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maria
April 29, 2015 01:16PM
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Registered: 7 years ago
Posts: 12
Hello,
I have read the above thread with interest because I am also working through steps to incorporate B0 distortion correction. I am using FSL for the correction and then include the corrected files in AFNI. I wanted to show you my steps to make sure they make sense. I also had a couple questions along the way.
1) Convert Siemens DICOM files to fsl NIFTI using MRIConvert
2) First, prepare the map images:
a. brain extract (bet_gui) and erode (fslmaths [mag_brain] 鈥揺ro [mag_brain_ero]) the magnitude image and
b. use fsl_prepare_fieldmap to create the fieldmap_radians image (command-line or fsl_prepare_fieldmap_gui).
c. More details can be found here: [fsl.fmrib.ox.ac.uk]
3) Instead of using FSL FEAT for B0 unwarping, use the command-line tool fugue (dwell is the effective EPI echo spacing)
fugue 鈥搃 [M001_r01.nii] --dwell=[0.00047] --loadfmap=[field_rad_ero.nii.gz] 鈥搖nwarpdir=y- -u [M001_r01_fmap]
4) Note specific to my epi files: Before running fugue, I first converted the DICOM files to AFNI using to3d because I used a sparse sampling study design and needed to convert the EPI raw files with the specific volume acquisition timing. Then, I converted the file using 3dAFNItoNIFTI. I double checked the headers to make sure the right information was displayed as far as the TR and volume acquisition timing and orientation.
a. The AFNI epi file had the correct the header info.
b. I used fslhd to look at the header of the converted .nii file. The TR was correct and orientation was also RAI. I did not see a way though to check that the sparse sampling volume acquisition timing was included. I can assume it though, right?
5) Then, I used the fieldmap corrected epi files directly in uber_subject.py without any further conversion.
6) uber_subject.py: I wanted to check on a string of warnings that I received during processing (I used non-linear alignment for the MNI template). I am not quite sure how to act on these warnings.
++ 3drefit: AFNI version=AFNI_2011_12_21_1014 (Apr 22 2015) [64-bit]
++ Authored by: RW Cox
++ Processing AFNI dataset __ats_tmp___upad40_pre.anat.un_XYZ_OYmeqfZ3JqF7n9LNC7gDAA.aff+orig
*+ WARNING: Changing the space of an ORIG view dataset may cause confusion!
*+ WARNING: NIFTI copies will be interpreted as TLRC view (not TLRC space).
*+ WARNING: Consider changing the view of the dataset to TLRC view also
++ 3drefit processed 1 datasets
Thanks for having a look at my steps.
Maria
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Posted
One way to incorporate FSL field map correction
Mingbo
July 09, 2013 02:41PM
Re: One way to incorporate FSL field map correction
Mingbo
July 09, 2013 02:44PM
Re: One way to incorporate FSL field map correction
Bob Cox
July 10, 2013 09:56AM
Re: One way to incorporate FSL field map correction
Mingbo
July 10, 2013 10:39AM
Re: One way to incorporate FSL field map correction
Phil Burton
April 14, 2014 02:18PM
Re: One way to incorporate FSL field map correction
Emperor Zhark
April 15, 2014 07:11PM
Re: One way to incorporate FSL field map correction
Phil Burton
April 16, 2014 06:05PM
Re: One way to incorporate FSL field map correction
jkeidel
December 09, 2014 09:31AM
Re: One way to incorporate FSL field map correction
jkeidel
November 28, 2014 09:29AM
Re: One way to incorporate FSL field map correction
maria
April 29, 2015 01:16PM
Re: One way to incorporate FSL field map correction
jmbjork
January 12, 2017 08:17AM
Re: One way to incorporate FSL field map correction
rick reynolds
January 12, 2017 09:31AM
Re: One way to incorporate FSL field map correction
jmbjork
January 25, 2017 11:26AM
Re: One way to incorporate FSL field map correction
rick reynolds
January 25, 2017 11:41AM
Re: One way to incorporate FSL field map correction
Cecil C. Yen
April 05, 2017 05:04PM
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