Single-excitation fat-water separation imaging error correction system and method

Abstract

The invention discloses a single-excitation fat-water separation imaging error correction system and method. A pre-scanning module and a fat-water scanning module are installed on a host of a magnetic resonance imager and are loaded to a sequence generator of a spectrometer, for controlling a radio frequency system and a gradient system to realize excitation, space encoding and acquisition of human body proton signals. A matched data preprocessing module, a primary amplitude correction module, a primary phase correction module, a phase unwrapping module, a high-grade error correction module and a fat-water image separation module are installed on the host. According to the invention, the problem of imperfect hardware of MRI equipment is effectively overcome, a field nonuniform effect and a chemical displacement effect of a TE period are taken into consideration, the error correction precision of echo amplitude errors and phase errors and the efficiency of a phase unwrapping algorithm are improved, and the need of clinic image diagnosis is satisfied.

Description

technical field

[0001] The invention relates to the technical field of medical magnetic resonance imaging, in particular to a single-shot water-fat separation imaging error correction system and method. Background technique

[0002] In medical magnetic resonance imaging (MRI), fat suppression imaging is significantly better than conventional imaging techniques in showing lesions. Commonly used fat suppression methods include selective fat magnetization saturation, water selective excitation and short TI recovery (STIR). Compared with these fat suppression imaging techniques, the chemical shift imaging technique that performs separate imaging of each component based on the chemical shift of different tissue components, Δf, is more sensitive to the radiofrequency field B 1 The homogeneity and magnetic field strength have no special requirements and the image signal-to-noise ratio is not lost. It can also determine the relative proportion of fat and water in the tissue, which i...

Examples

Embodiment 1

[0163] On the 0.35T medical magnetic resonance imager, set the center frequency of the radio frequency pulse to the water proton resonance frequency (14.9MHz), press Figure eight The workflow shown executes the modules.

[0164] First, run the pre-scan module, locate the signal acquisition area within the area of ​​interest of the human body, and run Figure 1 In the apparent transverse relaxation time test sequence shown, the data preprocessing module obtains the apparent transverse relaxation time constant through nonlinear fitting of the echo amplitudes of different TEs based on formula (1) When the eddy current effect is significant, the pre-scan module performs gradient waveform pre-emphasis compensation in the following manner:

[0165] A. The positioning signal acquisition area is located within the area of ​​interest of the human body. For Figure six The eddy current test sequence shown, sets the amplitude, width, and polarity of the read gradient pulse with the ...

Embodiment 2

[0186] On the 1.5T medical magnetic resonance imager, set the center frequency of the radio frequency pulse as the proton resonance frequency (63.8MHz), according to Figure 8 The workflow shown executes each module, starting with the pre-scan module run Figure 1 For the apparent transverse relaxation time test sequence shown, the data preprocessing module obtains the apparent transverse relaxation time constant + Then, the hydrolipid scan module runs Figure II In the three-dimensional version of the dual gradient echo chemical shift imaging sequence shown, the integral area of ​​the first frequency encoding gradient is set to be twice the integral area of ​​the pre-reading gradient in the sequence. The two polarities are opposite, and the second frequency encoding is set The polarity of the gradient is opposite to that of the first frequency encoding gradient, and the integral areas of the two are equal. The 180° hard pulse width is calibrated to 100 μs, and the time inte...

technical field

[0001] The invention relates to the technical field of medical magnetic resonance imaging, in particular to a single-shot water-fat separation imaging error correction system and method. Background technique

[0002] In medical magnetic resonance imaging (MRI), fat suppression imaging is significantly better than conventional imaging techniques in showing lesions. Commonly used fat suppression methods include selective fat magnetization saturation, water selective excitation and short TI recovery (STIR). Compared with these fat suppression imaging techniques, the chemical shift imaging technique that performs separate imaging of each component based on the chemical shift of different tissue components, Δf, is more sensitive to the radiofrequency field B 1 The homogeneity and magnetic field strength have no special requirements and the image signal-to-noise ratio is not lost. It can also determine the relative proportion of fat and water in the tissue, which i...

Examples

Embodiment 1

[0163] On the 0.35T medical magnetic resonance imager, set the center frequency of the radio frequency pulse to the water proton resonance frequency (14.9MHz), press Figure eight The workflow shown executes the modules.

[0164] First, run the pre-scan module, locate the signal acquisition area within the area of ​​interest of the human body, and run Figure 1 In the apparent transverse relaxation time test sequence shown, the data preprocessing module obtains the apparent transverse relaxation time constant through nonlinear fitting of the echo amplitudes of different TEs based on formula (1) When the eddy current effect is significant, the pre-scan module performs gradient waveform pre-emphasis compensation in the following manner:

[0165] A. The positioning signal acquisition area is located within the area of ​​interest of the human body. For Figure six The eddy current test sequence shown, sets the amplitude, width, and polarity of the read gradient pulse with the ...

Embodiment 2

[0186] On the 1.5T medical magnetic resonance imager, set the center frequency of the radio frequency pulse as the proton resonance frequency (63.8MHz), according to Figure 8 The workflow shown executes each module, starting with the pre-scan module run Figure 1 For the apparent transverse relaxation time test sequence shown, the data preprocessing module obtains the apparent transverse relaxation time constant + Then, the hydrolipid scan module runs Figure II In the three-dimensional version of the dual gradient echo chemical shift imaging sequence shown, the integral area of ​​the first frequency encoding gradient is set to be twice the integral area of ​​the pre-reading gradient in the sequence. The two polarities are opposite, and the second frequency encoding is set The polarity of the gradient is opposite to that of the first frequency encoding gradient, and the integral areas of the two are equal. The 180° hard pulse width is calibrated to 100 μs, and the time inte...

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