Diagnostic ultrasound ( PDFDrive )

CHAPTER 4 The Liver 113
A
B
C
D
FIG. 4.47 Characterization of Hemangioma With Deinity Enhancement. Resolution of an indeterminate mass on computed tomography
(CT) scan is shown in a 65-year-old man with carcinoma of the esophagus. (A) CT scan of the thorax shows an indeterminate incidental enhanced
mass in the left lobe of the liver. (B) Sagittal sonogram shows the mass is hypoechoic. (C)-(E) Frames taken between 10 and 14 seconds after
the injection of contrast agent showing peripheral nodular enhancement and centripetal progression of enhancement in spite of the rapidity of
lesion illing. This is a classic lash-illing hemangioma. The lesion remained enhanced to 5 minutes (not shown). See also Video 4.6. (With permission
from Wilson S, Burns P. Microbubble-enhanced US in body imaging: what role? Radiology. 2010;257[1]:24-39. 148 )
E
childbearing years. 152,153 As with hemangioma, FNH is invariably
an incidentally detected liver mass in an asymptomatic patient.
FNH is typically a solitary well-circumscribed mass with a
central scar. Most lesions are less than 5 cm in diameter. Although
usually single, multiple FNH masses have been reported. Microscopically,
lesions include normal hepatocytes, Kupfer cells,
biliary ducts, and the components of portal triads, although no
normal portal venous structures are found. As a hyperplastic
lesion, there is proliferation of normal, nonneoplastic hepatocytes
that are abnormally arranged. Bile ducts and thick-walled arterial
vessels are prominent, particularly in the central ibrous scar.
he excellent blood supply makes hemorrhage, necrosis, and
calciication rare. hese lesions oten produce a contour abnormality
to the surface of the liver or may displace the normal blood
vessels within the parenchyma.
On sonography, FNH is oten a subtle liver mass that is diicult
to diferentiate in echogenicity from the adjacent liver parenchyma.
Considering the histologic similarities to normal liver, this is
not a surprising fact and has led to descriptions of FNH on all
imaging as a “stealth lesion” that may be extremely subtle or
completely hidden. 154 Subtle contour abnormalities (Fig. 4.48)
and displacement of vascular structures should raise the possibility
of FNH. he central scar may be seen on gray-scale sonograms
as a hypoechoic, linear or stellate area within the central portion
of the mass 155 (Fig. 4.48A). On occasion, the scar may appear
hyperechoic. FNH may also display a range of gray-scale appearances,
from hypoechoic to rarely hyperechoic.
Doppler ultrasound features of FNH are highly suggestive,
in that well-developed peripheral and central blood vessels are
seen. Pathologic studies in FNH describe an anomalous arterial
blood vessel larger than expected for the location in the liver. 151
Our experience suggests that this feeding vessel is usually quite
obvious on color Doppler imaging, although other vascular masses
may appear to have unusually large feeding vessels as well. 156
he blood vessels can be seen to course within the central scar
with either a linear or a stellate coniguration. Spectral interrogation
usually shows predominantly arterial signals centrally, with
a midrange (2-4 kHz) shit.
Similar to hemangioma, FNH is consistently diagnosed with
CEUS. 157-160 In the arterial phase, lesions are hypervascular, and
highly suggestive morphologies include the presence of stellate
lesional vessels, a tortuous feeding artery, and a centrifugal illing