Infants may be clinically unstable, or sedation may wear off. The choice of sequences used for an examination is limited by their availability and the duration of the scan. Careful comparative studies between these techniques, ideally with additional histology, should result in MRI improving the abilities of cranial ultrasound to detect lesions rather than replacing it as an imaging technique.Ĭommercial scanners contain sequences that are appropriate for studying the adult brain but some sequences will need to be adapted for neonatal brain imaging (see Chapters 1 and 2). A combination of ultrasound and MRI is ideal for assessing the neurologically abnormal neonate.
It is multiplanar, which results in improved detection of lesions and better estimation of their exact site and size.
#BABY BORN MISSING PART OF SKULL NO GAG REFLEX SERIAL#
It does not involve the use of radiation and is therefore suitable for serial scanning. MR provides superb definition of the brain compared to both ultrasound and CT. In addition, a few MR suites are now being installed either within or adjacent to neonatal units. MRI is a relatively new technique but is becoming more widely available. In our experience CT is often unable to detect significant basal ganglia and thalamic lesions. A more recent study documented the presence of cortical abnormalities consistent with highlighting on MRI (see below) in infants with HIE 12. Decreased attenuation in the white matter during the second week from delivery has been associated with an abnormal outcome. CT has been used to study infants with HIE 1 but there are very few recent studies. However, the ability of the MR to detect acute hemorrhage has improved with gradient echo sequences and it is now less justifiable to use CT to image neurologically abnormal infants. CT is good for identifying acute hemorrhage and this has been the one advantage over MRI. It is not therefore suitable for serial scanning. However, machines, as with MRI, are usually at a distance from the neonatal unit and CT scanning involves exposure to a significant amount of radiation. The combination of cranial ultrasound and MRI is ideal for assessing the newborn brain.ĬT has the advantage that it is available in many hospitals and is relatively cheap. Cranial ultrasound will always provide a method for screening and monitoring the evolution of lesions but is not as good as MRI at determining the exact site, and extent of lesions. Using the posterior fontanelle improves the ability of cranial ultrasound to detect lesions following HIE 14. Cranial ultrasound is very good at identifying cystic lesions within the parenchyma. Using a 10Mhz transducer allows identification of areas of cortical highlighting and subcortical white matter infarction 16.
Using a 5MHz transducer to increase penetration, echo densities within the basal ganglia are easily visualized and are predictive of outcome 17, 23Īlthough they may take several days to become apparent. Areas of parenchymal infarction may take several days to be visualized as an echo density. Cranial ultrasound is valuable for identifying cerebral edema and parenchymal or intraventricular hemorrhage. It is exceedingly difficult to interpret paper reprints, particularly when they have been taken by a different operator. This is most easily done at the time of scanning, although video replay provides a suitable method of retrospective review. As with all techniques, expertise is needed not only to obtain the correct scan views but more importantly to interpret the results correctly. It is ideal for doing daily or twice daily scans to follow the evolution of changes within the brain.
Cranial ultrasound has the advantage of being mobile and easily used on the neonatal unit. Infants with signs of HIE may be scanned with three different techniques during the neonatal period: cranial ultrasound, computerized tomography (CT) and magnetic resonance imaging (MRI). Signs of fetal distress include abnormal cardiotocograph recordings such as decreased variability, late decelerations (type II dips), and a baseline bradycardia Imaging This term is used to describe mature neonates (gestation >37 weeks) who show signs of fetal distress prior to delivery, who have abnormal Apgar scores and require resuscitation at birth and who show specific neurological abnormalities during the first 24h after delivery. Infants who have been asphyxiated during delivery may develop signs of hypoxic–ischemic encephalopathy (HIE).
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