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Hyperpolarized magnetic resonance imaging method based on constant angle and variable angle optimization excitation

A magnetic resonance imaging and hyperpolarization technology, which is applied in the direction of using nuclear magnetic resonance imaging system for measurement, magnetic resonance measurement, magnetic variable measurement, etc., can solve the problems of linear reduction of FID amplitude and low FID amplitude, and achieve MR The effect of better image quality, avoidance of excessive losses, improved imaging speed and MR image quality

Active Publication Date: 2014-12-03
武汉中科极化医疗科技有限公司
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Problems solved by technology

However, the small-angle excitation method has certain shortcomings. For example, the fixed-angle excitation method leads to a linear decrease in the FID amplitude; although the variable-angle excitation method can keep the FID amplitude unchanged, compared with the initial FID amplitude of the fixed-angle excitation method, its FID amplitude is low

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  • Hyperpolarized magnetic resonance imaging method based on constant angle and variable angle optimization excitation
  • Hyperpolarized magnetic resonance imaging method based on constant angle and variable angle optimization excitation
  • Hyperpolarized magnetic resonance imaging method based on constant angle and variable angle optimization excitation

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Embodiment 1

[0033] Such as figure 1 As shown, a hyperpolarized magnetic resonance imaging method based on fixed-variable-angle optimal excitation is divided into three stages: fixed-angle excitation stage, variable-angle excitation stage, and MR image reconstruction stage, including the following steps:

[0034] Step 1, initialize the number of radio frequency (RF) excitations N of the fixed-variable angle optimization excitation method, and the value of N is generally 64, 96, 128, 192 or 256;

[0035] Step 2, initialize the excitation angle (flip angle) α in the fixed-angle excitation stage, and the value range of the flip angle α is (α min , α T ], where α min The value of arccos(e -1 / N ), the specific derivation process refers to step 3, α T The value of 2α min .

[0036] Step 3, determine the number of fixed-angle excitations n in the fixed-angle excitation stage * . After n times of excitation at a fixed angle, the SNR of the MR signal is proportional to the following formula...

Embodiment 2

[0062] Adopt the technical scheme in embodiment 1, when N=128, according to step 2, the value range of the excitation angle α of the fixed-angle excitation stage is [7.15°, 14.30°], and α=8.72°; according to step 3 The number of fixed-angle excitations can be obtained n * =86; According to step 4, the initial flip angle θ of the variable-angle excitation stage can be obtained * (1) range is [8.72°,8.82°], take θ * (1)=8.77°; according to step 5, a series of excitation angles of variable angle excitation 8.77°, 8.87°, 8.98°, ..., 35.15°, 44.76°; finally, according to step 6 and step 7, hyperpolarized MR signals are collected , and perform MR image reconstruction to obtain hyperpolarized magnetic resonance MR images.

Embodiment 3

[0064] The magnetization vector of hyperpolarized gas is irreversible, so it is expected that the Nth excitation will completely reverse the residual longitudinal magnetic field vector to the x-y plane. The excitation angle of the Nth excitation that satisfies the above requirements should be 90 degrees, then the relevant parameters in Embodiment 1—the excitation angle (flip angle) α of the fixed-angle excitation stage, the number of excitations n of the fixed-angle excitation stage * , and the initial flip angle θ of the variable-angle excitation stage * (1) Perform optimization to obtain an optimized fixed-variable-angle excitation strategy to obtain hyperpolarized magnetic resonance signals with high SNR.

[0065] Step 1, initialize the number of radio frequency (RF) excitations N of the fixed-variable angle optimization excitation method, and the value of N is generally 64, 96, 128, 192 or 256;

[0066] Step 2, determine the optimized fixed-angle excitation angle (flip an...

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Abstract

The invention discloses a hyperpolarized magnetic resonance imaging method based on constant angle and variable angle optimization excitation, and relates to the field of magnetic resonance imaging. Advantages of constant angle excitation and advantages of variable angle excitation are synthesized in the method, excitation operation is divided into a constant angle excitation phase and a variable angle excitation phase, in another word, a constant angle excitation method is adopted for previous n* times of excitation, a variable angle excitation method is adopted for consequent N-n* times of excitation, and N is the total number of times of excitation; meanwhile, appropriate constant angle excitation parameters and appropriate variable angle excitation parameters are chosen so that reconstructed MR images can have higher SNRs and better image quality, robustness of algorithms is high, and noise, artifact and the like are obviously reduced compared with those in the prior art.

Description

technical field [0001] The invention relates to the technical field of magnetic resonance imaging, in particular to a hyperpolarized magnetic resonance imaging method based on constant-variable angle optimal excitation. suitable for hyperpolarization 129 Xe or 13 Magnetic resonance fast echo imaging such as C can also be applied to other fields that require fast echo imaging. Background technique [0002] Air pollution (for example, smog) accelerates and exacerbates the malignant development of lung disease problems. Medical imaging diagnosis is the most commonly used and most intuitive way of diagnosing lung diseases. However, there are certain defects in the commonly used pulmonary medical imaging diagnostic techniques, for example, the rays emitted by chest X-ray fluoroscopy and computerized tomography (CT) all belong to high-energy rays, which will cause certain damage to the human body (high-energy rays will cause damage to the human body). kill white blood cells in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R33/54
Inventor 周欣邓鹤孙献平叶朝辉刘买利
Owner 武汉中科极化医疗科技有限公司
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