I was wondering if there is any way to extract MRI image (.nii format) intensities ? I have a set of MRI images (T1 maps) with dimensions: 256x256x175x20 where X=256, Y=256, Z=175 and # of time frames is 20.

I can see image intensities can be read using load_nii (available in NIFTI Matlab toolbox) but I have an ROI (in nii format) with same dimensions as MRI image (356x256x175) and I am able to overlay ROI over MRI images.

So I am interested in plotting image intensities for the voxels for this particular ROI vs. time frame.

I would really appreciate any help.

Thanks,

Sahil