Dear SPM experts,

I have some ROI masks constructed from 2nd-level results and they are in mm dimension. I would like to use those ROIs to extract values from some first-level statistical maps like beta or con.maps. From reading previous posts I get that I need to convert mm dimension to voxel dimension, so I constructed the following matlab scripts (ultilizing the spm_read_vols and spm_get_data functions):

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Y = spm_read_vols(spm_vol(ROI_path),1); 

indx = find(Y>0);

[x,y,z] = ind2sub(size(Y),indx);

XYZ = [x y z]';  %%%%% To get the coordinates of the ROI in voxel dimension

Extracted_data = mean(spm_get_data(Image_path, XYZ),2);  %%%%%% to extract data from the statistical maps on those coordinates

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The resultant data look reasonable, however I just want to make sure the approach is correct. Could anyone advise?

Many thanks in advance.

Robin