1.What is an MRI? 　　MRI (magnetic resonance imaging) produces images by means of nuclear magnetic resonance. Water molecules are formed by hydrogen and oxygen atoms. While the human body contains 60% water, "hydrogen atoms" are the richest content in the human body. The nuclear magnetic resonance uses a powerful external magnetic and radiofrequency pulse to promote hydrogen atom resonance. By converting the hydrogen nucleus distribution signals in the human body, we can obtain the information about the human anatomic structure. 　　MRI is a newly developed imaging diagnostic technique. In addition to providing clear anatomic structure, it delivers images in axial, coronal and sagittal planes without radiation.

2. How does MRI works? 　　An MRI scanner uses nuclear magnetic resonance to put the human body in an evenly distributed, powerful, static magnetic field. By changing the regional magnetic field with a particular radiofrequency pulse, it excites the hydrogen atoms in the human body to produce resonance in order to generate the magnetic matrix signals. 　　As the human body has different kinds of tissues and contents of different natures, different types of signals will produce. With the help of computing and imaging, the sectional tissue structure and lesions are presented in images of different plains.