The method of carrying out neurosonography

Standard neurosonography is carried out through a large (front) fontanelle, on which an ultrasound transducer is located for imaging in the frontal (coronary), sagittal, and parasagittal planes. When the sensor is positioned strictly along the coronal suture, the sections in the frontal plane are obtained, then, by turning the sensor 90 °, the sections in the sagittal and parasagittal planes are derived. By changing the tilt of the sensor forward-backward, right-left, successively a number of sections are obtained to evaluate the structures of the right and left hemispheres. Axial plane (study through the temporal bone) is used in rare cases when a more detailed assessment of additional pathological formations, in particular tumors, is needed, it is often used as an option for transcranial scanning in children after the fontanelle is closed (after 9-12 months). Additional fontanels (posterior, lateral) are used in isolated cases, since they are normally closed in a healthy full-term baby. Evaluation of the structures of the posterior cranial fossa through the large occipital foramen may be difficult due to the severity of the condition of the newborn baby.

In neurosonography, a qualitative assessment of the state of the liquor-containing formations (the ventricular system of the brain, cisterns, subarachnoid space, the cavity of the transparent septum and the Verg cavity) is performed; periventricular structures; large cerebral vessels and choroidal plexuses; visual hillocks and basal nuclei; stem structures and formations of the posterior cranial fossa (cerebellum), bones of the skull.

To obtain their image, a series of ultrasonic sections are used in the frontal and sagittally-parasagittal planes.

1. F-1. Cross section through frontal lobes. In it, bone formations are represented by bright hyperechoic structures of the frontal, lattice and bones forming orbits. Clearly visible interhemispheric fissure and sickle-shaped process in the form of hyperechoic, middle structure, dividing the brain into the right and left hemispheres. The lateral cracks, on both sides, define areas of moderately elevated echogenicity-semi-oval centers.
2. F-2. Cross section through the anterior horns of the lateral ventricles. On both sides of the interhemispheric fissure, thin anechogenic structures of the anterior horns of the lateral ventricles are revealed, separated by a transparent septum. The brain sulp is located midway over the corpus callosum, which is visualized as a hypoechogenic horizontal line, delimited by the roof of the lateral ventricles and a transparent septum. Above the corpus callosum pulsation of the anterior cerebral arteries is noted. Tailed nuclei have somewhat increased echogenicity and are localized symmetrically under the lower walls of the lateral ventricles. Hyperechoic bone structures are represented by parietal bones and wings of the sphenoid bone.
3. F-3. Section at the level of interventricular orifices (Monroe's openings) and III ventricle. In this section, the anterior horns of the lateral ventricles are detected in the form of symmetrically located narrow anehogenic structures. When the sensor moves forward and backward, linear anechoic interventricular orifices connecting the lateral and third ventricles are visualized, the latter being defined as a thin, vertically arranged, anechogenous band between the visual tubercles. On the left and right under the lower wall of the anterior horns of the lateral ventricles, the echocomplex of the caudate nucleus (nucleus caudatus) is revealed, below it is the cover (putamen) and the pallid globus (globus palidum). The lateral grooves are visualized in the form of symmetrically arranged lateral structures of the Y-shaped form, in which a pulsation of the middle cerebral arteries is seen in real time. Over the corpuscular body, perpendicular to the interhemispheric gap, the echopositive linear structures of the waist furrow are determined. In the parenchyma of the right and left hemispheres of the brain, hyperechoic curved convolutions of the hippocampus are clearly visible. Between them, pulsate vessels of the arterial circle of the big brain (Willis circle). Bony structures are represented by hyperechoic parietal and temporal bones.
4. F-4. Cross section through the body of the lateral ventricles. In this section, anechoic bodies of the lateral ventricles are visualized, located on either side of the interhemispheric fissure. The corpus callosum is represented by a hypoechoic structure along the midline, above which pulsation of the anterior cerebral arteries is determined. At the bottom of the lateral ventricles are located hyperechoic vascular plexuses, vertically visualize the brain stem and IV ventricle. Between the convolutions of the hippocampus and the hint of the cerebellum are the lower (temporal) horns of the lateral ventricles, the lumen of which is not normally visible. Next to the visual crescents, the caudate and basal nuclei are defined (a tire, a pale sphere). The lateral grooves are visualized as symmetrical Y-shaped structures in the middle cranial fossa. In the posterior cranial fossa, the hamstring and the cerebellum worm are shown to be highly echogenic, the cerebellar hemispheres are less echogenic; A large cerebral cortex located under the cerebellum is anechogenous.
5. F-5. Cross section through the triangle of the lateral ventricles. On the echogram the cavity of the lateral ventricles is partially or completely filled with hyperechoic, symmetrical vascular (choroid) plexuses, which are normally homogeneous, have a clear, even contour. A small anechoic streak of cerebrospinal fluid in the lateral ventricles is visible around the vascular plexuses. The admissible asymmetry of the plexus is 3-5 mm. The hemispheric fissure is located midway in the form of a hyperechoic linear form of the structure. In the posterior cranial fossa, the worm and the nerve of the cerebellum are determined.
6. F-6. Cross section through occipital lobes. Clearly visualize hyperechoic parietal and occipital bones. The medially located fine linear structure represents the interhemispheric fissure and the sickle-like process of the dura mater. In the parenchyma of the occipital lobes of the brain, a pattern of gyri and furrows is visible.

To obtain the mid-sagittal section (C-1), the sensor must be positioned strictly in the sagittal plane. The sections in the parasagittal plane (C 2-4) are obtained by successively conducting an inclination of 10-15 ° (section through the caudal-thalamic incision), 15-20 ° (section through the lateral ventricle) and 20-30 ° (section through the "island" ) from the sagittal plane of scanning in the right and left hemispheres of the brain.

1. C-1. The median sagittal section. Hyperechoic bone structures are represented by latticed and wedge-shaped bones, the posterior cranial fossa is delimited by the occipital bone. The corpus callosum is visualized in the form of an arcuate structure of reduced echogenicity and consists of a knee, trunk and roller. In the upper margin of it, along the furrow of the corpus callosum, the pulsation of the branch of the anterior cerebral artery - the percolous artery - is determined. Above the corpus callosum is the gyrus gyrus, beneath it is the anechogenic cavities of the transparent septum and Verga, which can be separated by a thin hyperechoic strip. In most cases, these anatomical structures are clearly visible in premature infants. Ill ventricle - anechogenous, triangular in shape, facing the apex to the pituitary fossa. Its shape is due to the presence of infundibular and supraoptic processes. The main cisterns of the brain are visible: intercutaneous, quadruple, cerebromedullary. The posterior wall of the hypothalamic pocket borders on the intercostal cistern. The high level of echogenicity of this cistern is caused by a multitude of branches of the basilar artery and septum of the choroid of the brain. Behind the mezhozhkovoy cistern are the legs of the brain of reduced echogenicity, in the thickness of which there is a water pipe, the latter in the norm is practically not visible. Below and anteriorly determine the area of the bridge, represented by a zone of increased echogenicity. Anechogenous, triangular IV ventricle is located under the bridge, its apex is inserted into the hyperechoic worm of the cerebellum. Between the lower surface of the cerebellar worm, the posterior surface of the medulla oblongata and the inner surface of the occipital bone is the anechoic large cisterna (cisterna magna). In the brain parenchyma, the waist, spurs, and occipital-temporal furrows of the high echogenicity are visualized. Clearly visible pulsation of the anterior, middle, posterior and basilar arteries.
2. P-2. Cross section through caudo-thalamic cut. On the echogram, there is a caudo-thalamic notch that separates the head of the caudate nucleus from the visual hillock.
3. P-3. Cross section through the lateral ventricle of the brain. In the study, anechoic parts of the lateral ventricle are visualized: anterior, posterior, lower horn, body and triangle surrounding the visual hillock and basal cores. In the cavity of the lateral ventricle there is a homogeneous, hyperechoic vascular plexus having an even, oval contour. In the anterior horn, there is no vascular plexus. In the hind horn is often noted for its thickening ("glomus"). Around the ventricle, in the periventricular area, a moderate increase in echogenicity from both sides is noted.
4. P-4. Cross section through the "island." The cut passes through the anatomical region of the "islet", in the parenchyma of which the hyperechoic structures of the lateral and minor furrows are visible.

A feature of the brain of premature infants is the visualization of the cavity of the transparent septum and the cavity of Verge. Also, in newborns born on the 26-28th week of gestation, a wide subarachnoid space is visualized. In preterm - 26-30 weeks of gestation - lateral (Silviev) furrow is a complex of increased echogenicity, reminiscent of the shape of a triangle or "flag" due to insufficiently formed brain structures that separate the frontal and temporal lobes. In preterm to 34-36 weeks of gestational age in the periventricular area, symmetric zones of increased echogenicity (periventricular aureole) are determined, which is related to the peculiarities of the blood supply of this zone. Because of the different rates of maturation of the brain and the ventricular system, the relative size of the lateral ventricles in a premature baby, as in a fetus, is considerably larger than that of a mature full-term newborn.

In children after the first month of life, the echographic characteristics of normal anatomical structures of the brain depend, first of all, on the gestational age at its birth. In children older than 3-6 months in the coronary plane, a "split" interhemispheric fissure is often seen. The size of a large tank after 1 month of life should not exceed 3-5 mm. If the dimensions of the cistern from birth remain more than 5 mm or increase, an MRI should be performed to exclude the pathology of the posterior cranial fossa and, above all, the hypoplasia of the cerebellum.

When measuring the ventricles of the brain (ventriculometry) the most stable are the dimensions of the anterior horn (1-2 mm in depth) and the body (depth not exceeding 4 mm) of the lateral ventricle. The anterior horns are measured in the coronary plane in sections through the front horns, interventricular orifices, the measurement of the body is carried out in a cut through the bodies of the lateral ventricles. III ventricle is measured in the coronary plane in a cut through the interventricular orifice and is 2-4 (2.0 ± 0.45) mm. Evaluation of the size of the IV ventricle is difficult, pay attention to its shape, structure and echogenicity, which can significantly change in the course of brain development abnormalities.

Scanning techniques

Use a 7.5 MHz sensor, if available: if - you can use a 5 MHz sensor.

Sagittal section: Place the sensor in the center on top of the front fontanelle with the scan plane along the long axis of the head. Tilt the sensor to the right to visualize the right ventricle, and then - left to visualize the left ventricle.

Frontal section: rotate the sensor 90 ° so that the scan plane is located transversely, tilt the sensor forward and backward.

Axial slice: place the sensor directly above the ear and tilt the scan plane up to the cranial vault and down to the base of the skull. Repeat the study on the other side.

Normal middle anatomy

In 80% of newborns, the liquid-containing structure of the cavity of the transparent septum creates a median structure. Below the cavity the triangular fluid-containing cavity of the third ventricle will be determined, and the surrounding structures will be normal brain tissues of different echogenicity.

Sagittal section

Inclined sections on each side of the brain need to visualize the lateral ventricles in the form of an inverted "U". It is important to visualize the structure of the thalamus and caudate nucleus below the ventricles, since this area of the brain most often has hemorrhages.

By tilting the sensor, you can get an image of the entire ventricular system.

Echogenic vascular plexus can be visualized inside from the vestibule and temporal horns. 

Frontal section

It is necessary to conduct multiple sections at different angles, individual for each patient, for visualization of the ventricular system and adjacent structures of the brain. Use the optimal scan angle to examine each specific area of the brain.

Axial section

First, the lowest cuts need to get an image of the legs of the brain in the form of structures resembling the shape of the heart, as well as the image of pulsating structures - the vessels of the Willis circle.

The following sections will give a slightly higher image of the thalamus and the centrally located structure of the cerebral crescent.

The highest (upper) slices will give an image of the walls of the lateral ventricles. In these sections, the ventricles and corresponding hemispheres of the brain can be measured.

The ratio of the diameter of the ventricle to the diameter of the hemisphere should not be more than 1: 3. If this ratio is greater, hydrocephalus may be present.