Generally speaking, abdominal magnetic resonance imaging (MRI) is radiation-free and is recommended to be performed under the supervision of a physician. The principle of MRI is to utilize the hydrogen nuclei, i.e. hydrogen protons, in the human body within a strong external magnetic field to produce magnetic resonance phenomena under the action of specific radio frequency pulses, and to use equipment to capture signals for processing to form the final image. This process mainly utilizes magnetic fields, which are found even in nature and are essentially harmless to the body, which has nothing to do with radiation; therefore, MRI examinations are radiation-free. With the advancement of medical technology, MRI has become a safe and common imaging technique. MRI is also used in the examination of some abdominal diseases, and it is more conducive to the diagnosis and differential diagnosis of peritoneal cavity diseases, for example, it is often used as a complementary technique after CT examination in peritoneal cavity diseases (such as peritoneal cavity effusion), and it can be examined with confidence.