Double-echo based single-sweep quantitative magnetic resonance T2* imaging method

Abstract

A double-echo based single-sweep quantitative magnetic resonance T2* imaging method relates to magnetic resonance imaging. Two low-angle excitation pulses of the same deflection angle are used, an evolution period is added after the first excited pulse, two echoes of different evolution time are generated, the two echoes include different horizontal relaxation time, and a shift gradient is added after each excitation pulse so that two echo signals are offset in the center of a signal space. The two echo signals are from the same imaging slice, so that the two echo signals can be separated by utilizing prior knowledge including structural similarity and sparsity of combined edges of the signals, and a proper separation algorithm corresponding to sparse transformation cooperation can be used to separate the two echo signals. T2* calculation is carried out on the two signals obtained by separating to obtain a quantitative T2* image.

Description

technical field [0001] The invention relates to magnetic resonance imaging, in particular to a double-echo-based single-scan quantitative magnetic resonance T2* imaging method. Background technique [0002] T2* imaging, as a type of quantitative MRI imaging, provides a contrasting mechanism for analyzing normal and diseased living tissues in a non-invasive manner, and the iron content of tissues can be obtained through the measurement of T2* relaxation. [1,2] The measurement of T2* relaxation has been applied to functional magnetic resonance imaging (fMRI), such as the measurement of brain oxygen uptake and venous blood volume, and the diagnosis of brain diseases. [3,4] T2* imaging needs to obtain a series of contrast-weighted images, and T2* can be calculated only through two or more T2* weighted images with different echo times, which requires multiple scans to achieve. Multiple scans not only make T2* imaging vulnerable to motion, but also make the measurement time longe...

AI Technical Summary

Problems solved by technology

However, this method has limitations. One is that this method needs to prolong the echo chain, which will inevitably lead to increased acquisition time and signal attenuation; on the other hand, compared with the conventional EPI method, the realization of this method is to prolong the repetition time ( TR), which may require sacrificing the spatial resolution of the resulting echo image

In addition, although different fast quantitative imaging methods have been proposed one after another, including gradient spin echo sequences, these methods all use multiple excitation sequences for quantitative imaging, which not only does not work well enough, but also does not greatly improve the imaging efficiency.

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