Detection and statistical analysis of human cortical sulci

Many studies dealing with the human brain use the spatial coordinate system of brain anatomy to localize functional regions. Unfortunately, brain anat omy, and especially cortical sulci, is characterized by a high interindivid ual variability. Specific tools called anatomical atlases must then be cons idered to make the interpretation of anatomical examinations easier. The wo rk described here first aims at building a numerical atlas of the main cort ical sulci. Our system is based on a database containing a collection of an atomical MRI of healthy volunteer brains. Their sulci have been manually dr awn and labeled for both hemispheres. Sulci are represented as 3D superfici al curves. After a nonlinear registration process, a statistical atlas of t he cortical topography of a particular MRI is built from the database. It i s an a priori model of cortical sulci, including three major components: an average curve represents the average shape and position of each sulcus; a search area accounts for its spatial variation domain; a set of quantitativ e parameters describes the variability of sulci geometry and topology. This atlas is completely individualized and adapted to the features of the brai n under examination. The atlas is represented by a graph, the nodes of whic h represent sulci and the edges the relations between sulci. It can also be considered a statistical model that describes the cortical topography as w ell as its variability. (C) 1999 Academic Press.