Advanced Neuroimaging in Children with Nonaccidental Trauma

Abstract

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.

Traumatic pediatric white matter injury

“…Large areas of dramatic diffusion restriction can be observed, supporting the belief that ischemia is a major component of brain injury in NAT, probably more so than DAI (Fig. 12) [31]. MRS has shown a strong correlation between Lac and outcome, primarily in infants who suffered NAT rather than after accidental trauma [31].…”

“…The primary and secondary phases of WM injury are best evaluated by advanced magnetic resonance imaging (MRI) techniques. Computed tomography (CT) scanning or conventional MRI may not adequately depict the presence or extent of brain injury [31,32]. Advances in neuroimaging over the past two decades have greatly helped in the clinical care and management of children with traumatic brain injury.…”

“…DWI is now being used to reveal the direct effects of a primary traumatic injury as well as those due to delayed secondary injury [31]. Diffusion imaging techniques include the creation of trace diffusion tensor maps, apparent diffusion coefficient (ADC) maps, fractional anisotropy (FA) maps, and diffusion tensor imaging (DTI) fiber tracking.…”

Magnetic resonance susceptibility weighted imaging in neurosurgery: current applications and future perspectives

“…SWI is an effective imaging method that can detect microhemorrhage in the white matter of patients with traumatic brain injury (TBI) 4,42 and can help dichotomize patients with diffuse axonal injury (DAI) as hemorrhagic or nonhemorrhagic. 101 The ability to distinguish hemorrhagic from nonhemorrhagic DAI is beneficial since treatment, outcome, and prognosis will differ between these 2 conditions.…”

“…By utilizing magnitude and phase information, both of which are normally acquired from conventional MRI data, susceptibility weighted imaging (SWI) has an enhanced ability to detect microhemorrhages 4,12,26 and microvasculature. 26,27,41,92 It is a highly sensitive imaging modality able to depict magnetic substances, such as deoxygenated hemoglobin, with high contrast 42 and to help investigate neurological diseases, 82 grade tumors, 25,63 and assist in determining treatment or prognosis.…”