Dear Experts,
I’ve encountered an error during the eddy current correction when preprocessing diffusion data with dwifslpreproc, and the error message is as follows:
EDDY::ECScanManager::GetGlobal2DWIIndexMapping: Global index not dwi
EDDY::ECScanClasses.cpp::: unsigned int EDDY::ECScanManager::GetGlobal2DWIIndexMapping(unsigned int) const: Exception thrown
EDDY::ECScanClasses.h::: void EDDY::ECScanManager::ApplyDWILocationReference(): Exception thrown
EDDY::ECScanClasses.cpp::: void EDDY::ECScanManager::SeparateFieldOffsetFromMovement(EDDY::ScanType, EDDY::OffsetModelType): Exception thrown
EDDY::eddy.cpp::: EDDY::ReplacementManager EDDY::Register(const EDDY::EddyCommandLineOptions&, EDDY::ScanType, unsigned int, const std::vector<float, std::allocator >&, EDDY::SecondLevelECModelType, bool, EDDY::ECScanManager&, EDDY::ReplacementManager, NEWMAT::Matrix&, NEWMAT::Matrix&): Exception thrown**
EDDY::: Eddy failed with message EDDY::eddy.cpp::: EDDY::ReplacementManager EDDY::DoVolumeToVolumeRegistration(const EDDY::EddyCommandLineOptions&, EDDY::ECScanManager&): Exception thrown*
The data I collected consists of low b-value measurements, with b-values including 0, 20, 40, 60, 80, 100, 150, 200, 400, 600, and 1000. Except for b0, the other b-values have 16 corresponding directions. After acquiring this dataset, I first performed dwidenoise and mrdegibbs, and then proceeded with motion and distortion correction, which resulted in the aforementioned error. I have tried various combinations of these b-values, such as removing some b-values below 100, and found that eddy current correction could pass, but only certain combinations of b-values below 100 with those above 100 could pass the eddy current correction, while others could not. It seems to be an issue with b80 and b100, but after carefully checking the data, I did not find any issues. I have also tried collecting data with different b-value schemes, and still encountered the same problems aformentioned during eddy current correction.
This issue has puzzled me for a long time, and I am unsure of the cause, as well as how to resolve it. I would greatly appreciate any assistance you can provide. Thank you very much!
Below is the command I used for the eddy current correction:
dwifslpreproc degibbs.mif geomocorr.mif -pe_dir PA -rpe_pair -se_epi b0_pair.mif -eddy_options " --data_is_shelled --slm=linear --niter=5 "
Best,
Yuyan