Pediatric MRI Brain: Normal or abnormal, that is the question.

Magnetic resonance imaging (MRI) of the pediatric brain has provided us with great insight into the maturation processes that take place after birth. However, in order for us to derive benefits from the information provided to us, it is imperative for us to first establish normality. This is extremely challenging especially in the first 2 years of life as the appearance of a normal brain changes according to the stage of development. Changes in normal appearances, clues on how to differentiate them from true pathologies as well as their clinical significance are outlined in this article. Several points of confusion that commonly arise in reviewing MR images of pediatric brain are emphasized, including 1) What are the normal signal intensities within the brain? When do we make a diagnosis of HIE or periventricular leukomalacia? 2) Ventriculomegaly : Is it benign external hydrocephalus, ex-vacuo ventricular dilatation or communicating hydrocephalus? 3) Corpus callosum : More than just another midline structure. When to call it abnormal, what are the common associated abnormalities and how to use it to estimate the time of insult? 4) Thickened cerebral cortex : Malformations of cortical development (MCD) and “pseudothickening” of cortex 5) Dandy Walker syndrome, inferior vermian hypoplasia, persistent Blake pouch cyst or mega cisterna magna?