As a general rule, the globus pallidi (∆) and the posterior limb of the internal capsules (long white arrows) should be more hyperintense than the posterolateral putamen (P). (a) Axial T1-weighted image at the level of the basal ganglia of a normal term neonate. Two major patterns of HIE are the border zone pattern and basal ganglia-thalamus pattern (Figure 2 a-b).įigure 2. The challenge in the implementation of neuro-protective measures is the narrow time window for therapy initiation, making early detection critically important. It is therefore important for radiologists to be familiar with its subtle findings. Hypoxic ischemic encephalopathy (HIE) is a key etiology of neonatal morbidity and mortality. These hypointense landmarks would be lost in the basal-ganglia-thalamus pattern of HIE. Faint T2 hypointense signal is also appreciated within the ventrolateral thalami and far lateral posterior putamen. (g) Axial T2-weighted image shows the normal hypointense signal within the posterior portion of the posterior limb of the internal capsules. Axial T1-weighted images demonstrate normal T1 hyperintense signal within the (a) posterior limb of the internal capsule, (b) optic tracts, (c) optic radiations, (d) peri-rolandic cortex, (e) superior cerebellar peduncles and (f) dorsal brainstem. Structures of the brain that are myelinated at birth in a term infant. Hence, absence of T1 hyperintense and T2 hypointense signal within the ventrolateral thalami and posterior portion of the posterior limb of the internal capsule in a term neonate would be abnormal. The thalamic nuclei and globus pallidi will start to myelinate at 24-25 weeks of gestation while the cortico-spinal tracts will myelinate by 36 weeks, best appreciated along the peri-rolandic cortex and posterior limb of the internal capsules (Figure 1 a - g). Hence, T1-weighted images are of little value after the first year. At one year of age, T1 contrast pattern would be similar to that of an adult, although the myelination process is still on going.
CONGESTION OF THE BRAIN 9 MONTHS OLD FREE
In the more advanced stages, when there is reduction in free brain water, T2-weighted images are deemed more useful, showing reduction in T2 signal.
T1-weighted images are useful in the earlier stages of myelination when an increase in levels of cholesterol and galactocerebrosides within the cell membranes result in an increase in T1 signal. The introduction of clinical MRI in the 1980s enables us to evaluate this complicated but important process.
CONGESTION OF THE BRAIN 9 MONTHS OLD HOW TO
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? What are the normal signal intensities within the brain? When do we make a diagnosis of HIE or periventricular leukomalacia?Īn understanding of the normal myelination process is crucial in allowing an accurate diagnosis of signal abnormalities within the pediatric brain. 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. Changes in normal appearances, clues on how to differentiate them from true pathologies as well as their clinical significance are outlined in this article. 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. However, in order for us to derive benefits from the information provided to us, it is imperative for us to first establish normality. Magnetic resonance imaging (MRI) of the pediatric brain has provided us with great insight into the maturation processes that take place after birth.
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