MR Imaging Applications in Mild Traumatic Brain Injury: An Imaging Update

Abstract

Mild traumatic brain injury (mTBI), also commonly referred to as concussion, affects millions of Americans annually. Although computed tomography is the first-line imaging technique for all traumatic brain injury, it is incapable of providing long-term prognostic information in mTBI. In the past decade, the amount of research related to magnetic resonance (MR) imaging of mTBI has grown exponentially, partly due to development of novel analytical methods, which are applied to a variety of MR techniques. Here, evidence of subtle brain changes in mTBI as revealed by these techniques, which are not demonstrable by conventional imaging, will be reviewed. These changes can be considered in three main categories of brain structure, function, and metabolism. Macrostructural and microstructural changes have been revealed with threedimensional MR imaging, susceptibility-weighted imaging, diffusion-weighted imaging, and higher order diffusion imaging. Functional abnormalities have been described with both task-mediated and resting-state blood oxygen leveldependent functional MR imaging. Metabolic changes suggesting neuronal injury have been demonstrated with MR spectroscopy. These findings improve understanding of the true impact of mTBI and its pathogenesis. Further investigation may eventually lead to improved diagnosis, prognosis, and management of this common and costly condition.q RSNA, 2016

Small world properties changes in mild traumatic brain injury

“…The PCSSs were assessed by using self-report questionnaires and were reported in Z-scores, for which higher scores indicated greater symptom. 26…”

Utilization of MRI for Cerebral White Matter Injury in a Hypobaric Swine Model—Validation of Technique

“…Susceptibility-weighted perfusion MRI may be difficult to obtain in the acute TBI setting secondary to patient contraindications and is limited by signal loss in the presence of blood products, but may be valuable in subacute or chronic TBI particularly when combined with other conventional and advanced MRI techniques including DTI. 40–42 Patients with mild TBI and normal conventional imaging have demonstrated perfusion deficits that correlate with neurocognitive impairment. 43,44 TBI causes axonal and capillary disruption 45 that can be observed as WMH on FLAIR MRI.…”

Abnormal structural and functional hypothalamic connectivity in mild traumatic brain injury

“…However, its underlying pathophysiological mechanisms of complex posttraumatic symptoms are poorly understood, leading to a paucity of successful treatment strategies . There is usually no evidence of brain structural abnormality on conventional neuroimaging, such as computed tomography (CT) and magnetic resonance imaging (MRI) scans, despite the fact that there are quite a few recently developed advanced neuroimaging techniques including functional (f)MRI for detecting brain abnormalities in MTBI such as thalamic injury and white matter atrophy . The commonly reported sequelae following TBI of any severity include fatigue, problems with sleep, problems with appetite and arousal, and lack of motivation, which are all closely related to hypothalamic dysfunction and neuropeptide dysregulation .…”

“…Resting‐state functional MRI (RS‐fMRI) has recently drawn more attention in detecting robust various neuronal functional connectivity patterns . Using RS‐fMRI, studies have consistently demonstrated phase‐locked low‐frequency oscillations (<0.1 Hz) of blood oxygenation level‐dependent (BOLD) signal across functionally connected brain regions (resting state networks, RSNs) in the resting brain . There are several well‐established intrinsic brain networks at resting stage including the default mode network (DMN), the anti‐DMN dorsal attention network, and sensorimotor and visual networks .…”

“…There are several well‐established intrinsic brain networks at resting stage including the default mode network (DMN), the anti‐DMN dorsal attention network, and sensorimotor and visual networks . There is also increasing evidence of functional connectivity between deep gray matter and cortex including basal ganglia and thalamus . In TBI, diffuse axonal injury resulting in disruption of functional networks in the brain is thought to be a major contributor to cognitive dysfunction in survivors of traumatic brain injury .…”