E1696. Imaging the Preterm Brain: What a Radiologist Needs to Know
  1. Won Kyu Choi; The Johns Hopkins Hospital
  2. Melike Guryildirim; The Johns Hopkins Hospital
  3. Doris Lin; The Johns Hopkins Hospital
  4. Aylin Tekes; The Johns Hopkins Hospital
Prematurity accounts for one-third of all infant deaths in the United States. The immature physiology of a premature neonate leaves the baby susceptible to inadequate defense against stressors. Brain injury is a common and serious complication of prematurity, with consequences such as major cognitive deficits and motor disability.

Educational Goals / Teaching Points
We aim to raise awareness of a spectrum of important prematurity-related brain injuries and review characteristic ultrasound (US) and magnetic resonance (MR) imaging features of these conditions. The most important conditions to consider include white matter injury, germinal matrix-intraventricular hemorrhage spectrum with post-hemorrhagic hydrocephalus, periventricular venous hemorrhagic infarction, cerebellar hemorrhage, and impaired myelination.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
White matter injury is the most frequent type of brain lesion in preterm infants. Premature infants are prone to experience episodes of cerebral ischemia and infection or inflammation, and an intrinsic susceptibility to excitotoxicity and free-radical accumulation. The cerebral white matter is the most sensitive part of the brain to ischemic injury in this age group, and preterm white matter injury has a prevalence ranging between 7 and 40% depending on the gestational age. Asymmetric white matter hyperechogenicities are the most reliable finding on head US. MRI would demonstrate foci of diffusion restriction or hemorrhage in the early phase, or T1 hyperintense and T2 hypointense white matter lesions with associated volume loss in the term-equivalent age or later. Hemorrhage spectrum is more easily identified with head US in preterm infants. Germinal matrix hemorrhage with intraventricular extension and ventriculomegaly is one of the dreaded types of injury with potential sequelae of posthemorrhagic hydrocephalus. Cerebellar hemorrhage may occur as an isolated injury in preterm infants and can be as severe as a completely destructive injury. Impaired myelination is an important potential complication of prematurity. Premyelinating oligodendrocytes (pre-OLs) are the most abundant cell type from 24 - 30 weeks of gestation, thus being a vulnerable cellular target in preterm brain injury. Reduced myelination can also lead to secondary trophic gray matter damage with resultant cortical or thalamic volume loss.

Preterm brain injury may have lasting consequences. Premature infants are vulnerable to brain injury due to their immature physiology and imaging is integral for diagnosis and monitoring of these conditions. Understanding key findings of each entity is essential for radiologists working with pediatric population.