SIXTO OBRADOR SENEC PRIZE 2019: Utility of diffusion tensor imaging as a prognostic tool in moderate to severe traumatic brain injury. Part II: Longitudinal analysis of DTI metrics and its association with patient's outcome.

BACKGROUND AND OBJECTIVES

Traumatic axonal injury is the main cause of the cognitive and neuropsychological situation of patients after head trauma (TBI). Additionally, there are some evidences about the dynamic evolution of traumatic axonal injury. Although the diffusion tensor MRI (DTI) sequence is considered a useful technique for modifying the extent of the traumatic axonal injury, few studies have evaluated the longitudinal changes in the characteristics of the DTI and its relation to evolution of patients.

MATERIALS AND METHODS

We performed a prospective observational study in 118 patients with moderate to severe TBI. The study included clinical outcome assessment based on the Glasgow Outcome Scale Extended and serial DTI studies in the early subacute setting (<60 days) and 6 and 12 months after injury. Fractional anisotropy, axial and radial diffusivities were measured in the 3 portions of corpus callosum (genu, body, splenium) at each time point and compared to normalized values from an age-matched control group. Longitudinal fractional anisotropy analysis and its correlation with patient improvement was also done by non-parametric testing and ordinal regression analysis.

RESULTS

Although dynamic changes in DTI characteristics have been detected in the 3 portions of corpus callosum, patients continue to show lower fractional anisotropy and axial diffusivities values and higher radial diffusivities values compared to controls at the end of the period of study. We have also found differences in the pattern of DTI metrics change between subgroups of patients according with their favorable outcome CONCLUSIONS: The temporal profile of the change in DTI characteristics seems to provide important information about the clinical recovery of patients after TBI.