Method for single sweep quantitative magnetic resonance T2 imaging based on overlapping echoes

Abstract

The invention provides a method for single sweep quantitative magnetic resonance T2 imaging based on overlapping echoes and relates to a magnetic resonance imaging method. Echo signals of two different evolution time are generated by adding two excitation pulses with the same deflection angle in single sweep. Though the evolution time of the two echo signals is different, the T2 weighing of the two echo signals is caused to be different, the two echo signals come from the same imaging slice, the two echo signals can be separated through prior knowledge between the two echo signals, namely the structural similarity in combination with edge sparsity, and the two echo signals are separated by utilizing a separation algorithm corresponding to sparse conversion matching; and finally the two signals obtained through separation undergo T2 calcualtion to obtain a quantitative T2 image. The quantitative T2 imaging in single sweep is acquired, the time of quantitative T2 imaging is reduced from the second grade and even minute grade to the ms grade, and the quality of the acquired T2 image can be equivalent to the quality of an image obtained in an EPI sequence in conventional single sweep.

Description

technical field [0001] The invention relates to a magnetic resonance imaging method, in particular to a single-scan quantitative magnetic resonance T2 imaging method based on overlapping echoes. Background technique [0002] Magnetic resonance parametric imaging (T2 imaging, T2 * Imaging and diffusion imaging) have been widely used in clinical diagnosis because of their ability to provide rich quantitative information on tissue characteristic properties ([1] B. Zhao, F. Lam, and Z. P. Liang, "Model-based MR Parameter mapping with sparsity constraints: parameter estimation and performance bounds , "IEEETrans.Med.Imag., vol.33, no.9, pp.1832-1844, 2014), such as: diagnosis of myocardial infarction, measurement of excessive iron content in the liver, etc. In particular, the quantitative analysis of T2 relaxation time has attracted more and more attention in clinical medical magnetic resonance imaging such as psychiatry and neurology. However, MRI parametric imaging often need...

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Problems solved by technology

However, this method has limitations. On the one hand, this method needs to extend the echo chain, which will inevitably lead to increased acquisition time and signal attenuation; At the expense of time (TR), it may be necessary to sacrifice the spatial resolution of the obtained echo image; and most importantly, this method can only be used for T2* quantitative imaging at present, and cannot be used for T2 quantitative imaging

In addition, although different fast T2 imaging methods have been proposed, including gradient spin echo sequences, these methods all use multiple excitation sequences for T2 imaging, so not only the effect is not satisfactory, but the imaging efficiency needs to be improved urgently

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