Spinal Cord Injury (SCI) results in temporary or permanent functional impairment of the spinal cord. It can be classified as traumatic or non-traumatic and is often associated with limited recovery[1]. To understand this pathophysiological mechanism, advanced imaging techniques such as quantitative magnetic resonance imaging (qMRI) have been developed. qMRI is a non-invasive method that provides reproducible maps of quantitative values proportional to tissue microstructure, enabling the assessment of myelin and axonal density[2].
We developed a spinal cord imaging and data analysis protocol, derived from the spine generic protocol, for the study of both injury types[3]. Our analysis focused on macrostructural and microstructural changes using qMRI biomarkers, including cross-sectional area (CSA) and magnetization transfer ratio (MTR)[4].
Macrostructural analysis showed a significant reduction in CSA in SCI patients compared to healthy controls (HC), with a mean decrease of 4% in T1-weighted images (p < 0.01) and 8% in T2-weighted images (p < 0.001). A significant interaction between vertebral level and group in T2-weighted images (p = 0.023) suggests that atrophy may vary depending on spinal level. MTR analysis revealed a significant reduction in white matter (p = 0.016), with traumatic patients showing the greatest decrease. In the lateral corticospinal tract, traumatic patients exhibited a significant reduction (p< 0.05), indicating more severe damage in motor pathways.
These findings confirm SCI-related atrophy and demyelination, varying based on vertebral level and injury type. qMRI provides valuable biomarkers to assess structural damage and could improve prognosis, therapeutic monitoring, and prediction of sensorimotor recovery.
Figura 1 T2w in sagittal view of a patient with a C5-level traumatic injury
Figura 2 Spinal Cord Cross Sectional Area mean values along vertebral levels in T2w images of healthy subjects (HC) and patients (PAT).
Figura 3 MTR mean values along vertebral levels from magnetization transfer contrast images of healthy controls (HC), no-traumatic patients (NT) and traumatic patients (T).
References
[1] Wyndaele et al. (2006). Incidence, prevalence and epidemiology of spinal cord injury: what learns a worldwide literature survey?. (Spinal cord, 44(9), 523–529).
[2] Seif et al. (2018). Quantitative MRI of rostral spinal cord and brain regions is predictive of functional recovery in acute spinal cord injury. NeuroImage (Clinical, 20, 556–563).
[3] Cohen-Adad et al. (2021). Generic acquisition protocol for quantitative MRI of the spinal cord. Nature Protocols (Vol. 16, Issue 10, pp. 4611–4632).
[4] Cohen-Adad et al. (2021). Open-access quantitative MRI data of the spinal cord and reproducibility across participants, sites and manufacturers. Scientific Data, 8(1).
