CN110780249A - Magnetic resonance imaging method using adiabatic radio frequency pulses to measure radio frequency B1 field distribution - Google Patents

Magnetic resonance imaging method using adiabatic radio frequency pulses to measure radio frequency B1 field distribution Download PDF

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CN110780249A
CN110780249A CN201911151143.1A CN201911151143A CN110780249A CN 110780249 A CN110780249 A CN 110780249A CN 201911151143 A CN201911151143 A CN 201911151143A CN 110780249 A CN110780249 A CN 110780249A
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周欣
袁亚平
郭茜旎
孙献平
叶朝辉
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Wuhan Institute of Physics and Mathematics of CAS
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    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/46—NMR spectroscopy
    • G01R33/4616—NMR spectroscopy using specific RF pulses or specific modulation schemes, e.g. stochastic excitation, adiabatic RF pulses, composite pulses, binomial pulses, Shinnar-le-Roux pulses, spectrally selective pulses not being used for spatial selection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
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    • G01R33/48—NMR imaging systems
    • G01R33/483—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy
    • G01R33/4831—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy using B1 gradients, e.g. rotating frame techniques, use of surface coils
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    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
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Abstract

The invention discloses a magnetic resonance imaging method for measuring radio frequency B1 field distribution by using adiabatic radio frequency pulse, which comprises the following steps of designing adiabatic pulse, setting frequency offset and adiabatic pulse time, calculating K value of the adiabatic pulse, obtaining initial magnetization vector size without applying adiabatic pulse sampling, and respectively applying frequency offset of △ omega rfAnd- △ omega rfAnd the magnitude of the magnetization vector M obtained by sampling z1And M z2(ii) a Calculation of B 1,obsAnd calculating the deviation of B1 measurement caused by B0 field deviation, and applying large △ omega to facilitate calculation and analysis rfThe values are good enough to avoid the effect of B0 field offset on the B1 measurement.

Description

Magnetic resonance imaging method using adiabatic radio frequency pulses to measure radio frequency B1 field distribution
Technical Field
The invention belongs to the technical field of nuclear magnetic resonance imaging, and particularly 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 the radio frequency B1 field in different tissues or samples when a surface coil, a body coil or a phase array coil transmits in magnetic resonance imaging, and is used for image reconstruction, B1 field correction and the like.
Background
Magnetic resonance imaging is an important clinical method for diagnosing and evaluating the progress of diseases, has the advantages of no ionizing radiation, non-invasiveness, high spatial resolution, imaging in any layer, high tissue contrast and the like, and has an irreplaceable effect on the diagnosis of tumors, visceral organs, soft tissue lesions and the like.
The B1 field represents the strength of the radio frequency pulse at the time of transmission by the magnetic resonance coil. In magnetic resonance imaging, the radio frequency B1 field appears unevenly distributed in space due to tissue irregularities and due to the uneven transmission field of the coil. With the increasing magnetic field strength of the current magnetic resonance spectrometer, the problem of nonuniform radio frequency B1 field becomes more serious. In parallel imaging and Chemical Exchange Saturation Transfer (CEST) imaging, which are commonly used in magnetic resonance, image reconstruction and correction of the radio frequency B1 field distribution are also required. The development of a magnetic resonance method for measuring the field distribution of the radio frequency B1 can solve the above problems.
The B0 field indicates the magnitude of the magnetic field induced at a point in space during magnetic resonance imaging, and is closely related to the nuclear spin frequency. The difference between the radio frequency and the nuclear spin frequency at radio frequency excitation is represented by the B0 field offset frequency. The B0 field shift affects the measurement of the B1 field distribution, mainly because the magnetic resonance signal under the off-resonance effect is related to both B0 and B1 when the B0 field shift is large. Therefore, the effect of B0 field shift cannot be neglected when measuring the B1 field distribution.
The existing magnetic resonance methods for measuring the B1 field distribution are mainly based on a dual flip angle method of signal amplitude, such as the B1 field measurement method based on different flip angles proposed by Insko EK et al [ Mapping of the radio frequency field.J.Magn.Reson.A.1993.45: p.82-85 ], and the B1 field measurement method based on different flip angles with higher speed proposed by Cunningham CH et al [ trained double-angle method for rapid B1+ Mapping. Magn.Reson.Med.2006.55: p.1326-1333 ]. However, the excitation waveforms of the pulses with different flip angles are not linear, and the method is sensitive to B0 field shifts.
The AFI (effective flip-angle) method proposed by Yarnykh VL et al [ effective flip-angle imaging in the pulsed step state: for radial-dimensional mapping of the transmitted radio frequency front-end field. Magn. Reson. Med.2007.57: p.192-200.] utilizes the ratio of signal intensities of two different recovery times TR1 and TR2 at the same excitation angle to calculate the B1 field distribution, which is fast but sensitive to B0 field offset and motion.
The method based on the signal phase mainly comprises a measuring method proposed by Sachalick LI et al [ B1 mapping by Bloch-Siegershift.Magn.Reson.Med.2010.63: p.1315-1322 ], wherein the phase change of the Bloch-Siegershift is in direct proportion to the square of a B1 field. The phase reconstruction in the phase method is complicated and may be accompanied by problems of phase convolution (phase exceeding 360 °).
In addition, other methods include the method proposed by PatrickSchuenke et al [ Silvery Mapping of WaterShiftand B1(WASABI) -Application to Field-innovation Correction of CEST MRIData.Magn.Reson.Med.2017.77: p.571-580 ] to simultaneously fit the B0 and B1 Field distributions using the partial resonance effect. The method is applied to chemical exchange saturation transfer imaging, and 10 or more images are required to be acquired for curve fitting.
The invention provides a magnetic resonance imaging method for measuring the field distribution of radio frequency B1 by using adiabatic radio frequency pulses, which is a B1 measuring method which is insensitive to B0 field offset and can be widely applied to different pulse sequences, and provides technical support for measurement of radio frequency B1 fields, image reconstruction correction and the like.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a magnetic resonance imaging method for measuring the rf B1 field distribution using adiabatic rf pulses, which is based on the following ideas:
in a rotating coordinate system, the magnetization vector can be considered to be along the effective B1 field, B effThe field precesses. Wherein, B eff＝[(γB1) 2+(△ω) 2] 1/2γ represents the gyromagnetic ratio of the nucleus, △ ω represents the magnitude of the B0 field offset, B effCharacterization B effThe strength of the field, B1, characterizes the strength of the B1 field. Precession frequency ω ═ γ B eff。B effThe field makes an angle θ with the Z axis (i.e., the main magnetic field direction) arctan (γ B1/| △ ω |).
Adiabatic pulsing is a radio frequency pulsing under special conditions. Under adiabatic conditions, with the initial B effThe magnetization vector parallel to the field will be spin-locked by the adiabatic pulse and always stay with B effThe field remains collinear.
Adiabatic pulsing requires satisfaction of adiabatic conditions, definition
Figure 1
Then require K>>1 to ensure thermal insulation, i.e. around B effThe field precession frequency is far greater than B effVariation of field angle with Z-axis to satisfy adiabatic conditions, a large frequency offset, defined as △ ω, is set for the RF pulses rfGuarantee △ omega rf>△ omega. addition of an offset value increases both B and B effThe value reduces the variation of theta along with the B1 field, and ensures the heat insulation of the radio frequency pulse.
Selecting a radio frequency pulse with initial intensity of 0 and maximum intensity at the end, and setting the maximum intensity of the radio frequency pulse as B 1maxUnder adiabatic conditions, i.e. setting the frequency offset of the RF pulses to △ omega rfGuarantee △ omega rf>△ omega, the included angle between the magnetization vector and the Z axis is 0 when the radio frequency pulse starts, and the included angle between the magnetization vector and the Z axis is theta when the radio frequency pulse ends 1＝arctan[γB 1max/|(△ω+△ω rf)|]。
Setting the initial magnetization vector to M 0After the adiabatic pulse is finished, the angle between the magnetization vector and the Z-axis direction is theta 1＝arctan[γB 1max/|(△ω+△ω rf)|]Applying a destruction gradient field to destroyBy dropping transverse magnetization vector, only the initial magnetization vector M remains 0Projection M in Z-axis direction z1Then M is z1＝M 0cos(θ 1) Similarly, the frequency offset was changed to- △ ω rfAngle theta between the magnetization vector and the Z axis 2＝arctan[γB 1max/|(△ω-△ω rf)|]，M z2＝M 0cos(θ 2)。
Let B 1,obsFor the calculated value of the B1 field, the calculation is disclosed as follows:
Figure BDA0002283581550000031
Figure BDA0002283581550000032
in equation 2, △ ω 2/(△ω rf 2-△ω 2) Term is observed B 1,obsAnd reality B 1maxAt selected △ omega rfAt 4000Hz, △ omega has a deviation of 1.01% or less in the range-400 to 400Hz, △ omega is insensitive to △ omega in order to ensure the thermal insulation of the pulses and to measure rfThe larger the selection value, the better, 2000Hz or more can satisfy the experimental conditions.
A magnetic resonance imaging method for measuring a radio frequency B1 field distribution using adiabatic radio frequency pulses, comprising the steps of:
step 1, designing adiabatic pulse, wherein the initial intensity of the adiabatic pulse is zero, and the adiabatic pulse is gradually increased to the maximum intensity B 1maxSet frequency offset △ ω rfAnd adiabatic pulse time;
and 2, calculating the K value of the adiabatic pulse to ensure that the K value meets the adiabatic condition. The K value is calculated by the formula Give out K>The adiabatic condition is satisfied in case 100. Maximum intensity B 1maxThe larger the K value, the smaller the △ omega rfThe larger the value of K; the pulse time is as short as possible to reduce the relaxation when K is satisfiedInfluence of Henan wherein B effCharacterization B effThe intensity of the field, gamma being the gyromagnetic ratio of the nucleus, theta being B effThe angle between the field and the Z axis (i.e., the main magnetic field direction), θ ═ arctan (γ B1/| △ ω |), B1 characterizes the strength of the B1 field, and △ ω is the magnitude of the B0 field offset;
step 3, maximum intensity B of adiabatic pulse is not applied or is applied 1maxSet to zero, the sample obtains the initial magnetization vector magnitude M 0；
Step 4, applying frequency offset of △ omega rfAnd the magnitude of the magnetization vector M obtained by sampling z1；
Step 5, applying frequency bias to- △ omega rfAnd the magnitude of the magnetization vector M obtained by sampling z2；
Step 6, calculate B using the following formula 1,obs，
Figure BDA0002283581550000041
Wherein M is 0Is the initial magnetization vector.
B is to be 1,obsDivided by the maximum intensity B 1maxNormalizing to obtain normalized radio frequency B1 field distribution;
step 7, △ ω is biased according to the selected frequency rfAccording to △ omega 2/(△ω rf 2-△ω 2) To calculate the deviation, △ ω, of the B1 measurement due to the B0 field offset rf>△ω。
Compared with the prior art, the invention has the following beneficial effects:
1. in the method, the adiabatic pulse intensity and the signal intensity under the adiabatic condition present a simple trigonometric function relationship, and are convenient to calculate and analyze.
2. The calculated deviation of the method due to the B0 field deviation △ omega is △ omega 2/(△ω rf 2-△ω 2) By applying large △ omega rfThe values are good enough to avoid the effect of B0 field offset on the B1 measurement.
3. In the method, before the adiabatic pulse and the damage gradient are applied to the sampling, the adiabatic pulse and the damage gradient can be integrated into a sub-module without being limited by the sampling method.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2(a) shows a simple linearly increasing pulse shape, B 1max40 muT, a duration of 2ms,
FIG. 2(b) shows the pulse of FIG. 2(a) at a bias △ ω rfThe K value is changed along with the pulse time at 4000Hz, and the K value is far more than 1 in the whole process, so that the adiabatic condition is met. The pulse used in the present invention is not limited to this pulse shape;
FIG. 3 is a pulse sequence diagram of a B1 field distributed magnetic resonance imaging method using adiabatic pulse measurements; only a pulse sequence diagram for carrying out data acquisition by using spin echo is introduced in the figure, and the data acquisition mode used by the invention is not limited;
FIG. 4 is a graph of the evolution of the magnetization vector with the pulse intensity under adiabatic conditions, the initial magnetization vector M 0Is pulsed to turn over to B effDirection, in this case projected in the Z-axis direction as M z1,2；
FIG. 5 is a normalized B1 field profile of a 3% agarose solution sample measured using the method of the invention;
fig. 6 shows measurement errors due to B0 field offset △ ω in a magnetic resonance imaging method using adiabatic pulses to measure the B1 field distribution.
Detailed Description
The present invention will be described in further detail with reference to examples for the purpose of facilitating understanding and practice of the invention by those of ordinary skill in the art, and it is to be understood that the present invention has been described in the illustrative embodiments and is not to be construed as limited thereto.
Example (b):
the sample used in this example was a 3% agarose solution and placed in a 10mm outer diameter nuclear magnetic sample tube. A Bruker400M wide chamber small animal imager was used, saddle coils with an inner diameter of 10mm, and the temperature was controlled at 300K. Under this condition, the T1 relaxation time of the sample was about 3400ms, the T2 relaxation time was about 40ms, and the pulse train TR time was set to 5 s. The test object of the method can be a sample, and can also be an animal or a human. The radio frequency coil may be a surface coil, a body coil, a phased array coil, or the like.
A magnetic resonance imaging method for measuring a radio frequency B1 field distribution using adiabatic radio frequency pulses, comprising the steps of:
step 1, as shown in the flow chart of fig. 1, the magnetic resonance imaging method using adiabatic pulse to measure B1 field distribution first determines the waveform of the adiabatic pulse to satisfy the condition that the initial intensity is 0 and the maximum intensity B is reached before the adiabatic pulse ends 1max. In this embodiment, a simple linearly varying pulse shape is used, as shown in fig. 4. Setting the maximum intensity B 1maxFor 40 μ T, set frequency offset △ ω rf4000Hz, adiabatic pulse time 2 ms. The pulse shape of the method using adiabatic pulses is not limited to linear pulses, but may be various pulses satisfying from 0 to B 1maxAn incrementally shaped pulse.
And 2, calculating the heat insulation degree, namely the K value. First, the adiabatic pulse in this embodiment is composed of 1000 points. From formula B eff＝[(γB 1) 2+(△ω rf) 2] 1/2Respectively calculating B corresponding to each point effValue, then using the formula θ ═ arctan [ γ B ═ 1/|(△ω rf)|]And respectively calculating the angle theta corresponding to each time point. The ratio of the difference between two adjacent points theta to the time difference between the adjacent points is d theta/dt, and finally, a formula can be used And calculating the K value. The distribution of the K value of the pulse used in this example with time is shown in FIG. 2(b), and K is satisfied>>1, adiabatic condition.
The pulse sequence used in this example is shown in FIG. 3, and after applying the adiabatic pulses in step 2, the initial magnetization vector will be inverted to the final B effOrientation, as shown in fig. 4. At this time, a destruction gradient in three X/Y/Z directions of 1ms is immediately applied to destroy the transverse magnetization vector, and then data acquisition is started. The data acquisition mode used in this example is fast spinThe echo mode is not limited to the sampling mode, and the sampling mode such as gradient echo or plane echo can be used after the adiabatic pulse and the damage gradient are applied.
Step 3, maximum intensity B of adiabatic pulse is not applied or is applied 1maxSet to zero, the sample obtains the initial magnetization vector magnitude M 0；
Step 4, applying frequency offset of △ omega rfAnd the magnitude of the magnetization vector M obtained by sampling z1；
Step 5, applying frequency bias to- △ omega rfAnd the magnitude of the magnetization vector M obtained by sampling z2；
Step 6, calculate B using the following formula 1,obs，
Figure BDA0002283581550000061
Wherein M is 0Is the initial magnetization vector.
B is to be 1,obsDivided by the maximum intensity B 1maxNormalizing to obtain normalized radio frequency B1 field distribution;
first, a first image without adiabatic pulse (or with a maximum pulse intensity of 0) is acquired, and then, a first image with a maximum pulse intensity of △ omega is acquired rfAnd- △ omega rfThe two images of the adiabatic impulse of (2) are a second image and a third image, respectively.
And respectively carrying out background segmentation on the first image, the second image and the third image to enable the image backgrounds of the first image, the second image and the third image to be zero. And then carrying out point-to-point calculation on the first image, the second image and the third image. Taking any point on the first image, and setting the signal intensity as M 0Respectively applying radio frequency bias of △ omega rfAnd- △ omega rfThe signal intensity of the point on the second image and the point on the third image at the same position as the point on the first image are respectively set as M Z1、M Z2. Then, B is measured 1,obsCan be calculated by the formula (1).
B corresponding to each point on the image by step 6 1,obsCalculated to obtain the B1 distribution map. Each point of the B1 profile is then divided by the system-set B 1maxValues, a normalized B1 profile was obtained. The normalized B1 distribution calculated in this example is shown in FIG. 5, where the sample tube has local B1 field inhomogeneity near the coil region.
Step 7, △ ω is biased according to the selected frequency rfAccording to △ omega 2/(△ω rf 2-△ω 2) To calculate the deviation, △ ω, of the B1 measurement due to the B0 field offset rf>△ω。
The calculation error brought by the B0 field offset △ omega is △ omega 2/(△ω rf 2-△ω 2) FIG. 6 shows a difference △ ω rfRelationship between the following calculation error and △ ω △ ω used in this example rfAt 4000Hz, the error of calculation is about 1% at △ ω of 400Hz, and the calculation result still has better accuracy under a certain B0 field offset.
It should be noted that the specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims (2)

1. A magnetic resonance imaging method using adiabatic radio frequency pulses to measure a radio frequency B1 field distribution, comprising the steps of:
step 1, designing adiabatic pulse, wherein the initial intensity of the adiabatic pulse is zero, and the adiabatic pulse is gradually increased to the maximum intensity B 1maxSetting the frequency offset △ omega rfAnd adiabatic pulse time;
step 2, calculating the K value of the adiabatic pulse, wherein K is gamma | B eff|/|dθ/dt|，B effCharacterization B effThe intensity of the field, gamma being the gyromagnetic ratio of the nucleus, theta being B effThe angle between the field and the main magnetic field direction;
step 3, maximum intensity B of adiabatic pulse is not applied or is applied 1maxSet to zero, the sample obtains the initial magnetization vector magnitude M 0；
Step 4, applying frequency offset of △ omega rfAnd the magnitude of the magnetization vector M obtained by sampling z1；
Step 5, applying frequency bias to- △ omega rfAnd the magnitude of the magnetization vector M obtained by sampling z2；
Step 6, calculate B using the following formula 1,obs，
Figure FDA0002283581540000011
Wherein M is 0In order to be the vector of the initial magnetization,
step 7, according to △ omega 2/(△ω rf 2-△ω 2) To calculate the deviation of the B1 measurement due to the B0 field offset.
2. A method as claimed in claim 1, wherein the frequency offset △ ω is offset from the frequency of the mr signals used to measure the rf B1 field distribution rfGreater than the magnitude △ ω of the B0 field offset.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113777545A (en) * 2020-06-10 2021-12-10 西门子医疗有限公司 Chemical exchange saturation transfer imaging correction method and device and readable storage medium

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN85103819A (en) * 1985-05-11 1986-11-05 菲利浦光灯制造公司 Method and apparatus for determining nuclear magnetic resonance distribution of a part of a human body
US5891032A (en) * 1997-04-10 1999-04-06 Elscint Ltd Fat free TOF angiography
US20040164737A1 (en) * 2002-12-02 2004-08-26 Thorsten Feiweier Method for determining the B1 field strength in MR measurements
CN1618398A (en) * 2003-10-30 2005-05-25 Ge医药系统环球科技公司 Method and system for optimized pre-saturation in mr with corrected transmitter frequency of pre-pulses
CN101266291A (en) * 2007-03-12 2008-09-17 西门子公司 Magnetic resonance method and apparatus with nuclear spins type-specific signal suppression
CN102621510A (en) * 2011-01-27 2012-08-01 美国西门子医疗解决公司 System for suppression of artifacts in MR imaging
CN102772209A (en) * 2011-01-27 2012-11-14 美国西门子医疗解决公司 MR imaging system for discriminating between imaged tissue types
WO2013105006A1 (en) * 2012-01-12 2013-07-18 Koninklijke Philips N.V. Mr imaging with b1 mapping
CN103969610A (en) * 2013-02-01 2014-08-06 西门子公司 Method and magnetic resonance system to acquire mr data and to determine a b1 magnetic field
CN104155621A (en) * 2014-09-11 2014-11-19 中国科学院武汉物理与数学研究所 Method used for accurately measuring static magnetic field B0 distribution
CN105388436A (en) * 2014-08-21 2016-03-09 西门子公司 method and apparatus for magnetic resonance data acquisition
CN106999092A (en) * 2014-11-11 2017-08-01 海珀菲纳研究股份有限公司 Pulse train for Low Magnetic field MRI
CN107966465A (en) * 2017-11-23 2018-04-27 中国石油大学(华东) A kind of collection of rock core nuclear magnetic signal and inversion method based on three-dimensional pulse train

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN85103819A (en) * 1985-05-11 1986-11-05 菲利浦光灯制造公司 Method and apparatus for determining nuclear magnetic resonance distribution of a part of a human body
US5891032A (en) * 1997-04-10 1999-04-06 Elscint Ltd Fat free TOF angiography
US20040164737A1 (en) * 2002-12-02 2004-08-26 Thorsten Feiweier Method for determining the B1 field strength in MR measurements
CN1618398A (en) * 2003-10-30 2005-05-25 Ge医药系统环球科技公司 Method and system for optimized pre-saturation in mr with corrected transmitter frequency of pre-pulses
CN101266291A (en) * 2007-03-12 2008-09-17 西门子公司 Magnetic resonance method and apparatus with nuclear spins type-specific signal suppression
CN102772209A (en) * 2011-01-27 2012-11-14 美国西门子医疗解决公司 MR imaging system for discriminating between imaged tissue types
CN102621510A (en) * 2011-01-27 2012-08-01 美国西门子医疗解决公司 System for suppression of artifacts in MR imaging
WO2013105006A1 (en) * 2012-01-12 2013-07-18 Koninklijke Philips N.V. Mr imaging with b1 mapping
CN103969610A (en) * 2013-02-01 2014-08-06 西门子公司 Method and magnetic resonance system to acquire mr data and to determine a b1 magnetic field
CN105388436A (en) * 2014-08-21 2016-03-09 西门子公司 method and apparatus for magnetic resonance data acquisition
CN104155621A (en) * 2014-09-11 2014-11-19 中国科学院武汉物理与数学研究所 Method used for accurately measuring static magnetic field B0 distribution
CN106999092A (en) * 2014-11-11 2017-08-01 海珀菲纳研究股份有限公司 Pulse train for Low Magnetic field MRI
CN107966465A (en) * 2017-11-23 2018-04-27 中国石油大学(华东) A kind of collection of rock core nuclear magnetic signal and inversion method based on three-dimensional pulse train

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
ZHAO ZHILONG ET.AL: "The Design and Measurement of Pulsed Magnetic Field", 《2011 THIRD INTERNATIONAL CONFERENCE ON MEASURING TECHNOLOGY AND MECHATRONICS AUTOMATION》 *
毕欣 等: "脉冲微波辐射场空间分布的热声成像研究", 《物理学报》 *
陈雷 等: "重聚INEPT和绝热脉冲结合的13C定量核磁共振", 《2018第二十届全国波谱学学术年会会议论文摘要集》 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113777545A (en) * 2020-06-10 2021-12-10 西门子医疗有限公司 Chemical exchange saturation transfer imaging correction method and device and readable storage medium
CN113777545B (en) * 2020-06-10 2024-07-05 西门子医疗有限公司 Chemical exchange saturation transfer imaging correction method, device and readable storage medium

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