Imaging of liver cancer

Abstract

Improvements in imaging technology allow exploitation of the dual blood supply of the liver to aid in the identification and characterisation of both malignant and benign liver lesions. Imaging techniques available include contrast enhanced ultrasound, computed tomography and magnetic resonance imaging. This review discusses the application of several imaging techniques in the diagnosis and staging of both hepatocellular carcinoma and cholangiocarcinoma and outlines certain characteristics of benign liver lesions. The advantages of each imaging technique are highlighted, while underscoring the potential pitfalls and limitations of each imaging modality.

Figure 1

HCC. B-mode US demonstrates a heterogeneous hypoechoic solid liver lesion (arrow) in segment IV, confirmed to be HCC at histological examination. Note the background of an echogenic liver with an irregular surface.

Figure 2

HCC. A: CEUS in the arterial phase (17 s following injection) demonstrates arterial phase enhancement of the solid lesion (corresponding grey scale image of the lesion is shown on the right hand side; software known as “twin view” which helps the sonologist track the lesion through the phases of enhancement). Note the “basket weave” pattern of angiogenic vessels with haphazard enhancement of this lesion; B: Twin view of the same segment IV lesion in the delayed phase (2 min 49 s following injection) of the same lesion as Figure 2A demonstrates contrast wash-out compared to the surrounding liver parenchyma which are features of a malignant lesion.

Figure 3

HCC. Contrast enhanced CT demonstrates heterogeneous arterial phase enhancement of a focal liver lesion (arrow) adjacent to a low attenuation area representing a previous radiofrequency ablation site (arrowhead).

Figure 4

HCC. T₂-weighted gradient echo sequence shows a solid lesion in segment V (arrow) of the liver which is of intermediate signal hyperintensity compared to the surrounding liver parenchyma.

Figure 5

HCC. A: T₁-weighted fat-suppressed sequence following gadolinium intravenous injection shows arterial phase enhancement of a focal liver lesion in segment IV (arrow); B: HCC: The same lesion as shown in Figure 5A becomes relatively less conspicuous on the portal phase images (arrow) as the surrounding liver parenchyma begins to enhance.

Figure 6

Cholangiocarcinoma. Contrast enhanced CT in the portal venous-dominant phase demonstrates a poorly-enhancing central liver lesion. The hypodensity appears to follow some of the biliary radicals.

Figure 7

Cholangiocarcinoma. A: Contrast-enhanced T₁-weighted magnetic resonance sequence shows irregular central liver mass (arrow) which enhances poorly in comparison to the adjacent liver parenchyma. There is intrahepatic bile duct dilatation and an external biliary drain (arrowheads); B: Maximum intensity projection image of the MRCP study of the same case as shown in Figure 7A demonstrates marked intrahepatic bile duct dilatation and abrupt cut-off at the liver hilum (due to obstructing tumour) (arrow) with non-visualisation of the extrahepatic ducts.

Figure 8

Hepatic metastases. Delayed phase CEUS (3 min 49 s following contrast injection) demonstrates two hypoechoic liver metastases following contrast washout with a residual peripheral rim of enhancement (arrows). Note that the adjacent image demonstrates that these lesions are echogenic on grey-scale and are poorly defined. The margins are better defined with contrast enhancement (right hand image).

Figure 9

Hepatic metastases. CEUS obtained in the arterial phase (17 s following contrast injection) demonstrates enhancement of a hypervascular liver metastasis from a colorectal primary tumor. It is the washout with peripheral rim enhancement in the delayed phase (see Figure 8) which helps confirm this to be a metastasis.