1. Hepatocellular carcinoma (HCC) appears as hyperenhancing lesions during the hepatic arterial phase of contrast enhanced CT or MRI due to its hypervascular nature. These lesions wash out during the portal venous phase. 2. Multiphase contrast enhanced imaging is important for diagnosing HCC as it allows evaluation of changes in intra-tumoral blood flow during different phases. Arterial phase hyperenhancement combined with washout or capsule appearance has near 100% specificity for HCC. 3. While imaging features such as arterial phase hyperenhancement and washout are characteristic of HCC, they are not entirely specific, and HCC must be differentiated from other malignancies and benign lesions.

1. PATTERNS OF EHNACEMENT IN
HEPATOCELLULAR CARCINOMA
Dr. Haseeb Manzoor
Department of Radiology
Shalamar Hospital

2. •Diagnosis of HCC larger than 2 cm can be made
without biopsy !
if,
•A mass in a cirrhotic liver shows the typical
features of HCC on contrast-enhanced CT or MRI
•α-fetoprotein level is greater than 200 ng/mL

3. •Any solid lesion in a cirrhotic liver that is not a
hemangioma is considered HCC until proven
otherwise.
•Imaging may be used to establish diagnosis of
HCC non-invasively.

4. Multiphasic Imaging

5. •Contrast agents permit diagnosis of HCC based
mainly on the physiologic changes in intra-nodular
blood flow.
•To evaluate these changes, multiphasic
examinations are performed.
•Typically, contrast agents are administered at
rates of;
•5 mL/sec for CT
•2 mL/sec for MR

6. Phase Comments
Pre-contrast Serves as a baseline to gauge subsequent enhancement.
Hemorrhage, calcification, central scar or gross fat may
be seen within the HCC tumor.
May be omitted to reduce radiation dose.
Late hepatic
arterial phase
Characterized by full enhancement of the hepatic artery
and its branches as well as enhancement of the portal
vein.
Fixed delay is not reliable.
Critical for detection and characterization of
hypervascular HCC.

7. Phase Comments
Portal venous
phase
characterized by enhancement of hepatic veins as well
as portal veins.
acquired at around 60–80 seconds after the start of
contrast agent injection.
Delayed phase acquired at 3–5 minutes after the start of contrast agent
injection.
critical for characterizing washout appearance and
capsule appearance.
To differentiate small HCCs from small ICCs.

8. A
C
B
D

9. •What to look for ?
•Hypodense on precontrast images
•Hyperdense during hepatic arterial phase
•Hypodense during portal venous phase
•Isodense during delayed phase

10. • Hepatocellular carcinoma in a 45-year-old man with hemophilia and
hepatitis C cirrhosis.
• Axial arterial phase CT shows hyperenhancement of the exophytic
mass (arrow).
• Delayed phase CT scan shows washout of contrast agent within the
mass (arrow).

11. •The combination of arterial phase
hyperenhancement + capsule appearance strongly
suggests the diagnosis of HCC, even in the absence
of washout appearance.

12. • 57 year old female with cirrhosis and HCC treated with RFA.
• CT in arterial (a) and venous (b) phases shows enhancement and
washout of a nodule adjacent to an RFA ablation zone.

13. HCC: Major Features

14. Feature Comments
Arterial phase
hyper-
enhancement
Characteristic of but not specific for progressed HCC.
Differential diagnosis:
benign perfusion alterations, small hemangiomas,
non-HCC malignancy e.g small ICC,
small hypervascular metastases e.g neuroendocrine
tumors.
Washout
appearance
Characteristic of but not specific for progressed HCC.
Differential diagnosis:
cirrhotic nodules and dysplastic nodules.
Pitfall: Focal areas of parenchymal distortion and
enhancing fibrosis may create false perception of
“washout.”

15. • 54 year old male with hepatitis C cirrhosis.
• CT shows an arterial enhancing nodule with washout of contrast in the
delayed phase consistent with hepatocellular carcinoma

16. Feature Comments
Capsule
appearance
Presence of a capsule or a pseudocapsule
differentiates HCC from regenerative and
dysplastic nodules.
Pitfall: peripheral enhancement of intrahepatic
cholangiocarcinoma and fibrous tissue surrounding
cirrhotic nodules and dysplastic nodules may be
mistaken for capsule appearance.
Arterial phase
hyperenhancement
plus washout or
capsule appearance
Diagnostic of HCC. In patients at risk for
developing HCC, this combination has near 100%
specificity.
Limitation: early HCCs, small progressed HCCs,
infiltrative HCCs may not exhibit this combination.

17. • 52-year-old man with combined hepatocellular carcinoma (HCC) and
cholangiocarcinoma. A, arterial phase, tumor shows strong
enhancement (arrowheads). portion of tumor shows low attenuation
without enhancement (arrow). Thin hyper-enhancing capsule around
mass is seen. B, portal venous phase, mass shows low attenuation due
to washout of contrast medium.

18. HCC: Ancillary Features

19. Feature Comments
Intra-lesional fat Characteristic of but not specific for early HCC.
Differential diagnosis: low-grade and high-grade
dysplastic nodule.
Limitation: often coincides with other more
discriminatory imaging features.
Nodule in nodule
architecture
Suggests emergence of progressed HCC within
dysplastic nodule or early HCC.
Limitation: uncommonly depicted in CT or MR
imaging

20. • 52-year-old man with focal fat within hepatocellular carcinoma. A,
arterial phase, hyperattenuating mass (arrowheads). Focal area of
hypoattenuation (–60 HU) (arrow) within lesion suggests fat. B, Portal
venous phase, hypoattenuation throughout lesion (arrowheads). Focal
area of fat (arrow) remains unchanged.

21. Feature Comments
Corona
enhancement
Characteristic of progressed, hypervascular HCC.
Helps to differentiate progressed, hypervascular HCC
from vascular pseudolesions e.g arterioportal shunts.
Limitations: May be difficult to recognize at CT or MR
imaging.
Pitfall: May overlap and blend with tumor enhancement,
causing tumor to appear larger than it really is.
Mosaic
architecture
Defined by the presence of multiple internal tumor
nodules, fibrous septations and areas of hemorrhage,
necrosis, fatty metamorphosis.
Characteristic of and frequently observed in large HCCs.
Helps in the differentiation of HCC from ICC.
Limitation: uncommon in small HCCs

22. • Corona (arrow)
manifested as a
peritumor enhancing
rim at the portal
venous phase (A),
• fades at delayed phase
(B).
• plain scan (C) shows a
mosaic architecture (*)
with lower attenuation
within tumor.
• more clear at portal
venous phase (D).

23. Growth Patterns

24. •Solitary mass:
•Bulk in one lobe with satellite nodules
•HCCs exceeding 2 cm in diameter are known as
“large HCCs”
•Large HCCs tend to have higher histologic grade,
more aggressive biologic behavior, higher
frequency of vascular invasion and metastasis.

25. • HCC in a 58-year-old man with hepatitis C
cirrhosis.
• (a) arterial phase CT shows hyperenhancement
of a solitary 4-cm mass (arrow).
• (b) portal venous phase CT shows washout
(arrow).

26. •Multifocal small nodular:
•Defined by the presence of tumor nodules
unmistakably separated by intervening non-
neoplastic parenchyma.
•Small foci of usually <2 cm in both hepatic lobes

27. • 55 year female.
• Cirrhotic liver with multifocal hepatocellular carcinoma

28. •Diffuse infiltrating form:
•Tiny indistinct nodules closely resembling
cirrhosis.

29. • 64-year-old man with infiltrative HCC and macrovascular invasion
• (a) late arterial, (b) portal venous, (c) 3-minute delayed phases.
• patchy areas (*) of arterial phase hyper-enhancement and delayed
phase partial washout appearance.

30. Stages of development

32. Nodule Type Unenhanced CT Arterial Phase Venous Phases
Cirrhotic
nodule
Iso Iso Iso
Or hypo
High-grade
dysplastic
nodule
Iso or hyper Iso or hypo Iso or hypo
Early HCC Iso Iso or hypo Iso or hypo
Progressed
HCC
Iso or hypo hyper hypo

33. Histological Variants

34. Type Comments
Clear cell fat is frequently present.
decreased attenuation on unenhanced CT.
Fibrolamellar Not associated with hepatitis or cirrhosis.
solitary, well-defined, lobulated mass.
Sarcomatoid Aggressive.
No capsule, intratumoral fat, or central scar.
Combined HCC-
cholangiocarcinoma
characteristics depend on the proportions of tumor
components
Sclerosing Rare
intense fibrosis

35. • 32-year-old man with fibrolamellar HCC.
• arterial phase CT (arrow) shows subtle peripheral enhancement.
• portal venous phase, peripheral portion of tumor shows isoattenuation
(arrowhead) relative to surrounding liver. Central portion of tumor
shows low attenuation.

36. • 63-year-old man with sarcomatoid HCC.
• A, arterial phase CT shows well-defined lobulated mass with
peripheral enhancement. B, Equilibrium phase CT shows
hypoattenuated peripheral portion of mass relative to surrounding
liver. Central portion of mass shows no enhancement, which reflects
necrosis.

37. Practice Cases

38. 48 years old male.
Hepatomegaly.
multiple heterogeneously enhanced nodules.
Rapid wash-out.

39. • 86 years old male.
• Multiple heterogeneous enhancement of
lesions in segment VII and VIII of liver.
• Rapid wash-out
• hepatic sub-capsular collection (probably
blood)

40. • 48years old male. cirrhosis and Hep C.
• Enhanced heterogeneous masses in the III
and IV segments
• Rapid wash-out
• Ascites

41. • 79 years old male.
• Multiple enhanced heterogeneous lesions
in I, IV, VII And VIII segments.
• Rapid wash-out

42. • 52-year-old woman. A, portal venous phase, large hypoattenuating
HCC (arrowheads) with extension of tumor into common bile duct
(arrow). B, Coronal CT image shows tumor extension into common bile
duct (arrow) and mild dilatation of intrahepatic biliary ducts
(arrowheads). Gallbladder (asterisk) is moderately distended.

43. 56-year-old man with jaundice. A, early hyperattenuation of HCC
(white arrow) but hypoattenuation within cholangiocarcinoma (black
arrow). biliary ductal dilatation (Arrowheads). B, delayed phase,
hypoattenuation of HCC (white arrow) and some delayed
hyperattenuation within cholangiocarcinoma (black arrow).