Inference of structural models

O. Coulon, J.-F. Mangin, J.-B. Poline, M. Zilbovicius,
D. Roumenov, Y. Samson, V. Frouin, and I. Bloch
Structural group analysis of functional activation maps
Neuroimage,
11:767--782,
2000

We present here a new method for cerebral activation detection over a group of subjects. This method is performed using individual activation maps of any sort. It aims at processing a group analysis while preserving individual information and at overcoming as far as possible limitations of the spatial normalization used to compare different subjects. We designed it such that it provides the individual occurrence of the activations detected at a group level. The localization can then be performed on the individual anatomy of each subject. The analysis starts with a hierarchical multiscale object-based description of each individual map. These descriptions are then compared, rather than comparing the images directly. The analysis is thus performed at an object level instead of voxel by voxel. It is made using a comparison graph, on which a labeling process is performed. The label field on the graph is modeled by a Markov random field, which allows us to introduce high-level rules of interrogation of the data. The process has been evaluated on simulated data and real data from a PET protocol. Copyright 2000 Academic Press.

A. Cachia, J.-F. Mangin, D. Rivière, F. Kherif, N. Boddaert,
A. Andrade, D. Papadopoulos-Orfanos, J.-B. Poline, I. Bloch,
M. Zilbovicius, P. Sonigo, F. Brunelle, and J. Régis
A Primal Sketch of the Cortex Mean Curvature:
a Morphogenesis Based Approach to Study
the Variability of the Folding Patterns
IEEE Trans. Medical Imaging,
22(6):754-765,
2003

In this paper, we propose a new representation of the cortical surface that may be used to study the cortex folding process and to recover some putative stable anatomical landmarks called sulcal roots usually buried in the depth of adult brains. This representation is a primal sketch derived from a scale space computed for the mean curvature of the cortical surface. This scale-space stems from a diffusion equation geodesic to the cortical surface. The primal sketch is made up of objects defined from mean curvature minima and saddle points. The resulting sketch aims first at highlighting significant elementary cortical folds, second at representing the fold merging process during brain growth. The relevance of the framework is illustrated by the study of central sulcus sulcal roots from antenatal to adult age. Some results are proposed for ten different brains. Some preliminary results are also provided for superior temporal sulcus.