Objective: To reveal the immediate extent of trauma-induced neurodegenerative changes rostral to the level of lesion and determine the predictive clinical value of quantitative MRI (qMRI) following acute spinal cord injury (SCI).
Methods: Twenty-four acute SCI patients and 23 healthy controls underwent a high-resolution T1-weighted protocol. Eighteen of those patients and 20 of controls additionally underwent a multi-parameter mapping (MPM) MRI protocol sensitive to the content of tissue structure, including myelin and iron. Patients were examined clinically at baseline, 2, 6, 12, and 24 months post-SCI. We assessed volume and microstructural changes in the spinal cord and brain using T1-weighted MRI, magnetization transfer (MT), longitudinal relaxation rate (R1), and effective transverse relaxation rate (R2*) maps. Regression analysis determined associations between acute qMRI parameters and recovery.
Results: At baseline, cord area and its anterior-posterior width were decreased in patients, whereas MT, R1, and R2* parameters remained unchanged in the cord. Within the cerebellum, volume decrease was paralleled by increases of MT and R2* parameters. Early grey matter changes were observed within the primary motor cortex and limbic system. Importantly, early volume and microstructural changes of the cord and cerebellum predicted functional recovery following injury.
Conclusions: Neurodegenerative changes rostral to the level of lesion occur early in SCI, with varying temporal and spatial dynamics. Early qMRI markers of spinal cord and cerebellum are predictive of functional recovery. These neuroimaging biomarkers may supplement clinical assessments and provide insights into the potential of therapeutic interventions to enhance neural plasticity.
Keywords: APW, anterior posterior width; Acute micro-structural changes; Brain and spinal cord atrophy; ISNCSCI, international standards for the neurological classification of spinal cord injury; LRW, left right width; MPM, multi-parameter mapping; MT, magnetization transfer; PD*, effective proton density; Quantitative neuroimaging; R1, longitudinal relaxation rate; R2*, effective transverse relaxation rate; ROI, region of interest; SCA, spinal cord area; SCI, spinal cord injury; SCIM, spinal cord independence measure; Spinal cord injury; VBCT, voxel based cortical thickness; VBM, voxel based morphometry; VBQ, voxel based quantification; Voxel-based morphometry and quantification.