The liver is the largest substantial organ in the body and is a high incidence site for tumors; liver tumors are classified into two categories: primary (primary hepatocellular carcinoma, etc.) and secondary (liver metastases). Both primary and secondary tumors can be effectively treated by applying ultrasound-guided ablation technology. To control liver tumors in the long term depends on the following aspects: i. Comprehensive and accurate guidance The accuracy of ultrasound guidance among the existing guidance means is much higher than that of CT and MR, and a skilled operator can accurately puncture a lesion of 2 to 4 mm in the liver. Since it is performed under real-time monitoring, the effect of breathing can be completely excluded, which is a great advantage over CT and MR. In the past, the biggest weakness of this guidance means is no therapeutic exploration and localization of tumors located at the top of the liver diaphragm, now we have solved this problem through the assistance of artificial chest water, from the perspective of ultrasound guidance, there is no longer a blind spot, and tumors in any part of the liver can be accurately punctured. Eliminate the forbidden zone of treatment Tumors can occur in any part of the liver, tumors located next to large vessels and hilar tumors can not be resected by surgery, tumors adjacent to the cavity organs can not be irradiated with radical dose by radiotherapy, but tumors in the above areas can be treated with radiofrequency therapy and anhydrous alcohol injection, and it is very safe. Radiotherapy for lesions close to cavity organs is risky. 3. Reliable therapeutic effect At present, the ablation effect of radiofrequency and anhydrous alcohol injection has been recognized internationally, and it is believed that the therapeutic effect of tumors with a diameter of less than 3cm is equivalent to that of surgical operation; with the improvement of radiofrequency ablation equipment, the range of the single ablation of some instruments has already reached 7cm (diameter), which has significantly increased the therapeutic effect on larger tumors. For tumors with a diameter of 10cm, radiofrequency treatment can also make them completely necrotic (the right figure shows that the tumor has been completely necrotic after treatment, with no blood supply). 4. Positioning of residual and recurrent foci after repeated treatments Ablation therapy is a kind of in situ inactivation of the tumor, and the tumor is necrotic after the treatment, but it is difficult to differentiate it from residual or recurrent tumors by imaging, which makes it difficult for ablation again. With very enhanced CT or MR, ultrasonography can solve this problem to a certain and degree, but the effect is not ideal. In recent years, we have applied PET-CT technology to guide the reablation treatment of residual and recurrent tumors after ablation therapy, and achieved good results. Fifth, the therapeutic means has little damage, no cumulative toxicity, and can be repeated many times Surgery is very traumatic and cannot be repeated many times; radiotherapy has hematopoietic and immunosuppressive effects, and when the cumulative dose is large, it will cause radioactive damage to liver and gastrointestinal tract, and it is also impossible to repeat the treatment. However, tumors in the liver can recur many times, so how to deal with it? Minimally invasive ablation therapy is the best choice. Theoretically, ablation therapy can be used repeatedly for unlimited times. Effective means to control the appearance of new metastatic foci After eliminating the visible metastatic foci in the liver, how to maintain the therapeutic effect and avoid the appearance of new metastatic foci? There is evidence that gastrointestinal tumors metastasize to the liver through the portal vein, and the portal vein is the main blood supply in the early stage. Previous clinical trials have proved that the incidence of liver metastasis of colorectal cancer can be reduced by 1/2 to 2/3 through portal vein chemotherapy. After the above six conditions are met, theoretically speaking, as long as the patient has enough financial conditions and sufficient functional reserve of the liver, the liver tumor may be completely relieved at the level of PET-CT and effectively controlled for a long period of time.