Diagnostic ultrasound ( PDFDrive )

CHAPTER 45 Neonatal and Infant Brain Imaging 1515
A B C
D
E
F
FIG. 45.3 Normal Coronal Brain Images: Premature Newborn Infant. (A)-(F) Coronal images in very premature infant; ventricles can be
larger with extreme prematurity. (C) Sylvian issures (arrows) appear boxlike.
lentiform nuclei may no longer be seen at this level. he temporal
horns of the lateral ventricles may be seen lateral and inferior
to the thalami, but are usually not seen unless there is
hydrocephalus.
Further posteriorly, the trigone or atrium of the lateral
ventricles and occipital horns are visualized (see Fig. 45.2E).
he extensive echogenic glomus of the choroid plexus nearly
obscures the lumen of the cerebrospinal luid (CSF)–illed ventricle
at the trigone. In the midline—the visualized portion of the
corpus callosum deep to the cingulate sulcus—is the splenium.
Inferiorly, the cerebellum is separated from the occipital cortex
by the tentorium cerebelli.
he most posterior section visualizes predominantly occipital
lobe cortex and the most posterior aspect of the occipital horns
of the lateral ventricles that do not contain choroid plexus (see
Fig. 45.2F). his section is angled posterior to the cerebellum.
Normal premature brain ultrasound images in the same planes
are shown in Fig. 45.3. he lateral ventricles are slightly larger;
the cavum septi pellucidi extends back to become the cavum
vergae between the lateral ventricle bodies and occipital horns.
here are only a few sulci, and the sylvian issures are wider and
typically appear boxlike rather than as thin issures. he basal
ganglia in premature infants are normally difusely homogeneously
echogenic, an appearance that is more prominent than in the
thalami and typically more echogenic than the cerebral cortex.
Basal ganglia and thalami do not show increased echogenicity
at term-equivalent age. 17
Sagittal Imaging
he sagittal images are obtained by placing the transducer
longitudinally across the anterior fontanelle and angling it to
each side (Fig. 45.4, Video 45.2). he midline is irst identiied
through the interhemispheric issure by recognition of the curving
line of the corpus callosum above the cystic cavum septi pellucidi
and cavum vergae. Below the cavum lies the choroid plexus in
the roof of the third ventricle. If there is third ventricular enlargement,
the massa intermedia will be outlined by CSF and the
aqueduct of Sylvius may be visualized. he fourth ventricle is
identiied as a notch in the anterior surface of the highly echogenic
cerebellar vermis 18 (Fig. 45.5).
he cingulate sulcus lies parallel to and above the corpus
callosum. he highly echogenic falx can be diicult to scan directly
through and obtain a clear midline sagittal image; therefore a
very slight movement to either side of the falx may be necessary
to adequately visualize midline brain structures. In this view,
the size of the cerebellar vermis has been used to assess gestational
age. 19 However, the degree of sulcal development is the most
reliable method for gestational age based on established pathologic
standards. 20 Shallow angulation to each side of about 10 degrees
will show the normally small lateral ventricles (Fig. 45.6A-B).
he ventricles are not located in a perfectly straight plane anterior
to posterior. he transducer must be angled so that the anterior
portion of the sector is directed more medially and the posterior
portion more laterally, to include the entire lateral ventricle in
a single image. 13