Diagnostic Ultrasound - Abdomen and Pelvis

Hepatocellular Carcinoma
TERMINOLOGY
Abbreviations
• Hepatocellular carcinoma (HCC)
Definitions
• Malignant neoplasm originating from hepatocytes
IMAGING
General Features
• Best diagnostic clue
○ Solid, intrahepatic mass > 1 cmin patient with risk factors
such as chronic hepatitis or cirrhosis
○ Portal vein or hepatic vein tumor invasion highly
suggestive of HCC
• Size
○ Small or large: < 3 cm to> 5 cm
○ Diffuse or infiltrative: Subcentimeter to > 5 cm
• Key concepts
○ Most frequent primary visceral malignancy globally
– Accounts for 80-90% of all adult primary liver
malignancies
– Usually arises in cirrhotic liver, due to chronic viral
hepatitis (HBV, HCV) or alcoholism
○ 2nd most common malignant liver tumor after
hepatoblastoma in children
○ Growth patterns of HCC: 3 major types
– Solitary, often large mass
– Multinodular or multifocal
– Diffuse or infiltrative
○ Metastases to lung, bone, adrenal, lymph node
Ultrasonographic Findings
• Grayscale ultrasound
○ Hypoechoic: Most common sonographic appearance
– Solid tumor
– May be surrounded by thin, hypoechoic halo (capsule)
○ Hyperechoic
– Indicates fatty metamorphosis/hypervascularity
– Simulates hemangioma/focal steatosis
□ If risk factors are present and hyperechoic lesion > 1
cm detected, cannot assume hemangioma
○ Mixed echogenicity: More common in larger HCC
– Indicates tumor necrosis/fibrosis
– Focal fat in some HCCs appear echogenic
○ Background cirrhosis (except for fibrolamellar HCC and
hepatitis B)
○ Calcification is rare unless treated
○ Invasion of portal vein & less commonly hepatic vein
highly suggestive of HCC
○ Hemoperitoneum if subcapsular or exophytic HCC
ruptures
○ Associated signs of portal hypertension: Ascites,
splenomegaly, portosystemic collaterals
○ Fibrolamellar carcinoma
– Rare, < 1% of all cases of primary liver cancer
– Well-defined partially/completely encapsulated mass
– Prominent central fibrous scar often with calcification
– Intralesional necrosis/hemorrhage
– Regional adenopathy and metastases to lung and
peritoneum
– Typically without chronic liver disease
– AFP usually negative or mildly elevated
• Pulsed Doppler
○ Arterial feeding vessels with low-resistance waveforms
indicate tumor vessels
○ Tumor thrombus with arterial neovascularity
• Color Doppler
○ Irregular hypervascularity within neoplasm
○ Tumor thrombus, typically in portal vein, with
neovascularity
CT Findings
• NECT
○ Iso- or hypodense liver mass, occasionally fat content
detected
– Characterization of lesion not possible on NECT
• CECT
○ Characterization and diagnosis of HCC can be made with
triphasic CT: Late arterial, portal venous,
delayed/equilibrium phase
– Late arterial phase: Hyperenhancing compared to
background liver
– Portal venous phase: Variable enhancement, may be
iso-, hypo-, or hyperdense compared to background
liver
– Delayed or equilibrium phase (3-5 min after contrast
injection): "Washout" is characteristic of HCC; lesion
hypodense compared to liver
□ May see delayed enhancing pseudocapsule
MR Findings
• T1WI
○ Typically hypointense compared to background liver but
may be iso- or hyperintense depending on fat content or
necrosis
• T2WI
○ Typically slightly hyperintense, similar intensity to spleen
• T1WI C+
○ Late arterial phase: Hyperenhancing compared to
background liver
○ Portal venous phase: Variable but typically hypointense
○ Delayed or equilibrium phase: "Washout" is characteristic
of HCC with lesion hypointense to background liver
– Hyperintense pseudocapsule typically best seen on
delayed or portal venous phase images
○ Hepatobiliary contrast (gadoxetate, Eovist, Primovist):
Uptake in hepatocytes related to OATP8 receptor, downregulated
in most HCC, up-regulated in focal nodular
hyperplasia (FNH)
– Pitfall: Up to 10% of HCC can be isointense or
hyperintense on hepatobiliary phase
Angiographic Findings
• Hypervascular tumor
○ Marked neovascularity and AV shunting
○ Large hepatic artery and vascular invasion
○ "Threads and streaks" sign in portal vein tumor thrombus
Nuclear Medicine Findings
• Hepatobiliary scan: Uptake in 50%
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Diagnoses: Liver
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