There are no reliable neuroimaging biomarkers to predict long-term outcome after spinal cord injury. This prospective longitudinal study evaluates diffusion tensor imaging (DTI) in predicting long-term outcome after cervical spinal cord injury (CSCI). We investigate the admission DTI parameters measured in 30 patients with CSCI, with 16 of them followed up to one year, and 15 volunteers serving as controls. All magnetic resonance imaging examinations were performed within 24 h of injury. The DTI parameters were measured in patients and controls, avoiding areas of hemorrhage in patients and at corresponding upper/middle/lower regions of the spinal cord in controls. Stepwise regression analysis was performed to find relevant parameters (normalized DTI values, age, sex, hemorrhagic contusion [HC or non-HC]) that correlated with two primary outcome measures: patient International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) motor and Spinal Cord Independence Measure (SCIM III) scores at one year. Among all DTI measures, axial diffusivity (AD) most strongly correlated with both motor (r2 = 0.76, p < 0.01) and SCIM III scores (r2 = 0.77, p < 0.01) at one year. Further stepwise regression indicated that including AD (p = 0.0001) and presence of HC (p < 0.0001) in the regression model provided the best model fit for one year ISNCSCI (r2 = 0.93). The AD is a more specific parameter for axonal injury than radial diffusivity; this may indicate that axonal injury in the cord is the main factor affecting patient recovery. Our study demonstrates DTI measurement at the CSCI is a potential neuroimaging biomarker in predicting long-term neurological and functional outcome in blunt CSCI.
Keywords: cervical spine; diffusion tensor imaging; magnetic resonance; traumatic spinal cord injury.