Magnetic resonance imaging method for measuring radio frequency B1 field distribution by means of adiabatic radio frequency pulses
An adiabatic radio frequency pulse and magnetic resonance imaging technology, which is applied in the measurement using nuclear magnetic resonance imaging system, the measurement using nuclear magnetic resonance spectrum, and the measurement using magnetic variables, etc. Effects of calculation and analysis
Active Publication Date: 2020-02-11
WUHAN INST OF PHYSICS & MATHEMATICS CHINESE ACADEMY OF SCI
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The phase reconstruction in the phase method is more complicated, and it may be accompanied by the problem of phase wrapping (the phase exceeds 360°)
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[0044] The sample used in this embodiment is a 3% agarose solution, placed in a NMR sample tube with an outer diameter of 10 mm. A Bruker400M wide-cavity small animal imager was used, with a saddle-shaped body coil with an inner diameter of 10mm, and the temperature was controlled at 300K. Under this condition, the T1 relaxation time of the sample is about 3400ms, the T2 relaxation time is about 40ms, and the TR time of the pulse sequence is set to 5s. The test object of this method can be a sample, or an animal or a human. The radio frequency coil can be a surface coil, a body coil or a phase array coil, etc.
[0045] Magnetic resonance imaging method for measuring radiofrequency B1 field distribution using adiabatic radiofrequency pulses, comprising the following steps:
[0046] Step 1, such as figure 1 As shown in the flow chart, the magnetic resonance imaging method using the adiabatic pulse to measure the B1 field distribution first needs to determine the waveform of t...
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The invention discloses a magnetic resonance imaging method for measuring radio frequency B1 field distribution by means of adiabatic radio frequency pulses. The method comprises the following steps of: designing adiabatic pulses, and setting frequency offset and adiabatic pulse time; calculating a K value of the adiabatic pulses; sampling without applying adiabatic pulses to obtain the magnitudeof an initial magnetization vector; applying adiabatic pulses with frequency offsets of Deltaomegarf and -Deltaomegarf and a damage gradient, and sampling to obtain the magnitudes Mz1 and Mz2 of magnetization vectors; and calculating B1 and obs as well as deviation of B1 measurement caused by field deviation of B0. The method facilitates calculation and analysis; and a large Deltaomegarf can be applied to effectively avoid influence of deviation of the B0 field on B1 measurement.
Description
technical field [0001] The invention belongs to the technical field of nuclear magnetic resonance imaging, and in particular relates to a magnetic resonance imaging method for measuring radio frequency B1 field distribution by using adiabatic radio frequency pulses. The invention is suitable for measuring the distribution of radio frequency B1 field in different tissues or samples when surface coils, body coils or phase array coils are emitted in magnetic resonance imaging, and is used for image reconstruction and B1 field correction. Background technique [0002] Magnetic resonance imaging is an important clinical method for diagnosing and evaluating disease progression. It has the advantages of no ionizing radiation, non-invasiveness, high spatial resolution, imaging at any level, and high tissue contrast. substitute role. [0003] The B1 field represents the strength of the radio frequency pulses when the magnetic resonance coil is fired. In magnetic resonance imaging, ...
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IPC IPC(8): G01R33/46G01R33/483G01R33/54
CPCG01R33/4616G01R33/4831G01R33/54
Inventor 周欣袁亚平郭茜旎孙献平叶朝辉
Owner WUHAN INST OF PHYSICS & MATHEMATICS CHINESE ACADEMY OF SCI