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GannetMask_SiemensTWIX.m
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GannetMask_SiemensTWIX.m
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function MRS_struct = GannetMask_SiemensTWIX(fname, nii_file, MRS_struct, ii, vox, kk)
% Co-registers Siemens TWIX data to a NIfTI structural image.
%
% Author:
% Dr. Georg Oeltzschner (Johns Hopkins University, 2018-02-24)
%
% Credits:
% The routine for correct determination of the phase and readout
% directions of the MRS voxel is adapted from
% vox2ras_rsolveAA.m
% (Dr. Rudolph Pienaar, Massachusetts General Hospital, Boston)
%
% History:
% 2018-02-24: New version of GannetMask_SiemensTWIX
% 2020-12-04: Updates to voxel dipaly in output figure
% 2023-03-29: Cosmetic edits
[path, name] = fileparts(fname);
fidoutmask = fullfile(path, [name '_mask.nii']);
% Extract voxel position and rotation parameters from MRS_struct
NormSag = MRS_struct.p.NormSag(ii);
NormCor = MRS_struct.p.NormCor(ii);
NormTra = MRS_struct.p.NormTra(ii);
VoI_InPlaneRot = MRS_struct.p.VoI_InPlaneRot(ii);
% Correct voxel offsets by table position (if field exists)
if isfield(MRS_struct.p,'TablePosition')
VoxOffs = [MRS_struct.p.voxoff(ii,1) + MRS_struct.p.TablePosition(ii,1), ...
MRS_struct.p.voxoff(ii,2) + MRS_struct.p.TablePosition(ii,2), ...
MRS_struct.p.voxoff(ii,3) + MRS_struct.p.TablePosition(ii,3)];
else
VoxOffs = [MRS_struct.p.voxoff(ii,1), MRS_struct.p.voxoff(ii,2), MRS_struct.p.voxoff(ii,3)];
end
% Parse direction cosines of the MRS voxel's normal vector and the rotation angle
% around the normal vector
% The direction cosine is the cosine of the angle between the normal
% vector and the respective direction.
% Example: If the normal vector points exactly along the FH direction, then:
% NormSag = cos(90) = 0, NormCor = cos(90) = 0, NormTra = cos(0) = 1.
Norm = [-NormSag -NormCor NormTra];
ROT = VoI_InPlaneRot;
% Find largest element of normal vector of the voxel to determine primary
% orientation.
% Example: if NormTra has the smallest out of the three Norm
% values, the angle of the normal vector with the Tra direction (FH) is the
% smallest, and the primary orientation is transversal.
[~, maxdir] = max([abs(NormSag) abs(NormCor) abs(NormTra)]);
switch maxdir % 't' = transversal, 's' = sagittal', 'c' = coronal
case 1
vox_orient = 's';
case 2
vox_orient = 'c';
case 3
vox_orient = 't';
end
% Phase reference vector
% Adapted from Rudolph Pienaar's "vox2ras_rsolveAA.m" and
% Andre van der Kouwe's "autoaligncorrect.cpp"
Phase = zeros(3,1);
switch vox_orient
case 't'
% For transversal voxel orientation, the phase reference vector lies in
% the sagittal plane
Phase(1) = 0;
Phase(2) = Norm(3) * sqrt(1/(Norm(2).^2 + Norm(3).^2));
Phase(3) = -Norm(2) * sqrt(1/(Norm(2)*Norm(2)+Norm(3)*Norm(3)));
case 'c'
% For coronal voxel orientation, the phase reference vector lies in
% the transversal plane
Phase(1) = Norm(2) * sqrt(1/(Norm(1).^2 + Norm(2).^2));
Phase(2) = -Norm(1) * sqrt(1/(Norm(1).^2 + Norm(2).^2));
Phase(3) = 0;
case 's'
% For sagittal voxel orientation, the phase reference vector lies in
% the transversal plane
Phase(1) = -Norm(2) * sqrt(1/(Norm(1).^2 + Norm(2).^2));
Phase(2) = Norm(1) * sqrt(1/(Norm(1).^2 + Norm(2).^2));
Phase(3) = 0;
end
VoxDims = [MRS_struct.p.voxdim(ii,1), MRS_struct.p.voxdim(ii,2), MRS_struct.p.voxdim(ii,3)];
% The readout reference vector is the cross product of Norm and Phase
Readout = cross(Norm, Phase);
M_R = zeros(4,4);
M_R(1:3,1) = Phase;
M_R(1:3,2) = Readout;
M_R(1:3,3) = Norm;
% Define matrix for rotation around in-plane rotation angle
M3_Mu = [cos(ROT) sin(ROT) 0
-sin(ROT) cos(ROT) 0
0 0 1];
M3_R = M_R(1:3,1:3) * M3_Mu;
M_R(1:3,1:3) = M3_R;
% The MGH vox2ras matrix inverts the Readout column
M_R = M_R * [1 0 0 0
0 -1 0 0
0 0 1 0
0 0 0 1];
% Final rotation matrix
rotmat = M_R(1:3,1:3);
V = spm_vol(nii_file);
[T1, XYZ] = spm_read_vols(V);
% Shift imaging voxel coordinates by half an imaging voxel so that the XYZ matrix
% tells us the x,y,z coordinates of the MIDDLE of that imaging voxel.
[~, voxdim] = spm_get_bbox(V,'fv');
voxdim = abs(voxdim)';
halfpixshift = -voxdim(1:3)/2;
halfpixshift(3) = -halfpixshift(3);
XYZ = XYZ + repmat(halfpixshift, [1 size(XYZ,2)]);
% We need to flip ap and lr axes to match NIfTI convention
VoxOffs(1) = -VoxOffs(1);
VoxOffs(2) = -VoxOffs(2);
% Define voxel coordinates before rotation and transition
vox_ctr = ...
[VoxDims(1)/2 -VoxDims(2)/2 VoxDims(3)/2;
-VoxDims(1)/2 -VoxDims(2)/2 VoxDims(3)/2;
-VoxDims(1)/2 VoxDims(2)/2 VoxDims(3)/2;
VoxDims(1)/2 VoxDims(2)/2 VoxDims(3)/2;
-VoxDims(1)/2 VoxDims(2)/2 -VoxDims(3)/2;
VoxDims(1)/2 VoxDims(2)/2 -VoxDims(3)/2;
VoxDims(1)/2 -VoxDims(2)/2 -VoxDims(3)/2;
-VoxDims(1)/2 -VoxDims(2)/2 -VoxDims(3)/2];
% Apply rotation as prescribed
vox_rot = rotmat * vox_ctr.';
% Shift rotated voxel by the center offset to its final position
vox_ctr_coor = [VoxOffs(1), VoxOffs(2), VoxOffs(3)];
vox_ctr_coor = repmat(vox_ctr_coor.', [1 8]);
vox_corner = vox_rot + vox_ctr_coor;
% Create a mask with all voxels that are inside the voxel
mask = zeros(1,size(XYZ,2));
sphere_rad = sqrt((VoxDims(1)/2).^2 + (VoxDims(2)/2).^2 + (VoxDims(3)/2).^2);
dist2voxctr = sqrt(sum((XYZ - repmat([VoxOffs(1), VoxOffs(2), VoxOffs(3)].', [1 size(XYZ,2)])).^2, 1));
sphere_mask(dist2voxctr <= sphere_rad) = 1;
mask(sphere_mask == 1) = 1;
XYZ_sphere = XYZ(:,sphere_mask == 1);
tri = delaunayn([vox_corner.'; [VoxOffs(1), VoxOffs(2), VoxOffs(3)]]);
tn = tsearchn([vox_corner.'; [VoxOffs(1), VoxOffs(2), VoxOffs(3)]], tri, XYZ_sphere.');
isinside = ~isnan(tn);
mask(sphere_mask == 1) = isinside;
% Take over the voxel dimensions from the structural
mask = reshape(mask, V.dim);
V_mask.fname = fidoutmask ;
V_mask.descrip = 'MRS_voxel_mask';
V_mask.dim = V.dim;
V_mask.dt = V.dt;
V_mask.mat = V.mat;
V_mask = spm_write_vol(V_mask, mask);
% Build output (code to make voxel mask yellow borrowed from SPM12)
MRS_struct.mask.(vox{kk}).outfile(ii,:) = cellstr(fidoutmask);
% Not clear how to formulate the rotations for triple rotations (revisit)
MRS_struct.p.voxang(ii,:) = [NaN NaN NaN];
% Transform structural image and co-registered voxel mask from voxel to
% world space for output
[img_t, img_c, img_s] = voxel2world_space(V, VoxOffs);
[mask_t, mask_c, mask_s] = voxel2world_space(V_mask, VoxOffs);
w_t = zeros(size(img_t));
w_c = zeros(size(img_c));
w_s = zeros(size(img_s));
T1 = T1(:);
img_t = repmat(img_t / (mean(T1(T1 > 0.01)) + 3*std(T1(T1 > 0.01))), [1 1 3]);
img_c = repmat(img_c / (mean(T1(T1 > 0.01)) + 3*std(T1(T1 > 0.01))), [1 1 3]);
img_s = repmat(img_s / (mean(T1(T1 > 0.01)) + 3*std(T1(T1 > 0.01))), [1 1 3]);
c_img_t = zeros(size(img_t));
c_img_c = zeros(size(img_c));
c_img_s = zeros(size(img_s));
vox_mx = 1;
vox_mn = 0;
mask_t(mask_t(:) < vox_mn) = vox_mn;
mask_t(mask_t(:) > vox_mx) = vox_mx;
mask_t = (mask_t - vox_mn) / (vox_mx - vox_mn);
mask_c(mask_c(:) < vox_mn) = vox_mn;
mask_c(mask_c(:) > vox_mx) = vox_mx;
mask_c = (mask_c - vox_mn) / (vox_mx - vox_mn);
mask_s(mask_s(:) < vox_mn) = vox_mn;
mask_s(mask_s(:) > vox_mx) = vox_mx;
mask_s = (mask_s - vox_mn) / (vox_mx - vox_mn);
mask_t = 0.4 * mask_t;
mask_c = 0.4 * mask_c;
mask_s = 0.4 * mask_s;
vox_color = [1 1 0];
c_img_t = c_img_t + cat(3, mask_t * vox_color(1,1), mask_t * vox_color(1,2), mask_t * vox_color(1,3));
c_img_c = c_img_c + cat(3, mask_c * vox_color(1,1), mask_c * vox_color(1,2), mask_c * vox_color(1,3));
c_img_s = c_img_s + cat(3, mask_s * vox_color(1,1), mask_s * vox_color(1,2), mask_s * vox_color(1,3));
w_t = w_t + mask_t;
w_c = w_c + mask_c;
w_s = w_s + mask_s;
img_t = repmat(1 - w_t, [1 1 3]) .* img_t + c_img_t;
img_c = repmat(1 - w_c, [1 1 3]) .* img_c + c_img_c;
img_s = repmat(1 - w_s, [1 1 3]) .* img_s + c_img_s;
img_t(img_t < 0) = 0; img_t(img_t > 1) = 1;
img_c(img_c < 0) = 0; img_c(img_c > 1) = 1;
img_s(img_s < 0) = 0; img_s(img_s > 1) = 1;
img_t = flipud(img_t);
img_c = flipud(img_c);
img_s = flipud(img_s);
size_max = max([max(size(img_t)) max(size(img_c)) max(size(img_s))]);
three_plane_img = zeros([size_max 3*size_max 3]);
three_plane_img(:,1:size_max,:) = image_center(img_t, size_max);
three_plane_img(:,size_max+(1:size_max),:) = image_center(img_s, size_max);
three_plane_img(:,size_max*2+(1:size_max),:) = image_center(img_c, size_max);
MRS_struct.mask.(vox{kk}).img{ii} = three_plane_img;
MRS_struct.mask.(vox{kk}).T1image(ii,:) = {nii_file};
end