Structural brain imaging in frontotemporal dementia.

Frontotemporal dementia (FTD) is the second commonest young-onset neurodegenerative dementia. The canonical clinical syndromes are a behavioural variant (bvFTD) and two language variants (progressive nonfluent aphasia, PNFA, and semantic dementia, SD) although there is overlap with motor neurone disease and the atypical parkinsonian disorders corticobasal syndrome (CBS) and progressive supranuclear palsy syndrome (PSPS). Characteristic patterns of atrophy or hypometabolism are described in each of the variants but in reality imaging studies are rather heterogeneous. This review attempts to address four key questions in the neuroimaging of FTD: 1) what are the early imaging features of the different FTD syndromes (and how do these change as the disease progresses); 2) what do studies of presymptomatic genetic cases of FTD tell us about the very early stages of the disease; 3) can neuroimaging help to differentiate the different FTD syndromes; and 4) can neuroimaging help to differentiate FTD from other neurodegenerative diseases? This article is part of a Special Issue entitled: Imaging Brain Aging and Neurodegenerative disease.