biac:analysis:topup_correction
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biac:analysis:topup_correction [2019/02/21 19:29] – cmp12 | biac:analysis:topup_correction [2019/02/22 17:41] – [Prepare your input datasets] cmp12 | ||
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[[https:// | [[https:// | ||
+ | |||
+ | If you are running dwidenoise, do it BEFORE dwipreproc. | ||
==== Calculate your readout time ==== | ==== Calculate your readout time ==== | ||
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there are 2 scenarios that typically apply here | there are 2 scenarios that typically apply here | ||
- | 1) a short acquisition with RPE B0s | + | 1) DWI and a short acquisition with RPE B0s |
- | 2) an entire | + | 2) 2 entire |
In both scenarios it is important to create your data with normal phase encoding direction first, followed by reversed. | In both scenarios it is important to create your data with normal phase encoding direction first, followed by reversed. | ||
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==== Prepare your input datasets ==== | ==== Prepare your input datasets ==== | ||
+ | |||
+ | Specify that a set of images (typically b=0 volumes) will be provided for use in inhomogeneity field estimation only | ||
For scenario 1, create your blip up / blip down B0 data the same way as above. | For scenario 1, create your blip up / blip down B0 data the same way as above. | ||
< | < | ||
- | bxhselect --timeselect 0 bia6_00197_012.bxh bu | + | bxhselect --timeselect 0 bi |
+ | a6_00197_012.bxh bu | ||
bxhselect --timeselect 0 bia6_00197_013.bxh bd | bxhselect --timeselect 0 bia6_00197_013.bxh bd | ||
fslmerge -t bud bu.nii.gz bd.nii.gz | fslmerge -t bud bu.nii.gz bd.nii.gz | ||
+ | rm bu.* bd.* | ||
</ | </ | ||
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#put THOSE back into the mif header | #put THOSE back into the mif header | ||
mrconvert -grad grads.b dwi.mif dwi.mif -force | mrconvert -grad grads.b dwi.mif dwi.mif -force | ||
+ | |||
</ | </ | ||
- | The last step seems redundant, but there is an issue with how mrtrix3 tools are handling the multi-shell GE data produced on our scanners. | + | The last step seems redundant, but there is an issue with how mrtrix3 tools are handling the multi-shell GE data produced on our scanners. |
- | ===== Run dwipreproc -rpe_pair | + | ==== Run dwipreproc -rpe_pair ==== |
Run [[https:// | Run [[https:// | ||
< | < | ||
- | dwipreproc | + | dwipre |
+ | proc dwi.mif dwi_corr.mif -rpe_pair -se_epi bud.nii.gz -pe_dir AP -readout_time 0.10656 | ||
-rpe_pair specifies you're providing a pair of B0s ( regular, reversed ) | -rpe_pair specifies you're providing a pair of B0s ( regular, reversed ) | ||
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===== Scenario 2 ===== | ===== Scenario 2 ===== | ||
- | You have an entire acquisition with the same gradient table as your DWI sequence, but with reverse phase encoding. | + | You have an entire acquisition with the same gradient table as your DWI sequence, but with reverse phase encoding. This information will be used to perform a recombination of image volumes (each pair of volumes with the same b-vector but different phase encoding directions will be combined together into a single volume). |
Calculate the readout time in the same way as above | Calculate the readout time in the same way as above | ||
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< | < | ||
#concat the 2 series ( regular, reversed ) | #concat the 2 series ( regular, reversed ) | ||
- | bxh_concat | + | bxh_concat |
+ | 7_LAS.bxh bia6_00260_008_LAS.bxh both | ||
#extract the gradients | #extract the gradients | ||
- | extractdiffdirs --fsl both bvecs bvals | + | extractdiffdirs --fsl both.bxh bvecs bvals |
#convert to mif | #convert to mif | ||
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dwipreproc dwi.mif dwi_corr.mif -rpe_all -pe_dir AP -readout_time 0.10656 -debug | dwipreproc dwi.mif dwi_corr.mif -rpe_all -pe_dir AP -readout_time 0.10656 -debug | ||
- | -rpe_all signals that you've replicated | + | -rpe_all signals that you've replicated |
+ | A | ||
+ | LL the directions with a rpe acquisition | ||
-pe_dir is the phase encode direction of your regular acquisition | -pe_dir is the phase encode direction of your regular acquisition | ||
-readout_time from above | -readout_time from above | ||
</ | </ | ||
+ | |||
+ | {{ : | ||
biac/analysis/topup_correction.txt · Last modified: 2024/06/21 15:44 by 127.0.0.1