Abstract

Background
：Diffusion tensor image tractography (DTT) can visualize white matter tracts and provide us with a powerful vehicle for investigating the neuralpathway at the subcortical level. Using DTT, we attempted to demonstrate abnormal transcallosal fibers from the corticospinal tract in patients with brain injury. Materials and Methods：Four adults with brain injury (2 patients: stroke, 1 patient: brain tumor with hemorrhage, 1 patient: diffuse axonal injury) and 14 normal control subjects were enrolled in this study. DTT was performed using 1.5-T with a Synergy-L Sensitivity Encoding head coil. Three-dimensional reconstructions of the fiber tracts were obtained with FA<3.0, and an angle change >45o as termination criteria.
Results
：Transcallosal fibers were observed in two of 14 normal controls, and ascended to the cortex leaving the corpus callosum. All four patients showed transcallosal fibers which stemmed from the corticospinal tract of the unaffected hemisphere, and descended to or around the lesion at the subcortical area.
Conclusion
：It seems that transcallosal fibers which arise from the corticospinal tract of the unaffected hemisphere may act as pathological fibers for motor deficit compensation.

• Keywords: Diffusion tensor image, Brain injury, Interhemispheric inhibition, Corpus callosum