Thank you for your fast response. Here are my follow-up questions:

1. In the DTIPrep manual, denoising is not default. One collaborator recommended me to denoise the DTI data. I wonder in which circumstance I should implement denoise procedure and how it influences the final analysis?

2. One participant are failed from DTIPrep pipeline with the reason "Single b value DWI without a b0/baseline". But when I checked this participant, it does have b0 and 64 gradients. What does this failing reason mean?

3. You mentioned "slice wise check detected an artifacts (mainly based on a low correlation of this slice to its neighboring slice)". I want to know whether DTIPrep calculates the correlation of this slice to its previous neighboring slice or more?

4. In the DTIPrep manual, the procedure first implement automated pipeline then visual check. In visual check, I found some DTIPrep-excluded gradient looks similar to the other unexcluded ones, while the other have the severe artifacts. I wonder whether there is a strong reason that I must exclude the "look-not-so-bad" gradients which has been detected? My rationale is to keep as much DTI gradients as possible at the beginning rather than losing them. Furthermore, could I perform visual check then automated pipeline?

5. I found I cannot implement visual check 2: "Directional Spatial Distribution QC". I can only see the lines starting from the centre of sphere, rather than dots. The lines change color when I move the sphere. My version of DTIPrep is 1.2.4.

5. I notices b0 in one brain scan have artifacts. Should I excluded this participant in this case?