HIPPO MORPHOMETRY IN FRONTOTEMPORAL DEMENTIA: A RADIAL ATROPHY MAPPING STUDY

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. 'Background: similar amount of hippocampal atrophy has been repeatedly detected in studies comparing FTD to AD patients, nonetheless the distribution of the atrophic changes may be different. Recent techniques such as radial atrophy mapping allow to characterize the atrophic changes of different kinds of dementia based not only on the absolute quantity of atrophy, but also on its spatial distribution. Methods: MRI images from 9 FTD patients and 27 controls were collected at the Radiology Department, University of Verona with a 1.5 Tesla unit (Siemens, Magnetom) and a standard head coil. A gradient-echo 3D-technique was employed for image acquisition with: TR 10 msec; TE 4 msec; TI 300 msec; flip angle 10?; field of view 250 mm; acquisition 2; matrix 160?256. Total acquisition time was 7:40 minutes. MRI images will be normalized by linear (12 parameter) transformation to a customized template using the Statistical Parametric Mapping (SPM99) software. The hippocampi will be manually traced according to a formal protocol with established inter- and intra-rater reliability and 3D parametric surface mesh models will be created to represent the hippocampus in each subject. In order to assess hippocampal morphology, a medial curve will be automatically defined as the 3D curve traced out by the centroid of the hippocampal boundary in each image slice. The radial size of each hippocampus at each boundary point will be assessed by automatically measuring the radial 3D distance from the surface points to the medial curve defined for individual's hippocampal surface model. Shorter radial distances will be used as an index of atrophy. Statistical maps will be generated indicating local group differences in radial hippocampal distance. Expected results: the experimental prediction consists in the detection of atrophy in the anteriormost sectors of the hippocampus, as already suggested by a study based on manual tracings (Laakso et al., 2000) or anyway in a different location from that of AD, that involves the CA1 sector and part of the subiculum. Laakso MP, Frisoni GB, Kononen M, Mikkonen M, Beltramello A, Geroldi C, Bianchetti A, Trabucchi M, Soininen H, Aronen HJ. Hippocampus and entorhinal cortex in frontotemporal dementia and Alzheimer's disease: a morphometric MRI study. Biol Psychiatry. 2000;47:1056-63. Frisoni GB, Sabattoli F, Lee AD, Dutton RA, Toga AW, Thompson PM. In vivo neuropathology of the hippocampal formation in AD: a radial mapping MR-based study. Neuroimage. 2006; 32(1):104-10.