X-ray is the most basic radiological imaging measure, it is through the body’s different absorption of X-ray to distinguish different densities, bone is high density, appearing as white, fat and water is low density, appearing as black. However, X-ray imaging is to compress all the contents on a plane, that is, all the organs and tissues are superimposed on a single level, which cannot be clearly distinguished, and is generally used only to determine fractures, or whether there are abnormalities in the outline of the organs, and has little diagnostic value for other organic diseases. CT imaging is a further upgrade based on X-ray, which can do tomography, with horizontal sections, so that each organ of the patient is clearly displayed in each horizontal plane, which is three-dimensional and does not superimpose on each other, and can clearly determine the location and size of the lesion, and can further do enhanced examination to determine the nature of the lesion. MRI is fundamentally different from X-ray and CT because it uses magnetic fields to image. The patient’s body cells contain positive and negative ions, which create a weak magnetic field. The magnetic field of MRI will be arranged differently, which also shows different signals. MRI is not called high-density and low-density, but low-signal or high-signal. For ischemic lesions in the brain, it shows better than CT, while hemorrhagic lesions are inferior to CT. For relatively small tumors or other diseases, the positive rate of MRI findings will be higher, and MRI has no radiation and is less damaging to the body.