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

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.