Diffusion tensor imaging with 3D high-resolution MRI of lumbosacral nerve roots in lumbar disc herniation with radiculopathy and its clinical correlations: a prospective study.

PURPOSE: To optimally visualize and identify the fiber bundle abnormalities of lumbosacral nerve roots in lumbar disc herniation (LDH) with radiculopathy by diffusion tensor imaging (DTI) based on 3D high-resolution MRI.

METHODS

Ninety-seven patients with unilateral LDH with radiculopathy were prospectively enrolled and underwent DTI and 3D high-resolution MRI. Quantitative DTI parameters including fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were obtained through continuous multi-point measurements along the nerve root trajectory, from the nerve root compression level to the distal end. These metrics were then correlated with nerve root compression grades and clinical scores for pain and functional disability.

RESULTS

At the compression site, affected nerve roots exhibited significantly lower FA and AD compared to the contralateral side (p < 0.001). Distal to this site, a distinct spatial gradient was observed: FA values increased while ADC and RD values decreased, whereas AD remained relatively stable. Key DTI parameters correlated significantly with both compression severity and clinical scores (p ranges: < 0.001 to 0.042). Specifically, lower FA and higher ADC and RD values were strongly associated with worse functional outcomes and greater pain (r = -0.42 to 0.41).

CONCLUSION

The combination of continuous multi-point DTI sampling with high-resolution 3D MRI provided effective means for quantitatively evaluating the compressed nerve in patients with LDH. This approach may facilitate a comprehensive understanding of the microstructural damage and its relationship to clinical severity in radiculopathy.