RC 912 - Understanding paediatric neuroradiology
1. To discuss the roles of US, (CT) and MRI in preterm imaging.
2. To give an overview of the different imaging findings in the preterm brain related to age.
3. To discuss the prognostic role preterm brain imaging.
Dramatic reduction in mortality rates of premature infants in recent times due to better perinatal care has not really translated to exceptional neurodevelopmental outcomes in these patients. Neuroimaging has taken a front stage in evaluation, diagnosis and prognostication of premature neonates. Ultrasound (US) forms the backbone of current neuroimaging practice in small babies. Magnetic resonance imaging (MRI) has matured recently as an excellent modality to better identify and classify intracranial structures. The premature brain is significantly different in terms of volume, structure, maturity (myelination pattern) and disease appearance as compared to childhood brain. Myelination progresses in the following order in human brain - caudal to cranial, centre to periphery and posterior to anterior. Identification of brain maturity by means of myelination pattern helps us in identifying and classifying white matter disorders. The distinctly variable patterns of involvement of susceptible structures, namely the deep grey nuclei and white matter in hypoxic-ischaemic brain injury in premature and mature brains is worth understanding as helps in evaluating and prognosticating such patients. MRI helps in comprehensive brain evaluation while US is a good, handy, radiation-free tool for follow-up.
1. To discuss the role of CT and MRI in imaging of abusive head trauma (AHT).
2. To give an overview of common CT and MRI findings in AHT.
3. To understand the strengths and limitations of CT and MRI in imaging AHT.
Abusive head trauma (AHT) is a leading cause of morbidity and mortality in infants. The presence of a diffuse subdural haematoma (SDH) with no evidence of accident is a key diagnostic clue. The haematoma is due to rupture of the cerebral bridging veins due to violent shaking. Neuroimaging is crucial for the diagnosis of AHT. The presence of SDHs, especially in multiple locations, such as the interhemispheric region, over the convexity and in the posterior fossa, is significantly associated with AHT. CT is the first-line imaging modality for suspected AHT, particularly in case of acute or subacute symptoms. CT exquisitely demonstrates intracranial haemorrhages, skull fractures and soft tissue swelling of the scalp. In addition of CT, early MRI within the first week provides a better estimation of parenchymal injuries (hypoxic-ischaemic insult, contusions). MRI can also disclose subtle key signs for the diagnosis of AHT such as rupture/thrombosis of bridging veins at the convexity and/or ligamentous cervical injuries. Both CT and MRI offer wide ranges for dating the causal event. In particular, mixed density/intensity pattern of SDHs is frequent and provides no reliable clues for assessing repeated violence. Only the finding of different density in two distant SDHs argues in favour of "age-different" injuries. As a reminder, in all cases of suspicion of AHT, the full skeletal survey is also mandatory.
1. To discuss the role of US, (CT) and MRI in hypoxic-ischaemic injury (including advanced MR techniques).
2. To give an overview of common imaging findings in hypoxic-ischaemic injury (HIE).
3. To understand the importance of timing and prognostic value of imaging in HIE.
The incidence of hypoxic ischaemic encephalopathy (HIE) ranges from 1 to 8 per 1000 live births in developed countries, it accounts for approximately 15%-20% of neonatal mortality in full-term neonates. Differently from adults, in whom acute anoxic-ischaemic injury causes diffuse brain injury predominantly involving gray matter, neonatal HIE is generally more selective. The most frequent type of injury on MRI in term newborns consists of selective involvement of areas with higher energy requirements, i.e. the lateral thalami, posterior lentiform nuclei, hippocampi and perirolandic cortex. Moreover, the absence of a normal PLIC on T1-weighted images in asphyxiated infants has a high positive predictive value (100% of abnormal neurodevelopmental outcome). In order of frequency, other locations of brain involvement in full-term newborns with HIE include the perirolandic and primary auditory cortex and optic radiation, the hippocampal formation and limbic cortex and the dorsal mesencephalic structures. Conventional MR sequences, diffusion, spectroscopy and more recently perfusion have been widely used in the last twenty years to find out the more reliable prognostic biomarker. There are now several evidences of benefits in neuroprotection by cooling treatment. No major complications are associated with therapeutic hypothermia and the predictive value of MRI for subsequent neurological impairment seems to be not affected by this kind of therapy. Being cooling therapy effective in the acute phase of HIE the role of MRI is now predominantly related to a better assessment of the brain damage in the subacute phase of asphyxia, when lesion load is well established.