[Magnetic resonance diffusion tensor imaging for diagnosis of pyramidal tract damage in rats].

Objective: To explore the applicability of magnetic resonance diffusion tensor imaging (DTI) for diagnosis of pyramidal tract damage in rats.

Methods: Marmarou's model was set up, followed by DTI scanning at 3, 12, 24 and 72 h post trauma to acquire the dispersion parameter of bilateral pyramidal tracts. Moreover, axonal varicosities per square millimeter and the percentage of positive area of axons demonstrated by beta-amyloid precursor protein (beta-APP) immunostaining were obtained, as well as the mean density and sum density of neurofilament (NF) 68 immunostaining.

Results: Axial diffusivity (AD), fraction anisotropy (FA) and relative anisotropy (RA) in the pyramidal tract were significantly and continuously reduced and reached to the bottom at 72h post trauma (P < 0.05) in accord with the gradient of axonal damage verified by beta-APP and NF68 immunostaining. Furthermore, the changes of AD, FA and RA showed a significant negative correlation with the beta-APP immunohistochemical results.

Conclusion: DTI has important value for early diagnosis in pyramidal tract damage.