Magnetic resonance imaging method and system for image water and fat separation

Abstract

The invention provides an image water-fat separation method and a water-fat separation system based on magnetic resonance imaging. The image water-fat separation method is characterized in that echo signals corresponding to at least two echo time combinations can be acquired; based on a MR signal model of water and fat chemical shift, the correspondence between the discrete field pattern value and the model fit error of every pixel of the image in the echo signal corresponding to every echo time combination can be acquired to generate the corresponding field pattern-model fit error curve; the field pattern value corresponding to the fit error at the minimum value in the preset field pattern value range can be searched from at least two model fit error curves corresponding to every pixel, and can be used as the to-be-estimated field pattern value; according to the searched to-be-estimated field pattern value, the actual field pattern value corresponding to every pixel can be acquired; according to the actual field pattern value corresponding to every pixel, the water image and the fat image can be acquired. The technical scheme capable of acquiring the field pattern and realizing the water-fat separation can be provided.

Description

technical field [0001] The invention relates to a water-fat separation technology in magnetic resonance imaging, in particular to a method and system for magnetic resonance imaging image water-fat separation. Background technique [0002] In Magnetic Resonance Imaging (MRI), it is generally believed that the signals generated by the water excitation in the tissue contain most of the pathological information in the tissue, but in some common MRI sequences, such as fast auto In fast spin-echo (FSE), steady-state free progression (SSFP) and spoiled gradient echo (spoiled gradient echo, SPGER) imaging sequences, the fat in the tissue presents high signal, and these The high signal from fat will cover up the signal generated by water excitation, so that some pathological information will be lost, so that some lesions cannot be displayed, and even cause misjudgment of lesions by clinicians, so the existence of fat signals is seriously reduced. Clinicopathological research value o...

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Problems solved by technology

However, since this method uses an iterative algorithm to estimate the inhomogeneity of the main magnetic field B0, it inevitably converges to a wrong field map value

Therefore, the IDEAL water-fat separation algorithm mainly has the following disadvantages: because the inhomogeneity of the main magnetic field B0 changes with the spatial variation of the magnetic susceptibility, in some parts where the magnetic susceptibility changes suddenly, such as the air-tissue contact surface, the main magnetic field B0 The inhomogeneity will also increase, making this part have a larger field image value, but the IDEAL algorithm is only suitable for the water-fat separation of the MR image where the inhomogeneity of the main magnetic field B0 is at a moderate level, because the iterative algorithm will converge to the local extreme values, and cannot estimate the correct field map with larger values

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