Application of Advanced Neuroimaging Modalities in Pediatric Traumatic Brain Injury

Abstract

Neuroimaging is commonly used for the assessment of children with traumatic brain injury and has greatly advanced how children are acutely evaluated. More recently, emphasis has focused on how advanced magnetic resonance imaging methods can detect subtler injuries that could relate to the structural underpinnings of the neuropsychological and behavioral alterations that frequently occur. We examine several methods used for the assessment of pediatric brain injury. Susceptibility-weighted imaging is a sensitive 3-dimensional high-resolution technique in detecting hemorrhagic lesions associated with diffuse axonal injury. Magnetic resonance spectroscopy acquires metabolite information, which serves as a proxy for neuronal (and glial, lipid, etc) structural integrity and provides sensitive assessment of neurochemical alterations. Diffusion-weighted imaging is useful for the early detection of ischemic and shearing injury. Diffusion tensor imaging allows better structural evaluation of white matter tracts. These methods are more sensitive than conventional imaging in demonstrating subtle injury that underlies a child’s clinical symptoms. There also is an increasing desire to develop computational methods to fuse imaging data to provide a more integrated analysis of the extent to which components of the neurovascular unit are affected. The future of traumatic brain injury neuroimaging research is promising and will lead to novel approaches to predict and improve outcomes.

Metabolic Alterations in Developing Brain After Injury: Knowns and Unknowns

“…N-acetylaspartate (NAA) is an amino acid synthesized in neuronal mitochondria which increases throughout early brain development, reaching a plateau at ~ 2 to 3 years of age [55, 56]. Reductions in NAA reflect severe alterations in neuronal mitochondrial function [56] and may reflect loss of viable neurons [55, 56].…”

“…Reductions in NAA reflect severe alterations in neuronal mitochondrial function [56] and may reflect loss of viable neurons [55, 56]. NAA is released by neurons and taken up by oligodendroglial cells which use the acetyl moiety as a substrate for the synthesis of myelin lipids [1].…”

“…Ultimately, post-traumatic changes in 1 H-MRS in infants and children must be interpreted by comparison to age-matched reference data [55]. Although alterations in metabolite ratios provide useful clinical information, they do not give an in depth understanding of the mechanisms underlying energy failure subsequent to HI.…”

N-Acetyl Aspartate

“…37 Changes in metabolites following traumatic brain injury (TBI) depend on several factors, including injury severity, time from injury, age at injury and complications associated with the injury. 38 Generally, total NAA is decreased in TBI, but longitudinal studies suggest it returns to normal levels with recovery. Therefore initial decreases are not indicative of irreversible neuronal loss.…”

CT should not be relied on for cases of isolated vomiting in children with blunt head trauma

“…It may be true that no findings are to be expected that require emergent neurosurgical treatment in this setting; however, a negative CT does not mean that the brain is not injured—instead the injury may not be visible on the acute CT. It is well known that CT may underestimate the degree of TBI 1. MRI may identify TBI, while CT appears unremarkable.…”