Diffuse axonal injury in mild traumatic brain injury: a diffusion tensor imaging study

Object. Diffuse axonal injury (DAI) is a major complication of traumatic brain injury (TBI) that leads to functional and psychological deficits. Although DAI is frequently underdiagnosed by conventional imaging modalities, it can be demonstrated using diffusion tensor imaging. The aim of this study was to assess the presence and extent of DAI in patients with mild TBI. Methods. Forty-six patients with mild TBI and 29 healthy volunteers underwent a magnetic resonance (MR) imaging protocol including: dual—spin echo, fluid-attenuated inversion recovery, T2-weighted gradient echo, and diffusion tensor imaging sequences. In 20 of the patients, MR imaging was performed at a mean of 4.05 days after injury. In the remaining 26, MR imaging was performed at a mean of 5.7 years after injury. In each case, mean diffusivity and fractional anisotropy were measured using both whole-brain histograms and regions of interest analysis. No differences in any of the histogram-derived measures were found between patients and control volunteers. Compared with controls, a significant reduction of fractional anisotropy was observed in patients' corpus callosum, internal capsule, and centrum semiovale, and there were significant increases of mean diffusivity in the corpus callosum and internal capsule. Neither histogram-derived nor regional diffusion tensor imaging metrics differed between the two groups. Conclusions. Although mean diffusivity and fractional anisotropy abnormalities in these patients with TBI were too subtle to be detected with the whole-brain histogram analysis, they are present in brain areas that are frequent sites of DAI. Because diffusion tensor imaging changes are present at both early and late time points following injury, they may represent an early indicator and a prognostic measure of subsequent brain damage.

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The persistent vegetative state after closed head injury: clinical and magnetic resonance imaging findings in 42 patients

Journal of Neurosurgery ◽

10.3171/jns.1998.88.5.0809 ◽

1998 ◽

Vol 88 (5) ◽

pp. 809-816 ◽

Cited By ~ 84

Author(s):

Andreas Kampfl ◽

Gerhard Franz ◽

Franz Aichner ◽

Bettina Pfausler ◽

Hans-Peter Haring ◽

...

Keyword(s):

Magnetic Resonance ◽

Mr Imaging ◽

Vegetative State ◽

Axonal Injury ◽

Persistent Vegetative State ◽

Diffuse Axonal Injury ◽

Resonance Imaging ◽

Content Type ◽

Temporal Lobes ◽

Fine Print

Object. In this retrospective study, the authors analyzed the frequency, anatomical distribution, and appearance of traumatic brain lesions in 42 patients in a posttraumatic persistent vegetative state. Methods. Cerebral magnetic resonance (MR) imaging was used to detect the number of lesions, which ranged from as few as five to as many as 19, with a mean of 11 lesions. In all 42 cases there was evidence on MR imaging of diffuse axonal injury, and injury to the corpus callosum was detected in all patients. The second most common area of diffuse axonal injury involved the dorsolateral aspect of the rostral brainstem (74% of patients). In addition, 65% of these patients exhibited white matter injury in the corona radiata and the frontal and temporal lobes. Lesions to the basal ganglia or thalamus were seen in 52% and 40% of patients, respectively. Magnetic resonance imaging showed some evidence of cortical contusion in 48% of patients in this study; the frontal and temporal lobes were most frequently involved. Injury to the parahippocampal gyrus was detected in 45% of patients; in this subgroup there was an 80% incidence of contralateral peduncular lesions in the midbrain. The most common pattern of injury (74% in this series) was the combination of focal lesions of the corpus callosum and the dorsolateral brainstem. In patients with no evidence of diffuse axonal injury in the upper brainstem (26% in this series), callosal lesions were most often associated with basal ganglia lesions. Lesions of the corona radiata and lobar white matter were equally distributed in patients with or without dorsolateral brainstem injury. Moreover, cortical contusions and thalamic, parahippocampal, and cerebral peduncular lesions were also similarly distributed in both groups. Conclusions. The data indicate that diffuse axonal injury may be the major form of primary brain damage in the posttraumatic persistent vegetative state. In addition, the authors demonstrated in this study that MR imaging, in conjunction with a precise clinical correlation, may provide useful supportive information for the accurate diagnosis of a persistent vegetative state after traumatic brain injury.

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MR imaging and differentiation of cerebral fat embolism syndrome from diffuse axonal injury: application of diffusion tensor imaging

Neuroradiology ◽

10.1007/s00234-013-1166-5 ◽

2013 ◽

Vol 55 (6) ◽

pp. 771-778 ◽

Cited By ~ 10

Author(s):

Uttam K. Bodanapally ◽

Kathirkamanathan Shanmuganathan ◽

Nitima Saksobhavivat ◽

Clint W. Sliker ◽

Lisa A. Miller ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Mr Imaging ◽

Diffusion Tensor ◽

Axonal Injury ◽

Diffuse Axonal Injury ◽

Fat Embolism ◽

Fat Embolism Syndrome ◽

Embolism Syndrome ◽

Cerebral Fat Embolism Syndrome

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Diffusion Tensor Imaging of the Kidneys: Influence of b-Value and Number of Encoding Directions on Image Quality and Diffusion Tensor Parameters

Journal of Clinical Imaging Science ◽

10.4103/2156-7514.122323 ◽

2013 ◽

Vol 3 ◽

pp. 53 ◽

Cited By ~ 14

Author(s):

Natalie C. Chuck ◽

Günther Steidle ◽

Iris Blume ◽

Michael A. Fischer ◽

Daniel Nanz ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Image Quality ◽

Fractional Anisotropy ◽

Diffusion Tensor ◽

Mean Diffusivity ◽

Renal Medulla ◽

Whole Body ◽

Acquisition Time ◽

Data Sets ◽

B Values

Objectives: The purpose of this study was to evaluate to which degree investment of acquisition time in more encoding directions leads to better image quality (IQ) and what influence the number of encoding directions and the choice of b-values have on renal diffusion tensor imaging (DTI) parameters. Material and Methods: Eight healthy volunteers (32.3 y ± 5.1 y) consented to an examination in a 1.5T whole-body MR scanner. Coronal DTI data sets of the kidneys were acquired with systematic variation of b-values (50, 150, 300, 500, and 700 s/mm2) and number of diffusion-encoding directions (6, 15, and 32) using a respiratory-triggered echo-planar sequence (TR/TE 1500 ms/67 ms, matrix size 128 × 128). Additionally, two data sets with more than two b-values were acquired (0, 150, and 300 s/mm2 and all six b-values). Parametrical maps were calculated on a pixel-by-pixel basis. Image quality was determined with a reader score. Results: Best IQ was visually assessed for images acquired with 15 and 32 encoding directions, whereas images acquired with six directions had significantly lower IQ ratings. Image quality, fractional anisotropy, and mean diffusivity only varied insignificantly for b-values between 300 and 500 s/mm2. In the renal medulla fractional anisotropy (FA) values between 0.43 and 0.46 and mean diffusivity (MD) values between 1.8-2.1 × 10-3 mm2/s were observed. In the renal cortex, the corresponding ranges were 0.24-0.25 (FA) and 2.2-2.8 × 10-3 mm2/s (MD). Including b-values below 300 s/mm2, notably higher MD values were observed, while FA remained constant. Susceptibility artifacts were more prominent in FA maps than in MD maps. Conclusion: In DTI of the kidneys at 1.5T, the best compromise between acquisition time and resulting image quality seems the application of 15 encoding directions with b-values between 300 and 500 s/mm2. Including lower b-values allows for assessment of fast diffusing spin components.

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Detecting diffuse axonal injury in rat brainstems by diffusion tensor imaging and AQP4 expression

Bio-Medical Materials and Engineering ◽

10.3233/bme-151413 ◽

2015 ◽

Vol 26 (s1) ◽

pp. S1169-S1175

Author(s):

Wenbin Zheng ◽

Chunlin Ma ◽

Lingmei Kong ◽

Xiran Chen ◽

Wenyao Fan

Keyword(s):

Diffusion Tensor Imaging ◽

Diffusion Tensor ◽

Axonal Injury ◽

Diffuse Axonal Injury ◽

Aqp4 Expression

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Diffusion Tensor Imaging Evaluation of Corticospinal Tract Hyperintensity in Upper Motor Neuron-Predominant ALS Patients

Journal of Aging Research ◽

10.4061/2011/481745 ◽

2011 ◽

Vol 2011 ◽

pp. 1-9 ◽

Cited By ~ 8

Author(s):

Venkateswaran Rajagopalan ◽

Didier Allexandre ◽

Guang H. Yue ◽

Erik P. Pioro

Keyword(s):

Diffusion Tensor Imaging ◽

Motor Neuron ◽

Corticospinal Tract ◽

Diffusion Tensor ◽

Mean Diffusivity ◽

Internal Capsule ◽

Proton Density ◽

Imaging Evaluation ◽

Axonal Pathology ◽

Als Patients

Amyotrophic lateral sclerosis (ALS) patients with predominant upper motor neuron (UMN) signs occasionally have hyperintensity of corticospinal tract (CST) on T2- and proton-density-(PD-) weighted brain images. Diffusion tensor imaging (DTI) was used to assess whether diffusion parameters along intracranial CST differ in presence or absence of hyperintensity and correspond to UMN dysfunction. DTI brain scans were acquired in 47 UMN-predominant ALS patients with (n=21) or without (n=26) CST hyperintensity and in 10 control subjects. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were measured in four regions of interests (ROIs) along CST. Abnormalities (P<0.05) were observed in FA, AD, or RD in CST primarily at internal capsule (IC) level in ALS patients, especially those with CST hyperintensity. Clinical measures corresponded well with DTI changes at IC level. The IC abnormalities suggest a prominent axonopathy in UMN-predominant ALS and that tissue changes underlying CST hyperintensity have specific DTI changes, suggestive of unique axonal pathology.

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Diffusion Tensor Imaging of the Evolving Response to Mild Traumatic Brain Injury in Rats

Journal of Experimental Neuroscience ◽

10.1177/1179069519858627 ◽

2019 ◽

Vol 13 ◽

pp. 117906951985862 ◽

Cited By ~ 5

Author(s):

Wouter S Hoogenboom ◽

Todd G Rubin ◽

Kenny Ye ◽

Min-Hui Cui ◽

Kelsey C Branch ◽

...

Keyword(s):

Traumatic Brain Injury ◽

Diffusion Tensor Imaging ◽

Brain Injury ◽

White Matter ◽

Mild Traumatic Brain Injury ◽

Diffusion Tensor ◽

Axonal Injury ◽

Mean Diffusivity ◽

Multiple Time ◽

Post Injury

Mild traumatic brain injury (mTBI), also known as concussion, is a serious public health challenge. Although most patients recover, a substantial minority suffers chronic disability. The mechanisms underlying mTBI-related detrimental effects remain poorly understood. Although animal models contribute valuable preclinical information and improve our understanding of the underlying mechanisms following mTBI, only few studies have used diffusion tensor imaging (DTI) to study the evolution of axonal injury following mTBI in rodents. It is known that DTI shows changes after human concussion and the role of delineating imaging findings in animals is therefore to facilitate understanding of related mechanisms. In this work, we used a rodent model of mTBI to investigate longitudinal indices of axonal injury. We present the results of 45 animals that received magnetic resonance imaging (MRI) at multiple time points over a 2-week period following concussive or sham injury yielding 109 serial observations. Overall, the evolution of DTI metrics following concussive or sham injury differed by group. Diffusion tensor imaging changes within the white matter were most noticeable 1 week following injury and returned to baseline values after 2 weeks. More specifically, we observed increased fractional anisotropy in combination with decreased radial diffusivity and mean diffusivity, in the absence of changes in axial diffusivity, within the white matter of the genu corpus callosum at 1 week post-injury. Our study shows that DTI can detect microstructural white matter changes in the absence of gross abnormalities as indicated by visual screening of anatomical MRI and hematoxylin and eosin (H&E)-stained sections in a clinically relevant animal model of mTBI. Whereas additional histopathologic characterization is required to better understand the neurobiological correlates of DTI measures, our findings highlight the evolving nature of the brain’s response to injury following concussion.

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