Diagnostic ultrasound ( PDFDrive )

1522 PART V Pediatric Sonography
below the columns of the fornices. 2,37 It may appear as an anechoic,
inverted, helmetlike space just inferior and posterior to the
splenium in the pineal region (see Fig. 45.12E). Blasi and colleagues
38 have described the prenatal diagnosis of the cavum
veli interpositi on 2-D and 3-D ultrasound with color low
Doppler. Careful study of the anatomic location of the cystic
structure, its size, and changes over time is required to be certain
this is a normal variant, not an arachnoid cyst with mass efect
or associated anomaly of the corpus callosum. Chen and colleagues
37 reported that 21% of neonates have a cavum veli
interpositi on sonography. By 2 years of age, this cystic area is
an uncommon inding and thus is thought to be a normal stage
of brain development. Rarely, a cyst is found in this area that
causes compression of other structures.
Frontal Horn Variants
A few newborns have cysts exactly parallel (not above or below)
and adjacent to the frontal horns (Fig. 45.14). hese cysts are
typically bilateral and have septations between the cyst and the
frontal horns. Frontal horn cysts, also called coarctation of
the frontal horn 39 and connatal cysts, 40 are caused by folding
of the frontal horn on itself, resulting in kinking (seen as a septation).
Typical normal frontal horns are directly lateral to the
cavum septi pellucidi on coronal images, below the corpus
callosum. he frontal horns are relatively thin compared with
the occipital horns.
Choroid Plexus and Variants
he choroid plexus is the site of CSF production in the ventricles
(Fig. 45.15). he largest portion of the choroid plexus is the
glomus, a highly echogenic structure attached to the trigone of
each lateral ventricle. he choroid tapers as it extends anteriorly
to the foramen of Monro and continues from each lateral ventricle
into and along the roof of the third ventricle. he choroid plexus
tapers laterally as it extends into the temporal horn of the lateral
ventricle. he choroid plexus does not extend into the frontal
CSP
Cavum vergae
Choroid third ventricle roof
Choroid glomus
in trigone of
lateral ventricle
FIG. 45.13 Cavum Septi Pellucidi (CSP). Arrow indicates cavum
vergae projecting on the medial surface of the lateral ventricles. (With
permission from Rumack CM, Manco-Johnson ML. Perinatal and infant
brain imaging: role of ultrasound and computed tomography. St Louis:
Mosby; 1984. 7 )
FIG. 45.15 Choroid Plexus. Drawing shows choroid plexus as it
courses through the third and lateral ventricles (arrows). (With permission
from Rumack CM, Manco-Johnson ML. Perinatal and infant brain imaging:
role of ultrasound and computed tomography. St Louis: Mosby; 1984. 7 )
A
B
FIG. 45.14 Frontal Horn Cysts. (A) and (B) Coronal and sagittal sonograms show the uncommon normal variant, also called “coarctation of
the frontal horn” or “connatal cysts,” which are immediately lateral (arrow) to the ventricle. They are thought to be caused by folding of the frontal
horn on itself. (There is also bilateral subependymal and intraventricular hemorrhage in both frontal horns.)