Diagnostic ultrasound ( PDFDrive )

1518 PART V Pediatric Sonography
A
B
C
D
FIG. 45.8 Occipital Horn. (A) Sagittal occipital horn from the posterior fontanelle. (B) Same sagittal occipital horn from the anterior fontanelle.
(C) Coronal occipital horns from the posterior fontanelle; echogenic clot visible in right occipital horn. (D) Same occipital horn; linear transducer
shows increased resolution.
echogenic midline vermis, which appears less echogenic in the
axial view compared with midline sagittal scans. When angled
axial images are obtained through the lower parts of the cerebellum
below the fourth ventricle, the (normally thin) vallecula
may be seen in the midline as a space between the cerebellar
hemispheres (see Fig. 45.9C), particularly in the presence of
hydrocephalus. In steeply angled axial scans, the foramen of
Magendie can be seen in the midline as a thin sonolucent line
between the cerebellar hemispheres extending from the fourth
ventricle to the cisterna magna. It should not be mistaken for a
Dandy-Walker variant. 25 he presence of an intact vermis on
higher images and the marked caudal angulation required to
see the vallecula allow diferentiation of this normal variant. 11,12,14
Color Doppler ultrasound in this view allows evaluation of low
in the transverse and straight sinuses to exclude venous
thrombosis.
A slightly higher axial scan should include the thalami,
midbrain, third ventricle, aqueduct of Sylvius, and quadrigeminal
plate cistern, with the transducer angled from the standard axial
plane and placed cephalad to the external auricle (Fig. 45.10).
At this level, the thalami are hypoechoic, inverted, heart-shaped
structures. he midbrain, including the cerebral peduncles and
corpora quadrigemina, consists of paired hypoechoic lenticular
structures just caudal to the thalami. he third ventricle is usually
a thin clet, barely visible between the thalami. he aqueduct is
usually a thin echogenic line but may occasionally be a thin slit
in the midbrain. he quadrigeminal cistern is echogenic and
surrounds the midbrain.
Three-Dimensional Ultrasound
hree-dimensional (3-D) ultrasound may be a useful adjunct to
standard two-dimensional (2-D) imaging of the neonatal brain. 26
A volume of brain can be acquired in a few seconds, and then
reconstructed displays of three octagonal slices at any angle can
be viewed, in addition to coronal, sagittal, and axial planes. Brain
lesions can be tracked in three views at once, which can better
identify the position in the brain and the most likely diagnosis.
Some authors recommend 3-D volume measurement of the
ventricles 27,28 ; the standard method is still a qualitative assessment
based on typical normal ventricles of diferent age groups.
STANDARDIZED REPORTS
Standardized Views for Display
Brain anatomy images should be displayed in a consistent manner
so that comparisons can be easily made. At our institution, routine
sagittal images are always shown with the infant’s face to the
let. Labels on sagittal scans should be “let” or “right.” Video
clips are more diicult to label and might be best done separately
on the let and right, in addition to a full sweep through the
entire brain from side to side.