Susceptibility-weighted imaging in traumatic brain injury

Introduction Traumatic brain injury (TBI) is a major public health burden worldwide. It has been described as "a silent epidemic"[1] and as many as 1.5 million people sustain TBI in the USA each year,[2,3] largely attributable to motor vehicle-related accidents, assaults, and falls. Although mortality has decreased over the years through improvements in automotive safety design and acute care of trauma, 80 000 people annually incur long-term disability following TBI, while more than 5.3 million Americans live with long-term disability as a result of TBI. In 1995, total direct and indirect costs of TBI in the USA were estimated by the US Centers for Disease Control and Prevention at $56 billion/year.[4] Improved detection of TBI and prediction of clinical outcome would improve both acute and long-term patient management. Clinical measures, such as the Glasgow Coma Scale (GCS),[5] are inconsistent predictors of neurological and functional outcome. Although neuroimaging has traditionally been used to triage patients in the emergency room, standard clinical imaging continues to underdiagnose injury. Computed tomography (CT) can detect large hemorrhages or other lesions that require surgical intervention but is insensitive to other primary and secondary injuries, some of which can be detected with conventional MRI.