Thanks Michael,

I will look into all of these over the next few days... Neither the first or 
second thing you suggested to check in the HCP scripts would've occurred to me. 
 So those suggestions are greatly appreciated.  The possibility that the HCP 
scripts somehow in their function assumes the phase encoding is the same sounds 
really possible.  I didn't try to see if the listserv could post *.jpgs of the 
results I'm getting.  But honestly, the funky result really looks like a 
fundamental mismatch of phase encoding setting.  However, I know I've got 
things set correctly for the EPI data phase encoding direction.  If the scripts 
are somehow doing the topup and applytop steps assuming both have the same 
phase encoding, that'd easily account for the wonky results.  So I'll go 
digging for that first.

I'll paste the code splice in for the spatial resolution problem and let you 
know if I have any problems.

Thanks again!

Best,
Mike

From: Harms, Michael [mailto:mha...@wustl.edu]
Sent: Monday, August 31, 2015 3:40 PM
To: Stephen Smith; Stevens, Michael
Cc: hcp-users@humanconnectome.org
Subject: Re: [HCP-Users] TOPUP options with HCP scripts - Phase Encoding and 
Voxel Size incompatibilty with EPI


Hi Michael,
I know of at least one adaptation that you'll need, but your particular 
situation may unfortunately need more.   Tthe issues at play involve a fairly 
complicated, dense section of code.  Hopefully Matt can chime in if he is 
available.

Your question involves the guts of the 
DistortionCorrectionAndEPIToT1wReg_FLIRTBBRAndFreeSurferBBRbased.sh and 
TopupPreprocessingAll.sh scripts.  (The latter is called as part of the 
former).  The relevant variables to try to keep track of initially are: 
DwellTime (--echospacing argument) and UnwarpDir.

First, your changing resolution probably resulted in a least a somewhat 
different bandwidth, and thus echo spacing between your SpinEcho EPIs and your 
Gradient Echo BOLD fMRI scans.  Based on a quick look, I can't tell if the echo 
spacing of the BOLD fMRI scan ever comes into the picture as part of the topup 
distortion correction.  If not, just set the ES according to your SE scans.

Second, you had a different phase encoding direction between the SE scans and 
the BOLD fMRI.  That I think is a problem, because I think that 
TopupPreprocessingAll.sh assumes that the supplied UnwarpDir is the same for 
both the SE scans and the BOLD fMRI -- in terms of the registration between 
scout and SE scans, and also possibly in terms of what gets encoded in the 
WarpField output of topup.  (Off the top of my head, I'm not sure if the 
WarpField is no longer dependent on the the UnwarpDir).

Last, the resolution mismatch will cause a problem, but that one I've dealt 
with previously as part of helping someone else that also acquired the BOLD 
fMRI at a different resolution from the SE scans.  For that, you can try the 
solution  below.

cheers,
-MH

--------

First, make a copy of the original TopupPreprocessingAll.sh in global/scripts
e.g.,
cp TopupPreprocessingAll.sh TopupPreprocessingAll.sh.orig

Then add the following line in red to the relevant section of the code in 
TopupPreprocessingAll.sh (should be around L260, but depending on the precise 
version you are using, may just be near L260):

# Scout - warp and Jacobian modulate to get distortion corrected output



${FSLDIR}/bin/applywarp --rel --interp=spline -i ${WD}/SBRef.nii.gz -r 
${WD}/SBRef.nii.gz -w ${WD}/WarpField.nii.gz -o ${WD}/SBRef_dc.nii.gz



${FSLDIR}/bin/applywarp --rel --interp=spline -i ${WD}/Jacobian.nii.gz -r 
${WD}/SBRef_dc.nii.gz --premat=$FSLDIR/etc/flirtsch/ident.mat -o 
${WD}/Jacobian.nii.gz

${FSLDIR}/bin/fslmaths ${WD}/SBRef_dc.nii.gz -mul ${WD}/Jacobian.nii.gz 
${WD}/SBRef_dc_jac.nii.gz



--
Michael Harms, Ph.D.
-----------------------------------------------------------
Conte Center for the Neuroscience of Mental Disorders
Washington University School of Medicine
Department of Psychiatry, Box 8134
660 South Euclid Ave.  Tel: 314-747-6173
St. Louis, MO  63110  Email: mha...@wustl.edu<mailto:mha...@wustl.edu>

From: Stephen Smith <st...@fmrib.ox.ac.uk<mailto:st...@fmrib.ox.ac.uk>>
Date: Monday, August 31, 2015 2:07 AM
To: "Stevens, Michael" 
<michael.stev...@hhchealth.org<mailto:michael.stev...@hhchealth.org>>
Cc: "hcp-users@humanconnectome.org<mailto:hcp-users@humanconnectome.org>" 
<hcp-users@humanconnectome.org<mailto:hcp-users@humanconnectome.org>>
Subject: Re: [HCP-Users] TOPUP options with HCP scripts - Phase Encoding and 
Voxel Size incompatibilty with EPI

Hi

AFAIK you can - in theory - use the topup-derived B0-fieldmap to unwarp the 
fMRI-EPI data even with these differences in acquisition.

However I can't comment at all on how much work it will be to adapt the HCP 
scripts to make this happen.  Would need advice from others on that point.

Cheers, Steve.



On 30 Aug 2015, at 14:05, Stevens, Michael 
<michael.stev...@hhchealth.org<mailto:michael.stev...@hhchealth.org>> wrote:

Hi folks,

I have a technical question about processing data using the HCP 3.5 pipeline 
scripts.  We recently set up an HCP MRI data collection protocol for one of my 
new R01s.  I just learned over the weekend that - although we did a very 
careful job ensuring that all the sequences being used for the primary 
experimentation were correctly configured - we made one mistake.  We added a 
resting state scan after the rest of it was set up and mistakenly pulled the 
wrong EPI sequence for it.  As a result, the voxel sizes and phase encoding for 
resting state do not match the spin echo sequences we were planning to use for 
TOPUP unwarping of our other EPI data.  Specifically, the spin echo sequences 
are L/R and R/L encoding at 2.1 mm isotropic resolution, while the EPI resting 
state data was collected using A/P at 3.0 mm isotropic.

So, we can process the primary fMRI task data just fine.  But, will it still be 
possible to process the resting state data using the HCP scripts and approach?  
We have to use TOPUP for distortion correction as we did not collect a gradient 
echo fieldmap scan.  I had understood that TOPUP didn't really care that much 
as long as you could create a valid fieldmap.  However, I've been primarily an 
SPM user for my MRI research until we started using the HCP approach a year 
ago.  So my FSL knowledge remains comparatively limited and I just don't know.

When I run the HCP scripts to try this out, the primary thing that seems to go 
wrong is it throws an error in from the TopupPreprocessingAll.sh script (line 
251) when it tries to multiply the Scout by the Jacobian.nii.gz b/c they're 
different voxel sizes.  Otherwise it runs through to the end (we've disabled 
Jacobian modulation option (so the OneStepResampling script never encountered 
the same problem).  However, visual inspection of the results for one sample 
dataset doesn't look like the later processing stages got things exactly 
right... There's some odd distortions down near the OFC where you'd expect the 
most amount of unwarping to be done.  I got to wondering whether there was a 
simple L/R vs A/P incompatibility, i.e, that this won't work at all.  Or maybe 
more complicated... if the different voxel sizes between the fieldmap and EPI 
might've put the origins of the images at different places and ended up 
confusing the OneStepResampling step.  Or something...

I'm testing this on all these datasets now to see whether the results across 
multiple subjects look visually OK or not.  But as I do this, it'd be great if 
someone could tell me a simple "Yes" or "No" if I'm wasting my time with this.  
Even if this is possible but it requires some modifications/recoding to the HCP 
scripts (e.g., to resample the fieldmaps to 3x3x3 resolution after they're 
calculated??).  I'm happy to do the latter if someone lays out for me what 
changes might needed.

Thanks,
Mike


Michael C. Stevens, Ph.D.
Director, Clinical Neuroscience & Development Laboratory
Director, Child & Adolescent Research, The Institute of Living
Associate Professor of Psychiatry (Adjunct), Yale University School of Medicine



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