Combined functional magnetic resonance imaging and diffusion tensor imaging demonstrate widespread modified organisation in malformation of cortical development

A patient with a mild left hemiparesis and a malformation of cortical devel opment in the right hemisphere was investigated with fMRI (functional magne tic resonance imaging) and DTI (diffusion tensor imaging). The motor cortex was studied using a finger tapping fMRI experiment, The fibre orientation was studied by displaying the principal eigenvector of the diffusion tensor in the spatially normalised brain of the patient and of control subjects, In addition, the anisotropy (directionality) of water diffusion of the pati ent was statistically compared with control subjects. The malformation was located in the right central region in the expected po sition of the motor cortex. fMRI showed activation anterior and posterior t o the malformation. DTI disclosed that fibres with rostrocaudal orientation , presumably representing the pyramidal tract, were deviating from their no rmal orientation and passing around the malformation, There were widespread regions of reduced anisotropy affecting both hemispheres. In conclusion, fMRI and DTI provided concordant information showing wide-sp read modified functional and structural organisation including regions whic h appeared normal on standard imaging.