Normally no injection is needed for MRI, only the MRI enhancement scan requires injection, which is mainly an injection of contrast agent in the body for vascular imaging. Although magnetic resonance is currently more advanced imaging examination, but the examination and diagnosis of some diseases are still insufficient, so certain diseases in the process of examination will need to use the contrast agent to enhance the examination. 1. Application principle: MRI enhancement scanning is through the vein to shorten the proton relaxation time of the paramagnetic contrast agent into the blood vessels, so that the normal and diseased tissues of the border is clear, the extent of the lesion can be more clearly presented. 2. Application advantages: the blood supply of lesions such as tumors can be judged by enhancement, which helps to identify the benign or malignant nature of the lesions, and in the case of intracranial neoplastic lesions, the degree of intracranial edema can be clearly presented, as well as some intracranial metastatic foci that are difficult to be detected. In some cases enhancement is used to determine the presence of intravascular lesions, such as the presence of thrombi or tumors in the vessels, or the presence of intimal tears. The exact choice of test needs to be made under the supervision of a physician.