Magnetic resonance is also known as nuclear magnetic resonance (MRI). It is to place the human body in a strong magnetic field, the magnetic distance of certain protons in human tissue is arranged along the magnetic field direction and moves around the magnetic field direction at a certain frequency. At this time, a radio frequency pulse with the same frequency as the proton movement is used to excite the proton magnetic distance, so that the level of thermal nucleation occurs, when the proton emits energy and produces a signal, the signal is amplified by a computer and reconstructed into an image, which is what we call a magnetic resonance image (MRI). MRI is an examination in which the patient is exposed to a high magnetic field, so the patient’s body should not have metal objects, such as watches and jewelry, which the patient should be careful to remove during the examination, and patients with pacemakers cannot have MRI examinations. MRI is non-invasive, non-radioactive, safe and reliable, and easily accepted by patients. It is suitable for examining lesions of the central system, and its superiority is shown in vascular lesions, posterior cranial recess lesions and spinal cord diseases. 1.Note on magnetic resonance examination 1.If there are magnet-like substances in the body, such as those equipped with pacemakers, artificial valves, and metal foreign body residues next to important organs, etc., they cannot do this examination, but the implants in the body confirmed by the surgeon as non-magnetic objects are feasible for magnetic resonance examination. 2, to explain to the technician the following: any history of surgery; any metal or magnetic material implanted in the body including metal birth control rings, etc.; any dentures, electronic ears, prosthetic eyes, etc.; any drug allergy; any metal foreign body splashed into the body. 3, do not wear underwear with metal substances, check the head and neck of the patient should be washed the day before the examination, do not rub any hair care products. 4. Before the examination, you should take off all the clothes except underwear and put on the special clothes for the MRI room. Remove metal items such as necklaces, earrings, watches and rings. Remove cosmetics, dentures, prosthetic eyes, glasses and other items from your face. 5.Provide all medical history, examination information and all X-rays, CT films, previous MRI films, etc. to the doctor before the examination. 6, abdominal (liver, spleen, kidney, pancreas, biliary tract, ureter, etc.) examiners should fast for 4 hours before the examination, and inject 654-2 one before the examination. 7. For magnetic resonance urography (MRU), take 20 mg of oral tachyphylaxis before the examination. 8. Be prepared for the MRI examination, do not be impatient and afraid, listen to the physician’s instructions and cooperate patiently. The difference between MRI and CT MRI is the abbreviation of Magnetic ResnaneIamge, and CT and MRI are two very different examination methods. The three directions are positioned and then computerized to form images of each direction. CT is the abbreviation of ComputerizedTomography, because the X-ray tube and detector are rotated around a certain part of the body, so it can only do cross-sectional imaging of the body, while MRI can do cross-sectional, sagittal, coronal and arbitrary section imaging. There are also water imaging, water suppression imaging, fat suppression, diffusion imaging, spectral imaging, functional imaging, etc. CT can only discriminate tissues with density differences and has low resolution of soft tissues while MRI has better resolution of soft tissues, such as muscle, fat, cartilage, and fascia with different signals. Therefore, CT and MRI are very different examination methods. The amount of information provided by MRI is not only greater than many other imaging techniques in medical imaging, but is also different from existing imaging techniques, making it potentially superior for the diagnosis of disease. MRI is very effective in detecting common cranio-cerebral diseases such as intracerebral hematoma, extracerebral hematoma, brain tumor, intracranial aneurysm, arteriovenous malformation, cerebral ischemia, intraspinal tumor, spinal cavernous disease and spinal fluid, as well as lumbar spine It is also effective in the diagnosis of posterior disc protrusion and primary liver cancer. MRI also has shortcomings. The spatial resolution of MRI is not as good as that of CT, and patients with pacemakers or certain metallic foreign bodies cannot be examined with MRI.