Diffusion tensor imaging in spinal cord injury

Abstract

Background and purpose: To assess the feasibility of spinal tractography in patients of spinal cord injury vs a control group and to compare fractional anisotropy (FA) values between the groups.

Materials and methods: Diffusion tensor imaging (DTI) was performed in the spinal cord of 29 patients (18 patients and 11 controls). DTI was done in the cervical region if the cord injury was at the dorsal or lumbar region and in the conus region if cord injury was in the cervical or dorsal region. FA was calculated for the patients and the controls and the values were compared.

Results: The mean FA value was 0.550±0.09 in the control group and 0.367±0.14 in the patients; this difference was statistically significant (P=0.001).

Conclusion: Spinal tractography is a feasible technique to assess the extent of spinal cord injury by FA, which is reduced in patients of spinal cord injury, suggesting possible Wallerian degeneration. In future, this technique may become a useful tool for assessing cord injury patients after stem cell therapy, with improvement in FA values indicating axonal regeneration.

Keywords: Fractional anisotropy; MRI; spinal cord injury; tensor imaging.

Figure 1 (A-E)

This patient sustained a road traffic accident with cervical cord injury. He had 0/5 power in both lower limbs and 4/5 power in both upper limbs. T2W sagittal MRI (A) shows cervical cord injury with a normal appearing lower cord. The line drawn at D11 shows the level of axial images. Figure B shows placement of the ROI with a colored map of the FA (C) and a colored ADC map (D). Figure E shows a colored fiber tractography image. The FA values at three ROIs were 0.275±0.0471, 0.315±0.0593, and 0.393±0.0687 which are significantly lower than the control group, suggesting possibly descending Wallerian degeneration in the lower cord.