How to Fuse image multimodality

Hi all,

I have 128 image SPECT (SPECT scan), and have 673 images CT (CT scan). how to fuse both, while one of the set images is not enough frame.

Below is coding that i used, but failed.

%read SPECT images
[spect map]=dicomread('SPECT.dcm');
info = dicominfo('SPECT.dcm');
gp=info.SliceThickness;
spect=(squeeze(spect));%smooth3

% Read CT Images
myFolder = ('C:\Users\Akmal\Downloads\SPECT-CT\SPECT-CT\CT');
filePattern = fullfile(myFolder, '*.dcm'); % Change to whatever pattern you need.
theFiles = dir(filePattern);
for L = 1 : length(theFiles)
    baseFileName = theFiles(L).name;
    fullFileName = fullfile(theFiles(L).folder, baseFileName);
    fprintf(1, 'Now reading %s\n', fullFileName);
    % Now do whatever you want with this file name,
    % such as reading it in as an image array with imread()
       RZ(:,:,L) = dicomread(fullFileName);
end

imshow3D (RZ, spect);

anyone can help me??