2. Radiology

HCV-associated cirrhosis or advanced fibrosis [12]. Annually, HCC develops in 2–8% of HCVinfected patients [13]. In North America, Latin America, Europe and Japan, HCV infection, together with alcohol abuse, represent the main risk factors [3, 13]. In Europe and Japan where HCV infection spread earlier than in the United States, HCC incidence has almost reached a plateau, while in the United States it is still increasing. HCV infection may have a synergistic

Globally, 15% of HCC cases can be attributed to alcohol-induced liver damage and non-alcoholic steatohepatitis [19], although the estimates range between 4 and 22% [20]. Non-alcoholic fatty liver disease (NAFLD) is the major hepatic manifestation of metabolic disturbances including obesity, type 2 diabetes mellitus, dyslipidaemia and metabolic syndrome [4]. As prevalence of these conditions is increasing, NAFLD has become the most common liver disorder in industrialised countries [21]. In NAFLD, HCC incidence reaches 44 (range, 29–66) per 100,000 personyears [22] contrasting with the general incidence of 6 per 100,000 in USA population [20]. The proportion of HCC related to NAFLD and non-alcoholic steatohepatitis (NASH) is increasing worldwide, especially in Western countries [20]. Although previously it was considered that HCC risk was limited to patients with liver cirrhosis, nowadays a significant fraction of NASH-

Aflatoxins are a group of mycotoxins produced by Aspergillus fungi (A. flavus; A. parasiticus), which can contaminate food products such as grains, rice, cassava, soybeans, corn and peanuts, stored in hot climate and high moisture. Aflatoxins are major risk factors of HCC in sub-Saharan Africa and Eastern Asia [23]. Chronic exposure to aflatoxin results in DNA damage, including mutation of the tumour suppressor gene TP53 in hepatocytes [13]. In people subjected to aflatoxin ingestion and chronic HBV infection, HCC risk is 30- to 60-fold higher, versus HBV-uninfected people exposed to aflatoxin alone. Synergistic action is observed also

Planning the surveillance for individual patient, the presence of known risk factors must be considered and the relative risk must be taken into account. Organising surveillance measures in the society, population-attributable fraction (PAF) is also important. PAF depends both on relative risk and population prevalence of the corresponding risk factor. Thus, in USA, the risk increase of HCC is highest in HCV infection (odds ratio (OR), 39.9), followed by HBV infection (OR, 11.2), alcohol-induced liver disease (OR, 4.1) and diabetes mellitus and/or obesity (OR, 2.3). However, considering the prevalence of these conditions, diabetes and/or obesity are associated with the highest population attributable fraction (36.6%), followed by alcohol (23.5%), HCV (22.4%) and HBV (6.3%) as reported by Welzel et al. [25]. PAFs differ by the population. Worldwide, 54% of HCC occur in HBV-infected patients, 31% can be attributed to

Considering the serious prognosis, early diagnosis is crucial, however, not always easy. Thus, correctly interpreted radiological findings, combined with biopsy when necessary, and appropriate immunohistochemical examination of biopsied tissues have diagnostic value. The molecular portrait of the tumour as well as easily available markers of the systemic inflammatory response, such as neutrophil-to-lymphocyte ratio or platelet-to-lymphocyte ratio, are recently

effect with other risk factors, such as non-alcoholic fatty liver disease [3].

20 Hepatocellular Carcinoma - Advances in Diagnosis and Treatment

associated HCC is found in non-cirrhotic liver or liver showing mild fibrosis [4].

between aflatoxin and HCV [14, 23, 24].

HCV and 15% to alcohol and NASH [19].

reported to have prognostic and predictive value in HCC.

Radiological imaging and functional evaluation are significant in screening and diagnostics of HCC [26]. The gold standard techniques comprise ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI). A major advance in the diagnostics of HCC was reached in 2001, when non-invasive criteria were developed and accepted by the European Association for the Study of the Liver (EASL) to diagnose HCC in cirrhotic liver [27]. In addition to the presence of liver mass, radiologic studies of HCC evaluate the typical vascularity. HCC receives enhanced arterial blood supply reflected histologically by unpaired arteries. The blood supply via portal vein decreases in comparison with surrounding parenchyma. However, in early stages of development, HCC can be hypovascular if the portal flow has already decreased but the arterial supply has not yet fully developed.

According to the guidelines, ultrasonography is advocated for screening and surveillance of patients having high risk to develop HCC due to HBV or HCV infection, cirrhosis or other known risk factors [28]. The specificity is mostly higher than 90%, ranging 45–94% [5, 27]. The reported sensitivity ranges widely from 33 to 96%, at least partially because of differences in the equipment and qualification of radiologists [18]. The sensitivity decreases in advanced chronic liver disease because of the coarse cirrhotic nodularity seen both grossly and by US [5]. In a large group of 200 patients undergoing US and liver transplantation, the sensitivity for HCC diagnostics was 29.6% in regard to patients and only 20.5% counting the tumours themselves. Even a large tumour exceeding the diameter of 5 cm was missed [29].

The typical US presentation of HCC is a hypoechoic nodule although iso- or hyperechogenicity is possible as is nodule-in-nodule appearance [7]. Small HCCs (less than 2 cm in the greatest diameter) are mostly hypoechoic with or without posterior enhancement. Hyperechoic appearance is seen in 17% of small HCCs and can be associated with fat accumulation. Larger HCCs are heterogeneous reflecting necrosis (hypoechoic), calcifications and fibrosis. If hypoechoic halo (seen in 50% of HCC) and posterior enhancement is evident, these findings increase the specificity of diagnosis [5, 7, 18]. HCC in dysplastic nodule might seem hyperechoic within a larger hypoechoic area. If a nodule is identified on US, either CT or MRI is indicated for masses larger than 20 cm, while both methods are advocated for pathologic foci measuring 10–20 mm. If either CT or MRI confirms HCC, the diagnosis is reliable. Biopsy is indicated only for lesions that remain controversial after both imaging modalities. Nodules measuring less than 10 mm are followed up by US every 4 months [18].

By Doppler US, HCC is characterised by so-called basket pattern reflecting rich arterial vascularisation. Benign cirrhotic nodules feature either low vascularity or arterial vessels with low frequency (high in HCC: >1 kHz) and normal resistive index (elevated in HCC: >0.71). However, the typical Doppler pattern is seen only in 50% of small HCC [7].

Examination of hypovascular or hypervascular liver metastases with multidetector CT is similar to CEUS. Hypovascular metastasis presents as rounded and uniformly hypoattenuating mass in portal venous phase and peripheral rim in arterial phase. Hypervascular metastasis is characterised by homogeneous late arterial enhancement. Inhomogeneous enhancement can develop

Diagnostic Algorithm of Hepatocellular Carcinoma: Classics and Innovations in Radiology and Pathology

http://dx.doi.org/10.5772/intechopen.76136

23

MRI has excellent results for detection and characteristics of HCC. By meta-analysis, MRI was characterised by sensitivity of 88% and specificity of 94%, exceeding the characteristics of multidetector CT [36]. Contrasting usually is applied in liver MRI, most frequently by gadolinium compounds. The gadolinium-based contrast agents can be classified as extracellular versus hepatobiliary. Extracellular agents are small molecules that can reach interstitium moving out from vascular space. In turn, hepatobiliary contrast agents move even further becom-

Classic MRI protocol for HCC includes a 3D T1-weighed fat saturated sequence with intravenous contrast. The first phase is called late arterial phase. It is seen 25–30 seconds after injection of contrast. This phase is followed by portal venous phase, at 65–70 seconds. In this phase, there is a dense contrast enhancement in portal vein, and hepatic veins also become highlighted. Finally, delayed phase develops 3 minutes after injection [38]. Before contrasting, classical HCC is hypointense in T1-weighted and hyperintense in T2-weighted images. Contrasting reveals similar enhancement pattern as in CT with arterial enhancement and subsequent washout [18]. In addition, MRI can be applied to disclose tumour thrombus in

Most metastases show mild-to moderate high signal intensity on T2-WI. In some cases, e.g., in

The sensitivity of MRI can be further improved by diffusion-weighted imaging, based on the assessment of Brownian motion of water molecules and water diffusion within a voxel (a tridimensional pixel). Cell membranes limit the diffusion, therefore greater cellularity, seen also in malignant tumours, results in diffusion restriction [40]. However, the fibrosis also decreases the mobility of water molecules. By different modalities, diffusion-weighted imaging can increase the sensitivity for HCC detection, the liver-to-lesion contrast and the specificity in

Another advance in liver pathology is represented by hepatobiliary phase MRI using contrast agents that are absorbed by hepatocytes and excreted in biliary system, e.g., gadoxetate disodium and gadobenate dimeglumine. These agents undergo dual elimination via biliary excretion (50%) and renal glomerular filtration, while the traditional agents, as gadopentetic acid, are almost completely excreted via kidneys [41]. The hepatobiliary phase of MRI corresponds to the peak parenchymal enhancement due to contrast uptake in hepatocytes. Depending on the agent, the hepatobiliary phase develops either 10–20 (gadoxetate) or 60 (gadobenate dimeglumine) minutes after injection [42]. Most of HCCs are hypointense in

MRI can be applied to distinguish between HCC and benign lesion in non-cirrhotic liver. In such patients, HCCs are hypointense in T1, hypo- or hyperintense in T2, lack central

in necrosis or haemorrhage [35].

ing absorbed by hepatocytes [37, 38].

portal venous system [39].

hepatobiliary phase [18].

cystic or necrotic metastases, T2 signal increases.

the differential diagnosis with benign cirrhotic nodules [27].

A significant innovation in ultrasonography is the application of contrast enhancement by stabilised gaseous microbubbles. Consequently, three phases can be assessed analogously to CT and MRI: arterial phase (beginning 20 seconds after injection and lasting for 30–45 seconds); portal venous phase (starting at 30–45 seconds and lasting for 2–3 minutes) and late phase (4–6 minutes). Some contrast agents display additional post-vascular phase characterised by contrast uptake in Kupffer cells (10–60 minutes). To avoid overlap with late phase, the postvascular phase must be assessed not earlier than 10 minutes after contrast injection. The typical pattern of HCC upon contrast-enhanced ultrasound (CEUS) examination is arterial hyperenhancement followed by washout in the late phase. The evaluation of washout is important in order to exclude arterial hyperenhancement in hemangioma or dysplastic cirrhotic nodule. However, well-differentiated HCC can remain isoechoic in portal venous or late phase; such pattern is suspicious for HCC, but CT or MRI is mandatory [7]. The benefits of CEUS include the easy procedure and high safety as the technique is not associated with ionising radiation or renal toxicity. Pitfalls include false positives in cholangiocarcinoma [30]. The lack of specificity is associated with the intravascular location of microbubbles in contrast to CT or MRI contrast agents that reach the extravascular extracellular space. At present, CEUS has been excluded from diagnostic guidelines provided by the European Association for the Study of the Liver (EASL) and the American Association for the Study of the Liver Diseases (AASLD) but is advocated by Asian Pacific and Japanese guidelines [27].

US can be applied to recognise benign or secondary liver tumours. Sensitivity of US to detect liver metastases varies between 40 and 80%, again depending on experience of radiologist and available US equipment. Metastases can be hypovascular, e.g., gastric or colorectal carcinoma, or hypervascular as malignant melanoma or sarcoma [18].

If US or CEUS discloses a suspicious nodule, in-depth evaluation by CT or MRI is indicated [31] based on the risk of malignancy. Nodules smaller than 1 cm are mostly benign. Risk of HCC is 66% in nodules measuring 10–20 mm, 80% in nodules 20–30 mm in size and 92–95% in nodules larger than 3 cm [7]. Both methods (CT and MRI) are advocated for lesions measuring 10–20 mm while one is sufficient for larger nodules (>20 mm). The diagnosis of HCC is confirmed by the typical pattern of arterial hypervascularity and late washout [27].

For CT, dynamic multidetector row, multiphase contrast-enhanced computed tomography approach is recommended [27, 32] as the diagnosis is based on dynamic evaluation of blood flow. However, contrasting is not possible in all patients in order to avoid anaphylactic reactions, acute renal failure or hyperthyroidism [33]. To disclose HCC, CT must be evaluated in three phases (late arterial, portal venous and equilibrium) in addition to the first unenhanced image. HCC classically is hypervascular, characterised by high contrast in the arterial phase, followed by washout in portal and/or equilibrium phases [27]. Portal venous phase can be useful in some cases of HCC when the tumour is otherwise not visible in CT. Portal venous phase is generally less informative for HCC because the tumour shows rarefaction similar as liver parenchyma. This phase is most useful for detecting hypovascular metastases, e.g., from colorectal carcinoma [34].

Examination of hypovascular or hypervascular liver metastases with multidetector CT is similar to CEUS. Hypovascular metastasis presents as rounded and uniformly hypoattenuating mass in portal venous phase and peripheral rim in arterial phase. Hypervascular metastasis is characterised by homogeneous late arterial enhancement. Inhomogeneous enhancement can develop in necrosis or haemorrhage [35].

low frequency (high in HCC: >1 kHz) and normal resistive index (elevated in HCC: >0.71).

A significant innovation in ultrasonography is the application of contrast enhancement by stabilised gaseous microbubbles. Consequently, three phases can be assessed analogously to CT and MRI: arterial phase (beginning 20 seconds after injection and lasting for 30–45 seconds); portal venous phase (starting at 30–45 seconds and lasting for 2–3 minutes) and late phase (4–6 minutes). Some contrast agents display additional post-vascular phase characterised by contrast uptake in Kupffer cells (10–60 minutes). To avoid overlap with late phase, the postvascular phase must be assessed not earlier than 10 minutes after contrast injection. The typical pattern of HCC upon contrast-enhanced ultrasound (CEUS) examination is arterial hyperenhancement followed by washout in the late phase. The evaluation of washout is important in order to exclude arterial hyperenhancement in hemangioma or dysplastic cirrhotic nodule. However, well-differentiated HCC can remain isoechoic in portal venous or late phase; such pattern is suspicious for HCC, but CT or MRI is mandatory [7]. The benefits of CEUS include the easy procedure and high safety as the technique is not associated with ionising radiation or renal toxicity. Pitfalls include false positives in cholangiocarcinoma [30]. The lack of specificity is associated with the intravascular location of microbubbles in contrast to CT or MRI contrast agents that reach the extravascular extracellular space. At present, CEUS has been excluded from diagnostic guidelines provided by the European Association for the Study of the Liver (EASL) and the American Association for the Study of the Liver Diseases (AASLD) but is advocated by

US can be applied to recognise benign or secondary liver tumours. Sensitivity of US to detect liver metastases varies between 40 and 80%, again depending on experience of radiologist and available US equipment. Metastases can be hypovascular, e.g., gastric or colorectal carcinoma,

If US or CEUS discloses a suspicious nodule, in-depth evaluation by CT or MRI is indicated [31] based on the risk of malignancy. Nodules smaller than 1 cm are mostly benign. Risk of HCC is 66% in nodules measuring 10–20 mm, 80% in nodules 20–30 mm in size and 92–95% in nodules larger than 3 cm [7]. Both methods (CT and MRI) are advocated for lesions measuring 10–20 mm while one is sufficient for larger nodules (>20 mm). The diagnosis of HCC is

For CT, dynamic multidetector row, multiphase contrast-enhanced computed tomography approach is recommended [27, 32] as the diagnosis is based on dynamic evaluation of blood flow. However, contrasting is not possible in all patients in order to avoid anaphylactic reactions, acute renal failure or hyperthyroidism [33]. To disclose HCC, CT must be evaluated in three phases (late arterial, portal venous and equilibrium) in addition to the first unenhanced image. HCC classically is hypervascular, characterised by high contrast in the arterial phase, followed by washout in portal and/or equilibrium phases [27]. Portal venous phase can be useful in some cases of HCC when the tumour is otherwise not visible in CT. Portal venous phase is generally less informative for HCC because the tumour shows rarefaction similar as liver parenchyma. This phase is most useful for detecting hypovascular metastases, e.g., from

confirmed by the typical pattern of arterial hypervascularity and late washout [27].

However, the typical Doppler pattern is seen only in 50% of small HCC [7].

22 Hepatocellular Carcinoma - Advances in Diagnosis and Treatment

Asian Pacific and Japanese guidelines [27].

colorectal carcinoma [34].

or hypervascular as malignant melanoma or sarcoma [18].

MRI has excellent results for detection and characteristics of HCC. By meta-analysis, MRI was characterised by sensitivity of 88% and specificity of 94%, exceeding the characteristics of multidetector CT [36]. Contrasting usually is applied in liver MRI, most frequently by gadolinium compounds. The gadolinium-based contrast agents can be classified as extracellular versus hepatobiliary. Extracellular agents are small molecules that can reach interstitium moving out from vascular space. In turn, hepatobiliary contrast agents move even further becoming absorbed by hepatocytes [37, 38].

Classic MRI protocol for HCC includes a 3D T1-weighed fat saturated sequence with intravenous contrast. The first phase is called late arterial phase. It is seen 25–30 seconds after injection of contrast. This phase is followed by portal venous phase, at 65–70 seconds. In this phase, there is a dense contrast enhancement in portal vein, and hepatic veins also become highlighted. Finally, delayed phase develops 3 minutes after injection [38]. Before contrasting, classical HCC is hypointense in T1-weighted and hyperintense in T2-weighted images. Contrasting reveals similar enhancement pattern as in CT with arterial enhancement and subsequent washout [18]. In addition, MRI can be applied to disclose tumour thrombus in portal venous system [39].

Most metastases show mild-to moderate high signal intensity on T2-WI. In some cases, e.g., in cystic or necrotic metastases, T2 signal increases.

The sensitivity of MRI can be further improved by diffusion-weighted imaging, based on the assessment of Brownian motion of water molecules and water diffusion within a voxel (a tridimensional pixel). Cell membranes limit the diffusion, therefore greater cellularity, seen also in malignant tumours, results in diffusion restriction [40]. However, the fibrosis also decreases the mobility of water molecules. By different modalities, diffusion-weighted imaging can increase the sensitivity for HCC detection, the liver-to-lesion contrast and the specificity in the differential diagnosis with benign cirrhotic nodules [27].

Another advance in liver pathology is represented by hepatobiliary phase MRI using contrast agents that are absorbed by hepatocytes and excreted in biliary system, e.g., gadoxetate disodium and gadobenate dimeglumine. These agents undergo dual elimination via biliary excretion (50%) and renal glomerular filtration, while the traditional agents, as gadopentetic acid, are almost completely excreted via kidneys [41]. The hepatobiliary phase of MRI corresponds to the peak parenchymal enhancement due to contrast uptake in hepatocytes. Depending on the agent, the hepatobiliary phase develops either 10–20 (gadoxetate) or 60 (gadobenate dimeglumine) minutes after injection [42]. Most of HCCs are hypointense in hepatobiliary phase [18].

MRI can be applied to distinguish between HCC and benign lesion in non-cirrhotic liver. In such patients, HCCs are hypointense in T1, hypo- or hyperintense in T2, lack central enhancement in the tumour, exhibit satellite lesions and do not uptake liver-specific contrast agents [43].

with known liver disease [49]. Percutaneous liver core biopsy is most frequently performed to evaluate the presence and activity of inflammation and extent of fibrosis/stage of frequent liver diseases, mostly chronic viral hepatitis, alcohol-induced liver disease and NAFLD. Regarding focal liver lesions, biopsy can yield the diagnosis. Molecular analyses of tissue may help determine the most appropriate individual treatment strategy for the patient with HCC [50] but are still under development for HCC. At present, biopsy from a nodule in cirrhotic liver is

Diagnostic Algorithm of Hepatocellular Carcinoma: Classics and Innovations in Radiology and Pathology

http://dx.doi.org/10.5772/intechopen.76136

25

Although biopsy is often essential, sometimes it may be difficult to undertake because of associated risks (see Table 3). Percutaneous, ultrasound-guided liver biopsy (the Menghini method) has become the worldwide standard [51]. However, it is appropriate only in cooperative patients. Thus, if the patient refuses from the procedure, it is absolutely contraindicated. Although precise blood clotting parameters are unsettled, coagulopathies should be mentioned as a serious contraindication [49]. In this case, mini-laparoscopy or transjugular liver biopsy might be considered [51]. Among relative contraindications, ascites should be pointed out, as it may prevent adequate sampling of tissue, as well as increase the risk of bleeding [49].

Significant complications due to liver biopsy arise in about 1% of cases, with less than 0.1% mortality [51]. The main complications are post-interventional haemorrhage and bile leakage; others, like injuries to gall bladder, lung, kidney, as well as bacteraemia are rare [49, 51].

The initial assessment of liver tissue starts with the overall evaluation of parenchymal architecture. Haematoxylin and eosin represents the generally accepted standard stain in liver pathology [6]. Helpful additional visualisation methods in liver pathology include Masson's trichrome to assess fibrosis, Gordon and Sweets reticulin to evaluate lobular architecture and hepatocyte plate thickness, Perl's iron to detect hemosiderin deposits and periodic acid-Schiff

Microscopically, cells of classical HCC resemble normal hepatocytes. The similarity to normal liver is most notable in well to moderately differentiated tumours. In such cases, the loss of the normal liver cell plates and plate thickness change from 1 to 2 cell nuclei to 3 or more nuclei

; prolonged

• Tendency to bleed (prothrombin time more than 3–4 seconds over control; platelet count <50,000 mm3

• Recurrent use of aspirin or other non-steroidal anti-inflammatory drugs within last 7–10 days

• Infection in the right pleural cavity or below the right hemidiaphragm

• Suspected haemangioma or other vascular tumour • Suspected hydatid disease (Echinococcal cysts)

Table 3. Contraindications of liver biopsy [49].

indicated if the findings of radiological imaging are controversial [6].

Biopsies of malignant liver lesions also carry a low risk of tumour seeding.

(PAS) stain to identify glycogen, mucus or chitin of certain liver parasites.

Absolute contraindications • Uncooperative patient • History of unexplained bleeding

Relative contraindications

• Ascites • Morbid obesity

bleeding time (≥10 minutes)) • Unavailability of blood transfusion support

Positron emission tomography (PET) is a non-invasive radiologic visualisation that demonstrates metabolic activity in normal or pathological tissue. It is usually performed in combination with CT to ensure both anatomical imaging and metabolic evaluation. 18-fluorodeoxyglucose (FDG) is one of the radiopharmaceuticals used in PET/CT. It discloses areas of high glucose uptake as many tumours including HCC are characterised by aerobic glycolysis: the Warburg effect [44].

The significance of FDG PET/CT in HCC evaluation is not unequivocal. The distinction between small, well-differentiated HCC versus regenerative or dysplastic nodules can be difficult. The positive aspect of PET/CT is the ability to detect extrahepatic metastases of HCC. Considering that PET/CT provides whole-body examination, it is recommended before liver transplantation [45, 46]. Hypothetically, prognostic role of PET/CT in HCC has been discussed as well as the ability to predict response to treatment [46]. Other radiopharmaceuticals are also under discussion, including lipid radiotracer on choline base, like 11C-choline or 18Ffluorocholine [47]. 68Ga-labelled prostate-specific membrane antigen, that is used to diagnose prostate cancer, is present in other tumours, including HCC [48].
