Diffuse Axonal Injury in Severe Traumatic Brain Injury Visualized Using High-Resolution Diffusion Tensor Imaging

Abstract

Traumatic brain injury (TBI) is the most common cause of death and disability in young people. The functional outcome in patients with TBI cannot be explained by focal pathology alone, and diffuse axonal injury (DAI) is considered a major contributor to the neurocognitive deficits experienced by this group. The aim of the present study was to investigate whether diffusion tensor imaging (DTI) offers additional information as to the extent of damage not visualized with standard magnetic resonance imaging (MRI) in patients with severe TBI. Nine chronic male TBI patients and 11 matched healthy controls were recruited. Results of the voxel-based analysis of fractional anisotropy (FA) maps and apparent diffusion coefficient (ADC) maps revealed significant differences in anisotropy in major white matter tracts, including the corpus callosum (CC), internal and external capsule, superior and inferior longitudinal fascicles, and the fornix in the TBI group. The FA and ADC measurements offered superior sensitivity compared to conventional MRI diagnosis of DAI. Region-of-interest (ROI) analyses confirmed these results in the investigated regions. The findings of this study support the hypothesis that severe TBI is accompanied by DAI. The DTI changes were more prominent on the right side that contained the focal pathology in most of the patients and accurately reflected differences in both hemispheres. In conclusion, DTI holds great promise as a diagnostic tool to identify and quantify the degree of white matter injury in TBI patients.

Diffusion MRI abnormalities in adolescent rats given repeated mild traumatic brain injury

“…DWI measures the motion of water molecules within the brain. As this diffusion is restricted by biological barriers and other molecules, abnormalities in DWI may reflect microscopic alterations to tissue organization due to factors such as white matter injury,35, 36 edema,37 and gliosis 38. Indeed, preliminary preclinical studies suggest that DWI may be a useful biomarker of mTBI23 and repeated mTBI 39, 40.…”

Diffusion Measures Indicate Fight Exposure-Related Damage to Cerebral White Matter in Boxers and Mixed Martial Arts Fighters

“…The corpus callosum is an area known to be involved in TBI. 7,16,17,[25][26][27][28][29][30] Several studies have demonstrated increased MD and/or decreased FA in various white matter regions among patients with mild TBI versus matched control subjects. 7,17,31 Inglese et al 17 found a significant reduction in FA in the corpus callosum, internal capsule, and centrum semiovale and a significant increase in MD in the corpus callosum and internal capsule in 46 patients with mild TBI.…”

“…Because DTI is sensitive to microstructural changes in white matter, this technique is often used to investigate white matter integrity in patients with TBI. [11][12][13][14][15][16][17] Previous studies have found that fractional anisotropy (FA) values in the corpus callosum, 14,16,17 internal capsule, 11,14,16,17 cingulum, 14 and centrum semiovale 11,14,16,17 are decreased in patients with TBI versus healthy control subjects. A longitudinal TBI study found that FA was decreased in the white matter of study participants because of decreased longitudinal diffusivity (LD) and increased transversal diffusivity (TD).…”

The role of biomarkers and MEG-based imaging markers in the diagnosis of post-traumatic stress disorder and blast-induced mild traumatic brain injury

“…In a rodent TBI model, axonal injury was the most prominent feature following blast exposure (Garman et al, 2011). In humans, the subsequent tissue injury is characterized by axonal stretching, inflammation, disruption, and separation of nerve fibers, although axotomy is relatively rare in even severe TBI (Adams et al, 1989;Basser and Pierpaoli, 1996;Gennarelli et al, 1982;Xu et al, 2007). Conventional CT and MRI are primarily sensitive to blood from nearby torn capillaries, rather than axonal damage itself, hence they underestimate the presence of DAI, especially in mTBI.…”