Radiological–pathological correlation of diffusion tensor and magnetization transfer imaging in a closed head traumatic brain injury model

This study investigated the radiological–pathological correlation between these imaging techniques and immunohistochemistry using a closed head rat model of TBI. MethodsTBI was performed on female rats followed longitudinally by magnetic resonance imaging (MRI) out to 30 days postinjury, with a subset of animals selected for histopathological analyses. A MRI‐based finite element analysis was generated to characterize the pattern of the mechanical insult and estimate the extent of brain injury to direct the pathological correlation with imaging findings. ResultsDTI axial diffusivity and fractional anisotropy (FA) were sensitive to axonal integrity, whereas radial diffusivity showed significant correlation to the myelin compactness. FA was correlated with astrogliosis in the gray matter, whereas mean diffusivity was correlated with increased cellularity. Secondary inflammatory responses also partly affected the changes of these DTI metrics. The magnetization transfer ratio (MTR) at 3.5ppm demonstrated a strong correlation with both axon and myelin integrity. Decrease in MTR at 20ppm correlated with the extent of astrogliosis in both gray and white matter. InterpretationAlthough conventional T2‐weighted MRI did not detect abnormalities following TBI, DTI and MTI afforded complementary insight into the underlying pathologies reflecting varying injury states over time, and thus may substitute for histology to reveal diffusive axonal injury pathologies in vivo. This correlati...
Source: Annals of Neurology - Category: Neurology Authors: Tags: Research Article Source Type: research