There are differences between CT and MRI in terms of imaging principle, scope of application, hazards to the human body, advantages and disadvantages, etc., and the means of examination should be selected reasonably. 1. Imaging principle: CT is the use of different densities of the body’s tissues to absorb different X-rays for imaging. MRI is through the magnetic field and the body of water molecules magnetic field formation reaction, so that in the normal and abnormal tissue signal difference. 2. Scope of application: CT is generally applicable to the whole body examination, enhanced CT can also clarify the nature of the disease, three-dimensional imaging can also be three-dimensional display of tissue structure. MRI is suitable for the examination of the nervous system, blood vessels, joints and muscles and other soft tissues as well as spinal lesions. 3. Harmful to human body: CT produces ionizing radiation, which is harmful to the human body, and women and children who are preparing for pregnancy or are pregnant should try to avoid undergoing related examinations. MRI does not produce radiation, which is less damaging to the human body and can be repeated several times. 4. Advantages and disadvantages: CT has higher radiation, clearer imaging and greater clinical value. MRI is clear and accurate, but more expensive, with more contraindications and longer examination time. When it is necessary to carry out the above examinations, it is recommended to go to the hospital and choose the appropriate examination method according to the needs of the disease under the guidance of the physician, so as to facilitate the identification of the cause of the disease.