I wanted to average 2 DTI acquisitions and was a little confused about a
couple of things. After going through the archives I found a method of
performing the averaging procedure (as posted by Matt), but had a few
questions about it. If I take 2 files called data1.nii.gz and data2.nii.gz
(converted from dicom using dicom2nii from mricron) and I have 109 volumes
(99 directions and 10 b0), I should perform the following steps:
fslmerge -t data_av.nii.gz data1.nii.gz data2.nii.gz
eddy_correct data_av.nii.gz data_av_corr.nii.gz 0
fslroi data_av_corr.nii.gz av1_corr.nii.gz 0 109
fslroi data_av_corr.nii.gz av2_corr.nii.gz 109 109
fslmaths av1_corr.nii.gz -add av2_corr.nii.gz -div 2 data_av_final.nii.gz
Is this correct?
If it is correct, what do I do with the two sets of bvals and bvecs files that
were created by dicom2nii? Do I just use one of them for the further analysis
or do I have to perform other manipulations of these files?
Also, if I were to perform eddy_correct on each of the data sets then
combined them with the last line of the above procedure, wouldn't that
essentially do the same thing? Is there any benefit of merging, correcting,
splitting, and then averaging vs. correcting each separately then just
averaging at the end?
Thank you in advance for your help.