After injecting a contrast agent into a blood vessel at high speed, the shape of the blood vessel is displayed with an X-ray called angiography. Angiography has important value in diagnosing vascular diseases. In addition, angiography can also be used for the diagnosis of tumors. The uncontrolled growth pattern of tumor depends on the generation of tumor blood vessels. Tumor vessels and normal vessels have different morphological characteristics, for example, the density of tumor vessels is higher than that of normal vessels due to rapid tumor growth; tumor vessels are compressed and pushed by tumor tissue causing abnormal morphology. Therefore, the tumor can be diagnosed based on the morphological characteristics of the vessels observed after angiography. A catheter is inserted into the hepatic artery through skin puncture, and the contrast agent is injected and then X-rayed, which is called hepatic arteriography. In the arterial phase after contrast injection, increased density, disorganized direction and vascular nudging of hepatocellular carcinoma vessels are observed, and in the parenchymal phase and venous phase, contrast agent is observed to stay in the tumor area to form tumor staining. By these features it is possible to diagnose hepatocellular carcinoma. Hepatic arteriography is the most sensitive method to diagnose hepatocellular carcinoma, and it can usually detect hepatocellular carcinoma with a diameter of 1 cm or even 0.5 cm. However, since hepatic arteriography is an invasive test, it is not a routine test for liver cancer. It is only used when non-invasive tests such as ultrasound, CT and MRI cannot detect liver cancer and when there is a high clinical suspicion of liver cancer.