Why MRI Can “See” Your Body
When you go to the hospital for a radiological examination, you should have heard of the “MRI” project, so do you know how this type of examination allows the doctor to “see” your body?
Magnetic resonance imaging is a new medical imaging technology using the principle of nuclear magnetic resonance. diagnostic function. Compared with other auxiliary examination methods, MRI has the advantages of many imaging parameters, fast scanning speed, high tissue resolution and clearer images, etc. It can help doctors “see” the early lesions that are difficult to detect. A powerful tool for early screening of cerebrovascular disease.
The “nucleus” in MRI refers to the nucleus of a hydrogen atom. 70% of the human body is composed of water. The nuclei are positively charged and have spin, which creates an electric current that creates a magnetic field, so each nucleus acts like a small magnet. When the object is placed in a magnetic field, the nucleus interacts with the external magnetic field, and atoms in different spin states have different energies; irradiate it with appropriate electromagnetic waves, when the energy of the applied electromagnetic wave is equal to the energy difference of the atomic nuclei in different states, the nucleus Resonates with the applied electromagnetic wave, jumping from the low-energy state to the high-energy state; removing the applied electromagnetic wave, the atomic nucleus in the high-energy state will emit part of the energy in the form of electromagnetic waves and be detected.
By analyzing the attenuation of this signal in different structures inside the material, the distribution image of the moving nuclei can be deduced, and the precise three-dimensional structure and motion inside the material can be reconstructed after computer processing. This is equivalent to saying: We can photograph the internal structure and changes of objects directly from the outside, just like Sun Wukong with golden eyes.
Human tissue contains a large amount of water and carbon-plastic compounds, and the NMR of hydrogen has high flexibility and strong signal, so ammonium hydrogen is usually chosen to image the human body. The water ratio of various tissues in the human body is different, and the signal strength is different, so it is very convenient to separate various structures, normal tissues and diseased tissues.
Magnetic resonance imaging is not only clear and precise, but it is also a rare safe, fast and accurate clinical diagnosis method that does not cause any harm to the human body. Today, at least 60 million cases worldwide are examined using MRI technology every year.