[Freesurfer] Surface area issue in longitudinal studies

We are using Freesurfer v5.3 with the recent Jacobian area correction, but there may be a subtle bug that affects longitudinal studies. In a pediatric population, we see area growth on top of gyrii, and area loss in the base of sulci. This effect may be a true morphological change, but it may be due to an approximation error of a curved area by planar surfaces in regions of high curvature. Is there a command or script to compute an "adjusted area" on a vertex-wise basis? For every vertex, I would like to compute something like: Adjusted area = Area*(1 + G*d^2*k^2) where Area is the v5.3 area, G is a constant, d is the local vertex spacing, and k is the local mean curvature.

Thank you, Paul K. Mazaika