Hippocampus and entorhinal cortex in frontotemporal dementia and Alzheimer's disease: A morphometric MRI study

Background: Magnetic resonance imaging (MRI) of hippocampal atrophy is a se nsitive but not specific method to support the clinical diagnosis of early Alzheimer's disease (AD). We recently described our findings that atrophy o f the entorhinal cortex (ERC) in frontotemporal dementia (FTD) is equal to that found in AD but that hippocampal atrophy in FTD is less than that foun d in AD, The MRI volumes of these structures provide a topographic represen tation of the region of interest. We hypothesized that two different dement ias with distinct histopathologic and clinical features might, in addition to quantitative patterns, display topographically different patterns of atr ophy. Methods: We adopted a morphometric approach to monitor the pattern of atrop hy of the hippocampus and the ERC by computing two-dimensional profiles fro m MRI volumes of the structures in control subjects and patients,with FTD a nd AD. Results: Compared with control subjects, atrophy of the hippocampus in pati ents with AD was diffuse. In patients with FTD, atrophy of the hippocampus was localized predominantly in the anterior hippocampus, suggesting a diffe rent pattern of hippocampal atrophy in FTD compared,with AD, The amount and pattern of atrophy of the entorhinal cortex was virtually equal in both de mented groups, Conclusions: This study provides novel data on the nature of medial tempora l lobe atrophy in FTD, Morphometric MRT may be a useful technique for chara cterizing different patterns of atrophy in primary degenerative dementias i n vivo. (C) 2000 Society of Biological Psychiatry.