Method for separate imaging of water and fat based on inversion recovery technology and system

Abstract

The invention discloses a method for separate imaging of water and fat based on inversion recovery technology, which includes the following steps of: determining a first inversion recovery time when the longitudinal magnetization component of hydrogen atomic nucleus in fat or water is zero; respectively selecting a second inversion recovery time and a third inversion time before and after the first inversion recovery time; during the second and the third inversion recovery time, respectively using a scanning sequence to excite a detected object and obtaining two images simultaneously including a pure water image and a pure fat image; synthesizing the two obtained images; and when the synthesis removes the pure fat image included in the two images, obtaining a pure water image, when the synthesis removes the pure water image included in the two images, obtaining a pure fat image. By the use of the invention, the pure water image and the pure fat image can be obtained at one time by using the scanning sequence to excite the detected object and the signal-to-noise ratio of the images is relatively high.

Description

technical field [0001] The present invention relates to magnetic resonance imaging technology, in particular to a water-fat separation imaging method and system based on inversion recovery (IR, Inversion Recovery) technology. Background technique [0002] Magnetic resonance imaging is a technique that uses the phenomenon of magnetic resonance to perform imaging. The principle of magnetic resonance phenomenon mainly includes: atomic nuclei containing a single number of protons, such as hydrogen nuclei widely present in the human body, the protons have spin motion, just like a small magnet, and the spin axes of these small magnets have no certain rules. External magnetic field, these small magnets will be rearranged according to the magnetic force lines of the external magnetic field, specifically in two directions parallel to or antiparallel to the magnetic force lines of the external magnetic field, and the above-mentioned direction parallel to the magnetic force lines of th...

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Problems solved by technology

The disadvantage of the three-point Dixon method is that the additional phase obtained from the two reversed-phase images cannot be directly used to correct the phase, but the phase must be unwrapped. However, phase unwrapping is a mathematically unsolvable problem, so assuming that the external magnetic field inhomogeneity changes slowly in space, the solution process will be quite time-consuming, and the calculation process is also more complicated

[0013] Although the use of IR technology for water-fat separation imaging can ignore the influence of external magnetic field inhomogeneity, and there will be no difficulty in designing narrow-band pulses when using frequency selection methods, but when acquiring pure water images or pure fat images, only The echo signal sent by hydrogen nuclei in water or fat is used, so that the signal amplitude is greatly reduced, and due to the randomness of noise, the large decrease in signal amplitude will reduce the signal-to-noise ratio of the image, thus affecting the imaging quality

In addition, it is impossible to obtain pure water images and pure fat images by using a scanning sequence to excite the subject once

[0014] In summary, among the currently existing water-fat separation imaging methods, the water-fat separation imaging method based on IR technology is a method with a simple calculation process and is least affected by the performance of the external magnetic field, but the water-fat separation imaging method based on IR technology The separation imaging method still has the disadvantages of low image signal-to-noise ratio and the inability to obtain pure water images and pure fat images by using a scanning sequence to excite the subject once

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