Purpose or Case Report: Ultrasound (US) is a powerful imaging tool in the evaluation of neonates with suspected hypoxic-ischemic encephalopathy (HIE). US evaluation of the neonatal brain has been mainly performed qualitatively, comparing intracranial structures with different echotextures. Qualitative US analysis of the neonatal HIE brain may vary according to technical variations, the severity of the injury and the presence of coexistent complications. Quantitative analysis of the neonatal brain echotexture has been seldom attempted. Our aim was to compare the echotextures of specific brain regions between HIE patients and controls.
Methods & Materials: Brain ultrasound of twenty term neonates with HIE with abnormal MRI findings and twenty term neonates with no clinical or MRI evidence of HIE were retrospectively evaluated. US imaging obtained in the coronal plane with slow anterior to posterior swipe technique was post-processed by an in-house parametric software. The six brain regions evaluated were the anterior, intermediate and posterior white matter (WM), the basal ganglia (BG), thalami and the perirolandic subcortical WM. One circular region of interest (ROI) was placed in each given brain region in both hemispheres. The sum of pixels of the two ROIs ranged between 2000 and 2050 pixels. The echotexture measurements were normalized to the echotexture of the choroid plexus (CP) in each given individual. The CP in the atria of the lateral ventricle (CP glomus) was chosen for normalization with circular ROIs. The number of ROIs of the CP also ranged from 2000 to 2050 pixels. Permutation test was used to compare differences in means between HIE patients and normal controls.
Results: The normalized echotexture of the brain regions in HIE patients vs control individuals were: anterior WM (0.76 vs 0.59, p<0.001), intermediate WM (0.75 vs 0.60, p=0.02), posterior WM (0.68 vs 0.54, p<0.001), BG (0.65 vs 0.53, p=0.006), thalami (0.78, vs 0.61 p<0.001) and perirolandic subcortical WM (0.77 vs 0.54, p<0.001).
Conclusions: Quantification of brain echotexture is a feasible method to differentiate HIE from control neonates in cases equivocal for qualitative diagnosis. Further work can also reveal whether a quantitative approach can also discern varying types and severity of HIE.