosed with Frontotemporal Degeneration – Behavioral Variant. This subtype of dementia is characterized by early personality changes, apathy, and emotional blunting.

Imaging findings can suggest the subtype of frontotemporal degeneration, in combination with differences in clinical presentation. The behavioral variant is characterized by predominant anterior frontal lobe hypometabolism and atrophy, which may be asymmetric. Progressive nonfluent aphasia is typically a left-predominant process, and asymmetrically decreased volume of the left caudate head has been described as a distinguishing feature in these patients. Looi JC, et al. AJNR 2008;29:1537-43. Semantic aphasia is associated with greater temporal lobe atrophy than frontal lobe involvement.

See Imaging of Dementia table