DOI: 10.7272/q6cc0xmh
title: White matter damage in frontotemporal dementia and Alzheimer's disease measured by diffusion MRI

description: Frontotemporal dementia (FTD) and Alzheimer's disease are sometimes
 difficult to differentiate clinically because of overlapping symptoms.
 Using diffusion tensor imaging (DTI) measurements of fractional anisotropy
 (FA) can be useful in distinguishing the different patterns of white
 matter degradation between the two dementias. In this study, we performed
 MRI scans in a 4 Tesla MRI machine including T1-weighted structural images
 and diffusion tensor images in 18 patients with FTD, 18 patients with
 Alzheimer's disease and 19 cognitively normal (CN) controls. FA was
 measured selectively in specific fibre tracts (including corpus callosum,
 cingulum, uncinate and corticospinal tracts) as well as globally in a
 voxel-by-voxel analysis. Patients with FTD were associated with reductions
 of FA in frontal and temporal regions including the anterior corpus
 callosum (P &lt; 0.001), bilateral anterior (left P &lt; 0.001;
 right P = 0.005), descending (left P &lt; 0.001; right P = 0.003)
 cingulum tracts, and uncinate tracts (left P &lt; 0.001; right P =
 0.005), compared to controls. Patients with Alzheimer's disease were
 associated with reductions of FA in parietal, temporal and frontal regions
 including the left anterior (P = 0.003) and posterior (P = 0.002) cingulum
 tracts, bilateral descending cingulum tracts (P &lt; 0.001) and left
 uncinate tracts (P &lt; 0.001) compared to controls. When compared
 with Alzheimer's disease, FTD was associated with greater reductions
 of FA in frontal brain regions, whereas no region in Alzheimer's
 disease showed greater reductions of FA when compared to FTD. In
 conclusion, the regional patterns of anisotropy reduction in FTD and
 Alzheimer's disease compared to controls suggest a characteristic
 distribution of white matter degradation in each disease. Moreover, the
 white matter degradation seems to be more prominent in FTD than in
 Alzheimer's disease. Taken together, the results suggest that white
 matter degradation measured with DTI may improve the diagnostic
 differentiation between FTD and Alzheimer's disease.
description: The dataset available here consists of Fractional Anisotropy (FA)
 and Mean Diffusivity (MD) images in Analyze format. There are FA &
 MD images for 55 subjects (some subjects have two timepoints, as indicated
 by a -1 or -2 following subject ID in the filename, please disregard
 timepoint 2 at this time), and a spreadsheet describing each subject’s age
 (at time of scan), gender, diagnosis (Normal Control, Alzheimer’s
 Dissease, or Frontotemporal Dementia), ApoE alleles, and Mini-Mental State
 Exam score. Data Acquisition Location: San Francisco VA Medical Center;
 Scanner Type: Siemens Bruker 4T, equipped with a birdcage transmit and
 eight channel receive coil. DTI was based on a dual spin-echo echo-planar
 imaging (EPI) sequence supplemented with parallel imaging acceleration
 (GRAPPA) with a factor 2 to reduce susceptibility distortions. Other
 imaging parameters were: TR/TE = 6000/77 ms; field of view 256 × 224 cm;
 128 × 112 matrix size, yielding 2 × 2 mm2 in-plane resolution; 40
 continuous 3 mm slices. A reference image (no diffusion gradient b = 0)
 and six diffusion-weighted images (b = 800 s/mm2 along six non-collinear
 directions) were acquired. Four DTI scans were acquired and averaged after
 motion correction to boost signal-to-noise.