MRI 1.5T means that the field strength of MRI is 1.5 Tesla. The field strength of MRI is divided into several kinds, generally the MRI instruments below 0.5T are called low field machines, 0.5-1.0T are called medium field machines, 1.0-2.0T are high field machines, and those greater than 2.0T are called ultra-high field machines. The higher the magnetic field strength, the higher the proton magnetization rate and image signal-to-noise ratio, the faster the detection speed, and the easier to achieve fat saturation technology, but it also increases the cost of the examination, and its impact on the human body is greater than that of the low field.