External Email - Use Caution
Hi all,
I am using TRACULA (v7.3.2) to examine longitudinal changes in WM integrity
by diagnostic groups.
For preprocessing, I did not use topup because my data have a single
acquisition (i.e., I do not have two acquisitions with opposing polarities
of the phase-encode blips). But I did utilize the Eddy command for eddy
current and motion correction. To do so TRACULA requires information
regarding the epi factor, echo spacing, and phase encoding direction. My
data are in BIDS format and so I used the dmri_bids_config script to
extract these factors. While the echo spacing and PE direction match the
information in my json files, I am finding that I am getting a large EPI
factor (e.g., 115001.0273).
I looked at the acqp.txt file generated for use with Eddy and the correct
values are stored in the file for each subject (PE direction [0 1 0] and
total readout time) so I believe the command was executed properly despite
the large magnitude EPI factor.
My questions are:
1. How is the EPI factor used in preprocessing by TRACULA?
2. Will the magnitude difference in the EPI factor affect the preprocessing
of the DWI data if topup is turned off and only eddy is used?
Thanks,
Jenna