Neuroimaging clinics of North America
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Remarkable advances have been made in the last decade in the use of diffusion MR imaging to study mild traumatic brain injury (mTBI). Diffusion imaging shows differences between mTBI patients and healthy control groups in multiple different metrics using a variety of techniques, supporting the notion that there are microstructural injuries in mTBI patients that radiologists have been insensitive to. Future areas of discovery in diffusion MR imaging and mTBI include larger longitudinal studies to better understand the evolution of the injury and unravel the biophysical meaning that the detected changes in diffusion MR imaging represent.
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Traumatic brain injury (TBI) is a significant problem worldwide and neuroimaging plays a critical role in diagnosis and management. Recently, perfusion neuroimaging techniques have been explored in TBI to determine and characterize potential perfusion neuroimaging biomarkers to aid in diagnosis, treatment, and prognosis. In this article, computed tomography (CT) bolus perfusion, MR imaging bolus perfusion, MR imaging arterial spin labeling perfusion, and xenon CT are reviewed with a focus on their applications in acute TBI. Future research directions are also discussed.
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Conventional imaging findings in patients with cerebral concussion and chronic traumatic encephalopathy are absent or subtle in the majority of cases. The most common abnormalities include cerebral volume loss, enlargement of the cavum of the septum pellucidum, cerebral microhemorrhages, and white matter signal abnormalities, all of which have poor sensitivity and specificity. Advanced imaging modalities, such as diffusion tensor imaging (DTI), blood oxygen level dependent functional MR Imaging (BOLD fMRI), MR spectroscopy, perfusion imaging, positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetoencephalography detect physiologic abnormalities in symptomatic patients and, although currently in the investigation phase, may become useful in the clinical arena.
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Myelin water imaging (MWI) provides mild traumatic brain injury (mTBI) researchers with a specific myelin biomarker and helps to further elucidate microstructural and microarchitectural changes of white matter after mTBI. Improvement of scanner hardware and software with the implementation of MWI across scanner platforms will likely result in increased research regarding the role of myelin in traumatic brain injury (TBI). Future research should include detailed investigation of myelin between 2 weeks and 2 months after injury, the use of MWI in moderate and severe TBI, and investigation of the role of myelin in chronic TBI.
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Conventional neuroimaging examinations are typically normal in concussed young athletes. A current focus of research is the characterization of subtle abnormalities after concussion using advanced neuroimaging techniques. ⋯ In the future, such biomarkers will likely provide important clinical information regarding the appropriate time interval before return to play, as well as the risk for prolonged postconcussive symptoms and long-term cognitive impairment. This article discusses results from advanced imaging techniques and emphasizes imaging modalities that will likely become available in the near future for the clinical evaluation of concussed young athletes.