Hi Paul,

Thank you for your detailed answers. I know how to pick out bad volumes now.

I am still not clear about the use of these volumes. The propose of my project is to compare the structure connections between fROIs of two group of people. So are all these volumes should be used? What is the effect of take all volumes, long processing time? And what information can be get from different range of b values?

Here is the warning, as you mentioned above, b=0 not found.

+ WARNING: NO reference gradients/values found.
++ Number of ref vec/mats (b<0.000001): 0
   Number of diffusion weighted  vec/mats: 129
++ Keeping all vec/mats.
++ Output dims to be: 129 x 3
++ DONE with grad/matr. Check output file 'tmpdir_001/fff.cvec'

And thanks for your suggestion to acquire repeated reference volumes. As you can see from the attached image, this patient did move when scanning the reference volume. Do you have any suggestions on processing this kind of data?

As for the dimmer band problem, I will PM you with more details.

Thank you again,

2086