Dear all,

I have access to a dataset of freesurfer segmentation products (i.e. cortical volume, surface area, cortical thickness average and standard deviation) for a number of patients. I wanted to merge the data of some segmented parts (e.g. to compute a general cortical thickness average for the inferior frontal gyrus using the pars orbitalis, pars opercularis and pars triangularis data).
I wanted to know if it is right to compute the average cortical thickness using the following formula:
Average cortical thickness= [(part 1 cortical thickness*part 1 surface area) + (part 2 cortical thickness*part 2 surface area) + …]/ (part 1 surface area + part 2 surface area + …)
BTW, I also checked whether the cortical volume equals ‘surface area*average cortical thickness’, to see if I could use the following formula instead:
Average cortical thickness= (part 1 cortical volume + part 2 cortical volume + …)/ (part 1 surface area + part 2 surface area + …)
But it simply proved wrong.

Any suggestion is greatly appreciated.

Thanks in advance.
Tina