High-resolution diffusion tensor imaging in cervical spondylotic myelopathy: a preliminary follow-up study

Diffusion imaging is a promising technique as it can provide microstructural tissue information and thus potentially show viable changes in spinal cord. However, the traditional single-shot imaging method is limited as a result of various image artifacts. In order to improve measurement accuracy, we used a newly developed, multi-shot, high-resolution, diffusion tensor imaging (DTI) method to investigate diffusion metric changes and compare them with T-2-weighted (T2W) images before and after decompressive surgery for cervical spondylotic myelopathy (CSM). T2W imaging, single-shot DTI and multi-shot DTI were employed to scan seven patients with CSM before and 3 months after decompressive surgery. High signal intensities were scored using the T2 W images. DTI metrics, including fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD) and mean diffusivity (MD), were quantified and compared pre-and post-surgery. In addition, the relationship between imaging metrics and neurological assessments was examined. The reproducibility of multi-shot DTI was also assessed in 10 healthy volunteers. Post-surgery, the mean grade of cervical canal stenosis was reduced from grade 3 to normal after 3 months. Compared with single-shot DTI, multi-shot DTI provided better images with lower artifact levels, especially following surgery, as a result of reduced artifacts from metal implants. The new method also showed acceptable reproducibility. Both FA and RD values from the new acquisition showed significant differences post-surgery (FA, p = 0.026; RD, p = 0.048). These changes were consistent with neurological assessments. In contrast, T2W images did not show significant changes before and after surgery. Multi-shot diffusion imaging showed improved image quality over single-shot DWI, and presented superior performance in diagnosis and recovery monitoring for patients with CSM compared with T2W imaging. DTI metrics can reflect the pathological conditions of spondylotic spinal cord quantitatively and may serve as a sensitive biomarker for potential CSM management.