Hi,

I have some questions regarding troubleshooting the QC output of eddy_quad.  The QC result in question can be viewed at:
https://drive.google.com/file/d/1200_hCTj28baeSfpYQCmzP0geTr0Gy7q/view?usp=sharing

As you can see, on the very last page,  there appears to be a large number of outliers in the first half of the scan, and I am wondering if this may indicate a processing error, scanning error, or whether it is even something to be concerned about.  This is observed on all of my scans.

The DWI data is a multishell sequence (25 * b = 700, 40 * b =1000, 75 * b = 2800, 8 * b = 0 @0,20,40,60 ...) TE=0.1152, TR = 4.245 acquired on a GE Discovery MR750w.  As you can see, the number/intensity of outliers seems to be related to the shell (volumes 1-27 are worst, then 28-68, and the remainer barely have any outliers).

I have used this data to produce DTI (only from the first 2 shells), DKE, and NODDI output.  None of the maps appear to have any major problems.

A quick outline of my workflow:
1) Run topup using a reverse phase encoded image
2) Use the output of topup to run eddy_openmp -- (this was actually done using 5.0.11; however, the change-logs indicate that nothing has changed moving to 6.0.0 so this shouldn't be causing any problems)
3) Run eddy_quad using the output of eddy_openmp

Any insights would be much appreciated.

Kind Regards,
Forrest


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