Hi.  I have a set of T1 MR images (lets say N=10) that are intensity normalized and registered to the same target space. I have a scalar value for each of these N images (lets say age).

I'm looking for a simple, quick voxel-by-voxel correlation coefficient calculation that I can run from the command line on my Mac.
Something like
> correlation_program -i my_images.nii.gz -ref age_values.txt -o correlation_map.nii.gz

which take my N images, applies my reference vector to generate a correlation (r) map.

I know that there are 'fancy' and statistically rigorous ways to do this in FSL, SPM, AFNI, etc. but that's kind of 'heavy weight' for what I'm after in this case. 

Thanks in advance!