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Radiology.Academy.Sk

Intracranial Ultrasound

Most pediatric intracranial ultrasounds are performed under 6 months of age. Posterior fontanelle closes around 6 months, anterior fontanelle closes between 6-18 months. Scans through anterior, posterior and mastoid (pterion) fontanelle. Cranial ultrasound allows visualization of the following structures:




Soft tissue of the head and cranial vault


Sutures (sagittal craniosynostosis), Cephalohematoma, LCH (Langerhan’s cell hystiocytosis), Hemangioma, Tumors, Encephalocele, Post-op changes


Superior sagittal sinus


Thrombosis


Brain surface


Smooth under 32 wks, Lissencephaly if after 36wks


Subarachnoid space


If > 5 mm: macrocranium, brain atrophy, subdural hygroma, subdural effusion or empyema (from meningitis), subdural hematoma (non visualization of bridging veins w/ color Doppler)


Lateral ventricles


Consist of atrium, body and three horns (frontal, temporal, occipital). Fontal horns are slit-like, they are often asymmetric (right larger), choroid plexus is in the body and extends to temporal horns through foramina of Monro, thickness < 3 mm at f. Monro, 2 mm at 3rd ventricle


Corpus callosum


Agenesis: batwing appearance on frontal image


Cavum septum pellucidum


Fluid filled structure between 2 layers of septum pellucidum, diseappears before 2nd year of life


Posterior fossa


Scan through the posterior lateral fontanelle to differentiate normal f. Magendie from Dandy-Walker variant, atrium of lateral ventricles, occipital horns, basilar cisterns for hemorrhage; mega cisterna magna > 8 mm (surrounds cerebellum), congenital aqueductal stenosis



Sonographic Anatomy


Ventricles, corpus callosum, cavum septum pellucidum, foramina of Monro, third ventricle, sylvian fissure, sulci, cingulate sulcus, choroid plexus, 4th ventricle, cerebellar vermis, corpus callosum (rostrum, genu, body, splenium), Caudate, Putamen, Globus pallidum, Thalamus, Caudothalamic groove




Intracranial hemorrhage


Premies < 1500g or < 32wks, in first 3 days of life, 90% before 6th day, in germinal matrix/intraventricular hemorrhage (fragile vessels in the wall of lateral ventricles [near caudothalamic groove and roof of 4th ventricle], involute after 34th week)




US grading of hemorrhage:


PVL: periventricular leukomalacia