Hyperpolarized angle calibration method based on multi-angle excitation in single breath hold

Abstract

The invention discloses a hyperpolarized angle calibration method based on multi-angle excitation in a single breath hold. The method comprises the steps of: using a multi-angle excitation mode in the single breath hold of a subject to obtain signals excited by different angles; then setting a group of longitudinal relaxation time T1 values, and fitting out a primary angle [theta]' by the signals of the different angles; utilizing the [theta]' to successively calculate a residual longitudinal magnetized vector M after the final time of excitation of each angle, and then utilizing M and signals of the first time of excitation of each angle to calculates a secondary angle [phi], wherein in one group of set T1 values, the T1 value, enabling the primary angle [theta]' to be closest to the secondary angle [phi], is the most accurate longitudinal relaxation time; and then utilizing the T1 value to calculate all the angles, and finishing angle calibration. The method has the advantages that the operation is simple, the calibration of the plurality of angles and the measurement of T1 are simultaneously completed in the single breath hold, the time is saved, and the cost is also saved.

Description

technical field [0001] The invention relates to the technical field of magnetic resonance imaging, in particular to a hyperpolarization angle calibration method based on multi-angle excitation in a single breath-hold. suitable for hyperpolarization 129 Xe, 3 He, 83 Kr and other hyperpolarized gases and hyperpolarization 13 C for magnetic resonance imaging, suitable for magnetic resonance radiofrequency coils in the shape of birdcages, surfaces, saddles, phased arrays, etc. of the corresponding resonance nuclei. Background technique [0002] Magnetic resonance (MRI) gas contrast agents (eg 129 Xe, 3 He, 83 Inert gases such as Kr) become hyperpolarized state after optical pumping, and its detection sensitivity can be enhanced by 10 compared with the conventional level. 3 ~10 5 Times, has become a visual detection medium for pulmonary gas exchange in scientific research work, and is expected to be extended to clinical practice. [0003] The flip angle calibration of th...

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Problems solved by technology

[0005] Some existing hyperpolarized radio frequency coil angle calibration methods have certain deficiencies, such as a breath-hold can only calibrate an angle (see Measurements of hyperpolarized gas properties inthelung. PartIII: He-3T-1. Magnetic Resonance In Medicine, 2001.45 (3 ): p.421-430. etc.), T cannot be obtained when calibrating the angle 1 Therefore, its influence can only be neglected (see K-space filter deconvolution and flip angle self-calibration in 2 Dradial hyperpolarized 3 Helung MRI of Marshall, H. et al. NMR in Biomedicine, 2012.25(2): p.389-399; etc.), it takes multiple breaths and breath-holding to measure T 1 Also calibrate the angle (see Flipangle considerations in (3) Helium-MRI.NmrInBiomedicine, 2000.13(4):p.190-193. of Markstaller, K. et al., etc.)

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