Corticospinal tract extraction combining diffusion tensor tractography with FMRI in patients with brain diseases

Our goal was to visualize diffusion tensor tractography (DTT) of the corticospinal tract (CST) with areas of activation on functional magnetic resonance imaging (fMRI) to acquire useful, highly accurate preoperative information. We investigated the usefulness of the technique and our method of precisely evaluating the depicted DTT in patients with brain disease.

Nineteen subjects underwent 3-dimensional T(1)-weighted imaging for anatomical reference; gradient-echo, echo-planar imaging (EPI) for fMRI; and single-shot, diffusion-weighted EPI for DTT. The target point for DTT was placed within activated areas in the primary motor area on fMRI, and the seed point was placed in the cerebral peduncle. DTT was depicted with the seed and target points. We examined the precision of DTT using this method by assessing the anteroposterior relationship of depicted DTTs of the upper and lower extremities in the posterior limb of the internal capsule.

DTT was depicted in 18 of 19 cases of the upper extremity and in 12 of 19 cases of the lower extremity. In the evaluation of precision, DTT reflected the posterior limb of the internal capsule in all cases. In terms of the anteroposterior relationship of DTTs, nine of 12 cases showed that fibers in the upper extremities passed in front of fibers in the lower extremities.

This technique allows depiction of DTT associated with a local brain function in the CST in patients with brain disease and may be useful for operative planning. Our method of evaluating precision is also likely to prove useful.