Fernanda Tovar Moll MD, Presenter: Nothing to Disclose

Jorge N Moll MD, Abstract Co-Author: Nothing to Disclose

Ricardo Oliveira-Souza MD, Abstract Co-Author: Nothing to Disclose

Ivanei Edison Bramati PhD, Abstract Co-Author: Nothing to Disclose

Pedro Angelo Andreiuolo MD, Abstract Co-Author: Nothing to Disclose

Roberto Lent MD, Abstract Co-Author: Nothing to Disclose

Callosal dysgenesis (CD) is observed in many neurodevelopmental conditions, but its subjacent mechanisms are unknown. Diffusion Tensor Imaging (DTI) and tractography are unique tools for characterizing white matter (WM) in vivo. We employed DTI and tractography to study human CD and to search for evidence of plasticity.

Eleven patients with CD and ten normal controls were studied with a 1.5 T scanner (Philips Medical Systems). Color-coded fractional anisotropy (FA) maps were created. Fiber tracking was performed using a marching algorithm, with ROI analyses and thresholding based on FA. Results were compared to control subject data.

In additional to the typical anatomical features of CD depicted by conventional MRI, DTI and tractography provided three main findings: (1) in the presence of a callosal remnant or of a hypoplastic corpus callosum (CC), fibers therein largely connect the expected neocortical regions; (2) callosal remnants and hypoplastic CCs display a fiber topography similar to normal; (3) two long abnormal tracts are formed in patients with defective CC: the well-known Probst bundle (PB), and a so far unknown asymmetrical bundle connecting the frontal lobe with the contralateral occipito-parietal cortex.

DTI can be successfully employed to reveal abnormal white matter development in CD. Specific connectivity patterns could be demonstrated, some of them abnormal, as a consequence of ontogenetic plasticity. These observations suggest that when the developing human brain is confronted with factors that hamper CC fibers to cross the midline, some properties of the miswired fibers are maintained (such as side-by-side topography), while others are dramatically changed, leading to the formation of grossly abnormal white matter tracts.

DTI-tractography allows detailed characterization of normal and abnormal WM human tracts in vivo and may provide key information for the understanding of neurodevelopmental disorders.

Moll, F, Moll, J, Oliveira-Souza, R, Bramati, I, Andreiuolo, P, Lent, R, Neuroplasticity in Human Callosal Dysgenesis: A Diffusion Tensor Imaging Study.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4441081.html