state of-the-art cranial - copy
TRANSCRIPT
Cranial Sonography: Techniques and Image
Interpretation
Lisa H. Lowe
Zachary Bailey
OBJECTIVE
• To discuss the modern approach for cranial ultrasound of grey scale technique and interpretation
• Use of linear imaging and use of multiple fontanels and screening doppler techniques
Cranial ultrasound technique
• Performed using linear array transducer via anterior fontanel in coronal and sagittal planes
• 6 to 8 coronal images from frontal lobes ant to frontal horns of lateral ventricle to occipital lobes posterior to lateral ventricle trigones
• Sagittal midline view of corpus callosum and cerebellar vermis and bilateral parasagittal images
• Four doppler images for screening vascular structures, arterial system for patency and resistance to flow by obtaining color doppler images of circle of Willis obtained via anterior or temporal fontanel to localize MCA or ICA and obtain spectral tracing with PSV, EDV and RI
• Venous system is evaluated for patency by obtaining color doppler images of sagittal sinus and vein of Galen
• Areas of hyper or hypovascularity for vascular ischemia or infarction
• CD via posterior fontanel or foramen magnum used for screening for patency of transverse sinuses
• Linear transducer via anterior fontanel allow detailed interrogation of convexity of subarachnoid space and superficial cortex and deep brain matter.
Cranial ultrasound interpretation
GREY SCALE IMAGING
CORONAL VIEWS
SAGITTAL VIEW
PARASAGITTAL VIEW
DOPPLER IMAGING
Conclusion
• With modern protocols used in cranial sonography is highly accurate in detection of cranial abnormalities
discussion
• Coronal brain scans of skull with transducer held along anterior fontanalle six standard frozen images are acquired1. Most anterior scan is anterior to frontal horn of
lateral ventricle contains• Frontal lobes of cerebral cortex• Orbits deep to internal floor of skull base
Orbital ridges
Frontal lobes
Interhemispheric fissure
INTERHEMISPHERIC FISSURE
CHOROID PLEXUS
FRONTAL LOBES
• Next is section through frontal horns of lateral ventricle : symmetric anechoic and comma shaped
– Structures from superior to inferior in midline are
1. Interhemispheric fissure2. Cingulate sulcus3. Genu and anterior body of corpus callosum4. Septum pellucidum5. Lateral to putamen is the echogenic septum pellucidum6. Inferiorly the ICA bifurcates to form ACA and MCA which
appear echogenic
INTERHEMISPHERIC FISSURE
CINGULATE SULCUS
GENU AND BODY OF CORPUS CALLOSUM
SEPTUM PELLUCIDUM
FRONTAL HORNS OF LATERAL VENTRICLE
TEMPORAL LOBES
ICA BIFURCATION TO ACA AND MCA
• More posteriorly the body of lateral ventricles and either cavum septum pellucidum are noted
• Other structures are
1. Thalami on either side of 3rd ventricle2. Deep to thalami is the brainstem3. Lateral to lentiform nucleus is the deep white matter of
brain called the centrum semiovale
THALAMUS
CAUDATE NUCLEUS
SYLVIAN FISSURE
3RD VENTRICLE
CAVUM SEPTUM PELLUCIDUMBODY OF LATERAL VENTRICLE
BRAINSTEM (PONS)
INTERNAL CAPSULE
• More posteriorly the body of lateral ventricle becomes more rounded and size of caudate nucleus decreased in size posterior to foramen of Monroe
• Echogenic matter in floor is choroid plexus
• Prominent thalami • Posterior fossa contain echogenic vermis• If cavum septum pellucidum is cystic
posteriorly it is labelled as cavum vergae• Temporal horns of lateral ventricle are
seen only in case of hydrocephalus
BODY OF LATERAL VENTRICLE
CHOROID PLEXUS
THALAMUS POSTERIOR FOSSA WITH VERMIS
CAVUM VERGAE
• Posterior sections reveal :-– Trigone or atrium of lateral ventricle is visualised – Echogenic glomus of choroid plexus obscures lumen of
CSF
GLOMUS
PARIETAL LOBE
CENTRUM SEMIOVALE
• Most posterior section :-1. Occipital lobe2. Occipital horns of lateral ventricle angled posterior to
cerebellum
SAGITTAL BRAIN SCANS
1. Midline– Curving line of corpus callosum– Cystic cavum septum pellucidum– Cerebellar vermis
• Shallow angulation 10 to either sides :-– Normal lateral ventricles– Anterior sector medial and posterior sector lateral – Caudate nucleus and thalamus with in arms of ventricle– Caudothalamic groove area to recognise germinal matrix
hemorrhage– Normal hyperechoic blush posterior and superior to
ventricular trigones on parasagittal views– Normal peritrigonal echogenity
FRONTAL LOBE
CAUDOTHALAMIC GROOVE
CAUDATE NUCLEUS
THALAMUS
CHOROID PLEXUS
SYLVIAN FISSURE
INSULAR CORTEX
TEMPORAL LOBE
Through posterior fontanalle
• AFFORDED GREATER ACCURACY IN DETECTION OF INTRAVENTRICULAR HEMORRHAGE THAN ANTERIOR FONTANALLE IMAGING WHEN VENTRICLES ARE NOT DILATED
• POSTERIOR FONTANALLE IMAGING ALSO HELPED IN DETERMINING POSTERIOR FOSSA MALFORMATIONS
LATERAL VENTRICLE
THALAMUS
OCCIPITAL LOBE
CHOROID
TRIGONE OF LATERAL VENTRICLE
Doppler sonography
SYLVIAN FISSURE
THALAMUS
MCA
BRAINSTEM
CORPUS CALLOSUM
PONS
BRANCH OF PERICALLOSAL ARTERY
CEREBELLUM
OCCIPITAL LOBE
4TH VENTRICLE
CINGULATE GYRUS
CIRCLE OF WILLIS MCA
CEREBELLUM VERMIS
BRAINSTEM
CIRCLE OF WILLIS
MCA
TEMPORAL LOBES
Normal variants and pitfalls that mimics pathologic abnormalities
• Immature sulcation in premature infants• Persistent fetal fluid filled spaces• Mega cisterna magna• Asymmetric ventricular size• Choroid plexus variants• Periventricular cystic lesions• Hyperechoic white matter pseudolesions or
periventricular halo• Lenticulostriate vasculopathy
• Immature sulcation– Infants born before the 24th week possess a
smooth cerebral cortex exhibiting only the sylvian fissures.
– a diagnosis of lissencephaly should not be made in patients younger than 24 weeks’ gestational age
• Persistent fetal fluid filled spaces– Persistent fetal fluid–filled spaces, a common
finding in healthy neonates, include the cavum septi pellucidi (CSP), cavum vergae, and cavum veli interpositi.
– The CSP is the most anterior and the most common of the fetal fluid–filled spaces.
– Persistent fetal fluid–filled spaces occasionally persist into adulthood and are a normal variant of no significance
• Mega cisterna magna1. The typical cisterna magna is less than 8 mm
in both the sagittal and axial planes 2. A mega cisterna magna, which some believe
is due to cerebellar damage and volume loss, measures greater than 8 mm and is seen in 1% of postnatally imaged brains
3. A mega cistern magna is a normal variant distinguished from an arachnoid cyst by its lack of mass effect and from a Dandy Walker malformation by the presence of the cerebellar vermis
• Assymetric ventricles1. Normal ventricles measure less than 10 mm in
transverse diameter, with 60% of full term and 30% of premature infants having ventricles smaller than 2–3 mm
2. Asymmetry between the sizes of the ventricles has been observed in 20–40% of infants
• Choroid Plexus Variants1. It does not extend past the caudothalamic
grooves into the frontal horns or past the ventricular atria into the occipital horns.
2. Echogenic material anterior to the caudothalamic groove or in the dependent portions of the occipital horns suggests germinal matrix and intraventricular hemorrhage
3. Lobular or bulbous variants of the choroid plexus occur most frequently in the glomus within the ventricular atria and lateral ventricles
4. Choroid cysts smaller than 1 cm are incidentally noted in 1% of infants at autopsy
• Periventricular Cystic Lesions1. Cystic lesions in the periventricular region
include connatal cysts, subependymal cysts,and white matter cysts due to periventricular leukomalacia
2. Connatal (or subfrontal) cysts are seen most often during the early postnatal period and may regress spontaneously
3. The sonographic appearance includes bilateral symmetric cysts located adjacent to the frontal horns, just anterior to the foramina of Monro. The cysts frequently appear in multiples and take on a classic appearance that has been likened to a string of pearls
4. Two indistinguishable cysts are located at the caudothalamic groove, including a subependymal cyst due to germinal matrix hemorrhage and a germinolytic cyst due to metabolic disorders such as Zellweger syndrome
5. cysts found in the white matter adjacent to lateral ventricles are typically the result of periventricular leukomalacia,which is caused by hypoxic ischemic injury in the premature infant
• Hyperechoic White Matter Pseudolesion or Periventricular Halo1. Hyperechoic white matter pseudolesions, or
periventricular halos, may appear as artifacts due to anisotropic effect
2. Additional images obtained at a 90° angle resolve the finding and prevent misinterpretation
3. periventricular white matter pseudolesions and halos are normally less echogenic than the adjacent choroid plexus
• Lenticulostriate Vasculopathy1. thought to be due to thickening of the
lenticulostriate artery walls secondary to a variety of pathologic conditions and infections
2. lenticulostriate vasculopathy often occurs without a specific cause being identified and thus remains a nonspecific finding seen on sonography as unilateral or bilateral branching,linear, or punctate increased echogenicity within the thalami