MRI examinations can be performed by different machines depending on the field strength, and the results can vary, with the common ones being 0.35 T, 1.0 T, 1.5 T and 3.0 T. T is short for “Tesla”, which is the unit of magnetic field strength. Low-field MRI machines can be made open-ended with permanent magnets. As a high-field MRI machine, 3.0 T has more advantages compared to 1.5 T, such as higher signal-to-noise ratio, higher spatial resolution, better image quality, faster scanning speed, better enhancement, higher detection rate of microhemorrhage in the brain, better joint imaging, abdominopelvic organ imaging and CeMRA than 1.5. Moreover, 3.0 can do a lot of functional imaging, such as perfusion ASL and diffusion imaging DWI (better display of early cerebral ischemia, especially ischemic semidark zone), as well as spectral imaging MRS (of great significance for differential diagnosis of tumors), and magnetic sensitivity imaging SWAN. However, there are also some disadvantages, such as metal artifacts are more obvious, so it is more restrictive for patients with metal foreign bodies; magnetic sensitivity artifacts are more more obvious, greater artifacts at the intersection of bone tissue and soft tissue; greater artifacts of chemical displacement, greater artifacts at the intersection of adipose tissue; greater artifacts in obese patients, patients with ascites, pregnant women and other patients with large abdominal circumference, which affects the diagnosis; motion artifacts are more difficult to control and less cost-effective, and MRA, MRM, and cristae imaging are relatively poor, etc. In addition, there is more tissue heat production, so patients will feel more pronounced body heat. Experienced doctors will make appropriate judgments based on the patient’s medical history and condition, whether to do it and when to do it. Doctors will prefer the most favorable lesion display, the most favorable patient cooperation, and the least impact on the patient to help diagnosis and treatment.