The MRI pattern of frontal and temporal brain atrophy in fronto-temporal dementia

OBJECTIVE: To compare patterns of brain atrophy in fronto-temporal dementia (FTD) and Alzheimer's disease (AD) since atrophy in individual areas may not be sufficiently specific as diagnostic marker. METHODS: Frontal, temporal and hippocampal atrophy was measured from MRI of 10 FTD patients, 27 AD, and 27 controls. Corrected atrophy and asymmetry were computed (W-scores). RESULTS: FTD had mild atrophy in the hippocampus (average W-score=-1.3), severe in the frontal (W-score=-2.4) and very severe in the temporal lobes (W-score=-2.9). AD had moderate atrophy in the hippocampus and temporal lobes (W-score=-1.8 and -1.9, respectively), and very mild frontal atrophy (W-score=-0.9). Atrophy was more asymmetrical in FTD (left more atrophic) than in AD patients, particularly in the temporal lobes. A discriminant function including the asymmetry values of frontal and temporal regions could separate FTD from AD with 90% sensitivity and 93% specificity. CONCLUSIONS: FTD is characterized by a specific pattern of atrophy, more useful than atrophy of single regions in the differential diagnosis.