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hMRI-toolbox-public/hmri_create_B1Map_unwarp.m
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function [fmap_img,unwarp_img] = hmri_create_B1Map_unwarp(fmfnam, anatfnam, otherfnam, b1map_params) | |
%========================================================================== | |
% PURPOSE | |
% For B0 undistortion of EPI-based B1 maps, part of the hMRI toolbox. | |
% | |
% FORMAT [fmap_img,unwarp_img] = hmri_create_B1Map_unwarp(magfnam, phasefnam, anatfnam, otherfnam, b1map_params) | |
% INPUT ARGUMENTS | |
% - fmfnam filename of the fieldmap images (must be char) | |
% - anatfnam filename of the image to be undistorted ("anatomical" reference, i.e. SSQ image) | |
% - otherfnam filenames of the other images to undistort (B1 and SD maps) | |
% - b1map_params effective parameters defined for the current B1 map | |
% calculation, including B0 unwarping parameters. | |
% OUTPUT ARGUMENTS | |
% - fmap_img{1} = IP.fpm = phase-unwrapped regularised field map (Hz) | |
% - fmap_img{2} = IP.vdmP = vdm5_* file name | |
% - unwarp_img{1} = IP.uepiP = unwrapped anat image | |
% - unwarp_img{2,3,...} = unwrapped other image{1,2,...} | |
%========================================================================== | |
% Written by Antoine Lutti, based on Chloe Hutton's code and the FieldMap | |
% toolbox. | |
if nargin < 4 | |
error('Enter field map images, distorted anatomical image, images to unwarp and defaults'); | |
end | |
% initialise parameters (default values) | |
pm_defaults; | |
pm_defs = pm_def; | |
IP = FieldMap('Initialise'); % Gets default params from pm_defaults | |
% fill in with effective parameters for fieldmap undistortion | |
IP.et{1} = b1map_params.b0acq.shortTE; | |
IP.et{2} = b1map_params.b0acq.longTE; | |
IP.maskbrain = b1map_params.b1proc.b0maskbrain; | |
IP.ajm = pm_defs.DO_JACOBIAN_MODULATION; | |
IP.blipdir = b1map_params.b1acq.blipDIR; | |
IP.tert = b1map_params.b1acq.tert; | |
%IP.epifm = 0; % already in the default IP | |
%IP.pedir = 2; % already in the default IP ([1] A>>P, [2] R>>L) | |
% default unwarp parameters (uflags) and a few derived from the metadata | |
IP.uflags.iformat = b1map_params.b0acq.iformat; % input format = 'PM' | |
IP.uflags.method = pm_defs.UNWRAPPING_METHOD; | |
IP.uflags.fwhm = pm_defs.FWHM; | |
IP.uflags.pad = pm_defs.PAD; | |
IP.uflags.ws = pm_defs.WS; | |
IP.uflags.etd = IP.et{2}-IP.et{1}; | |
% default brain extraction parameters (mflags) | |
IP.mflags.template = pm_defs.MFLAGS.TEMPLATE; | |
IP.mflags.fwhm = pm_defs.MFLAGS.FWHM; | |
IP.mflags.nerode = pm_defs.MFLAGS.NERODE; | |
IP.mflags.ndilate = pm_defs.MFLAGS.NDILATE; | |
IP.mflags.thresh = pm_defs.MFLAGS.THRESH; | |
% Clear any old handles etc | |
IP.fm = []; | |
IP.vdm = []; | |
IP.jim = []; | |
IP.pP = []; | |
IP.epiP = []; | |
IP.uepiP = []; | |
IP.vdmP = []; | |
%-------------------------------------------------------------------------- | |
% Load measured field map data - phase and magnitude or real and imaginary | |
% NOTE: only the magnitude + presubtracted phase option has been used and | |
% tested at this stage, therefore the other options are commented out. | |
%-------------------------------------------------------------------------- | |
n_fms = size(fmfnam,1); | |
switch n_fms | |
% case 4 % real, imaginary pairs | |
% for i = 1:n_fms | |
% IP.P{i} = spm_vol(fmfnam(i,:)); | |
% end | |
case 2 % precalculated phase map and magnitude image | |
% first rescale phase map between +/-pi | |
scphase = FieldMap('Scale', fmfnam(1,:)); | |
try | |
movefile(scphase.fname, fullfile(b1map_params.outpath, spm_file(scphase.fname,'filename'))); | |
scphase.fname = fullfile(b1map_params.outpath, spm_file(scphase.fname,'filename')); | |
catch % will fail if trying to movefile onto itself | |
end | |
IP.P{1} = spm_vol(scphase.fname); | |
IP.P{2} = spm_vol(fmfnam(2,:)); | |
% case 1 % precalculated and unwrapped Hz map | |
% IP.pP = spm_vol(fmfnam); | |
% IP.fm.fpm = spm_read_vols(IP.pP); | |
% IP.fm.jac = pm_diff(IP.fm.fpm,2); | |
% if isfield(IP,'P') & ~isempty(IP.P{1}) | |
% IP.P = cell(1,4); | |
% end | |
% if isfield(pm_defs,'magfieldmap') | |
% IP.fmagP=pm_defs.magfieldmap; | |
% end | |
otherwise | |
error('Funny number of input fieldmap images') | |
end | |
if ~isempty(IP.P{1}) | |
%---------------------------------------------------------------------- | |
% Create field map (in Hz) - this routine calls the unwrapping | |
%---------------------------------------------------------------------- | |
IP.fm = hmri_create_FieldMap('CreateFieldMap',IP); | |
% TL: move created maps to outpath | |
if IP.maskbrain==1 | |
% move bmask file (brain mask) and m file (magnitude image normalised (?)) | |
try | |
bmaskfnam = spm_file(IP.P{2}.fname, 'prefix','bmask'); | |
movefile(bmaskfnam, fullfile(b1map_params.outpath, spm_file(bmaskfnam,'filename'))); | |
mfnam = spm_file(IP.P{2}.fname, 'prefix','m'); | |
movefile(mfnam, fullfile(b1map_params.outpath, spm_file(mfnam,'filename'))); | |
catch % will fail if trying to movefile onto itself | |
end | |
end | |
%---------------------------------------------------------------------- | |
% Write out IP.fm.fpm = phase-unwrapped, regularised field map (Hz) | |
% Outputs -> fpm_NAME-OF-FIRST-INPUT-IMAGE.nii | |
% NB: no need to movefile since it is written in same directory as | |
% scphase which had been moved already. | |
%---------------------------------------------------------------------- | |
fmap_img{1} = FieldMap('Write',IP.P{1},IP.fm.fpm,'fpm_',64,'Smoothed phase map'); | |
end | |
%-------------------------------------------------------------------------- | |
% Convert Hz to voxels and write voxel displacement map | |
% Outputs -> vdm5_NAME-OF-FIRST-INPUT-IMAGE.nii | |
% NB: no need to movefile since it is written in same directory as | |
% scphase which had been moved already. | |
%-------------------------------------------------------------------------- | |
[IP.vdm, IP.vdmP] = FieldMap('FM2VDM',IP); | |
%-------------------------------------------------------------------------- | |
% Match voxel displacement map to distorted anatomical image | |
% Outputs -> mag_NAME-OF-FIRST-INPUT-IMAGE.nii | |
%-------------------------------------------------------------------------- | |
% To DO!!! | |
%-------------------------------------------------------------------------- | |
% Match voxel displacement map to distorted anatomical image and | |
% then unwarp the distorted anatomical image | |
%-------------------------------------------------------------------------- | |
IP.epiP = spm_vol(anatfnam); | |
if b1map_params.b1proc.match_vdm | |
IP.vdmP = FieldMap('MatchVDMxy',IP); | |
% write forward warped magnitude image (i.e. magnitude image from | |
% fieldmap acquisition, coregistered & resliced to anat image) | |
% wfmag_NAME-OF-ANAT-IMAGE.nii. Result is written directly in output | |
% directory, no need to movefile. Also coregister (not reslice) vdm5_* | |
% image with it (IP.vdmP.fname = vdm5_* file name). | |
end | |
IP.uepiP = FieldMap('UnwarpEPIxy',IP); | |
unwarp_info = sprintf('Unwarped image:echo time difference=%2.2fms, EPI readout time=%2.2fms, Jacobian=%d',IP.uflags.etd, IP.tert,IP.ajm); | |
% write uNAME-OF-ANAT-IMAGE.nii in output directory, no need to movefile. | |
unwarp_img{1} = FieldMap('Write',IP.epiP,IP.uepiP.dat,'u',IP.epiP.dt(1),unwarp_info); | |
% set second fmap_img output to the coregistered VDM | |
fmap_img{2} = IP.vdmP; | |
%---------------------------------------------------------------------- | |
% Unwarp the other images, assumed to be in same space as anatomical | |
%---------------------------------------------------------------------- | |
for filenum = 1:numel(otherfnam) | |
IP.epiP = spm_vol(otherfnam{filenum}(1,:)); | |
IP.uepiP = FieldMap('UnwarpEPIxy',IP); | |
%---------------------------------------------------------------------- | |
% Write unwarped EPI | |
% Outputs -> uNAME-OF-EPI.nii | |
%---------------------------------------------------------------------- | |
unwarp_info = sprintf('Unwarped image:echo time difference=%2.2fms, EPI readout time=%2.2fms, Jacobian=%d',IP.uflags.etd, IP.tert,IP.ajm); | |
OrigMat = spm_read_vols(IP.epiP); | |
NewMat = IP.uepiP.dat; | |
% AL - 05/10/2016 | |
% In the unwarped images, replace voxels set to zero by the Fieldmap | |
% toolbox by their original values in the warped data. It's a fudge but: | |
% 1. Not expected to do any harm in normal circumstances (voxels set to | |
% 0 are outside the brain) | |
% 2. Helps when fieldmap data doesn't quite cover the whole brain due to | |
% FOV restrictions: in this case, the voxels in the B1 (and SD) maps | |
% outside the fieldmap FOV are set to 0 | |
NewMat(NewMat==0) = OrigMat(NewMat==0); | |
IP.uepiP.dat = NewMat; | |
unwarp_img{1+filenum} = FieldMap('Write',IP.epiP,IP.uepiP.dat,'u',IP.epiP.dt(1),unwarp_info); %#ok<AGROW> | |
end | |
end |