Imaging assessment of traumatic brain injury

Abstract

Traumatic brain injury (TBI) constitutes injury that occurs to the brain as a result of trauma. It should be appreciated as a heterogeneous, dynamic pathophysiological process that starts from the moment of impact and continues over time with sequelae potentially seen many years after the initial event. Primary traumatic brain lesions that may occur at the moment of impact include contusions, haematomas, parenchymal fractures and diffuse axonal injury. The presence of extra-axial intracranial lesions such as epidural and subdural haematomas and subarachnoid haemorrhage must be anticipated as they may contribute greatly to secondary brain insult by provoking brain herniation syndromes, cranial nerve deficits, oedema and ischaemia and infarction. Imaging is fundamental to the management of patients with TBI. CT remains the imaging modality of choice for initial assessment due to its ease of access, rapid acquisition and for its sensitivity for detection of acute haemorrhagic lesions for surgical intervention. MRI is typically reserved for the detection of lesions that may explain clinical symptoms that remain unresolved despite initial CT. This is especially apparent in the setting of diffuse axonal injury, which is poorly discerned on CT. Use of particular MRI sequences may increase the sensitivity of detecting such lesions: diffusion-weighted imaging defining acute infarction, susceptibility-weighted imaging affording exquisite data on microhaemorrhage. Additional advanced MRI techniques such as diffusion tensor imaging and functional MRI may provide important information regarding coexistent structural and functional brain damage. Gaining robust prognostic information for patients following TBI remains a challenge. Advanced MRI sequences are showing potential for biomarkers of disease, but this largely remains at the research level. Various global collaborative research groups have been established in an effort to combine imaging data with clinical and epidemiological information to provide much needed evidence for improvement in the characterisation and classification of TBI and in the identity of the most effective clinical care for this patient cohort. However, analysis of collaborative imaging data is challenging: the diverse spectrum of image acquisition and postprocessing limits reproducibility, and there is a requirement for a robust quality assurance initiative. Future clinical use of advanced neuroimaging should ensure standardised approaches to image acquisition and analysis, which can be used at the individual level, with the expectation that future neuroimaging advances, personalised to the patient, may improve prognostic accuracy and facilitate the development of new therapies.

Sleep, Sleep Disorders, and Mild Traumatic Brain Injury. What We Know and What We Need to Know: Findings from a National Working Group

“…Both approaches have further refined our understanding of the localized and neural underpinnings of healthy and disrupted sleep, as well as of circadian variations in brain functions [68][69][70]. The use of neuroimaging methods such as positron emission tomography and structural and functional magnetic resonance imaging during sleep and wakefulness in concussed, recovered, and never concussed individuals remain scarce, but has a high potential to provide unique and novel insights into the underpinnings of sleep and circadian disturbances in mTBI, and therefore may guide the development of innovative and targeted diagnostic and therapeutic strategies [70][71][72][73][74][75].…”

Mapping the functional connectome in traumatic brain injury: What can graph metrics tell us?

“…Previous studies have shown that TBI is associated with changes in brain structure and function (for recent reviews, see (Currie et al, 2016;Hannawi and Stevens, 2016;Hayes et al, 2016;Rincon et al, 2016). The most prominent anatomical alterations are changes in prefrontal cortex morphology (Cristofori and Levin, 2015;Killgore et al, 2016), volume loss (Farbota et al, 2012;Hulkower et al, 2013;Ross, 2011) and reduced whitematter integrity (for a review, see (Hulkower et al, 2013)) and cerebellar atrophy (Drijkoningen et al, 2015;Sidaros et al, 2009).…”

Functional magnetic resonance imaging in dermatology: The skin, the brain and the invisible

“…The purpose of fMRI is already being evaluated in other specialties. [55,[144][145][146][147][148][149] Ultra-high field MR scanners, the use of other MRI methods such as ASL, diffusion tensor imaging, magnetic resonance spectroscopy or the combination with EEG/MEG or functional near infrared spectroscopy should optimise attainment of such goals.…”