MR examination is also known as MRI examination, which is the acronym for magnetic resonance imaging, and is often referred to as MRI. MRI is a frequently used test in clinical practice. The approximate principle is to use electromagnetic fields to image soft tissues and other tissues in the body to aid in the diagnosis of disease. MRI is very sensitive to soft tissues, whether they are nerve tissues, tendons, ligaments or cartilage structures of the meniscus, the more watery the structure, the more sensitive the MRI is. However, the sensitivity is relatively low for structures with very high mineral content and very low water content, such as bones. Therefore, MRI is more accurate and practical when applied to brain tissue, body joints, nerves, angiography, etc.