We are conducting a study and so far have analyzed 40 subjects using FreeSurfer.

We have some doubts regarding cortical thickness:

1) Why the maximum value of cortical thickness in lh.thickness or rh.thickness is 5.0 mm? We have case in which clearly the thickness is greater than that in some areas.

2) In the thickness scale for one individual there are colors for negative values. We don’t see a topological or mathematical sense in negative thickness, is there any info on that?

3) We found out that in many cases even in healthy subjects the Insular cortex area presents 5.0 mm thickness in a great area. We think the algorithm may face difficulties in this area since its much convoluted. Is that assumption true?

Thanks in advance for the help.

Pedro Paulo Oliveira Jr

InRad - HCFMUSP