In vivo three-dimensional reconstruction of human median nerves by diffusion tensor imaging.

The in vivo assessment of axonal projections of the peripheral nervous system has been severely limited by the lack of noninvasive techniques. We examined whether MR diffusion tensor imaging with fiber tracking of the human median nerve is feasible. The median nerve was examined with a 3-T MRI scanner in wrists of three healthy volunteers and the wrist of a patient after median nerve repair. In vivo three-dimensional (3D) reconstruction of axonal projections of the median nerve could be achieved in healthy volunteers with intact median nerves and a patient with a transected median nerve using diffusion tensor imaging combined with fiber tracking. The median nerve could be visualized and correlated well to the expected location on T1-weighted images in the patient and all volunteers. The transected median nerve in the patient could be detected up to the site of repair one month postoperatively, whereas the nerve could not be detected more distally immediately after repair. Two months postoperatively, it could clearly be tracked more distally, indicating nerve regeneration. Diffusion tensor imaging can detect the median nerve in healthy individuals as well as up to the lesion site in a patient with a complete transection of the median nerve.