Neonatal Neurosonography – The Premature Infant - HD

Introduction

Hi, I'm Harris Cohen.
I'm professor and chairman of radiology at the University of Tennessee Health Science Center in Memphis and radiologist in chief of the Le Bonheur Children's Hospital, also in Memphis, Tennessee.
This topic is neonatal neurosonography: the premature infant in a limited amount of time.
We will discuss a few methods in head ultrasound technique, review some normal intracranial ultrasound anatomy, note some current axioms of head ultrasound evaluation and diagnosis in the premature infant discussing intracranial hemorrhage, IVH and IPH and to a lesser extent, periventricular leukomalacia, PVL and hypoxic ischemic encephalopathy, HIE.

History with Head Ultrasound

My history with head ultrasound began with the emergence of head ultrasound in the United States.
I did my fellowship in 1980.
We were in the beginning of the year.
We were evaluating IVH by CAT scan.
Two events occurred around that time that shifted the paradigm to ultrasound.
Between 1979 and 1982, clinical radiologists were obtaining real-time ultrasound units and in 1980 an oral and others discovered in quotes, the anterior fontanelle as an ultrasound window.
This resulted in ultrasound beginning to be used for bedside evaluation in my children's hospital, for neonatal brains.
Let me repeat that thing.
By the middle of my fellowship in January, 1981, ultrasound was being used for bedside evaluation of neonatal brains.
Our first realtime unit looked very similar to what is shown here, not the flexible wire, but very small screen and wide linear array transducer used.
We needed a transducer that could fit into the fontanel and that could see deeper structures.
A transducer I used for many years was this offset probe that could be placed in the anterior fontanel and we could evaluate patients at the bedside within their isolette, within their controlled environment, which allowed analysis earlier than we would've with CT when we had to wait for the babies to be stabilized before they could days or weeks later go to CT for analysis.

Ultrasound Technique

The key area of insonation was and is, through the anterior fontanel.
There's an image of the baby looked at in anterior position showing how we would approach taking midline para sagittal and peripheral para sagittal views, and then an image of the infant in sagittal view showing how we would angle anteriorly and further back on several angles to get the contents of the brain.
Certain areas of the brain, such as cerebral vertex, would not be as well seen using the anterior fontanel.
There are other helpful windows to the brain.
The various sutures and fontanels can be used to see the contents of the brain.
This is just an image of the posterior fontanel view in which one can imagine lines going through the posterior fontanel and cutting different sections of the brain.
Posterior fontanel sonography, which was seen in the early eighties, was reviewed in an article by Korea August, 2004, which noted that in 164 cases in which the posterior fontanel was added to images obtained through the anterior fontanel, there was an increase in diagnosis of grade two hemorrhages by 32%.
And that two cerebellar hemorrhages in one abscess were seen.
It did not help them with the diagnosis of per ventricular leukomalacia, but it did prove that looking from other paradigms can aid analysis.
These are two images of the brain studied through the posterior fontanel that on your left shows no ventricular magaly or hemorrhage.
One sees brain parenchyma choroid plexus marked off a c and some fluid seen superior to the brain.
On the image to your right, one can see the cerebellum or two cerebellar hemisphere is separated By fluid that extends from the cisterna magna region through to the area of the fourth ventricle showing a dandy walker malformation.
This is an example of, again, the hemispheres labeled H separated and a cyst posterior cyst communicating with the fourth ventricle because in classic dandy walker cyst, there is a verian dysgenesis and communication between the cisterna magnum and the fourth ventricle.
I mark off the line of sight.
So you note that if you're going through a posterior approach, you would first hit the posterior most structure, the ci sternum magna before you entered anteriorly to see the fourth ventricle and the separated hemispheres in this case.
This is just an example of a sagittal view of the enlarged ci sternum magna the small portion of the verus in this case of verian dysgenesis in a patient with a dandy walker cyst that allowed lifting of the tentorium to a higher position than normal.
Over the last two years in my facility, we've increased the use of the mastoid fontanel view, which was discovered as other fontanels and other sutures have been discovered in the past as used as ways of seeing intracranial contents.
Posterior fontanel view is usually obtained posterior to the ear of the neonate.
It's predominantly helped us evaluate the cerebellum for hemorrhage, the fourth ventricle and its relationship to the cisterna magna.
It allows us to analyze for Dandy Walker complex, including classic dandy walker malformation and what has been called in the past dandy walker variants.
It also has allowed us to see cerebellar arachnoid cysts and allow us to evaluate flow in the transverse sinus via doppler.
Sagittal and transverse planes are obtained using a small convex high frequency linear array placed poster to the ear in the mastoid area, the linear array probe has to conform to the small opening and obviously not be one with an elongated base.
Here are some images looking at the cerebellum, on your left is a routine midline sagittal view, which we'll go through the anatomy later.
And on your right is a mastoid view highlighting the cerebellum.
The near field, the more superior portion is seen at times better than the far field, but in this case you see this both cerebellar hemispheres and the more echogenic verma well as well as the fourth ventricle separated from the cy sternum Magna.
This again is normal midline and again we have mastoid views, but in the case of the image on your left, Just at the inferior aspect of the cerebellum, there is communication between the ci sternum magna and the fourth ventricle seen in many, many normal individuals and thought to be the foramen of magdi.
And on your right, there is an echogenicity within the ci sternum magna that is thought to be Blake's pouch cyst, which will eventually fenestrated and not be seen during neonatal life unless there's an abnormality.
And there are the orders of Blake's patch cyst.
Again, mastoid views are seen.
I mark off the side that is the upside of the patient.
So the left side is up and we're examining the patient through the area posterior to the left ear.
And again, sometimes the upside areas seem better than the downside area, which in this case is the right.
So one sees the cerebellum without a problem.
One has some echogenicity in the ci sternum magnar region, which at one time was called dural folds.
On the image on your right, you see the cerebellar area with a large echogenic structure seen on the left side, which was an intra cerebellar hemorrhage.
So again, the image on your left shows no hemorrhage shows no ventricular magaly because you can see the atrium and the occipital horn of the ventricle as non dilated with no CSF surrounding the echogenic choroid plexus while on your right is a left cerebellar hemorrhage And dilated lateral ventricles.
And again, here is an image in this case, not an image of a neonate, but just showing the equivalent image of what I've shown you in a fetus who has a communication between the cisterna magna and the fourth ventricle with separation of the cerebellar hemispheres and non visualization of the verus
Transcranial views are also used.
We use them mostly in kids Who In clinicians would like us to evaluate for ventricular magaly and their fontanels have already closed.
The methodology is used more often in work in sickle cell disease patients in evaluating the middle cerebral artery as well as other vessels within the circle of Willis, but we use it In neonates as well.
So transcranial views because they go through bone and they're not using fontanels or sutures require lower frequency transducers to penetrate the calvarium.
This is not as difficult in the premature with less thick bones.
Here's some views with transcranial head ultrasound.
On your left is an eight month old.
We closed Fontanels who had a large head, a transcranial ultrasound probe placed, for example here, penetrated the skull and showed choroid plexus not surrounded by CSF, but in normalized ventricles and there was no ventricular magaly.
This information could be passed on to the parents and they were happy they were trying to avoid a cat scan and its radiation in making that diagnosis.
On the other hand, here's a premature with overlapping sutures on your right who could not be well evaluated via routine approach through the anterior fontanel.
And this was a transcranial image that allowed us to see CSF in this case with debris from hemorrhage surrounding the choroid plexus and another image in which there is a choroid plexus and there's much CSF within the ventricle.

Doppler Use in Neonatal Head Ultrasound

Routine imaging with doppler of the neonatal head is not that common except for a midline image Taken of the intercerebral artery on a sagittal image because if the corpus callosum is present, the a CA, the anterior cerebral artery will conform to the shape of the corpus callosum.
If it was not present, the anterior cerebral artery would go superiorly and not go over the area of the corpus callosum.
We sometimes use doppler also for the pentagram of the circle of Willis and we've used it sparingly for hydrocephalus analysis to prove mineralizing vasculopathy to look at the vein of Galen or another arterial venous malformation and not uncommonly to look at the superior sagittal sinus and other venous structures such as transverse sinus to make sure there's no clot in some of the sickly prematures who when dehydrated may develop superior sagittal sinus thrombosis and occasionally to separate out an arachnoid cyst from a blood vessel color.
Doppler simply allows you to see whether something remains cystic or has vascular flow within it.
This is an example of a transcranial technique showing the middle cerebral arteries, the one on the left being the upside.
And so this is the left middle cerebral artery.
In this case a para sagal view to one side is showing the red marked structures which are middle cerebral artery tributaries in the sylvan fissure.
So this is an example of what we look at from an anterior cerebral artery analysis and one can see that there's a corpus callosum here and the anterior cerebral artery crosses over, crosses over and is present signifying that this is a corpus callosum that's present.
Here are another two examples in which one sees the circle of Willis on a transcranial approach, the equivalent of an axial view and on a coronal approach in which one sees middle sra cerebral artery tributaries.
And we also see vessels that are the lamo dry eight vessels.
Vascular flow can obviously be assessed for peak systolic velocity.
Resistance index impulsivity index
I Linear array transducers are used as I stated for their high higher frequency and are used for high resolution analysis of superficial structures.
This is an example of one seeing flow within the superior sagittal sinus, which is very superficial compared to the remainder of the brain.
The fact that it's red in one area and blue in another area just has to do with the relationship of flow toward and away from the transducer and non visualization at a 90 degree angle to the transducer.
In this patient's case, they have a thrombosis.
There's sup sagittal sinus thrombosis so that the superficial area one is wider than normal and two is clot filled and there is no vascular flow within it.
On this sagittal view and on this coronal view, one sees the area of the superior sagittal sinus without vascular flow.
Superior sagittal sinus thrombosis can be seen for a variety of reasons including polycythemia and dehydration.
This coronal view was mostly shown to show you that this area is not echo list but echo filled
Transducer choice is a matter of a balance between the excellent near field resolution using higher frequency transducers and the better far field penetration provided by lower frequency transducers.
Desirable transducer shapes will fit fontanelles and adequately image through suture openings.
If I was to use a high frequency linear a transducer to evaluate for superior sagittal sinus thrombosis, I'll have no problem superiorly, but at the vertex and as the skull becomes rounder, I'll have more trouble using that transducer.
And I'm fortunate when I have a machine that has a smaller footprint for a high frequency curve, linear array,
Some limitations head ultrasound include hair transducer shape overlapping sutures and again as we talked about the megahertz used for penetration such that a lower frequency transducer will allow better penetration but will not allow good near field resolution.

Normal Intracranial Ultrasound Anatomy

A key to all radiologic analysis is knowledge of what's abnormal and what's normal.
Anatomically the routine exam consists of coronal views through the anterior fontanel.
Sometimes with small sutures, one can move the transducer far to the right and point to the left or far to the left and point to the right and that may help contact with the anterior fontanel.
People then evaluate patients with sagittal midline views and then right and left para sagittal views angling from the midline through the lateral ventricles and peripherally to the the sylvan fishers.
And again, we discussed additional views like the posterior fontanel view and the mastoid view.
This is a typical coronal plane view done in the area of the frontal horns when sees the in hemispheric fissure, the corpus callosum and the two frontal horns as well as the cave septum lucidum, which is seen more commonly in the premature than in the older infant.
And again, we look for the anchor sign, the corpus callosum, the court eight head, the thalamus, the frontal horn, and the Sylvie and fisher.
This is an image of a more posterior coronal plane view That's through the body of the lateral ventricles.
Among can see the entire lateral ventricle as echogenic surrounded by The ventricle without significant CSF lateral to it, suggesting that there's no ventricular magaly.
Midline images are shown here.
Look for the corpus callosum, the Cajun septum, lucidum gyr and sulci.
The third ventricle the cerebellar verus and the fourth ventricle green arrow points to the corpus callosum.
CSP stands for the cavem septum lucidum, which extends more posteriorly as the cavem virgie and the cavem velain deposit them a um, gyrus and sulcus is pointed out.
The verus of the cerebellum is marked off with a small V.
The fourth ventricle sits as if it is the mouth of a pacman as described by one of our neuroradiologist when it is normal.
So the fourth ventricle is seen here and the third ventricle is not typically seen unless dilated an additional fine point.
In this case we saw small lines in the ca septum lucidum that could worry someone, but they are normal septal veins.
The para sagal view in the just off the midline one sees the lateral ventricle and one sees a key area to look for in hemorrhage, the head of the chordate and the thalamus because where they meet is a germinal matrix area where hemorrhage tends to occur mostly.
So the lateral ventricles in pointed out C stands for the head of the chordate.
T is thalamus And gyre and salsa would be linear echogenic lines which are not seen in particular here.
One because of the positioning and two because younger neonates do not have readily seen multiple gyre or sci.
One can see over here a sulcus with its echogenic area related to a gyrus surrounding it anyway, near para sagittal plane.
In this case there are a greater amount of gyri evidence of this being an older, premature, lesser gyri obviously are evidence of a younger premature.
This is a far peripheral para sagittal plane view.
We can see greater amount of gyre here, evidence that this is an older premature, I'm saying 36 weaker, 38 weaker as opposed to somebody less than 30 weeks who would have very few gyre and sci.
And this is an example of someone with fewer gyre and ssci peripherally who's a younger neonate.
This is an example of well-known pathology images in the literature in which individual brains of different neonatal age groups are shown.
And I'm just showing you the example of the very few gyr seen at 22 weeks and at 24 weeks compared to the significant amount of gyr seen at 36 and 38 weeks.
This is an example of a coronal image on a head ultrasound showing a 24 week gestation with few gyr, which I called a toast sign 'cause this looks like a piece of toast to me.
But mostly I'm highlighting the fact that few gyr and sulci are seen.
This in a 24 weeker does not suggest lissencephaly, but if this was a 38 weeker, it might con, it might suggest lissencephaly.
So again, 24 week gestation, the Sylvie and Fisher is squarer because there's less brain to compress it and therefore it does not look like the typical Y shape of the more aged, the older neonate.

Axioms for Evaluating Premature Head Ultrasound

Things to consider before calling something abnormal and evaluating the premature head ultrasound is the periventricular white matter.
If concern because of the degree of echogenicity, particularly there is asymmetry wait 10 days to see if cysts develop so that you're not over calling echogenic PVL.
The per atrial white matter echogenicity may be an anisotropic effect only seen where sound crosses the white matter at 90 degrees.
If that's true and one worries about it, consider evaluating the brain at a different angle.
One could go through the posterior fontanel and one would not see it as abnormally echogenic.
Extra al fluid is commonly seen.
We see more now than we considered normal in the past because our paradigms have shifted because of all the CT one looks at in pediatrics and the reconstruction of those cts in sagittal and coronal planes.
There is a concept of normal fluid, particularly anterior to the neonatal brain subdural effusions of infancy.
A term that changes with time just to make sure clinicians are not worried about something that's normal.
There is symmetric periventricular white matter, which is usually normal and not evidence of echogenic PVL.
Echogenic PVL would be seen early in white matter abnormality and it would eventually break down into cystic changes that would be seen for example, two to three weeks later.
But when I see the echogenic areas not particularly white and symmetric with Either side, then it is usually normal.
And this is an example of the per atrial area, which work by de Pietro helped indicate was normal.
Not white matter abnormality but normal based on an an isotropy that occurs because of the 90 degree angle in the analysis of this area when taking an image via transducer through the anterior fontanel.
This is just an example of some extra axial fluid seen in neonates.
This is a sagittal view, this is a coronal view.

Indications for Neonatal Cranial Ultrasound

There are a number of indications for neonatal cranial ultrasound and prematures and if you look at C'S 11th edition, they will discuss screening particularly for intracranial hemorrhage in those less than a thousand or 1,250 grams in those less than 28 weeks of age.
Hypoxic ischemic encephalopathy including periventricular leukomalacia, which is focal white matter necrosis birth trauma if the kid cannot be transported to CT and prenatally detected abnormalities that are being confirmed.
Postnatally follow up are done for intercranial hemorrhage and the development of post hemorrhagic hydrocephalus, hydrocephalus itself, dilated ventricles, extra axial collections, the cause traumatic extra axial collections can occur.
Initial evaluations are done via neonatal cranial ultrasound and perhaps then moving on to MR for seizures for congenital abnormality.
For macrocephaly, for CNS infections and for suspected superior sagittal sinus thrombosis,
IVH continues to be a problem even today.
Volpes 2008 fifth edition noted a relative increase in the incidences of prematurity over time and a relative increase in preemie survival in which 85 to 90% of 500 1500 gram preemies now survive increasing the number of preemies one analyzes in an NICU,
there's been a relative increase in the incidence of IVH once of those less than 2,250 grams, 49% at IVH.
Now it's closer to 20 to 25% that develop IVH, but of those less than 1500 grams IVH incidences has increased from 1.17 to 1.45% according to his numbers almost a decade ago.
Keto IVH is bleeding in the subdermal germinal matrix, which is a highly cellular richly vascularized gelatinous area with active cell proliferations.
It obviously can occur in fetuses as well.
And this MR of a fetus shows this low intensity clot both in the lateral ventricle on the left and the third ventricle seen over here.
IV H is of great concern for the premature infant, particularly of less than 1500 grams and or less than 32 weeks gestational age.
Some groups are lowering the numbers that they evaluate premature infants looking really only at the 28 weeker or younger and the 1200 gram or younger group,
the opal area has one cell blood vessels in neuronal tissue.
The neurons are at risk for hemorrhage.
The brains of premature infants cannot change vascular inflow pressure with a change in overall neonatal blood pressure.
Such brains are pressure passive and are therefore at greater risk for injury
Appeal classified many, many years ago in 1979, germinal matrix hemorrhages grade one hemorrhages are limited to the germinal matrix area.
Grade two hemorrhages are intraventricular without dilation of the ventricles or at least less than 50% dilation.
Grade three hemorrhages or intraventricular extension from the germinal matrix area with significant ventricular dilation and grade four once thought as interventricular extension with extension into the parenchyma has been known for many years now as an interventricular extension with an associated periventricular infarction.
Tips for diagnosis include using orthogonal views to prove what one sees using other ultrasound windows to prove what one sees on a, in comparing one window to another, separating the choroid plexus from clot.
This becomes easy with time as clot becomes less echogenic, but it's sometime clot is as echogenic as hemorrhage.
Doppler can sometimes help Because choroid plexus will have vascular flow within it, but clot will not.
Fluid debris levels in the fluid-filled ventricle can help indicate that there's been hemorrhage and again, being aware of normal structures will allow one to avoid calling a normal structure and abnormality linked to hemorrhage.
Not all IVH has a subependymal origin hemorrhage originating from the choroid plexus was once thought a common cause.
Now it's thought of as a far less usual cause but can be seen according to some more often in infants and according to some perhaps related to elevated venous pressures of asphyxia or mechanical causes.
There's an evolution of hemorrhages imaged by diagnostic ultrasound.
Acute hemorrhages e echos immediately after fibrin deposition and is homogeneously echogenic with time.
However the hemorrhage becomes heterogeneous and eventually hypoechoic at some point it may have a peripheral echogenicity with an echoic center
Grade one hemorrhage is shown on these images on coronal view.
One sees echogenicity inferior on this image to the frontal horn area, but seen in the germinal matrix region on sagittal view, it's seen in the area between the head of the chordate and the thalamus, perhaps including some of the posterior aspect of the chordate.
People With grade one and grade two hemorrhages clinically do well when the grade one hemorrhages ages when the grade one hemorrhage ages, it may appear cystic as it does in the germinal matrix region in this image on sagittal view and on both sides in this image on coronal view.
Good. When the echogenicity of hemorrhage is seen within the ventricle, one must consider a grade two IVH or greater.
And this is an example of a grade two hemorrhage.
I'm pointing at the clot on the left again a gray two hemorrhage clot filling the left frontal horn and partially filling the right frontal horn and seen on the sagal view anterior to the expected area of the foramen and Monroe foramen.
And Monroe is the communication between lateral ventricle and third ventricle and choroid plexus is never seen anterior to it.
This is a grade two hemorrhage again and one sees how the clot is now more echoic compared to the choroid plexus.
This is an example of the use of colored doppler to prove that there is vascular flow within choroid plexus, the echogenic area because if it was clot there would be no vascular flow within it.
And here's another example of that.
Grade three hemorrhage, one sees this para sagittal view in which there is clot anterior to where the foramen and Monroe would be seen.
It's seen in the frontal horn region.
So therefore this is clot.
In addition, there is much debris in the temporal horn area in the occipital area consistent with hemorrhage Greater than 50%.
Dilation of the ventricle suggests that this is a grade three IVH and again, here is an image of an older clot and one one sees cast of clot near the white choroid plexus.
The echogenic choroid plexus grade four hemorrhage.
The right frontal horn is dilated filled with clot, but the clot extends anterior to where it would've been expected to be as symmetric with the left frontal horn.
So the left frontal horn is marked off with a white line and the involvement on the right side goes to the yellow line suggesting that there is associated white matter infarction.
This can be seen on the sagittal view, the right para sagittal view seen on your right, which echogenic material is seen above the area of the ventricle.
Eventually that will become cystic with time when the white matter infarct contents resorbs, one may be left with a por pha cyst, which is what you're seeing on the left.
On this patient's left side clot is seen between a much larger cystic area than just the expected frontal horn based upon the size on the right side.
And here's another example of a coronal image with early, echogenic white matter infarction.
One sees it on the para sagittal view.
This may be clot with in ventricle, but the linear markings are consistent with white matter infarction And with time these areas become cystic.
Once clot occurs, clot can physically block outflow from the ventricles or inflammation and irritation of the ian Granulations at the vertex may occur from the hemorrhage yielding post hemorrhagic hydrocephalus communicating more often than non communicating type.
Once hemorrhage occurs, post hemorrhagic hydrocephalus may occur, one third will improve over time.
One third will stay the same and one third may worsen and may require shunting.
So this is a case of post hemorrhagic hydrocephalus in which we see dilated ventricles moderately to severely dilated with contained clot that is aged enough that one sees peripheral echogenicity and central echoic area.
There also is some clot that has that has moved to the dependent surface of the ventricle in a child who is supine,
Post hemorrhagic hydrocephalus can even be seen in fetuses.
And this is an example of an MRI of a fetus with clots seen within the left lateral ventricle, dilated ventricles and a dilated third ventricle, dilated third ventricle.
This is an obstetrical ultrasound to your left and the fetal mr to your right.
Sometimes the third and fourth ventricles may be dilated.
And this is an example in which you can actually see the framing in Monroe leading to a very dilated lateral ventricle.
The third ventricle is dilated and the fourth ventricle is very dilated.
Sometimes even if there is a communicating hydrocephalus, however, you may not see the fourth ventricular dilation

Cerebellar Hemorrhage

Cerebellar hemorrhage can occur.
It often is not picked up through an anterior fontanel approach unless looked for use of the posterior fontanel and the posterolateral mastoid fontanel views evaded its diagnosis.
These techniques place the transducer closer to the sub tentorial pathology than does using the anterior fontanel.
And this is an example over time of a cerebellar hemorrhage seen earlier on and then when it was more cystic later on using a posterior fontanel or mastoid approach.
This is an example of the coronal view using an anterior fontanel in which because the clot existed and now is replaced by cystic area as residua, it can be readily seen as an abnormality in the not as well seen typically sub tentorial area on an anterior fontella view.
Lvu cerebellar hemorrhages are a type of intraparenchymal hemorrhage seen occasionally in prematures.
They may be underdiagnosed.
They're said to be found in 10 to 25% of low birth weight infants at autopsy.
70 to 85% are said to have had difficult deliveries, whether prolonged or precipitous delivery, whether forceps or breach delivery.

Hypoxic Ischemic Encephalopathy and Periventricular Leukomalacia

Neonatal hypoxic ischemic brain disease.
Volpe is indicated is related to selective neuronal necrosis.
There's para sagittal cerebral injury and watershed or vascular border injuries.
There's periventricular leukomalacia, focal coagulation necrosis in white matter and there are focal and multifocal ischemic areas of brain necrosis.
He states that patterns of brain injury, depending on gestational age, that subplate cortex is more at risk in the premature that periventricular white matter is most vulnerable to oxidative stress in the premature that there's a question of increased free radicals due to excessive nitrous oxide production, damaging oligodendrocytes it's oxidative stress.
Exo excitotoxicity activated glutamate leading to nitrous oxide increase increasing radical production and inflammation yields accelerated cell death or apoptosis.
It's a significant neonatal problem.
It occurs in one to two per thousand births, but has significant sequelae in 0.3 per thousand births.
Cystic fibrosis is a major end result periventricular white matter injury, cystic lesions or diffuse extensive high signal intensity.
D-E-H-S-I lesions are typical and prematures.
Mild to moderate injury is related to germinal matrix and periventricular white matter disease.
Both groups have affected gray matter.
Cerebral white matter disease is a better predictor of poor neurological outcome than is IVH intraventricular hemorrhage.
They are not truly periventricular since the discrete foci of coagulation necrosis are found throughout the white matter of the brain pathologically better.
It's called focal necrosis of white matter and only some of the areas are cystic.
Most remain solid areas of coagulation necrosis.
So ultrasound picks up the cystic areas very well, but MR will pick up More areas.
The areas of involvement include most often those that are dorsal and lateral to the external angles of the lateral ventricles.
PVL is seen predominantly in prematures necrosis occurs in the periventricular regions.
Glial injury with hypertrophic astrocytes occur throughout the white matter on ultrasound, acute necrosis appears echogenic and become cystic in one to three weeks.
50 to 70% of cases may be missed by ultrasound compared to autopsy.
MRI, especially the DWI sequence is helpful.
Cystic white matter necrosis occurs in three to 5% of very low birth weight infants, those less than 1500 grams and diffuse non-cystic form, which can be missed by ultrasound, diffuse non-cystic form, which can be seen better by MR than by ultrasound exists.
Examples of paraventricular leukomalacia on this coronal view one see cystic area is lateral to the right lateral ventricle and anterior to it.
And here is an example of a patient who is long-term in the nursery, develops seizures and one saw these cystic areas which are older versions of the echogenic white matter disease they had earlier in the per ventricular white matter.
Very significant involvement in this case.

Summary

In summary, this was a brief review of head ultrasound and prematures.
Ultrasound is a fine tool for the analysis of the premature brain within the safe confines of the IS isolate and NICU.
Some basic technique considerations were reviewed.
The imaging of the key abnormalities in the premature IVH and PVL were discussed.
I left out a lot that could not be fit into a 45 minute talk, which are well within ultrasound scope within the premature age group, including perinatal identification of CNS anomalies, infections, infarctions, et cetera, et cetera.
The end, I.