What is radiofrequency needle ablation of intratissue tumors?

Radiofrequency ablation, also known in some literature as cold-pole radiofrequency, can result in two different treatments, cold and heat. The simplified principle of the treatment is that single or multi-needle ablation electrode is directly inserted into the tumor site of the patient under the guidance of B ultrasound or CT. The generator forms a current loop through the ablation electrode, grounding electrode and body tissue. Conductive ions and polarized molecules in the body tissue rapidly change their direction of motion under the action of RF alternating current. However, due to the different volume and mass of various conducting ions and the amount of electricity they carry, their inversion and motion speed will be different. Therefore, friction heat will be generated between them. Due to the extremely high current density around the ablation electrode, a local high temperature zone will be formed around the electrode. When the temperature reaches more than 60℃, the protein in the tissue will denature, and the tumor cells will become irreversible necrosis. At the same time, outside the coagulated necrotic zone, there is a 43℃-60℃ hyperthermia zone, in which tumor cells are killed, while normal cells can recover.

After radiofrequency ablation, a coagulated necrotic area with a clear and nearly spherical boundary was formed around the ablation electrode, and the tumor tissue covered by this area was destroyed and inactivated. Some of the coagulated necrotic tissues are absorbed by the human body, and these necrotic tissues have the function of tumor vaccine due to the change of cellular immunophenotype, thus playing a special anti-cancer role, strengthening the immune function of patients and further improving the curative effect.

To extend the range of primary ablation, a radiofrequency ablation system called a cool-tip electrode is used, which uses cooling water and a circulating pump instead of a temperature control system. The cold cycle electrode consists of a thin conventional RF electrode incorporated into a double cavity 18 gauge insulated pipe. The chamber is connected at the electrode tip so that the inside of the electrode tip is cooled by injection of cold brine. As a result, the heat of the tissue near the tip of the radiofrequency electrode decreased, allowing more energy to accumulate. This allows the electrode to further increase the thermal energy and solidification of the tissue without carbonization.