title: Mapping the structural brain changes in Alzheimer's disease: the independent contribution of two imaging modalities.
abstract: The macrostructural atrophy of Alzheimer's disease (AD) has been fully described. Current literature reports that also microstructural alterations occur in AD since the early stages. However, whether the microstructural changes offer unique information independent from macrostructural atrophy is unclear. Aim of this study is to define the independent contribution of macrostructural atrophy and microstructural alterations on AD pathology. The study involved 17 moderate to severe AD patients and 13 healthy controls. All participants underwent conventional and non conventional MRI (respectively, T1-weighted and diffusion-weighted MR scanning). We processed the images in order to obtain gray and white matter volumes to assess macrostructural atrophy, and fractional anisotropy and mean diffusivity to assess the microstructural damage. Analyses of covariance between patients and controls were performed to investigate microstructural tissue damage independent of macrostructural tissue loss, and vice versa, voxel by voxel. We observed microstructural differences, independent of macrostructural atrophy, between patients and controls in temporal and retrosplenial regions, as well as in thalamus, corticopontine tracts, striatum and precentral gyrus. Volumetric differences, independent of microstructural alterations, were observed mainly in the entorhinal cortex, posterior cingulum, and splenium. Measures of microstructural damage provide unique information not obtainable with volumetric mapping in regions known to be pivotal in AD as well as in others thought to be spared. This work expands the understanding of the topography of pathological changes in AD that can be captured with imaging techniques.
authors.affiliation: LENITEM - Laboratory of Epidemiology Neuroimaging and Telemedicine, IRCCS Centro San Giovanni di Dio FBF, The National Centre for Research and Care of Alzheimer's and Mental Diseases, Brescia, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Canu
authors.forename: Donald G
authors.initials: DG
authors.lastname: McLaren
authors.forename: Michele E
authors.initials: ME
authors.lastname: Fitzgerald
authors.forename: Barbara B
authors.initials: BB
authors.lastname: Bendlin
authors.forename: Giada
authors.initials: G
authors.lastname: Zoccatelli
authors.forename: Franco
authors.initials: F
authors.lastname: Alessandrini
authors.forename: Francesca B
authors.initials: FB
authors.lastname: Pizzini
authors.forename: Giuseppe K
authors.initials: GK
authors.lastname: Ricciardi
authors.forename: Alberto
authors.initials: A
authors.lastname: Beltramello
authors.forename: Sterling C
authors.initials: SC
authors.lastname: Johnson
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: Frisoni
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid / Q000473:pathology*; D000704:Analysis of Variance; D001284:Atrophy; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D001931:Brain Mapping; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests