FreeSurfers,

I have a couple of questions regarding normalization for brain/head size.

We are trying to analyze a pediatric population with subjects between age 4 and 16 with variable brain (and head) sizes. We are mainly interested in measuring cortical thickness in these children, but not sure whether volumetric normalization should be performed or the output of the recon-all -all script is already comparable among subjects with different ages and brain sizes. As per the eTIV page (http://surfer.nmr.mgh.harvard.edu/fswiki/eTIV) of the FreeSurfer website, cortical thickness information cannot be normalized using volumetric information. Does this mean it doesn't have to be normalized in our population at all?

If normalization for cortical thickness is necessary, what approach at what stage would you suggest to use?

For volumetric information, is there any data suggesting normalization to the estimated intracranial volume does not work in children?

Your help is much appreciated!

David Olayinka Kamson, MD Research Associate PET Center Children's Hospital of Michigan 3901 Beaubien, Detroit, MI 48201 Phone: 313-745-0668 FAX: 313-966-9228 david.kamson@pet.wayne.edu