A scan sequence and method for correcting magnetic resonance center frequency and radio frequency power
A technology of center frequency and radio frequency power, which is applied in the field of magnetic resonance center frequency and radio frequency power correction scan sequence, can solve the problem of long correction process time and achieve the effect of shortening the pre-scan correction time
Active Publication Date: 2019-11-05
ALLTECH MEDICAL SYST
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Since the magnetic resonance signal needs a certain relaxation time to recover after being excited, a longer TR (Repetition Time, repetition time) is required to recover the signal, making the entire calibration process take longer
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[0031] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.
[0032] figure 1 It is an existing scan sequence diagram for MR RF power correction, a classic (α-α-α) type 3-pulse sequence for 90-degree flip angle correction. The three radio frequency pulses have the same transmission power, and only a constant gradient field is applied on the Z axis, which is both a layer selection gradient and a readout gradient. Two echo signals are collected, S1 is the first spin echo signal, and S2 is the stimulated echo signal. Through the signal strengths of S1 and S2, the excitation flip angle can be calculated and used to correct the radio frequency power.
[0033] figure 2The scan sequence diagram of the embodiment of the present invention, the pulse sequence is an improved version of the (α-α-α) type 3 pulse sequence, including: t...
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The invention discloses a magnetic resonance center frequency and radio frequency power correction scanning sequence and method, which belong to the technical field of magnetic resonance imaging. On the basis of the existing classic three-pulse sequence used for 90-degree flip angle correction, a new pulse sequence larger than the original is added. The second gradient field of the constant gradient field, so that under the action of the second gradient field, the refocused second spin echo signal can be collected; under the new gradient field, the first spin echo signal, the stimulated echo signal, the second half echo of the condensed second spin echo signal, and obtain the corrected radio frequency power according to the first spin echo signal and the stimulated echo signal; according to the condensed second spin echo signal The second half of the echo obtains the corrected center frequency. The technical solution provided by the invention can realize the correction of the center frequency while performing the radio frequency power correction, thereby greatly shortening the pre-scanning correction time.
Description
technical field [0001] The present invention relates to the technical field of magnetic resonance imaging, in particular to a scanning sequence and method for correcting magnetic resonance center frequency and radio frequency power. Background technique [0002] Magnetic resonance imaging is a technique that uses the nuclear magnetic resonance phenomenon of hydrogen protons for imaging. Nuclei containing a single number of protons in the human body, such as the ubiquitous hydrogen nucleus, have spin motions for the protons. The spin motion of charged atomic nuclei is physically similar to individual small magnets, and the directionality distribution of these small magnets is random in the absence of external conditions. When the human body is placed in an external magnetic field, these small magnets will be rearranged according to the magnetic force lines of the external magnetic field, specifically in two directions parallel to or antiparallel to the external magnetic fiel...
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IPC IPC(8): G01R33/565
CPCG01R33/56536G01R33/543G01R33/583
Inventor 罗海朱高杰周翔王文周陈梅泞王超刘霞吴子岳
Owner ALLTECH MEDICAL SYST