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Hi FSL Experts, I used "dcm2nii" to convert a set of PAR/REC (v3) DTI data acquired from 3T Philips Gyroscan at the F.M. Kirby Research Center to NIFTI format. dcm2nii did not automatically output the bvecs and bvals data, so I use a free matlab script (dti_gradient_table_creator.m) to create the gradient direction data. Suggested by the previous threads, I also eliminate the last entry of the gradient table [100,100,100], which left me with 33 entry (b0+32 directions). I also used fslroi to eliminate the last volume which said to be a diffusion traced image. However, when I run dtifit, I got the following error message: ysheu$ dtifit -k data.nii.gz -o dti -m nodif_brain_mask.nii.gz -r bvecs -b bvals "terminate called after throwing an instance of 'NEWMAT::IndexException' Abort trap" I really don't know what went wrong. The number of volumes matched to the bvecs and bvals, so it should not be the problem. Is there something wrong with my DTI data? Any input is appreciated. Thanks. Yi-Shin PS. I attached my bvecs and bvals and below is the info related to my data.nii.gz 4D DTI image: ysheu$ fslinfo data.nii.gz data_type FLOAT32 dim1 256 dim2 256 dim3 60 dim4 33 datatype 16 pixdim1 0.8281250000 pixdim2 0.8281250000 pixdim3 2.2000000477 pixdim4 6.0850000381 cal_max 0.0000 cal_min 0.0000 file_type NIFTI-1+