This document provides information about performing a fetal neurosonogram. It begins with basic embryology of the developing central nervous system. It then discusses the key features to evaluate in a neurosonogram, including biometric measurements and assessment of brain structures. Different imaging planes and techniques like 3D and tomographic ultrasound are described. Common central nervous system anomalies that can be detected on ultrasound are listed and briefly described. The document emphasizes the importance of understanding fetal brain development and utilizing multiple imaging planes and advanced techniques to thoroughly evaluate the fetal central nervous system.
2. Special thanks from the heart to
PROF. DR. MOHAMED ABDEL-ALEEM NAFADY
Professor of radiodiagnosis
faculty of medicine, Al-Azhar university , Assuit
For his never end support during the conduction of this work
It is a great honor to work under his supervision.
PROF. DR. ABDEL-AZEZ GALAL ALDEN ALDARWESH
Professor of gynecology and obstetrics
faculty of medicine, Al-Azhar university , Assuit
For his never end support during the conduction of this work
It is a great honor to work under his supervision.
DR.SAAD REZK ABDEL WAHED
Assistant professor and head of radiodiagnosis department
faculty of medicine, Al-Azhar university , Assuit
For his guidance, support and perseverance.
3. Also , I would like to express my deepest thanks to
PROF. DR/ MUSTAFA THABET HUSSIN
Professor of radiodiagnosis
Faculty of medicine , Assuit university
And
PROF. DR/ MOHAMAD ABDEL SAMIE MOHAMAD
Professor of gynecology and obstetrics
Faculty of medicine , Al azhar university , Assuit.
For honoring us today to come , and for their effort in reviewing this study.
6. The brain is the only fetal organ that continuously
develops & changes during fetal life
The largest changes occur within the 1st 20 wks,
when most scans are done
CNS anomalies are among the most common fetal
anomalies (second after cardiac anomalies).
To do fetal ultrasound neuroscan one has to:
1. know some basic embryology
2. Know the developmental milestones
3. Have a high frequency transducer and understand
how 3D works
4. Understand the most frequent CNS anomalies
7.
8. Graphic shows the formation, closure of the neural tube. The neural
plate (red) forms, folds, and fuses in the midline. The neural and
cutaneous ectoderm then separate. Notochord (green), neural crest
(blue) are shown.
A. Consists of 3 layers of cells:
endoderm, mesoderm, and
ectoderm.
B. Thickening of the ectoderm
leads to the development of the
neural plate
C. The neural groove begins to
develop at 20 days.
D. At 22 days the neural groove
closes along the length of the
embryo forming the neural tube.
9. The neural tube closes in a bidirectional
zipper-like manner, starting in the
middle and proceeding
toward both ends.
Development of primary vesicles is depicted.
The prosencephalon (green) gives rise to the
forebrain, the mesencephalon (purple) to
the midbrain, and the rhombencephalon
(light blue) to the hindbrain.
10. Embryonic brain at 22 weeks is mostly agyric
with shallow sylvian fissures .
Prosencephalon (green), metencephalon
(yellow), and myelencephalon (light blue)
are shown. Mesencephalic, midbrain
structures are not visible.
With advancing gestational age, multiple
secondary and tertiary gyri develop, and the
number and complexity of the cerebellar
folia increase.
11. Three orthogonal images and thick slice of three-dimensional reconstructed image
(lower right) of normal brain at the end of 8 weeks of gestation. The development of
premature ventricular system is seen.
13. Three-dimensional (3D) sonography should be
accepted as a natural development of ultrasound
imaging technology.
Fast computer processing is essential for 3D and 4D
sonography.
The first 3D-capable systems were developed in the
mid-1990s.
3D acquisition was performed by moving the
transducer over the region of interest (ROI) with the
operator’s hand at a constant speed.
14. On reaching the ROI, the operator must keep the
transducer stable while the patient stays still, so that
the probe may continue scan.
Images are then captured and processed by a computer
that will display them three-dimensionally.
In the multiplanar volume mode three planes are
shown – longitudinal or sagittal (A-plane), transverse
(B-plane), and coronal (C-plane) – and an orthogonal
reconstruction is obtained, which may be rotated
around three axes (x, y, z)
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22.
23. 1- Maternal factors:
Abdominal wall
thickness.
Colitis.
Mother breathing.
Obesity.
3- Amniotic fluid
(oligohydramnios).
2- Fetal factors:
Position (face down).
Age of fetus.
Movement of the fetus.
Multiple fetuses.
4- Operator skills and
experience.
5- Machine capabilities.
24.
25. The most useful features of 3D scanning of the fetal
CNS:
– Orthogonal planes
–Tomographic imaging
–Angiography
– Inversion mode.
–Thick slice/volume contrast imaging
26. 3D multiplanar image
analysis (normal brain at
18 weeks of gestation).
The use of three
orthogonal views is
helpful in obtaining the
orientation of the brain
structure. Coronal (A),
sagittal (B), and axial (C)
images can be visualized
on a single screen. Any
rotation of the brain
image around any (x,y,z)
axis is possible
27. Tomographic ultrasound imaging (TUI) of the fetal brain. Normal brain in coronal
section at 31 weeks of gestation. Intracranial structures, including gyral formation,
are clearly demonstrated and also compare both cerebral hemisphere
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32.
33. Normal brain at 9 weeks of gestation. Tomographic ultrasound imaging of sagittal (A),
coronal (B), and axial (C) sections. The premature ventricular system is demonstrated.
In the coronal and axial sections, the already-divided bilateral hemispheres can be
visualized
34. Normal brain at 12 weeks and 5 days of gestation. Tomographic ultrasound imaging of
sagittal (A), coronal (B), and axial (C) sections. The rate of occupation of the cerebral
hemispheres becomes larger compared with previous images. The bilateral echogenic
structure is the choroid plexus filled the lateral ventricles
35. Normal brain at 17 weeks of gestation. Tomographic ultrasound imaging of sagittal
(A), coronal (B), and axial (C) sections. The choroid plexus (echogenic part) shifts to
the posterior half of the lateral ventricles
36. Normal brain at 31 weeks of gestation. Tomographic ultrasound imaging of sagittal (A),
coronal (B), and axial (C) sections. Formation of sulci and gyri is clearly observed from
around 30 weeks of gestation. The Sylvian fissure (arrows) is formed as the lateral
sulcus
37.
38. Sonography of the CNS
Basic examination
Axial plane Sagittal plane
Neuroscan or extended
examination
48. Better demonstration of the midline structures esp.
corpus callosum and cerebellar vermis.
Visualization of both hemispheres.
Better identification of cerebral sulci.
Detailed examination of fetal spine.
51. 1/1000, M:F = 4:1
Anencephaly/exencephaly sequences.
Absent cranial vault.
Begins as exencephaly (exposed neural tissue) that
gets eroded by amniotic fluid and fetal movement.
1st trimester: exposed brain tissue gives Mickey Mouse
appearance.
2nd & 3rd trimester: neural tissue has resolved (frog like
appearance).
52. The three orthogonal planes and a rendered
three-dimensional image of the fetus seen in
The coronal image (C) demonstrates lack of
calvarial bon
A typical-appearing fetus with exencephaly-
anencephaly sequence is shown using the
tomographic feature. there is less visible
brain tissue.
53. Excess CSF production or obstructed flow.
Measures the posterior horn of lateral ventricle > 10
mm in 2nd trimester.
Choroid plexus to medial border of lateral ventricle
wall > 3 mm.
Maximum cortical thickness < 1o mm. denoting poor
prognosis.
Aqua ductal stenosis lead to third ventricle dilatation.
Time of delivery: when doppler shows increase MCA
PI which mean increase intracranial tension.
54.
55. Hydrocephalus (left) and ventriculomegaly (right). Tomographic ultrasound imaging of
X-linked hydrocephalus at 21 weeks and ventriculomegaly at 25 weeks .
59. Extensive ONTD triad of:
1. Occipital encephalocele.
2. Fixed hyperextension of the fetal head.
3. Cervical dysraphism.
US findings:
1. Short CRL due to absent cervical spine.
2. Head fixed in hyperextension.
3. Cephalocele.
3/10,000 F:M 9:1
Lethal condition.
60.
61. Spina bifida, ONTD, spinal dysraphism.
US findings:
1. Obliterated cisterna magna.
2. Banana sign (cerebellum raped around brain stem
90%).
3. Lemon sign (depressed frontal bone 98%).
4. Ventriculomegaly.
5. Lumbo-sacral myelo-meningocele.
High morbidity.
62.
63.
64. Dysgenesis of the cerebellar vermis.
Dilated 4th ventricle connected with cisterna magna.
Mortality
1. 50% when isolated.
2. 80% when associated with other anomaly.
Karyotyping: 30% chromosomal.
1:30 000
Low intelligence is 80% of isolated cases.
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70. 1: 20, 000
US findings:
1. Absent cavum septum pellucidum in axial planes.
2. Lateralization of lateral ventricles.
3. Tear drop shape.
4. Mild ventriculomegaly.
Mid sagittal plane is diagnostic.
85% isolated.
71. Ventriculomegaly in a case of complete agenesis of the corpus callosum (frontal
horns scalloped outward)
72. Sever brain and facial malformations.
Incomplete cleavage of prosencephalon at 4-6 W.
1:16,000.
Three forms:
1. Alobar: single ventricle & fused thalami.
2. Semi lobar: Partially separated hemispheres & partially
fused thalami.
3. Lobar: separated hemispheres& thalami with absent CSP.
Prognosis:
1. Alobar: incompatible with life.
2. Semi lobar and lobar: mental retardation
73. Alobar holoprosencephaly at 15 weeks of gestation. (A–C) Three orthogonal images of
intracranial structure showing a complete single ventricle within a single-sphered
cerebral structure
74.
75. Complete destruction of cerebral hemispheres with normal
cerebellum and brain stem.
May be due to vascular occlusion or toxoplasmosis.
Lethal.
US findings:
1. No cerebral tissue (No MCA flow).
2. Falx cerebri may be seen.
3. Normal posterior fossa.
4. Brain stem protrude to fluid filled calvaria.
76. Hydranencephaly. The absence of brain high
in the convexities distinguishes
hydranencephaly from severe hydrocephaly.
The midbrain and posterior fossa (arrows)
are normal
77. Arachnoid cyst is encysted CSF displaced normal brain
tissue of good prognosis if isolated.
This is the three orthogonal planes taken during the primary vesicles formation and premature ventricular system more evident at sagittal reconstruction
This explain how 3D machine work.
The probe move in constant speed then the images are captured and processed by a computer that will display them in 3D image and in multiplanar volume mode of three orthogonal planes.
This is the final result after the computer processing images and display them as three orthogonal volume on the screen.
The region inside the box will appear as 3D image while the structures that not selected will be cut from the 3D reconstruction
These are the regions included inside the box.
In 3D volume we see three orthogonal planes axial, coronal and sagittal
We can rotate them on their axes X, Y, Z, to obtains a good image, the colored dot should be in the same region center and perpendicular on the region of interest.
We rotate the volume to align axial and coronal midline so we see good sagittal plane
Midline structures axial, coronal and sagittal
Posterior fossa axial, coronal and sagittal
When we take a multiplanar volume image what we can do
Can assess brain vascularity as circle of wills and pericallosal artery
The commonest anomaly more in males
Rt. Shows dilated 3rd vent. Denoting aqua ductal stenosis. Left shows ventriculomegaly
Differential diagnosis of ventriculomegaly
Occipital meningo-encephalocele in tomographic sagittal plane
Cervical spine anomaly, encephalocele and hyperextension of the head
Herniated cerebellar tonsil, ventriculomegaly, lemon and panana signs
DD of Skull shape
Wide 4th ventricle connected to cisterna magna in sagittal view, coronal 3D image and ventriculomegaly inversion.
Facial anomalies with holoprosencephaly in alobar and semi lobar