In the new century, minimally invasive imaging-guided interventional therapy for tumors has been developing rapidly in the field of global medicine due to its unique advantages, and its main feature is to eliminate tumors in situ and protect the organism to the maximum extent. Imaging-guided minimally invasive interventional therapy can be divided into two categories, vascular and non-vascular, in terms of diagnostic and therapeutic methods; vascular interventional therapy mainly consists of transvascular selective cannulation of tumors for local perfusion chemotherapy and embolization, while non-vascular interventional therapy mainly consists of percutaneous puncture of tumors for ablation therapy (Ablation) and radioactive particle implantation. At present, minimally invasive surgery in China has been able to treat a variety of tumors such as lung cancer, liver cancer, breast cancer, prostate cancer, kidney cancer and so on. Minimally invasive treatment of tumor has the following six characteristics: 1) precise positioning and accurate treatment; 2) sequential joint treatment of multiple minimally invasive treatments; 3) minimally invasive treatment and multidisciplinary comprehensive treatment of tumor; 4) minimally invasive treatment of radical tumor: local and regional minimally invasive interventional treatment combined with systemic multi-level treatment; 5) humanized and rationalized treatment; 6) minimally invasive lymph node dissection of tumor. Zhao Wenhua, Minimally Invasive Tumor Section, Shandong Qianfoshan Hospital I. Chemoablation is the procedure of percutaneous puncture of tumor tissue under the guidance of imaging equipment to inject ablating agent directly into the tumor to achieve the purpose of in situ inactivation of the tumor. Chemoablation is suitable for primary and metastatic tumors in all parts of the body, primary liver cancer with lack of blood supply, metastatic liver cancer, lung cancer, benign and malignant tumors of adrenal gland, pelvic tumors, etc., or liver cancer with incomplete iodine oil filling in the lesion after TACE and lymph node metastasis. Commonly used ablation agents include tumor cytotoxic agents (various chemotherapeutic drugs) and protein coagulants. 1.Tumor cytotoxic agent: the commonly used method is to inject chemotherapeutic drugs proportioned according to the cytological type of the tumor mixed with a small amount of iodized oil percutaneously into the tumor interior or metastatic lymph nodes, so that the anti-tumor drugs are slow-released in the tumor body to kill the tumor cells directly, which improves the local chemotherapeutic concentration of the tumor, and at the same time, it reduces the toxicity of the chemotherapeutic drugs on the whole body of the patient’s injury, but it needs to be repeatedly injected. In ultrasound, CT guided percutaneous puncture injection into the tumor, increasing the drug release time and smoothness, compared with systemic drugs to reduce the peak concentration of drugs in the blood and the number of times of drug administration. 2.Protein coagulant: commonly used anhydrous ethanol and so on. The clinical application of anhydrous ethanol is the most widely used, and its principle is to make the tumor cells coagulate, cytoplasm dehydration, tumor vascular epithelial cell necrosis, small blood vessel thrombosis so that the tumor tissue ischemic necrosis. For smaller tumors, due to the consistent tissue structure of the tumor body, anhydrous ethanol can be easily dispersed to make the necrosis of the tumor more complete, while the dispersion of ablating agent for larger tumors is limited due to the mixed composition of the tumor body and the existence of fibrous segregation. Physical ablation (Physical ablation) is the process of necrosis of a lesion through the cold or hot effect of physics by puncturing the lesion under image guidance. Physical ablation is also divided into thermal ablation and cold ablation. Commonly used thermal ablation methods include radiofrequency ablation, microwave ablation and laser ablation. 1, cryoablation: the recent cryotherapy equipment argon helium knife is the use of Joule-Thomson effect, the use of room temperature high-pressure argon refrigeration, the lowest temperature in the tip of the part of the needle can reach -185 ℃, high-pressure helium rewarming, the temperature can reach 70 ℃. Tumor necrosis is accelerated by cycles such as freezing-rewarming. The commonly used probe is an ultrafine probe with a diameter of 1.47 mm, and cryoablation of larger lesions can be performed by combining multiple needles. The principle of cryogenic freezing is the formation of ice crystals in the intercellular matrix. Changes in intra- and extracellular electrolytes and osmotic pressure lead to cell dehydration, damage to cell membranes, which in turn leads to intracellular ice crystal formation and cell degeneration and necrosis. The swelling and rupture of the endothelium and basement membrane of microarteries and microveins during cryoablation leads to extensive thrombosis in the local microcirculation after rewarming, which further aggravates tissue hypoxia and promotes tissue necrosis. Cryoablation is currently the best treatment for large tumors (diameter > 75px) without any toxic side effects, and the long-term follow-up results have proved that the survival rate is high. 2.Thermal ablation (Thermal ablation): Tumor cells are very sensitive to temperature and cannot tolerate temperatures above 60℃, and all of them will be apoptotic above 70℃. In-situ inactivation of tumor can be achieved by generating high temperature inside the tumor through physical methods. Radiofrequency thermal ablation (RFA) is the most widely used thermal ablation therapy. Its basic principle is to introduce high-frequency oscillating current into the tumor tissues through the ablation electrode, so that the ions and polarized molecules of the local tissues will oscillate rapidly with the direction of the current, leading to friction and heat generation of the tissues, and the heat comes from the tissues themselves, not from the RF electrode. The heat comes from the tissue itself and not from the RF electrode. When the local temperature reaches 50℃, the tissue cells will start to die in 4-6 minutes; when the temperature exceeds 70℃, the cells will die immediately; when the temperature reaches 100℃, the cell membrane will be dissolved, the intercellular water will evaporate, and the tissues will be disintegrated and charred. Tumor ablation area is spherical or elliptical, and the maximum ablation diameter of the current multicellular needle ablation electrode can be up to 55 mm at one time. As a minimally invasive treatment technology, radiofrequency thermal ablation has been widely used in the treatment of tumors of liver, kidney, prostate and other substantial organs, and has achieved ideal curative effect. 3.Laser ablation: This technique is to send/scatter laser light in the lesion through 1 optical fiber of 0. 4 mm in diameter and convert it into heat energy, which makes the tumor tissue cells undergo coagulation and necrosis without damaging the surrounding tissues. The laser energy can cause spherical coagulative necrosis around the laser beam, and the size of the laser ablation range is not only related to its energy accumulation, but also depends on the blood supply of the tumor and the vasodilatory response of the surrounding normal tissues. The efficacy of LITT depends on the precise position of the laser probe, the temperature change of the local tumor tissue and other factors. Radioactive particle implantation Radioactive particle (seed source) implantation for the treatment of malignant tumors is an advanced minimally invasive treatment method, which belongs to one kind of brachytherapy, with the advantages of safety, reliability, wide indications, easy operation, etc. It is a new minimally invasive in vivo radiotherapy for malignant tumors. The clinical efficacy of low-energy radiation seed source originates from the interaction between the excited ion stream and the tissue and organ where it is located so as to irradiate the tumor site at a close distance.DNA is the key target of the action of radiation on the cells, and radiation irradiation leads to the breakage of the DNA strand, which causes the tumor cells to lose the ability to reproduce. Studies have shown that during tumor growth, the late stage of DNA synthesis and mitosis in the reproductive cycle are the most sensitive to radiation, while cells in the quiescent stage are the least sensitive to radiation. In vitro radiotherapy can only treat cells in a small portion of the reproductive cycle of the tumor by irradiating them for a short period of time. Although the energy of radiation generated by implanting radioactive particles between tumor tissues is not large, it can continuously act on tumor cells and kill tumor stem cells uninterruptedly, and after sufficient dosage and half-life, it can make all tumor cells lose the ability to reproduce, and achieve complete treatment effect. Various imaging-guided percutaneous minimally invasive interventional techniques have shown remarkable application prospects for the treatment of malignant tumors, and flexible selection of the best method or combined treatment methods can improve the cure rate and long-term survival rate of tumors.