Advanced neuroimaging in children with nonaccidental trauma

Physical abuse associated with nonaccidental trauma (NAT) affects approximately 144,000 children per year in the USA and, frequently, these injuries affect the developing brain. Most infants with suspected NAT are initially evaluated by skull X-rays and computed tomography to determine whether fractures are present, the severity of the acute injury and the need for urgent neurosurgical intervention. Increasingly, magnetic resonance imaging (MRI) is conducted as it provides additional diagnostic and prognostic information about the extent and nature of the injury. In this review, we examine 4 MRI techniques as they apply to children who present acutely after NAT. Susceptibility-weighted imaging is a 3-D high-resolution MRI technique that is more sensitive than conventional imaging in detecting hemorrhagic lesions that are often associated with diffuse axonal injury (DAI). Magnetic resonance spectroscopy acquires metabolite information reflecting neuronal integrity and function from multiple brain regions and provides a sensitive, noninvasive assessment of neurochemical alterations that offers early prognostic information regarding outcome. Diffusion-weighted imaging (DWI) is based on differences in the diffusion of water molecules within the brain and has been shown to be very sensitive in the early detection of ischemic injury. It is now being used to study the direct effects of traumatic injury as well as those due to secondary ischemia. Diffusion tensor imaging is a form of DWI and allows better evaluation of white matter fiber tracts by taking advantage of the intrinsic directionality (anisotropy) of water diffusion in the human brain. It has been shown to be useful in identifying white matter abnormalities after DAI when conventional imaging appears normal. Although these imaging methods have been studied primarily in adults and children with accidental traumatic brain injury, it is clear that they have the potential to provide additional value in the imaging and clinical evaluation of children with NAT.