I used the dual_regression below command :

dual_regression melodic_IC.nii.gz 1 design.mat design.con 500 Dual_regression `cat RS_fmri_AD.txt` `cat RS_fmri_EOAD.txt`

My design : I have two groups AD (31 subjects) and EOAD (33 subjects) and 5 five group-ICA maps of interest concatened in melodic_IC.nii.gz. I used a two-sample T-test with two T contrasts (AD > EOAD and AD < EOAD). Please find attached my design.mat and design.con files

On output of this command I had no stage1 images. I could see that the temporary mask_*.nii.gz files were all empty and no error message associated

1) Where could it come from ? I verified that my melodic_IC.nii.gz images were the same dimensions (fslsize) than my RS-fMRI images contained in RS_fmri_AD.txt and RS_fmri_EOAD.txt files.

2) How these mak images are computed on this first stage ?

3) I have ICA group maps obtained from an other command than MELODIC. Should these ICA t-maps be thresholded ?

Many thanks !

Best regards,