Diagnostic ultrasound ( PDFDrive )

122 PART II Abdominal and Pelvic Sonography
TABLE 4.4 Schematic of Algorithm for Diagnosis of Nodules in Cirrhotic Liver on Computer-
Enhanced Ultrasound
Typical
AP: Hypervascular
PVP: Washout
HCC
AP variation
PVP variation
AP: Isovascular
PVP: Washout
AP: Hypervascular
PVP/Delayed PVP: No washout
AP: Hypervascular
Delayed washout
Benign
DN
AP: Transient hypovascular
PVP: Isovascular
Nodules
RN
AP and PVP: Isovascular
AP
PVP
Delayed PVP
(+) Enhancement Isovascular
(–) enhancement
(wash out)
Overlap between DN and WDHCC
(Any arterial enhancing foci or dysmorphic vessels within a nodule or
obvious washout during portal phase should raise a suspicion of HCC.)
AP, Arterial phase; HCC, hepatocellular carcinoma; PVP, portal venous phase; WDHCC, well-differentiated hepatocellular carcinoma.
With permission from Wilson SR, Burns PN. Microbubble-enhanced US in body imaging: what role? Radiology. 2010;257(1):24-39. 148
slow and weak. Variations to this classic pattern are well
described 184 and include arterial phase hypovascularity and
delayed or no washout in the portal venous phase (Fig. 4.58).
Regenerative nodules, by comparison, show similar arterial phase
and portal venous phase vascularity and enhancement to the
remainder of the cirrhotic liver. Dysplastic nodules may
show transient arterial phase hypovascularity followed by isovascularity.
Identiication of this feature prompts biopsy in our
institution.
Microbubble-enhanced sonography may contribute also to
the detection of HCC. Sweeps of the liver in the arterial phase
may detect hypervascular foci potentially representing HCC.
Sweeps in the portal venous and late phases, by comparison,
show HCC as hypoechoic or washout regions, again allowing
for the detection of unsuspected lesions. he arterialized liver
of cirrhosis, however, is problematic for several reasons. First,
it shows dysmorphology of all liver vessels, in general, and the
appreciation of focal increased vascularity in a small nodule is
more diicult. Portal venous phase imaging is also weakened
when the liver receives a greater proportion of its blood supply
from the hepatic artery. herefore washout of a speciic nodule
may not be as evident as in a normal liver. CT and MRI are
frequently performed to screen for and evaluate HCC. he
importance of CEUS for the management of small nodules
detected in the surveillance for HCC is controversial and CEUS
is included in some international guidelines but not others. 185
CEUS may play a pivotal role on the basis of its real-time
demonstration of continuous hemodynamic changes of liver
tumors, a purely intravascular contrast material, availability in
patients with renal failure, excellent patient compliance, and
repeatability in short intervals. CEUS is integrated into our
approach for management and diagnosis of nodules in patients
at high risk for HCC.
Fibrolamellar carcinoma is a histologic subtype of HCC
found in younger patients (adolescents and young adults) without
coexisting liver disease. he serum alpha-fetoprotein levels are
usually normal. he tumors are usually solitary, 6 to 22 cm, well
diferentiated, and oten encapsulated by ibrous tissue. 186-188 With