The basic principle is to put the human body in a special magnetic field, with radio frequency pulses to stimulate the hydrogen nucleus in the human body, causing the hydrogen nucleus **** vibration, and absorbing energy. After stopping the radio frequency pulse, the hydrogen nucleus sends out radio signals at a specific frequency and releases the absorbed energy, which is recorded by the receiver outside the body and processed by an electronic computer to obtain an image, which is called nuclear magnetic **** vibration imaging.
Nuclear magnetic **** vibration is a physical phenomenon, as a means of analysis is widely used in the field of physics, chemistry biology, etc., to 1973 it will be used for medical clinical testing. To avoid confusion with radiographic imaging in nuclear medicine, it is referred to as magnetic *** vibration imaging (MR).
MR is a biomagnetic spin imaging technology, it is the use of atomic nuclei spin motion characteristics, in the applied magnetic field, by radio frequency pulse excitation after the generation of signals, detected by a detector and input into the computer, after the processing of the converted images displayed on the screen.
The amount of information provided by MR is not only greater than many other imaging techniques in medical imaging, but also different from existing imaging techniques, so it has a great potential superiority in the diagnosis of diseases. It can directly make cross-sectional, sagittal, coronal, and various oblique images, and will not produce the artifacts in CT detection; does not require injection of contrast media; no ionizing radiation, no adverse effects on the body.MR is very effective in detecting common cranio-cerebral disorders, such as intracerebral hematomas, extracerebral hematomas, brain tumors, intracranial aneurysms, arterio-venous vascular malformations, cerebral ischemia, intradural tumors, spinal cavernous disease, and hydrocephalus.
MR also has shortcomings. Its spatial resolution is not as good as that of CT, and patients with pacemakers or certain metallic foreign bodies cannot be examined with MR, and it is also expensive.