Voxel-based analysis of diffusion tensor imaging in mild traumatic brain injury in adolescents.
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ABSTRACT: Background and purpose
DTI of normal-appearing WM as evaluated by conventional MR imaging in mTBI has the potential to identify important regional abnormalities that relate to PCS. VBA was used to examine WM changes in acute mTBI.Materials and methods
WM was assessed between 1 and 6 days postinjury with voxel-based DTI analyses in 10 adolescent patients with mTBI and 10 age-matched control participants. In addition to the voxel-based group, analysis used to identify brain pathology across all patients with mTBI, 2 voxel-based linear regressions were performed. These analyses investigated the relation between 1) the ADC and PCS severity scores, and 2) ADC and scores on the BSI of emotional symptoms associated with mTBI. We hypothesized that frontotemporal WM changes would relate to symptoms associated with PCS and endorsed on the BSI.Results
Patients with mTBI demonstrated significant reductions in ADC in several WM regions and in the left thalamus. As expected, no increases in ADC were found in any region of interest. All injury-affected regions showed decreased radial diffusivity, unchanged AD, and increased FA, which is consistent with axonal cytotoxic edema, reflective of acute injury.Conclusions
Whole-brain WM DTI measures can detect abnormalities in acute mTBI associated with PCS symptoms in adolescents.
SUBMITTER: Chu Z
PROVIDER: S-EPMC7964133 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:ObjectivesOnly a handful of studies have investigated the nature, functional significance, and course of white matter abnormalities associated with mild traumatic brain injury (mTBI) during the semi-acute stage of injury. The present study used diffusion tensor imaging (DTI) to investigate white matter integrity and compared the accuracy of traditional anatomic scans, neuropsychological testing, and DTI for objectively classifying mTBI patients from controls.MethodsTwenty-two patients with semi-acute mTBI (mean = 12 days postinjury), 21 matched healthy controls, and a larger sample (n = 32) of healthy controls were studied with an extensive imaging and clinical battery. A subset of participants was examined longitudinally 3-5 months after their initial visit.ResultsmTBI patients did not differ from controls on clinical imaging scans or neuropsychological performance, although effect sizes were consistent with literature values. In contrast, mTBI patients demonstrated significantly greater fractional anisotropy as a result of reduced radial diffusivity in the corpus callosum and several left hemisphere tracts. DTI measures were more accurate than traditional clinical measures in classifying patients from controls. Longitudinal data provided preliminary evidence of partial normalization of DTI values in several white matter tracts.ConclusionsCurrent findings of white matter abnormalities suggest that cytotoxic edema may be present during the semi-acute phase of mild traumatic brain injury (mTBI). Initial mechanical damage to axons disrupts ionic homeostasis and the ratio of intracellular and extracellular water, primarily affecting diffusion perpendicular to axons. Diffusion tensor imaging measurement may have utility for objectively classifying mTBI, and may serve as a potential biomarker of recovery.
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Project description:ObjectivesTo assess the possibility that diffusion tensor imaging (DTI) can detect white matter damage in mild traumatic brain injury (mTBI) patients via systematic review and meta-analysis.MethodsDTI studies that compared mTBI patients and controls were searched using MEDLINE, Web of Science, and EMBASE, (1980 through April 2012).ResultsA comprehensive literature search identified 28 DTI studies, of which 13 independent DTI studies of mTBI patients were eligible for the meta-analysis. Random effect model demonstrated significant fractional anisotropy (FA) reduction in the corpus callosum (CC) (p=0.023, 95% CIs -0.466 to -0.035, 280 mTBIs and 244 controls) with no publication bias and minimum heterogeneity, and a significant increase in mean diffusivity (MD) (p=0.015, 95% CIs 0.062 to 0.581, 154 mTBIs and 100 controls). Meta-analyses of the subregions of the CC demonstrated in the splenium FA was significantly reduced (p=0.025, 95% CIs -0.689 to -0.046) and MD was significantly increased (p=0.013, 95% CIs 0.113 to 0.950). FA was marginally reduced in the midbody (p=0.099, 95% CIs -0.404 to 0.034), and no significant change in FA (p=0.421, 95% CIs -0.537 to 0.224) and MD (p=0.264, 95% CIs -0.120 to 0.438) in the genu of the CC.ConclusionsOur meta-analysis revealed the posterior part of the CC was more vulnerable to mTBI compared with the anterior part, and suggested the potential utility of DTI to detect white matter damage in the CC of mTBI patients.
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Project description:In this prospective cohort study, we investigated associations between acute diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) metrics and persistent post-concussion symptoms (PPCS) 3 months after mild traumatic brain injury (mTBI). Adult patients with mTBI (n = 176) and community controls (n = 78) underwent 3 Tesla magnetic resonance imaging (MRI) within 72 h post-injury, estimation of cognitive reserve at 2 weeks, and PPCS assessment at 3 months. Eight DTI and DKI metrics were examined with Tract-Based Spatial Statistics. Analyses were performed in the total sample in uncomplicated mTBI only (i.e., without lesions on clinical MRI), and with cognitive reserve both controlled for and not. Patients with PPCS (n = 35) had lower fractional anisotropy (in 2.7% of all voxels) and kurtosis fractional anisotropy (in 6.9% of all voxels), and higher radial diffusivity (in 0.3% of all voxels), than patients without PPCS (n = 141). In uncomplicated mTBI, only fractional anisotropy was significantly lower in patients with PPCS. Compared with controls, patients with PPCS had widespread deviations in all diffusion metrics. When including cognitive reserve as a covariate, no significant differences in diffusion metrics between patients with and without PPCS were present, but patients with PPCS still had significantly higher mean, radial, and axial diffusivity than controls. In conclusion, patients who developed PPCS had poorer white matter microstructural integrity acutely after the injury, compared with patients who recovered and healthy controls. Differences became less pronounced when cognitive reserve was controlled for, suggesting that pre-existing individual differences in axonal integrity accounted for some of the observed differences.
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Project description:Diffusion tensor imaging (DTI) parameters can detect changes in the brain microstructure in mild traumatic brain injury (mTBI). Whether these parameter changes can predict neural functional recovery after mTBI is still relatively unknown. The present study aimed to investigate the radiological-prognostic correlation between these radiological parameters and learning and memory deficits using an in-house constructed rat model of mTBI. We established a rat model of diffuse axonal injury (DAI) at different injury levels, followed by magnetic resonance imaging at 6, 24, and 72 h, and 1, 2 weeks post injury, and randomly selected the rats for analysis of histopathology and learning and memory deficits. DTI parameters and β-amyloid precursor protein (β-APP) levels were obtained to estimate the extent of brain injury and the correlation with the times of crossing the safety platform as measured using a water maze test. The results revealed that fractional anisotropy (FA) was sensitive to axonal integrity. FA values of the corpus callosum in the injury groups decreased at all time points post injury, except in the mild injury group, which recovered to normal levels at 1 and 2 weeks post-injury. The neural function of the mild injury group recovered to normal compared with the normal control group. FA value, β-APP of corpus callosum in different groups at 24 h post injury showed obvious correlation with learning and memory deficits at the recovery stage (r=0.881, r=-0.931). In conclusion, DTI can reflect varying injury states of DAI over time with direct comparison to histopathology and could be used to predict the neural functional recovery at the early stage post-injury in a rat model.
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Project description:BackgroundA subgroup of patients with mild traumatic brain injury (TBI) experiences residual symptoms interfering with their return to work. The pathophysiological substrate of the suboptimal outcome in these patients is a source of debate.ObjectiveTo provide greater insight into the pathophysiological mechanisms of mild TBI.MethodsDiffusion tensor imaging (DTI) was performed during follow-up of 18 patients with mild TBI and compared with healthy control subjects. DTI data of the patient group were also compared with perfusion CT imaging in the acute phase of injury.ResultsIn patients with mild TBI, a trend was observed for a decreased fractional anisotropy (FA) in widespread bilateral frontal white matter areas with increased mean diffusivity (MD) in the parieto-temporal regions, compared to healthy control subjects. Cerebral blood volume (CBV) correlated significantly with FA in several white matter tracts including the corpus callosum, the internal capsule, the inferior fronto-occipital fascicle, the corticospinal tract, the superior and the inferior longitudinal fascicle.ConclusionIn mild TBI with normal conventional imaging significant associations between cerebral perfusion in the acute phase of injury and DTI analyses in the chronic phase of injury were discerned. The pathophysiological concept of these findings is being outlined.
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Project description:Diffusion tensor imaging is a magnetic resonance imaging technique that is uniquely capable of detecting microstructural tissue damage in mild and moderate traumatic brain injuries (TBIs). To date, it remains unknown if two common analytic techniques, region of interest (ROI) versus voxel-wise (VW) analyses, detect injury in similar locations. The purpose of this systematic review and meta-analysis was to directly compare the regions of abnormality elucidated by each method. Twenty-seven ROI and 11 VW studies met our inclusion criteria. Our ROI meta-analysis identified 11 regions, including the splenium of the corpus callosum, where fractional anisotropy (FA) was significantly decreased in TBI patients, compared with controls. Likewise, we identified higher mean diffusivity/apparent diffusivity constant in the genu, body, and splenium of the corpus callosum. Alternatively, our VW analysis identified one region of high FA in the right superior longitudinal fasciculus and seven regions of low FA, with the two largest located in the corpus callosum. High mean diffusivity and high radial diffusivity, both in the right inferior longitudinal fasciculus, also was revealed by our VW analysis. Moreover, we have shown that the magnitude of damage in the corpus callosum revealed by ROI analysis (z = -3.15) is greater than that demonstrated by VW analysis (z = -1.41). Overall, this study indicates that both ROI and VW analytic methods are sensitive to low FA in the corpus callosum; however, the ROI method has more power to detect the full extent of tissue abnormality in the corpus callosum. More research utilizing standardized methods and reporting is essential to fully characterize the extent to which ROI and VW analyses can concordantly detect other locations of pathology in mild and moderate TBI patients.
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