Disease States

Cortical structure is severely affected in a variety of disease states such as Alzheimer's disease, Pick's disease, and other dementias, by tumor growth, and in cases of epilepsy, cortical dysplasias, and schizophrenia. Cortical matching approaches can be exploited by algorithms that detect these alterations. In one approach [109], a probability space of random transformations, based on the theory of anisotropic Gaussian random fields, encodes information on complex variations in gyral and sulcal topography from one individual to another (Fig. 6). Confidence limits in stereotaxic space are determined, for cortical surface points in a new subject's brain, and color-coded probability maps are created to highlight and quantify regional patterns of deformity in the anatomy of new subjects (q.v, Thompson and Toga, this volume).

10.1 Genotype vs Phenotype

Structural image databases from twin monozygotic versus dizygotic populations provide tremendous opportunities to investigate the relationship between genotype and phenotype. Striking similarities in brain structure for both mono- and dizygotic twins have been reported in studies of corpus callosum morphology [6,72] and gyral patterning [70]. These structural affinities can be exploited in clinical studies, since twins discordant for a specific disease-linked gene may be examined for regional structural differences in a context where effects of their shared genes are factored out [46,70]. An ongoing twin study [41] focuses on 200 MR scans acquired from elderly Swedish twin pairs, where one member of each twin pair has Alzheimer's disease or vascular dementia. Among 12 pairs of twins discordant for AD, the affected twin had greater temporal horn dilation, temporal lobe atrophy, and third ventricle enlargement, while significant within-pair correlations were found for measures of intracranial area, cerebellar area, temporal lobe volume, and white matter lesions [41].

Displacement (mm)

Spherical Tensor Maps

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