Matlab Code for Reducing FA

Return to 2009 Christine McLeavey & Jessica Tsang

function alteredFAmasked = AlterFA(dt6, mask, densitymap, effectsize)

fa = dtiComputeFA(dt6);
brainMask=readFileNifti(mask);
brainMask.data=double(brainMask.data);

weightedESmap = effectsize*densitymap;  % effectsize=.085
alteredFA = fa.*(1-weightedESmap);
alteredFAmasked = alteredFA.*brainMask.data;

% Historical:
% input:
% dt6: ie dt.dt6 (can use dt=dtiLoadDt6('dt6.mat'))
% mask: name of brain mask, ie 'ab_mask.nii.gz'
% densitymap: image of fiber density (betw 0 and 1), i.e. using
% dtiComputeFiberDensityNOGUI
% effectsize: the factor by which to lower/raise FA (to be weighted by
% fiber density). With effectsize of 0.1, weighted effectsize =
% 0.1*fiberdensity, and newFA = origFA*[1-(weighted effectsize)]
%
% returns:
% XxYxZ image with altered fa, in image space
%
% 2009.11.15 JT
% effectsize = .1;
% fa = dtiComputeFA(dt6);
% weightedESmap = effectsize*densitymap;
% alteredFA = fa.*(1-weightedESmap);

return