Neurosonogram /Cranial USG

Dr.Padmeshhttp://oscepediatrics.blogspot.in/

• Images are usually taken through the anterior fontanelle.• In the coronal plane, a series of images are taken through the

frontal lobes, more posteriorly through the ventricles and thalami, then along the plane of the choroid plexus, then superior to that.

• The sagittal images are initially taken in the midline, with images then taken on both sides at the level of the lateral ventricles then periventricular areas.

Coronal Views

The transducer is angled back. The CSF in the lateral ventricles appears as a dark image. The lateral ventricles are larger in preterm infants than in term infants. Asymmetry between the lateral ventricles is common and is not necessarily abnormal. The cavum septum pallucidum sits between the lateral ventricles and is often large in preterm infants. The corpus callosum appears above the cavum.

With the transducer shifted slightly further back, the third ventricle appears below both lateral ventricles and the septum pallucidum. It is often small and difficult to see, but can vary considerably in size. The foramen of Monro (connecting lateral and 3rd ventricles) may be clearly seen. The brainstem may be seen as a tree-like shape.

Angling further back cuts through the trigones of the lateral ventricles. The choroid plexus fills the lateral ventricles in this view and is prominent in preterm infants. Choroid plexus haemorrhage may be difficult to differentiate from bulky choroid. The white matter around the lateral ventricles may appear quite echodense (bright) in this plane and is sometimes called a "blush" or "flare".

Angling the transducer even more results in an image that slices above the lateral ventricles. In this plane, the occipital cortex may be visualised.

Sagittal Views

Midline SagittalThis identifies useful landmarks. The cerebellar vermis shows up as an echogenic image in the posterior fossa. The 4th ventricle sits in front of this. The cisterna magna sits below the cerebellar vermis and is not very echogenic. The corpus callosum is seen sweeping from anterior to posterior with the cingulate gyrus above and parallel to it. The parieto-occipital sulcus is seen well above the posterior fossa.

Angled Parasagittal View:The shape of the lateral ventricle is the key landmark for this view. The caudate nucleus lies below the floor of the frontal horn of the lateral ventricle; the thalamus lies behind and below it. The occipital horn of the lateral ventricle is filled with choroid plexus. The choroid tucks up in the caudothalamic groove in the floor of the lateral ventricle and may be echogenic.

Tangential Parasagittal View:Further angulation of the transducer laterally results in a section lateral to the lateral ventricles. The Sylvian fissure is the key landmark in this view.

ABNORMALITIES:

PVL

DeVries classification of PVL grading on ultrasound

• Grade I PVL: Prolonged periventricular flare present for 7 days or more.

• Grade II PVL: Presence of small-localized fronto-parietal cysts.

• Grade III PVL: Extensive periventricular cystic lesion involving occipital and fronto-parietal white matter.

• Grade IV PVL: Areas of extensive sub cortical cystic lesions.

Sagittal image of a child with PVL grade 1

Transverse and sagittal image of a child with PVL grade 2.

Sagittal image demonstarting extensive PVL grade 3

Coronal and transverse images demonstrating PVL grade 4

Frontal and parieto-occipital Flare: Grade I PVL (sagittal view)

B/L extensive parieto-occipital cystic PVL: Grade III PVL (sagittal view).

PVLCoronal cranial US scans show symmetric, diffuse periventricular white matter echogenicity (arrows ) and loss of regular parenchymal spacing.

PVL

IVH

IVH/GMH GRADING –VOLPEBy CUS (Cranial US)

Parasaggital view

IVH/GMH GRADING –PAPILEBy CT SCAN

GRADE 1 - Isolated GMH (no IVH)GRADE 2 - IVH without ventricular dilatationGRADE 3 - IVH with ventricular dilatationGRADE 4 - IVH with parenchymal hemorrhage

A, Grade I: Note the echogenic blood in the germinal matrix (arrowheads) just anterior to the anterior tip of the choroid plexus, which (normally) is also echogenic.

B, Grade II: Note the echogenic blood (arrowheads) filling <50% of the ventricular area.

C, Grade III: Note the large blood clot nearly completely filling and distending the entire lateral ventricle

COMPARISON

Grade 1 intracranial hemorrhageSagittal and coronal US of subependymal hemorrhage located in the groove between the thalamus and the nucleus caudatus. (hemorrhage confined to the caudothalamic groove.)

Sagittal and coronal US of a grade 2 hemorrhage;

On the coronal image only the cavum septi pellucidi is seen.Both lateral ventricles are filled with blood, but there is no ventricular dilatation.

MISCELLANEOUS

MISCELLANEOUS• Doppler Vascular Measurements:• The vessels that are the easiest to access are

– the anterior cerebral artery (ACA), best seen through the anterior fontanelle in the sagittal plane and

– the middle cerebral artery (MCA) best seen through the temporal window in the axial plane.

• The Resistivity index (RI) : PS – ED SV - DV PS SV

• Where PS= peak systolic velocity and ED = end diastolic velocity. • The normal range is about 0.65 - 0.90. • Values below 0.5 or above 0.9 are abnormal.

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