Neuroimaging in the term newborn with neonatal encephalopathy

Abstract

Neuroimaging is widely used to aid in the diagnosis and clinical management of neonates with neonatal encephalopathy (NE). Yet, despite widespread use clinically, there are few published guidelines on neuroimaging for neonates with NE. This review outlines the primary patterns of brain injury associated with hypoxic-ischemic injury in neonates with NE and their frequency, associated neuropathological features, and risk factors. In addition, it provides an overview of neuroimaging methods, including the most widely used scoring systems used to characterize brain injury in these neonates and their utility as predictive biomarkers. Last, recommendations for neuroimaging in neonates with NE are presented.

Keywords: Advanced MRI techniques; Asphyxia; Diffusion-tensor imaging; Diffusion-weighted imaging; Hypoxic-ischemic brain injury; Magnetic resonance spectroscopy imaging; Neonatal encephalopathy; Neonates; Outcome prediction; Predictive values.

Fig. 1.

Patterns of brain injury in neonates with NE as shown on DWI images obtained at days 4–5 of life. Details regarding the patterns and associated neuropathological findings and clinical risk factors are found in the text and summarized in Table 1. Note that the parenchyma lesion (H) is associated with a subpial hemorrhage, which is better visualized on T2-weighted images (center) and SWI (right).

Fig. 2.

cUS performed on day 2 of life, including coronal (A) and parasagittal (B) views. Increased echogenicity is seen in the thalami and to a lesser degree in the basal ganglia, with reduced echogenicity in between suggestive of involvement of the PLIC. The ventricles are slit-like and there is increased echogenicity of the white matter as well. The axial MRI-DWI, performed on day 3 of life (C), shows extensive diffusion restriction in the thalami as well as in the subcortical white matter and cortex.

Fig. 3.

MRI and MRS biomarkers indicate the degree of injury to the BGT, cortex, and white matter. The top panel depicts Trace-DTI, ADC, and T2-weighted images obtained at the level of the parietal white matter (pWM, upper) and BGT (lower) from a typically developing term neonate, with the major metabolite peaks labeled for reference. Short-echo MRS spectra obtained from the corresponding voxels (red boxes on the anatomical images) in the BGT and pWM are shown to the right. The lower panels depict Trace-DTI, ADC, T2w and MRS spectra from six neonates with NE imaged at days 4–5 of life. Note how the lactate-lipid signals in the BGT and pWM voxels increase in line with the degree of injury to the BGT-cortex and white matter, respectively, while NAA decreases. Cho = choline; Cr = creatine; NAA = nacetylaspartate; lac + lip = combined signal from lactate and lipids.