A diffusion tensor imaging technique was compared with conventional MRI to measure and quantify corticospinal dysgenesis in 12 patients with congenital hemiplegia and 12 matched control subjects, in a study at Universite Catholique de Louvain, Brussels, Belgium. A symmetry index computed between the area of the contralateral and ipsilateral corticospinal tracts was similar for the two methods, but the diffusion tensor imaging indexes were significantly smaller. This suggests that the use of the conventional MRI measurement of the cross-sectional area of cerebral peduncles on T1 MRI might lead to an underestimate of cortical dysgenesis. Hand-movement deficits, particularly precision grasping, and stereognosis were examined and correlated with the neuroimaging findings. The symmetry index computed from MRI peduncle measurements correlated solely with deficits in stereognosis, while the diffusion tensor imaging index correlated with stereognosis, digital and manual dexterities, and a measure of manual ability in daily life activities. 
COMMENT. Diffusion tensor imaging symmetry index may prove useful in predicting motor and sensory deficits in children with congenital cerebral dysgenesis.