Computational protocol: Structural and functional brain abnormalities place phenocopy frontotemporal dementia (FTD) in the FTD spectrum

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Protocol publication

[…] The ASL data consisted of a difference image and a control image. Quality of all images were visually assessed by checking for motion, susceptibility and watershed artifacts. GM maps were rigidly registered with the difference image (Elastix registration software ()) and registrations were checked visually. Tissue maps were transformed to ASL image space to perform partial volume (PV) correction, and PV effects in ASL difference and control images were subsequently corrected using local linear regression within a 3D kernel based on tissue maps (). We quantified PV-corrected ASL images as CBF maps using the single-compartment model (). CBF maps were transformed to T1w image space for further analysis. [...] We defined regions of interest (ROIs) for each participant using a multi-atlas approach. This involved registration of 30 labeled T1w images, each containing 83 cortical and subcortical ROIs (, ), to the participants' T1w images. The labels of the 30 atlas images were fused by means of majority voting to obtain a final ROI labeling (). Rigid, affine, and non-rigid B-spline transformation models were applied successively for registration to the participants' nonuniformity-corrected T1w images (). Both the participants' and the labeled T1w images were masked for this registration using the Brain Extraction Tool (). [...] Using SPSS Statistics, version 20.0 (New York, USA) we first analyzed differences in gender and scanner across groups with Fisher's exact test. As these were significantly different between groups (p < 0.05), we then used hierarchical regression to sequentially assess the effects of scanner, gender, and group on nGM and CBF. Only the nGM and regional CBF ROIs that showed a significant effect of group but did not show significant effects of scanner and/or gender were further tested for differences between groups. This was done using a nonparametric Kruskal-Wallis test with Dunn-Bonferroni correction for multiple comparisons as nGM, CBF, age and MMSE were not normally distributed across groups (Shapiro-Wilk test p < 0.05). The findings were visually represented in boxplots of nGM and CBF for each of the brain lobes. Statistical thresholds were set at p < 0.05. Results were visualized by overlaying the ROIs as defined by and that showed group differences on a volume render of a skull-stripped T1w template in MRIcron NIfTI viewer (Chris Rorden, Version 1, April 2010). […]

Pipeline specifications

Software tools elastix, BET, SPSS, MRIcron
Applications Miscellaneous, Magnetic resonance imaging
Organisms Homo sapiens
Diseases Brain Diseases, Neurodegenerative Diseases, Chromosome Disorders, Leukoencephalopathies, Frontotemporal Dementia