Transmitting frequency calibration method for chemical saturation in MRI and MRI system

Abstract

The invention relates to a transmitting frequency calibration method for chemical saturation in MRI and a MRI system. The invention provides a transmitting frequency calibration method for chemical saturation, which relates to the chemical saturation imaging technology of magnetic resonance imaging (MRI) technology. The method of the invention adopts the decrease of water signal amplitude as standard to judge that the fat is fully saturated, therefore obtaining the transmitting frequency of fat saturation. And in addition, the invention also can confirm the best saturation transmitting frequency through combining with other prescan method. With the method of the invention, the fat-suppression effect is stable than before, and the method is less rely on the experience of the operator, and the image quality of chemical saturation (particularly the image quality of chemical saturation in low field MRI) is improved.

Description

technical field [0001] The present invention relates to magnetic resonance imaging (MRI) technology, in particular to chemical saturation imaging technology. Background technique [0002] MRI systems work on the principle of nuclear magnetic resonance to obtain images of the human body. Human tissue is made up of molecules like water and fat that contain hydrogen atoms. The nucleus of a hydrogen atom has an associated magnetic moment, which is a measure of the net magnetic properties of the hydrogen nucleus. When human tissue is in the magnetic field B 0 Under the action of the magnetic field B 0 Interacts with the magnetic moments of the hydrogen nuclei and aligns a fraction of the nuclei with the magnetic field B 0 In the same direction. Magnetic field B 0 Also make the magnetic moments of the same direction atomic nuclei go around the magnetic field B at a frequency (ω) (called the precession frequency, frequency of precession) 0 Direction precession. The precessi...

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Problems solved by technology

[0013] However, this method has the following disadvantages: (1) The field strength is highly dependent

(3) When scanning with a large FOV, the fat suppression effect in the peripheral area of ​​the field of view is poor, which is also related to the uniformity of the magnetic field and the linearity of the gradient

[0015] 1) Relatively poor field uniformity;

[0016] 2) It is not easy to get the correct center frequency;

[0018] 4) Center frequency drift

[0024] The disadvantages of this method are: on the one hand, it largely depends on the experience of the operator; on the other hand, in some cases, it is difficult to judge whether the fat is well saturated, because the fat signal and the water signal may Mix together

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