I. Overview Primary liver cancer (PLC, hereinafter referred to as hepatocellular carcinoma) is a common malignant tumor. Due to its insidious onset, lack of symptoms or insignificant symptoms in the early stage, and rapid progression, most patients have already reached the locally advanced stage or developed distant metastasis when diagnosed, which makes treatment difficult and prognosis very poor, and if only supportive and symptomatic treatments are taken, the natural survival time will be very short, thus seriously threatening people’s health and safety of life. Primary liver cancer mainly includes different pathological types such as hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC) and mixed hepatocellular carcinoma-intrahepatic cholangiocarcinoma, etc., which are distinctly different in terms of their pathogenesis, biological behaviors, histological morphology, clinical manifestations, therapeutic methods, and prognosis; since HCC accounts for more than 90% of the cases, the term “liver cancer” is referred to in this paper. As HCC accounts for more than 90% of the cases, the term “hepatocellular carcinoma” in this paper mainly refers to HCC. Diagnostic techniques and applications (a) Monitoring and screening of high-risk groups. The etiologic factors of hepatocellular carcinoma in China mainly include hepatitis virus infection, food aflatoxin contamination, long-term alcohol abuse, and blue-green algae toxin contamination of rural drinking water, other liver metabolic diseases, autoimmune diseases, and cryptogenic liver disease or cryptogenic cirrhosis. Since early diagnosis of hepatocellular carcinoma is crucial for effective treatment and long-term survival, early screening and early monitoring of hepatocellular carcinoma are highly emphasized. Routine monitoring screening indicators mainly include serum alpha-fetoprotein (AFP) and liver ultrasonography (US). Screening is generally performed at 6-month intervals for men ≥40 years of age or women ≥50 years of age with HBV and/or HCV infection, alcoholism, comorbid diabetes, and a family history of hepatocellular carcinoma in high-risk individuals. It is generally believed that AFP is a relatively specific tumor marker for HCC, and that persistent elevation of AFP is a risk factor for the development of HCC. Recently, some European and American scholars believe that the sensitivity and specificity of AFP are not high, and the 2010 edition of the American Association for the Study of Liver Diseases (AASLD) guidelines no longer use AFP as a screening indicator. However, most of the HCCs in China are associated with HBV infections, which are different from the causative factors of HCCs in the western countries (mostly HCV, alcohol, and metabolic factors), and combined with the results of the randomized studies (RCTs) in China and the practical situation, AFP continues to be retained in the routine monitoring and screening indicators for HCC. (ii) Clinical manifestations. Symptoms. The preclinical stage of hepatocellular carcinoma refers to the period from the beginning of the lesion to the diagnosis of subclinical hepatocellular carcinoma, in which the patient has no clinical symptoms and signs, and is difficult to be detected clinically, which usually lasts for about 10 months. In the subclinical stage (early stage) of hepatocellular carcinoma, the tumor is about 3-5cm, most patients still have no typical symptoms, and the diagnosis is still difficult, and most of them are detected by serum AFP screening, which lasts about 8 months on average, during which a few patients can have the symptoms related to chronic underlying liver diseases, such as epigastric stuffiness, abdominal pain, fatigue and loss of appetite. Therefore, for those who have high risk factors and experience the above conditions, they should be alerted to the possibility of hepatocellular carcinoma. Once typical symptoms appear, liver cancer is often in middle or advanced stage, at this time, the disease develops rapidly, about 3-6 months in total, and its main manifestations are: (1) Pain in the liver area. Right upper abdominal pain is the most common, which is an important symptom of the disease. It is often intermittent or persistent vague, dull or distending pain, and intensifies with the development of the disease. The site of pain is closely related to the site of the lesion, the lesion located in the right lobe of the liver is pain in the right quaternary rib area, and the pain located in the left lobe of the liver is pain in the subxiphoid region; if the tumor invades the diaphragm, the pain can be dispersed to the right shoulder or the right back; the tumor that grows to the right rear can cause pain in the right lumbar region. The cause of pain is mainly due to the tautness of hepatic envelope caused by tumor growth. Sudden severe abdominal pain and peritoneal irritation may be caused by peritoneal irritation due to rupture and bleeding of subperitoneal cancer nodules. (2) Loss of appetite. Symptoms such as epigastric fullness after meals, dyspepsia, nausea, vomiting and diarrhea are easy to be neglected due to lack of specificity. (3) Loss of weight and fatigue. Generalized weakness, a few advanced patients may present malignant condition. (4) Fever. It is common, mostly persistent low-grade fever, around 37.5-38℃, or irregular or intermittent, persistent or spasmodic high fever, similar to liver abscess, but without chills before fever, and antibiotic treatment is ineffective. Fever is mostly cancerous fever, which is related to the absorption of tumor necrotic material; sometimes it can be caused by cholangitis due to the compression or invasion of bile ducts by the cancer, or due to the combination of other infections with low resistance. (5) Symptoms of extrahepatic metastases. For example, lung metastasis can cause cough and hemoptysis; pleural metastasis can cause chest pain and bloody pleural effusion; bone metastasis can cause bone pain or pathological fracture. (6) Jaundice, hemorrhagic tendency (gums, nosebleeds and subcutaneous bruises, etc.), upper gastrointestinal hemorrhage, hepatic encephalopathy, and hepatic and renal failure often appear in patients with advanced stage. (7) Paraneoplastic syndrome, i.e. endocrine or metabolic disorders caused by metabolic abnormality of liver cancer tissues or various effects of cancer tissues on the body. Clinical manifestations are diverse and lack of specificity, common ones are spontaneous hypoglycemia, erythrocytosis; others are hyperlipidemia, hypercalcemia, precocious puberty, gonadotropin secretion syndrome, cutaneous porphyria, abnormal fibrinogenemia and paraneoplastic syndrome, etc., but they are rare. Signs. In the early stage of hepatocellular carcinoma, most patients do not have obvious positive signs, and only a few patients can find mild hepatomegaly, jaundice and itchy skin on physical examination, which should be non-specific manifestations of underlying liver disease. In middle and advanced hepatocellular carcinoma, jaundice, hepatomegaly (hard texture, uneven surface, with or without nodules, vascular murmur) and peritoneal effusion are common. If there is a background of hepatitis and cirrhosis, liver palms, spider nevi, red nevi, abdominal wall varicose veins and enlarged spleen can be found. (1) Enlargement of liver: it is often progressive, hard, uneven surface, with nodules of different sizes or even huge lumps, with clear margins, often with varying degrees of tenderness and pressure pain. If the liver cancer protrudes to the right subcostal arch or subcordate, the corresponding part can be seen as localized fullness and elevation; if the cancer is located in the diaphragmatic surface of the liver, the diaphragm is mainly confined to elevation and the lower edge of the liver may not be enlarged; cancerous nodules located on the surface of the liver close to the lower edge are the easiest to palpate. (2) Vascular murmur: due to rich and tortuous blood vessels of liver cancer, sudden thinning of arteries or compression of hepatic artery and abdominal aorta by cancer mass, about half of the patients can hear windy vascular murmur in the corresponding parts; this sign has important diagnostic value, but it has little significance in early diagnosis. (3)Jaundice: yellowing of the skin and sclera, which often appears in the late stage, mostly due to the bile duct obstruction caused by the compression of bile ducts by cancerous tumor or enlarged lymph nodes, and also due to the damage of liver cells. (4) Signs of portal hypertension: patients with hepatocellular carcinoma often have cirrhosis background, so they often have portal hypertension and enlarged spleen. Abdominal fluid is the manifestation of late stage, which is usually leakage fluid; bloody fluid is mostly caused by the cancer breaking into the abdominal cavity, and can also be caused by peritoneal metastasis; cancer thrombus in portal vein and hepatic vein can accelerate the growth of abdominal fluid. Infiltration and metastasis. (1) Intrahepatic metastasis: initially, liver cancer is mostly intrahepatic metastasis, which is easy to invade portal vein and its branches and form tumor embolus, and cause multiple metastatic foci in the liver after detachment. If the tumor thrombus of portal vein branches is obstructed, it will often cause or aggravate the existing portal hypertension. (2) Extra-hepatic metastasis: ① hematogenous metastasis, most common is lung metastasis, and it can also be transferred to pleura, adrenal glands, kidneys, bones and other parts of the body. Lymphatic metastasis is most common in the hilar lymph nodes, but can also be transferred to the pancreas, spleen and para-aortic lymph nodes, and occasionally involves the supraclavicular lymph nodes. Plantation metastasis is rare, but occasionally it can be planted in the peritoneum, diaphragm and thoracic cavity, causing bloody abdominal and thoracic effusion; women can have ovarian metastasis, which can lead to the formation of larger lumps. 4.Common complications. (1) Upper gastrointestinal bleeding: hepatocellular carcinoma often has hepatitis and cirrhosis background accompanied by portal hypertension, while portal vein and hepatic vein thrombosis can further aggravate portal hypertension, so it often causes bleeding from varicose vein fracture in the middle and lower esophagus or gastric fundus. If the cancer cells invade the bile duct, it may cause biliary hemorrhage, vomiting blood and black stool. Some patients may suffer from extensive bleeding due to erosion of gastrointestinal mucosa, ulcer and coagulation dysfunction, and hemorrhage may lead to shock and hepatic coma. (2) Hepatopathic nephropathy and hepatic encephalopathy (hepatic coma): In the advanced stage of hepatocellular carcinoma, especially diffuse hepatocellular carcinoma, hepatic insufficiency or even failure can occur, which can cause hepatorenal syndrome (HRS), i.e. functional acute renal failure (FARF), which is manifested mainly by Significant oliguria and decreased blood pressure with hyponatremia, hypokalemia and azotemia, often progressive. Hepatic encephalopathy (HE), i.e. hepatic coma, is often a manifestation of terminal stage of hepatocellular carcinoma, which is often induced by gastrointestinal hemorrhage, large amount of diuretics, electrolyte disorders and secondary infection. (3) Hepatocellular carcinoma nodal rupture and bleeding is the most urgent and serious complication of hepatocellular carcinoma. Necrosis and liquefaction of cancer foci in late stage may rupture spontaneously or due to external force, therefore, it is advisable to palpate gently during clinical physical examination and do not press with force. Rupture of cancer nodule may be confined to the subperitoneum of liver, causing acute pain, rapid enlargement of liver, and localization of soft mass; if rupture enters into the abdominal cavity, it may cause acute abdominal pain and peritoneal irritation sign. A small amount of bleeding can be manifested as bloody peritoneal fluid, and a large amount of bleeding can lead to shock or even rapid death. (4) Secondary infection: due to long-term consumption and bed rest, liver cancer patients’ resistance is weakened, especially when the white blood cell decreases after chemotherapy or radiotherapy, it is easy to be complicated with many kinds of infections, such as pneumonia, intestinal infections, fungal infections and sepsis. (C) Auxiliary examination. (1) Blood biochemical examination. Hepatocellular carcinoma may show elevation of aspartate aminotransferase (AST or GOT) and glutamate aminotransferase (ALT or GPT), serum alkaline phosphatase (AKP), lactate dehydrogenase (LDH) or bilirubin, and decrease of albumin and other liver function abnormalities, as well as change of immune indexes, such as subpopulation of lymphocytes. Hepatitis B surface antigen (HBsAg) positivity or “two-to-half” five quantitative tests (including HBsAg, HBeAg, HBeAb and anti-HBc) positivity and/or hepatitis C antibody positivity (anti-HCVIgG, anti-HCVst, anti-HCVns and anti-HCVIgM) are important markers of hepatitis infection; while HBV is the most important indicator of hepatitis infection. HBV DNA and HCV mRNA can reflect hepatitis viral load. Tumor marker test. Serum AFP and its isoforms are important indicators and the most specific tumor markers for diagnosing hepatocellular carcinoma, which are commonly used for liver cancer screening, early diagnosis, postoperative monitoring and follow-up in China. For AFP ≥400 μg/L for more than 1 month or ≥200 μg/L for 2 months, excluding pregnancy, gonadal embryonal carcinoma and active liver disease, hepatocellular carcinoma should be highly suspected; the key is to carry out imaging (CT/MRI) in the same period for whether there is a characteristic occupancy of hepatocellular carcinoma. There are still 30%-40% of liver cancer patients with negative AFP test, including ICC, highly differentiated and lowly differentiated HCC, or HCC with necrosis and liquefaction, AFP may not be increased. Therefore, AFP alone cannot diagnose all hepatocellular carcinomas. The positive rate of AFP for hepatocellular carcinoma diagnosis is generally 60%-70%, sometimes with large differences, emphasizing the need for regular testing and dynamic observation, and with the help of imaging or even ultrasound-guided puncture biopsy and other means to make a clear diagnosis. Other markers that can be used to assist in the diagnosis of HCC include a variety of serum enzymes, including r-glutamyl transpeptidase (GGT) and its isoenzymes, alpha-L-fucosidase (AFU), abnormal plasminogen (DCP), Golgi Protein 73 (GP73), 5’Nucleotide phosphodiesterase (5’NPD) isoenzymes, aldolase isoenzymes A (ALD-A), and placental glutathione S -transferase (GST), etc., as well as abnormal plasminogen (DCP), ferritin (FT) and acid ferritin (AIF). Some HCC patients may have abnormal increase of carcinoembryonic antigen (CEA) and glycan antigen CA19-9. 3.Imaging examination. (1) Abdominal ultrasound (US) examination: because of easy operation, visualization, non-invasive and inexpensive, US examination has become the most common and important method of liver examination. This method can determine whether there are occupying lesions in the liver, suggest their nature, identify whether they are fluid or substantial occupations, clarify the specific location of the cancer foci in the liver and its relationship with the important blood vessels in the liver, which can be used to guide the choice of treatment and surgery; it can help to understand the spread and infiltration of hepatocellular carcinoma in the liver as well as in the neighboring tissues and organs. It is of great reference value for the differential diagnosis of hepatocellular carcinoma with liver cysts and hepatic hemangiomas, etc. However, the sensitivity of detection and accuracy of characterization are affected by the limitations of instrumentation, anatomical site, operator’s technique and experience. Real-time US imaging (ultrasonography CEUS) can dynamically observe the hemodynamics of the lesion, which can help to improve the qualitative diagnosis, but it can be false-positive for patients with ICC, which should be noted; and intraoperative US, which directly probes the surface of the liver from the open abdomen, can avoid ultrasonographic attenuation and the interference of the abdominal wall and the ribs, and can detect small intrahepatic lesions that are not detected by the preoperative imaging examination. (2) Computerized tomography (CT): at present, it is the most important imaging method for diagnosis and differential diagnosis of hepatocellular carcinoma, which is used to observe the morphology of hepatocellular carcinoma and the status of blood supply, detection, characterization and staging of hepatocellular carcinoma, as well as the review of hepatocellular carcinoma after treatment; CT has high resolution, especially multislice CT, which has a high scanning speed, and it can complete the scanning of the whole liver in a few seconds to avoid the respiration artifacts, and is able to carry out multiple dynamic enhancement scanning, and the minimum scanning layer thickness is as small as 0.5 mm. It can perform multi-phase dynamic enhancement scanning and the minimum scanning layer thickness is 0.5mm, which significantly improves the detection rate and characterization accuracy of small lesions of hepatocellular carcinoma. Usually, under plain scanning, hepatocellular carcinoma is usually occupied by low density, with different manifestations of clear or blurred edges, and some of them have halo sign, and large hepatocellular carcinoma often has central necrosis and liquefaction; it can suggest the nature of lesions and understand whether there are cancer foci in tissues and organs around the liver, which can help the localization of radiotherapy; enhanced scanning can clearly show the number, size, morphology and enhancement characteristics of lesions, and also clarify the relationship between lesions and important blood vessels, and whether there are lymph nodes in the hepatoportal and abdominal cavities. In addition to clearly showing the number, size, morphology and enhancement characteristics of the lesions, enhancement scan can also clarify the relationship between the lesions and important blood vessels, the hepatic hilar and abdominal cavity with or without lymph node enlargement and the invasion of neighboring organs, which can provide a reliable basis for the accurate staging of the clinic and help to identify hepatic hemangiomas. (3) Magnetic resonance imaging (MRI or MR): non-radioactive radiation, high tissue resolution, multi-directional and multi-sequence imaging, better than CT and US in displaying and resolution of internal tissue structure changes of hepatocellular carcinoma foci, such as hemorrhage, necrosis, steatosis, and peritoneum, and it may be better than CT for benign and malignant intrahepatic space occupation, especially for differentiating with hemangiomas, and at the same time, it can show the branches of the portal vein and hepatic vein without enhancement. For small hepatocellular carcinoma, MRI is superior to CT, and there is more evidence at present. In particular, the popularization and development of high field strength MR equipment has greatly accelerated the speed of MR scanning, which can complete thin-layer, multi-phase dynamic enhancement scanning like CT, fully displaying the enhancement characteristics of lesions and improving the detection rate and characterization accuracy of lesions. In addition, MR functional imaging techniques (e.g., diffusion-weighted imaging, perfusion-weighted imaging, and spectral analysis) and the application of hepatocyte-specific contrast agents can provide valuable complementary information for lesion detection and characterization, which can help to further improve the sensitivity of detection and accuracy of characterization of hepatocellular carcinoma, as well as to comprehensively and accurately assess the efficacy of various local therapies. The above three important imaging techniques have their own characteristics and complementary advantages, and should be emphasized for comprehensive examination and evaluation. (4) Selective hepatic arteriography (DSA): digital subtraction angiography is mostly used nowadays, which can clearly show small liver lesions and their blood supply, and at the same time, chemotherapy and iodine oil embolization can be carried out. The main manifestations of hepatocellular carcinoma in DSA are: (1) tumor blood vessels, appearing in the early arterial phase; (2) tumor staining, appearing in the parenchymal phase; (3) larger tumors can be seen as displacement, straightening and twisting of intrahepatic arteries; (4) intrahepatic arteries invaded by liver tumors can be jagged, bead-like or stiff; (5) arteriovenous fistulae; “pooling” or “lake-like”; (6) “lake”. (v) arteriovenous fistula; “pool” or “lake” contrast-filled area, and so on. The significance of DSA examination not only lies in diagnosis and differential diagnosis, but also can be used to estimate the scope of lesions before operation or treatment, especially to understand the situation of sub-nodules disseminated in the liver; it can also provide correct and objective information for the anatomical variations of vascular anatomy and anatomical relationship of important blood vessels, as well as portal infiltration, which is of great value for judging the possibility and thoroughness of surgical resection and deciding the reasonable treatment plan.DSA is a kind of invasive traumatizing test and can be used in patients who have not been diagnosed after other tests. In addition, for resectable hepatocellular carcinoma, even if the imaging shows limited resectable hepatocellular carcinoma, some scholars advocate preoperative DSA, which is likely to find lesions that cannot be detected by other imaging means and clarify the presence or absence of vascular invasion. (5) Positron emission computed tomography (PET-CT): PET-CT is a functional molecular imaging system that integrates PET and CT, which can reflect the biochemical and metabolic information of liver occupancy by PET functional imaging, and can carry out precise anatomical localization of lesions by CT morphology imaging, and at the same time, whole-body scanning can be used to understand the overall condition and assess the metastatic situation, so as to achieve the purpose of early detection of lesions. At the same time, whole-body scanning can understand the overall condition and assess the metastatic situation, so as to achieve the purpose of early detection of lesions, and at the same time can understand the size and metabolic changes of the tumor before and after treatment. However, the sensitivity and specificity of clinical diagnosis of hepatocellular carcinoma by PET-CT need to be further improved, and the application of PET-CT has not been popularized in most of the hospitals in China. PET-CT is not recommended to be used as a routine examination for the diagnosis of hepatocellular carcinoma, and it can be used as a supplement to other means. (6) Emission single-photon computed tomography (ECT): ECT whole-body bone imaging can help the diagnosis of bone metastasis of hepatocellular carcinoma, and it can be used to detect bone metastasis of cancer 3-6 months in advance compared with X-ray and CT examination. 4. Liver puncture biopsy. Percutaneous liver puncture with core biopsy or fine needle aspiration (FNA) under ultrasound guidance for histological or cytological examination can obtain the basis of pathological diagnosis of liver cancer and molecular markers, which is very important for clarifying the diagnosis, pathological type, judging the condition, guiding the treatment and evaluating the prognosis. In recent years, it has been increasingly used, but it has certain limitations and dangers. When liver puncture biopsy is performed, attention should be paid to preventing bleeding of the liver and planting of cancer cells in the needle tract; contraindications are patients with obvious bleeding tendency, serious cardiopulmonary, cerebral and renal disorders and systemic failure. (D) Diagnostic criteria of hepatocellular carcinoma. 1. Pathological diagnostic standard: HCC is diagnosed by pathological histological and/or cytological examination of biopsy or surgical resection of tissue specimens from liver occupying lesions or extrahepatic metastases, which is the gold standard. Clinical diagnostic criteria: Among all solid tumors, only HCC can be diagnosed by clinical diagnostic criteria, which are recognized both domestically and internationally, non-invasive, simple, convenient and operable, and generally considered to be mainly dependent on three major factors, i.e. background of chronic liver disease, results of imaging examinations and serum AFP level; however, the understanding and specific requirements of the academic community are different, often with changes, and there are also errors in practical application, therefore, in light of China’s national conditions, established history, the clinical diagnosis of HCC should be based on the following criteria Therefore, combining the national conditions of China, the previous domestic standards and clinical practice, the expert group proposes to strictly control and jointly analyze the following conditions, requiring that the clinical diagnosis of HCC can be established when the following conditions are simultaneously met: (1) evidence of cirrhosis and HBV and/or HCV infection (HBV and/or HCV antigen-positive); (2) evidence of chronic liver disease; (3) evidence of HCC; (4) evidence of HCC; (5) evidence of HCC; (6) evidence of HCC; (7) evidence of HCC; (8) evidence of HCC; (9) evidence of HCC; (10) evidence of HCC. (1) evidence of cirrhosis and HBV and/or HCV infection (HBV and/or HCV antigen-positive); (2) typical imaging features of HCC: simultaneous multislice CT scans and/or dynamic contrast-enhanced MRI showing rapid heterogeneous vascular enhancement of hepatic occupations in the arterial phase (arterial hypervascularity), and rapid washout in the venous or delayed phase (venous or delayed phase washout). HCC can be diagnosed if the diameter of liver occupation is ≥2cm, and one of the two imaging examinations, CT and MRI, shows that the liver occupation has the characteristics of hepatocellular carcinoma as mentioned above; ② If the diameter of liver occupation is 1-2cm, HCC can be diagnosed if both CT and MRI imaging examinations show that the liver occupation has the characteristics of hepatocellular carcinoma as mentioned above, so as to strengthen the specificity of diagnosis. (3) Serum AFP ≥ 400 μg/L for 1 month or ≥ 200 μg/L for 2 months, and other causes of AFP elevation can be excluded, including pregnancy, tumors of germline embryonic origin, active liver disease and secondary liver cancer. 3, Precautions and instructions. (1) A number of foreign guidelines (including AASLD, EASL and NCCN’s CPGs) emphasize that multislice CT scanning and/or dynamic contrast-enhanced MRI should be performed for liver occupancy and should be performed in experienced imaging centers; at the same time, it is believed that a definitive imaging diagnosis of HCC requires a four-phase scanning examination of the scanning, arterial, venous and delayed phases, and that the lesion The localization should be 5mm thin scanning, and attach great importance to the important role of imaging examination of arterial phase enhancement.HCC is characterized by early arterial lesions can be obvious enhancement, density higher than normal liver tissue, venous phase enhancement disappears rapidly, density lower than the surrounding normal liver tissue. If the imaging characteristics of liver occupancy are not typical, or the two examinations of CT and MRI are inconsistent, liver puncture biopsy should be performed, but even if the negative results can not be completely ruled out, it is still necessary to follow up and observe. (2) In recent years, clinical observations and research results at home and abroad suggest that serum AFP can be elevated in some patients with ICC and liver metastasis of gastrointestinal cancer, and ICC is also mostly accompanied by cirrhosis. Although the incidence of ICC is much lower than that of HCC, both of them are common in patients with cirrhosis, therefore, hepatic space-occupying lesions with elevated AFP are not necessarily HCC, and need to be carefully differentiated. In China and most countries in the Asia-Pacific region, patients with significantly elevated AFP are mostly HCC, which still has differential value compared with ICC, and is therefore used as a diagnostic indicator for HCC. (3) For patients with serum AFP ≥ 400 μg/L and no liver occupancy detected by ultrasound, attention should be paid to exclude pregnancy, germline tumors of embryonic origin, active liver disease, and gastrointestinal hepatoid adenocarcinoma, etc.; if it can be excluded, multislice CT and/or dynamic contrast-enhanced MRI scanning must be carried out in time. The diagnosis of HCC is made if the typical imaging features of HCC are present (abundant vascularity in the arterial phase and fading in the portal or delayed phase); if the findings or vascularity are not typical, contrast-enhanced examination should be performed using other imaging modalities or a liver biopsy of the lesion should be performed. Simple enhancement of the arterial phase without regression of the venous phase is not sufficient evidence for the diagnosis of HCC. If AFP is elevated but not at diagnostic level, in addition to the above conditions that may cause AFP increase should be ruled out, it is important to closely observe and follow up the changes of AFP, shorten the interval of ultrasound examination to 1-2 months, and perform CT and/or MRI for dynamic observation when needed. If hepatocellular carcinoma is highly suspected, selective hepatic arteriography (DSA) is recommended, and liver puncture biopsy can be performed if necessary. (4) For those with occupying liver lesions without elevated serum AFP and no imaging features of hepatocellular carcinoma, close observation is possible if the diameter is <1cm. If the liver occupancy does not show vascular enhancement in dynamic imaging, malignancy is unlikely. If the occupancy gradually increases in size or reaches a diameter of ≥2 cm, further examination such as ultrasound-guided liver puncture biopsy should be performed. Even if the liver biopsy result is negative, it should not be easily dismissed and should be tracked and followed up; imaging follow-up should be carried out at 6-month intervals until the lesion disappears, enlarges, or presents the diagnostic features of HCC; if the lesion enlarges but still does not have the typical changes of HCC, repeat liver biopsy can be considered. (5) It should be pointed out that: 5-20% of HCC patients in China do not have cirrhosis background, about 10% of patients do not have evidence of HBV/HCV infection, and about 30% of patients have serum AFP always <200μg/L; at the same time, most of the HCC on imaging has the characteristic of vascularization, but there are a small number of patients who have lack of vascularity. In addition, in Europe and the United States, non-alcoholic steatohepatitis (NASH) patients may develop cirrhosis and then HCC (NASH-associated HCC), which has been reported, but there is a lack of relevant data in China.