Magnetic Resonance Imaging in (Near-)Term Infants with Hypoxic-Ischemic Encephalopathy

Abstract

Hypoxic-ischemic encephalopathy (HIE) is a major cause of neurological sequelae in (near-)term newborns. Despite the use of therapeutic hypothermia, a significant number of newborns still experience impaired neurodevelopment. Neuroimaging is the standard of care in infants with HIE to determine the timing and nature of the injury, guide further treatment decisions, and predict neurodevelopmental outcomes. Cranial ultrasonography is a helpful noninvasive tool to assess the brain before initiation of hypothermia to look for abnormalities suggestive of HIE mimics or antenatal onset of injury. Magnetic resonance imaging (MRI) which includes diffusion-weighted imaging has, however, become the gold standard to assess brain injury in infants with HIE, and has an excellent prognostic utility. Magnetic resonance spectroscopy provides complementary metabolic information and has also been shown to be a reliable prognostic biomarker. Advanced imaging modalities, including diffusion tensor imaging and arterial spin labeling, are increasingly being used to gain further information about the etiology and prognosis of brain injury. Over the past decades, tremendous progress has been made in the field of neonatal neuroimaging. In this review, the main brain injury patterns of infants with HIE, the application of conventional and advanced MRI techniques in these newborns, and HIE mimics, will be described.

Impact of Hypoxia-Ischemia on Neurogenesis and Structural and Functional Outcomes in a Mild–Moderate Neonatal Hypoxia-Ischemia Brain Injury Model

“…To substantiate these findings in our model, we assessed area loss using two different methods: histology and T2-weighted MRI scans. MRI including DTI is the gold standard for diagnosing HIE [ 33 ]. Neonatal MRIs are also of great prognostic value as they are a good predictor of the functional outcome [ 33 , 42 , 43 ].…”

“…MRI including DTI is the gold standard for diagnosing HIE [ 33 ]. Neonatal MRIs are also of great prognostic value as they are a good predictor of the functional outcome [ 33 , 42 , 43 ]. Three different regions and patterns of injury can be predominantly distinguished: (1) basal ganglia and thalamus; (2) white matter; and (3) global injury [ 33 ].…”

“…Neonatal MRIs are also of great prognostic value as they are a good predictor of the functional outcome [ 33 , 42 , 43 ]. Three different regions and patterns of injury can be predominantly distinguished: (1) basal ganglia and thalamus; (2) white matter; and (3) global injury [ 33 ]. However, when using a small animal model, the exact areas affected by the injury cannot be directly translated.…”

“…Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured using ImageJ. ADC is the rate of the diffusion ability of water molecules in tissues [ 32 , 33 ]. FA also reflects the diffusivity of water molecules along fibers and considers different factors such as myelination, axonal integrity, and fiber diameter [ 34 ].…”

Proton MR Spectroscopy of Pediatric Brain Disorders

“…MR imaging of the newborn brain provides biomarkers of disease status and predictors for outcome [ 60 , 61 , 62 , 63 ]. MRS complements conventional MRI and diffusion MRI by providing direct measures of metabolites that reflect the severity of injury [ 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 ] ( Figure 7 ). Meta-analyses that compared various imaging modalities showed high sensitivity (82%) and specificity (95%) for the lactate to NAA ratio (Lac/NAA) for predicting neurodevelopmental outcomes [ 71 , 72 ].…”