Gradient-echo multi-echo water and fat separation method and magnetic resonance imaging system using method

Abstract

The invention discloses a gradient-echo multi-echo water and fat separation method. The method includes the following steps of 1, using a three-dimensional gradient-echo N echo sequence for conductingimaging scanning on a magnetic resonance imaging region, collecting N pieces of echo data, and using a GRAPPA technology for accelerating data collection during collection, wherein N is greater thanor equal to 4; 2, using the GRAPPA technology for fitting and restoring to-be-collected phase encoding data of the N pieces of echo data within respective K spaces, and then conducting preliminary data processing to obtain complete image domain data of N echoes; 3, substituting the image domain data of the N echoes into a water and fat separation algorithm of a multi-peak water-fat model, introducing T2* variables, conducting iterative calculation, obtaining a T2* distribution map of an imaged object, and meanwhile obtaining water and fat images through calculation. According to the method, the T2* distribution can be accurately estimated, the signal attenuation between the echoes is effectively corrected, and phase changes caused by inhomogeneity of a magnetic field are reduced, so that results of the quantitative analysis images are more accurate and stable. A magnetic resonance imaging system using the method is also provided.

Description

technical field [0001] The invention belongs to the technical field of magnetic resonance imaging, and in particular relates to a gradient echo multi-echo (four or more) water-fat separation method and a magnetic resonance imaging system applying the method. Background technique [0002] Magnetic resonance imaging (MRI) technology has become a commonly used technique in modern medical diagnosis. In MRI, due to the different molecular environment of hydrogen protons in human tissue water and fat, there is a certain difference in the resonance frequency, which is called chemical shift. Dixon was the first to use this principle to obtain water and fat images in MRI. Assuming that human tissue only contains two components of water and fat, that is, human tissue only contains two resonance frequencies in MRI. When the human body is excited by radio frequency pulses, the relaxation time of the two tissues is different, and the signals are collected at different echo times. Water...

AI Technical Summary

Problems solved by technology

However, in the existing reports, there is an unavoidable underestimation of T2*

Especially when the number of collected echoes is small, the calculated T2* is greatly shortened compared with the ideal value. Increasing the number of echoes will make the calculated T2* gradually approach the ideal value, but it will greatly increase the data acquisition time

The underestimation of T2* not only affects the diagnosis of its own clinical significance (such as iron deposition), but also affects the T2* attenuation correction of the signal itself, which greatly reduces the accuracy of quantitative analysis of water and fat separation

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