A longitudinal study of changes in Diffusion Tensor Value and their association with cognitive sequelae among patients with mild head injury.

Abstract

Diffusion tensor imaging (DTI) is an advanced and sensitive technique that detects sub-threshold pathology in normal imaging brain injury patients. Currently, there are no longitudinal DTI studies to look for time-based changes. The present study has investigated longitudinal imaging and its association with cognitive deficits. Twenty-one patients were available for MRI and neuropsychological test (NPT) assessment for all the 3 time points. Initially (<36 hours), all patients presented with GCS 15 and normal scan findings. The DTI (P<0.0001) and NPT scores (P<0.05) were analyzed using repeated-measure of analysis. The tensor values were correlated with specific time-point NPT scores using partial correlation (0.05). Right cerebral-hemisphere showed significant alterations in both anisotropy and diffusivity values overtime. Cingulate gyrus and occipital lobe showed prominent changes in anisotropy value. Significant improvement in thalamo-cortical anisotropy value after 3-4 months after injury was seen. The changes in diffusivity values were mainly seen in frontal, parietal lobe, right inferior fronto-occipital and superior longitudinal fasciculus, and posterior supramarginal gyrus. Time-related changes of tensor values of thalamus, frontal and temporal lobe had persistent and significant association with attention and learning/memory aspects. The findings of this study suggest that DTI detects and observes natural-recovery of brain regions affected by sub-threshold force.