Diagnostic ultrasound ( PDFDrive )

1584 PART V Pediatric Sonography
.06
.06
.40
.40
m/s
m/s
.40
No comp
.40
Comp
FIG. 46.10 Left-Sided Germinal Matrix Hemorrhage (GMH) With
Obstruction of Terminal Vein Resulting in Periventricular Venous
Stasis and Hemorrhagic Infarction. Flow in left subependymal vein
(curved arrow) is obliterated by the hematoma. Flow in normal right
subependymal vein (straight arrow) is shown.
FIG. 46.12 Hydrocephalus Causes Increased Resistive Index (RI)
When Gentle Anterior Fontanelle Pressure Is Added. Pulsed wave
Doppler tracing of the anterior cerebral artery with transducer held lightly
over anterior fontanelle (No comp) shows an RI of 0.69. Repeat tracing
obtained a few seconds later with transducer irmly held over fontanelle
(Comp). RI has increased to 0.99, indicating abnormal intracranial compliance.
Comp, Compression.
Resistive index in the anterior cerebral artery
110
100
90
80
70
60
Pre-tap
Post-tap
Baseline
Compression
Fontanelle compression
FIG. 46.13 Shunted Hydrocephalus Is Less Sensitive to Pressure
Effects on Fontanelle. Graph of serial resistive index (RI) determinations
in an infant with hydrocephalus before (Pre-tap) and after (Post-tap)
shunt shows greatly diminished hemodynamic response to fontanelle
compression after ventricular drainage. Note that RI is quite similar at
baseline and increases with fontanelle compression.
FIG. 46.11 Luxury Perfusion Secondary to Left Middle Cerebral
Artery Ischemic Stroke in Full-Term Neonate. Coronal amplitude-mode
Doppler image shows greatly increased blood low to the ischemic
mildly hyperechogenic area (arrows), consistent with luxury perfusion.
which may dilate owing to the venous overload. Consequently,
the correct terminology would be “vein of Galen aneurysmal
dilation” (VGAD). Ultrasound is an important imaging tool
that allows the direct visualization of the dilated vessels of vein
of Galen aneurysms as well as possible complications such as
brain edema and hydrocephalus. VGAM and VGAD are typically
diagnosed prenatally by ultrasound screening. 63 Prenatal and
postnatal color low sonography and spectral analysis of the
blood low curves within the supplying and draining vessels give
important hemodynamic data both before and ater treatment
(Figs. 46.14 and 46.15). Spectral Doppler imaging typically shows
arterialization of venous low and increased low velocities, with
reduced pulsatility of the arterial feeders. Blood low in the more
peripheral portions of brain may show diminished or absent
low as a result of a “vascular steal” away from the normal cerebral
circulation through the low-resistance malformation. 64,65
Sinus pericranii is a congenital venous vascular malformation
characterized by a luctuating, compressible subcutaneous venous
mass lesion in which the intracranial and extracranial veins are
connected through a calvarial defect (Fig. 46.16). he lesion
typically increases in size during crying. Duplex Doppler sonography
easily diferentiates the lesion from various diferential
diagnoses including meningoencephaloceles, dermoids (Fig.