Introduction: High field MRI imaging of the human spine has resulted in the ability to perform complex functional imaging of neural tissue. Much like the brain, we are know not only able to generate diffusion/tractography images of intracranial contents, but also that of the human spinal cord despite tremendous challenges with artifact from surrounding tissues. We present one of the first depictions of clear fiber tractography of the human cervical spine nerve roots.
Methods: Using a 3 Tesla clinical magnet, we performed diffusion imaging in 21 directions with simple tractography producing ADC (apparent diffusion coefficient), b0 (vector direction) and FA (fractional anisotropy), and color FA. The images were from a human subject without any significant clinical evidence of cervical spondylosis, negative history for neck disease, and without history of neck surgery/radiation/trauma of any kind.
Results: At the C2 level (i.e. the greater occipital nerve), we were able to visualize fiber tracts with tractography. Similar to the brain, color represents direction and intensity of flow. Due to the degree of distortion, we were not able to produce meaningful quantitative values (e.g. FA values).
Conclusions: To our knowledge, this is the first clear MRI deptiction of tractography at the nerve root level in the human cervical spine produced from diffusion data. This preliminary work with modifications in diffusion gradients and other sequence parameters will lead to quantitative analysis of nerve root function. In multi-level cervical radiculopathy, such objective data will greatly aid in determining the most symptomatic nerve roots.
Patient Care: Diffusion values in the nerve roots of the human spinal cord will provide objective data regarding nerve root function. In combination with clinical evaluation and judgement, this technology will greatly aid in determining truly symptomatic radiculopathy, as it is well known that MRI of the spine generally only has about a 60-80% correlation with actual physical symptoms.
Learning Objectives: 1. High field MRI provides superior signal-to-noise ratio which is key in peforming diffusion imaging of the human spinal cord and its nerve roots.
2. Tractography is possibe in the human cervical spine at the nerve root level.
3. Further work is being conducted to improved data quality to provide more clinically relevant diffusion values.
References: 1. Tractography of lumbar nerve roots: initial results.
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