CN104771167B - Magnetic resonance scanning method, magnetic resonance imaging equipment and system - Google Patents
Magnetic resonance scanning method, magnetic resonance imaging equipment and system Download PDFInfo
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Abstract
The invention discloses a kind of magnetic resonance scanning method, magnetic resonance imaging equipment and systems.The method includes：It determines the default level of subject, obtains the standard three-dimensional data of the default level；The acquisition level of subject and the relative position of the default level are fixed；Obtain the real-time three-dimensional data of the default level；The standard three-dimensional data and the real-time three-dimensional data are fed back into sequence timing control unit；The sequence timing control unit calculates the gradient modification amount and radio frequency correction amount for obtaining the acquisition level；The gradient modification amount is sent to gradient unit by the sequence timing control unit, and the radio frequency correction amount is sent to radio-frequency unit.The present invention can improve the real-time of motion correction in magnetic resonance scan sequences.
Description
Technical field
The present invention relates to medical imaging field more particularly to a kind of magnetic resonance scanning method, magnetic resonance imaging equipment and it is
System.
Background technique
Currently, mr imaging technique（Magnetic Resonance Imaging, MRI）Physics has been concentrated as a kind of
Computer algebra method including the multi-field research achievement such as, chemistry, biology, medicine, has been widely used in medicine shadow
As learning in inspection.The basic principle is that：It is different according to the decaying of the energy that is discharged inside the substance in different structure environment,
External high-frequency alternating electromagnetic field on the basis of uniform magnetic field, by detecting the RESONANCE ABSORPTION phenomenon to electromagnetic field of high frequency, to learn
The nuclear position of this object and type are constituted, the structural images of interior of articles can be drawn accordingly.
Primary complete magnetic resonance imaging usually requires 10~30 minutes.During the scanning process, it is desirable that subject is kept as far as possible
It is stationary, motion artifacts are otherwise be easy to cause, image quality is influenced.But in practical diagnosis and treatment process, subject is tieed up for a long time
It is highly difficult for holding a posture.Some subjects itself suffer from certain disease, such as：Apoplexy, epilepsy etc. can can't help earth tremor
It trembles.Majority subject is in the magnetic resonance chamber put under house arrest for a long time, also needs appropriate adjustment position to alleviate discomfort.
Traditional MRI motion correction is after the scanning, to be influenced using post-processing algorithm with eliminating movement.In recent years,
Occur some prior arts successively, carries out real-time motion correction during the scanning process.Application publication number is
In the Chinese invention patent application of CN103315739A, it is total to disclose a kind of magnetic that motion artifacts are exempted based on Dynamic Tracing Technology
Vibration image method and system.It tracks the spatial attitude of subject, estimation movement ginseng in the collection process of magnetic resonance imaging data
Number, and it is based on kinematic parameter, pulse train parameters are modified, send pulse sequence control unit for the sequential parameter of update, are adjusted
The visual field, position and the plane of whole scanning, make the image finally obtained seemingly be regarded as collecting figure there is no movement
As.But inventor has found：With current software and hardware condition, Real-time Feedback is realized in this way and modifies sequence, together
Shi Jinhang control scanning, is difficult to accomplish in reality.
Summary of the invention
The technical problem to be solved by the present invention is to how improve the real-time of motion correction in magnetic resonance scan sequences.
To solve the above-mentioned problems, the present invention provides a kind of magnetic resonance scanning methods, including：
It determines the default level of subject, obtains the standard three-dimensional data of the default level；The acquisition level of subject and institute
The relative position for stating default level is fixed；
Obtain the real-time three-dimensional data of the default level；
The standard three-dimensional data and the real-time three-dimensional data are fed back into sequence timing control unit；
The sequence timing control unit calculates the gradient modification amount and radio frequency correction amount for obtaining the acquisition level；
The gradient modification amount is sent to gradient unit by the sequence timing control unit, and the radio frequency correction amount is sent out
It send to radio-frequency unit.
Optionally, the standard three-dimensional data for obtaining the default level include：Using the three-dimensional sensing of fixed installation
Device acquisition obtains；The real-time three-dimensional data for obtaining the default level includes：It is adopted using the three-dimension sensor of fixed installation
Collection obtains.
Optionally, the data transmission rate of the three-dimension sensor is at least 30 frames/second, the nuclear-magnetism essence of the three-dimension sensor
Degree is at least 1mm.
Optionally, the visual field of the three-dimension sensor is greater than or equal to 60 °, and the radius of investigation of the three-dimension sensor is greater than
Or it is equal to 30cm.
Optionally, at least 1 three-dimension sensor is fixedly installed in the top of magnetic resonance chamber inner wall.
Optionally, at least 2 three-dimension sensors are fixedly installed in the two sides of magnetic resonance chamber inner wall.
Optionally, the three-dimension sensor is at least 3, and the three-dimension sensor is fixedly installed in magnetic resonance chamber
The angle of wall, the overlapping of adjacent three-dimensional sensor field of view is greater than or equal to 60 °.
Optionally, the standard three-dimensional data are located under physical coordinates system, and the standard three-dimensional data include at least：Level
Center, normal vector, level internal rotation angle degree；The real-time three-dimensional data is located under physical coordinates system, the real-time three-dimensional
Data include at least：Level center, normal vector, level internal rotation angle degree.
Optionally, the standard three-dimensional data and the real-time three-dimensional data are stored in predeterminated position；
The magnetic resonance scanning method further includes：Marker is added in magnetic resonance imaging sequence, runs the magnetic resonance
When scanning sequence to the marker, the sequence timing control unit is triggered from the predeterminated position and obtains the standard three-dimensional
Data and the real-time three-dimensional data.
Optionally, the gradient modification amount includes：Under physical coordinates system, component GX of the gradient on three axis of x, y, z,
GY,GZ；The radio-frequency unit includes：Emission element and receiving part；The radio frequency correction amount includes：The frequency of the emission element
Rate correction amount TX_freq, the phase error TX_phase of the emission element, the receiving part correction quantity of frequency RX_
The phase error RX_phase of freq, the receiving part；
The sequence timing control unit calculates the gradient modification amount for obtaining the acquisition level and radio frequency correction amount includes：
According to formula 1 obtain the current logical coordinates system of pulse train of the acquisition level to physical coordinates system spin matrix,
RotMatrix_log2phy_Current=RotMatrix_Tracking*RotMatrix_log2phy formula 1
Wherein, RotMatrix_log2phy_Current is that the current logical coordinates system of pulse train of the acquisition level is sat to physics
The spin matrix of system is marked, RotMatrix_Tracking is the spin matrix of the corresponding default level of the real-time three-dimensional data,
RotMatrix_Tracking is related to the normal vector of the real-time three-dimensional data and level internal rotation angle degree, RotMatrix_
Log2phy is spin matrix of the initial logical coordinates system of pulse train of the acquisition level to physical coordinates system；
Component GX, GY, GZ in physical coordinates system Gradient on tri- axis of X, Y, Z are obtained according to formula 2,
[GX, GY, GZ]T=RotMatrix_log2phy_Current* [GRO, GPE, GSS]TFormula 2
Wherein, [GX, GY, GZ] is component GX, GY, GZ in physical coordinates system Gradient on tri- axis of X, Y, Z,
RotMatrix_log2phy_Current is spin moment of the current logical coordinates system of pulse train of the acquisition level to physical coordinates system
Battle array, [GRO, GPE, GSS] are point in logical coordinates system of pulse train Gradient on readout direction RO, phase directional PE, readout direction SS
Measure GRO, GPE, GSS；
The current position of the acquisition level under physical coordinates system is obtained according to formula 3,
Shift_Phy_Current=Shift_Tracking+Shift_SlicePhy formula 3
Wherein, Shift_Phy_Current is the current position of the acquisition level, Shift_ under physical coordinates system
Tracking is the displacement of the corresponding default level of the real-time three-dimensional data, Shift_Tracking and the real-time three-dimensional number
According to level center it is related to the level center of the standard three-dimensional data, Shift_SlicePhy be the acquisition
The initial position of level；
The current position of the acquisition level under logical coordinates system of pulse train is obtained according to formula 4,
Shift_Log_Current=(RotMatrix_log2phy_Current)-1*Shift_Phy_Current=
[Shift_RO, Shift_PE, Shift_SS]TFormula 4
Wherein, Shift_Log_Current is the current position of the acquisition level under logical coordinates system of pulse train,
RotMatrix_log2phy_Current is spin moment of the current logical coordinates system of pulse train of the acquisition level to physical coordinates system
Battle array, Shift_Phy_Current are the current position of the acquisition level, [Shift_RO, Shift_ under physical coordinates system
PE, Shift_SS] be the acquisition layer currently in logical coordinates system of pulse train bottom offset in readout direction RO, phase directional PE, select layer side
Component Shift_RO, Shift_PE, Shift_SS on SS；
The correction quantity of frequency of the emission element is obtained according to formula 5,
TX_freq=gamma*B0+freq_per_SS*Shift_SS formula 5
Wherein, TX_freq is the correction quantity of frequency of emission element, and gamma is gyromagnet specific ray constant, and B0 is magnetic field strength,
Freq_per_SS is the frequency variation that logical coordinates system of pulse train lower edge selects layer direction SS per unit length to generate, and Shift_SS is described
Acquisition layer is currently selecting the component on the SS of layer direction in logical coordinates system of pulse train bottom offset；
The phase error of the emission element is obtained according to formula 6,
TX_phase=-gamma*GSS*Duration_RF*AsymmetricFactor_RF*Shift_SS+
Phase_RF formula 6
Wherein, gamma is gyromagnet specific ray constant, and GSS is to select the component on the SS of layer direction in logical coordinates system of pulse train Gradient,
Duration_RF is the duration of radio-frequency pulse, AsymmetricFactor_RF is the asymmetric factor of radio-frequency pulse,
Shift_SS is that the acquisition layer is currently selecting the component on the SS of layer direction in logical coordinates system of pulse train bottom offset, and phase_RF is given
Phase；
The correction quantity of frequency of the receiving part is obtained according to formula 7,
RX_freq=gamma*B0+freq_per_RO*Shift_RO formula 7
Wherein, RX_freq is the correction quantity of frequency of receiving part, and gamma is gyromagnet specific ray constant, and B0 is magnetic field strength,
Freq_per_RO is the frequency variation generated under logical coordinates system of pulse train along readout direction RO per unit length, and Shift_RO is described
The current component in logical coordinates system of pulse train bottom offset on readout direction RO of acquisition layer；
The phase error of the receiving part is obtained according to formula 8,
RX_phase=phase_RO+phase_per_PE*Shift_PE+phase_per_SPE*Shift_SPE formula 8
Wherein, RX_phase is the phase error of receiving part, and phase_per_PE is under logical coordinates system of pulse train along phase
The phase change that direction PE per unit length generates, Shift_PE are the acquisition layer currently in logical coordinates system of pulse train bottom offset in phase
Component on the direction PE of position；Phase_per_SPE is to produce under logical coordinates system of pulse train along the every element length of level phase-encoding direction SS
Raw phase change, Shift_SPE are the acquisition layer currently under logical coordinates system of pulse train on level phase-encoding direction SS
Displacement.
The present invention also provides a kind of magnetic resonance imaging equipments, including：
Storage assembly, the standard three-dimensional data and real-time three-dimensional data of the default level for storing subject；Subject is adopted
Collection level and the relative position of the default level are fixed；
Sequence timing control unit is calculated and is obtained for being based on the standard three-dimensional data and the real-time three-dimensional data
The gradient modification amount and radio frequency correction amount of the acquisition level, and the gradient modification amount is sent to gradient unit, it will be described
Radio frequency correction amount is sent to radio-frequency unit；
Gradient unit generates gradient magnetic for being based on the gradient modification amount；
Radio-frequency unit, for being based on the radio frequency correction amount, transmitting signal and reception signal.
Optionally, further include：It is total to run the magnetic for adding marker in magnetic resonance imaging sequence for module
When scanning sequence to the marker of shaking, triggers the sequence timing control unit and obtain the three-dimensional from the storage assembly
Data.
Optionally, the standard three-dimensional data are located under physical coordinates system, and the standard three-dimensional data include at least：Level
Center, normal vector, level internal rotation angle degree；The real-time three-dimensional data is located under physical coordinates system, the real-time three-dimensional
Data include at least：Level center, normal vector, level internal rotation angle degree.
The present invention also provides a kind of magnetic resonance scanning systems, including：Above-mentioned magnetic resonance imaging equipment；
The three-dimension sensor of fixed installation, the standard three-dimensional data and real-time three-dimensional number of the default level for obtaining subject
According to.
Optionally, the data transmission rate of the three-dimension sensor is at least 30 frames/second, the nuclear-magnetism essence of the three-dimension sensor
Degree is at least 1mm.
Optionally, the visual field of the three-dimension sensor is greater than or equal to 60 °, and the radius of investigation of the three-dimension sensor is greater than
Or it is equal to 30cm.
Optionally, at least 1 three-dimension sensor is fixedly installed in the top of magnetic resonance chamber inner wall.
Optionally, at least 2 three-dimension sensors are fixedly installed in the two sides of magnetic resonance chamber inner wall.
Optionally, the three-dimension sensor is at least 3, and the three-dimension sensor is fixedly installed in magnetic resonance chamber
The angle of wall, the overlapping of adjacent three-dimensional sensor field of view is greater than or equal to 60 °.
Compared with prior art, technical solution of the present invention has the following advantages that：
The real-time motion data of acquisition is fed back to the hardware cell of control sequence timing by the present invention, will by the hardware cell
Motion correction amount is sent directly to gradient hardware and RF hardware, to realize Motion correction.Due to the hardware of control sequence timing
Closer to bottom hardware, Motion correction is measured to be quickly applied in data acquisition, so real-time is more preferable unit.
Detailed description of the invention
Fig. 1 is the flow diagram of one embodiment of magnetic resonance scanning method of the invention；
Fig. 2 is the structural schematic diagram of the three-dimension sensor of embodiment illustrated in fig. 1；
Fig. 3 is the data flow diagram of embodiment illustrated in fig. 1；
Fig. 4 is the standard three-dimensional data of embodiment illustrated in fig. 1 and the data structure diagram of real-time three-dimensional data；
Fig. 5 is the floor plan of three-dimension sensor in embodiment illustrated in fig. 1；
Fig. 6 is the structural schematic diagram of one embodiment of magnetic resonance imaging equipment of the invention；
Fig. 7 is the structural schematic diagram of one embodiment of magnetic resonance scanning system of the invention.
Specific embodiment
In the following description, numerous specific details are set forth in order to facilitate a full understanding of the present invention.But the present invention can be with
Much it is different from other way described herein to implement, those skilled in the art can be without prejudice to intension of the present invention the case where
Under do similar popularization, therefore the present invention is not limited to the specific embodiments disclosed below.
Secondly, the present invention is described in detail using schematic diagram, when describing the embodiments of the present invention, for purposes of illustration only, institute
Stating schematic diagram is example, should not limit the scope of protection of the invention herein.
Inventor's discovery：The real time kinematics bearing calibration of the prior art is with current software and hardware condition, in actual operation
Real-time and bad.Inventor is further discovered that：The bad reason of the real-time of the prior art is based on movement ginseng in real time
Number, has modified sequence.Sequence is usually provided by the software view in magnetic resonance system.It, will also be after modification after modifying sequence
Sequence be sent to hardware view, just can control gradient unit and radio-frequency unit and be scanned according to modified sequence, so
It takes a long time, real-time is bad.Moreover, because sequence is that doctor customizes according to the physical condition of each patient, do not have
Standby reusability will not save the behaviour of next patient's magnetic resonance imaging even if having modified sequence in real time kinematics correction
Make time and process.On this basis, inventor is made that improvement to the prior art, and Motion correction amount is directly sent to hardware
Level enables gradient unit and radio-frequency unit to be quickly scanned according to new sweep parameter, to improve real-time.
In order to solve the technical problem in background technique, the present invention provides a kind of magnetic resonance scanning methods.Fig. 1 is this hair
The flow diagram of bright one embodiment of magnetic resonance scanning method.As shown in Figure 1, the magnetic resonance scanning method of the present embodiment includes
Following steps：
Step S10 is executed, determines the default level of subject, obtains the standard three-dimensional data of the default level.
Specifically, the prediction level can be checked in interface in patient by doctor and be determined.The patient checks that interface is
What is provided in magnetic resonance scanning system determines the soft of the acquisition level of the subject and the scanning sequence of the subject for doctor
Part interface.Further, the acquisition level of subject and the relative position of the default level are fixed, therefore, the prediction level
Movement and the movement of the acquisition level can be considered as and be consistent.In the present embodiment, the default level is the acquisition
Level.In other embodiments, the default level can also be the scanning level near the acquisition level, and the present invention is to this
It is not construed as limiting.
It continues to refer to figure 1, executes step S20, obtain the real-time three-dimensional data of the default level.
It should be noted that the three-dimensional of fixed installation can be used in the standard three-dimensional data and the real-time three-dimensional data
Sensor acquisition is obtained.The three-dimension sensor can be fixedly installed in magnetic resonance imaging chamber, can also be fixedly mounted
In on magnetic resonance imaging hospital bed, the present invention is not especially limited this.In the present embodiment, the standard three-dimensional data are described three
Sensor first group of three-dimensional data collected is tieed up, the real-time three-dimensional data is the several of three-dimension sensor acquisition later
Group three-dimensional data.In other embodiments, the standard three-dimensional data can also be as doctor from three-dimension sensor described in several groups
It is specified in the three-dimensional data of acquisition, the present invention is not especially limited this.
The standard three-dimensional data and the real-time three-dimensional data are respectively positioned under physical coordinates system.The physical coordinates system is
Rectangular coordinate system in space, including：Three X-axis, Y-axis, Z axis reference axis.One group of standard three-dimensional data or one group of real-time three-dimensional number
Group includes at least 7 components, is respectively：The level center of X-axis, the level center of Y-axis, Z axis level centre bit
It sets, the normal vector of the normal vector of the normal vector of X-axis, Y-axis, Z axis and level internal rotation angle degree.
It will be understood by those skilled in the art that there are many three-dimension sensors of the prior art can provide comprising above-mentioned 7
The three-dimensional data of component, such as：The Leapmotion sensor of Leapmotion company production.
In order to meet the needs of real time scan, the data transmission rate of the three-dimension sensor U3 is at least 30 frames/second, i.e.,：
It is per second at least to acquire 30 groups of three-dimensional datas.The nuclear-magnetism precision of the three-dimension sensor U3 is at least 1mm, i.e.,：It can at least distinguish
The change in location of the three-dimensional data 1mm.The visual field of the three-dimension sensor is greater than or equal to 60 °, the three-dimension sensor
Radius of investigation is greater than or equal to 30cm.
Fig. 2 is the structural schematic diagram of the three-dimension sensor of embodiment illustrated in fig. 1.As shown in Fig. 2, the three-dimensional in the present embodiment
The visual field α of sensor U3 is 120 °, and the radius of investigation d of the three-dimension sensor is equal to 60cm.In order to ensure the three-dimensional sensing
Device U3 can provide the location information of the default level, and the default level should be located in the visual field of the three-dimension sensor U3,
The three-dimension sensor U3 should be controlled within 60cm at a distance from the default level.
The three-dimension sensor of three fixed installations is used in the present embodiment.It is total that one three-dimension sensor is fixedly installed in magnetic
The top of vibration chamber inner wall.Another two three-dimension sensor is fixedly installed in the opposite two sides in left and right of magnetic resonance chamber inner wall, with
Convenient for identifying the front and back sides of physical feeling（Such as：Hand）.Using the three-dimension sensor of multiple fixed installations, to improve data
Reliability.In other embodiments, three three-dimension sensors can also be equally spaced fixedly installed in magnetic resonance chamber inner wall,
The angle of adjacent three-dimensional sensor field of view overlapping is at least 60 °, and the three-dimension sensor of a fixed installation can also be used only, this
Invention is not construed as limiting this.
It continues to refer to figure 1, executes step S30, standard three-dimensional data and real-time three-dimensional data are fed back into sequence timing control
Unit processed.
The sequence timing control unit is the hardware cell of control sequence timing.The sequence timing control unit operation
Sweep parameter in the scanning sequence is passed to gradient unit and radio-frequency unit by scanning sequence, make the gradient unit and
Radio-frequency unit carries out magnetic resonance imaging according to the sweep parameter received.
It should be noted that the standard three-dimensional data and the real-time three-dimensional data can directly feed back to the sequence
Timing control unit.The standard three-dimensional data and the real-time three-dimensional data can also be stored in predeterminated position, such as：It is interior
Specific storage unit in depositing.And marker is added in the scanning sequence（shot trig）, when the operation scanning sequence
When to the marker, the sequence timing control unit is triggered from the predeterminated position and obtains the standard three-dimensional data and institute
State real-time three-dimensional data.This mode can make three-dimensional data acquisition and MR data acquisition it is independent mutually, while into
Row.
It continues to refer to figure 1, executes step S40, sequence timing control unit calculates the gradient modification amount for obtaining acquisition level
With radio frequency correction amount.
Specifically, the gradient modification amount includes：Under physical coordinates system, component GX of the gradient on tri- axis of X, Y, Z,
GY,GZ.The radio-frequency unit includes：Emission element and receiving part.The radio frequency correction amount includes：The frequency of the emission element
Rate correction amount, the phase error of the emission element, the correction quantity of frequency of the receiving part, the phase of the receiving part
Correction amount.
Since the scanning sequence is under logic-based coordinate system, and the three-dimensional data that three-dimension sensor provides is to be based on
Under physical coordinates system, therefore, it is necessary to carry out the unification of coordinate system just to can be carried out the calculating of Motion correction amount.
Firstly, according to formula（1）Obtain the current logical coordinates system of pulse train of the acquisition level to physical coordinates system spin moment
Battle array,
RotMatrix_log2phy_Current=RotMatrix_Tracking*RotMatrix_log2phy（1）
Wherein, RotMatrix_log2phy_Current is that the current logical coordinates system of pulse train of the acquisition level is sat to physics
The spin matrix of system is marked, RotMatrix_Tracking is the spin matrix of the corresponding default level of the real-time three-dimensional data,
RotMatrix_Tracking is related to the normal vector of the real-time three-dimensional data and level internal rotation angle degree, RotMatrix_
Log2phy is spin matrix of the initial logical coordinates system of pulse train of the acquisition level to physical coordinates system.
Specifically, RotMatrix_Tracking can be according to formula（1a）It obtains,
Wherein, θ is the level internal rotation angle degree of the real-time three-dimensional data,（ux, uy, uz）For the real-time three-dimensional data
Normal vector.
Then, according to formula（2）Component GX, GY, GZ in physical coordinates system Gradient on tri- axis of X, Y, Z are obtained,
[GX, GY, GZ]T=RotMatrix_log2phy_Current* [GRO, GPE, GSS]T（2）
Wherein, [GX, GY, GZ] is component GX, GY, GZ in physical coordinates system Gradient on tri- axis of X, Y, Z,
RotMatrix_log2phy_Current is spin moment of the current logical coordinates system of pulse train of the acquisition level to physical coordinates system
Battle array, [GRO, GPE, GSS] are point in logical coordinates system of pulse train Gradient on readout direction RO, phase directional PE, readout direction SS
Measure GRO, GPE, GSS.[GX, GY, GZ]TFor the inverse matrix of [GX, GY, GZ].[GRO, GPE, GSS]TFor [GRO, GPE, GSS]
Inverse matrix.
Then, according to formula（3）The current position of the acquisition level under physical coordinates system is obtained,
Shift_Phy_Current=Shift_Tracking+Shift_SlicePhy （3）
Wherein, Shift_Phy_Current is the current position of the acquisition level under physical coordinates system.Shift_
Tracking is the displacement of the corresponding default level of the real-time three-dimensional data, and Shift_Tracking is the real-time three-dimensional number
According to level center and the standard three-dimensional data level center difference.Shift_SlicePhy is described adopts
The initial position of collection level can be checked in interface in patient by doctor and be determined.
Then, according to formula（4）The current position of the acquisition level under logical coordinates system of pulse train is obtained,
Shift_Log_Current=(RotMatrix_log2phy_Current)-1*Shift_Phy_Current=
[Shift_RO, Shift_PE, Shift_SS]T（4）
Wherein, Shift_Log_Current is the current position of the acquisition level under logical coordinates system of pulse train.
RotMatrix_log2phy_Current is spin moment of the current logical coordinates system of pulse train of the acquisition level to physical coordinates system
Battle array, (RotMatrix_log2phy_Current)-1For the transposed matrix of RotMatrix_log2phy_Current.Shift_
Phy_Current is the current position of the acquisition level under physical coordinates system.[Shift_RO, Shift_PE, Shift_
SS] be the acquisition layer currently logical coordinates system of pulse train bottom offset readout direction RO, phase directional PE, select on the SS of layer direction point
Measure Shift_RO, Shift_PE, Shift_SS, [Shift_RO, Shift_PE, Shift_SS]TFor [Shift_RO, Shift_
PE, Shift_SS] inverse matrix.
Then, according to formula（5）The correction quantity of frequency of the emission element is obtained,
TX_freq=gamma*B0+freq_per_ss*Shift_SS （5）
Wherein, TX_freq is the correction quantity of frequency of emission element.Gamma is gyromagnet specific ray constant.B0 is magnetic field strength.
Freq_per_ss is the frequency variation that logical coordinates system of pulse train lower edge selects layer direction SS per unit length to generate, and is known quantity.Shift_
SS is that the acquisition layer is currently selecting the component on the SS of layer direction in logical coordinates system of pulse train bottom offset.
Then, according to formula（6）The phase error of the emission element is obtained,
TX_phase=-gamma*GSS*Duration_RF*AsymmetricFactor_RF*Shift_SS+phase_RF （6）
Wherein, gamma is gyromagnet specific ray constant.GSS is to select the component on the SS of layer direction in logical coordinates system of pulse train Gradient.
Duration_RF is the duration of radio-frequency pulse.AsymmetricFactor_RF is the asymmetric factor of radio-frequency pulse.
Shift_SS is that the acquisition layer is currently selecting the component on the SS of layer direction in logical coordinates system of pulse train bottom offset.Phase_RF is given
Phase.
Then, according to formula（7）The correction quantity of frequency of the receiving part is obtained,
RX_freq=gamma*B0+freq_per_ro*Shift_RO （7）
Wherein, RX_freq is the correction quantity of frequency of receiving part.Gamma is gyromagnet specific ray constant.B0 is magnetic field strength.
Freq_per_ro is the frequency variation generated under logical coordinates system of pulse train along readout direction RO per unit length, and freq_per_ro is
The amount of knowing.Shift_RO is the acquisition layer currently component in logical coordinates system of pulse train bottom offset on readout direction RO.
According to formula（8）The phase error of the receiving part is obtained,
RX_phase=phase_per_pe*Shift_PE+phase_per_SS*Shift_SS（8）
Wherein, RX_phase is the phase error of receiving part, and phase_per_pe is under logical coordinates system of pulse train along phase
The phase change that direction PE per unit length generates is known quantity.Shift_PE is the acquisition layer currently in logical coordinates system of pulse train
Component of the bottom offset on phase directional PE；Phase_per_SS is every along level phase-encoding direction SPE under logical coordinates system of pulse train
The phase change that element length generates is known quantity.Shift_SS is the acquisition layer currently under logical coordinates system of pulse train in level
Component on phase-encoding direction SPE.
It continues to refer to figure 1, executes step S50, gradient modification amount is sent to gradient unit by sequence timing control unit, will
Radio frequency correction amount is sent to radio-frequency unit.
Fig. 3 is the data flow diagram of embodiment illustrated in fig. 1.As shown in figure 3, doctor provides magnetic resonance in operation interface first
The enabling signal of scanning.
The enabling signal triggering opens patient and checks interface.Doctor checks the acquisition layer that subject is determined in interface in patient
Face（It is exactly to acquire level that level is preset in the present embodiment）And the sequence being adapted with subject.The data bit of the acquisition level
Under logical coordinates system of pulse train, withIt indicates.
The enabling signal triggers the acquisition that three-dimension sensor carries out three-dimensional data simultaneously.Wherein, first group three of acquisition
Dimension data is standard three-dimensional data.The three-dimensional data acquired later is real-time three-dimensional data.The three-dimensional data（Including standard three
Dimension data and real-time three-dimensional data）Under physical coordinates system, withIt indicates.The three-dimensional dataMemory can be stored in
Specific storage unit in, can also directly feed back to sequence timing control unit.
Then, the data of level are acquiredWith sequence inputting sequence alignment software layer, in the sequence alignment software layer, to sequence into
Row parsing, formation sequence data.The sequence data is located under patient coordinate system, withIt indicates.The patient coordinate system is based on
The medical perspective is established.
In the sequence alignment software layer, marker can also be added in the sequence（shot trig）, the marker
The sequence timing control unit can be triggered and obtain the three-dimensional data from the memory.
In the sequence timing control unit, to the three-dimensional data being located under physical coordinates systemPositioned at logical coordinates
Acquisition plane data under systemAnd the sequence data under patient coordinate systemThe unification and calculating for carrying out coordinate system are swept
Retouch parameter.The sweep parameter includes at least gradient modification amount and radio frequency correction amount.It, will by gradient modification amount input gradient component
Radio frequency correction amount input radio frequency component.
The gradient unit will excite gradient magnetic according to the gradient modification amount.The radio-frequency unit will be penetrated according to described
Frequency correction amount sends signal and receives signal.It can get the image-forming information of the subject after carrying out image procossing to the signal,
So far magnetic resonance imaging is completed.
Fig. 4 illustrates the process that triggering in embodiment illustrated in fig. 1 obtains standard three-dimensional data and real-time three-dimensional data.Such as figure
Shown in 4, the three-dimension sensor acquires the three-dimensional data of default level according to the clock cycle of itself（Including standard three-dimensional data
And real-time three-dimensional data）.Every group of three-dimensional data includes 7 components, is component X, the layer of the X-direction of level center respectively
The component of the X-direction of the component Y of the Y direction of face center, the component Z of the Z-direction of level center, normal vector
ux, normal vector Y direction component uy, normal vector Z-direction component uz, level internal rotation angle degree θ.
Three timing instr in sequence are shown in Fig. 4.Marker shottrig is wherein had in second timing.
Three timing list entries timing control units.The sequence timing control unit will run the sequence to second timing
When, the three-dimensional data is obtained from the memory.By the Real-time Feedback of the three-dimensional data of optically detecting, adjustable radio frequency
Frequency shift (FS) and gradient magnitude can effectively reduce MR data and adopt so that magnetic resonance always acquires data in correct position
The artifact as caused by movement is concentrated, and allows patient's move body posture in collection process, is patient's more preferably user experience.
Fig. 5 is the floor plan of three-dimension sensor in embodiment illustrated in fig. 1.As shown in figure 5, the acquisition in the present embodiment
Level（I.e. default level）For positioned at the level a on head.3 three-dimension sensor U3 are used in the present embodiment.One sensor
U3 is located at the top of the inner wall of magnetic resonance chamber U1.Other 2 sensor U3 are positioned opposite, are located at the magnetic resonance chamber U1
Inner wall at left and right sides of.Three three-dimension sensor U3 acquire three-dimensional data, and are stored in the storage of sequence timing control unit U6
In device.Every group of three-dimensional data includes at least the Y direction of the component X of the X-direction of level center, level center
The component u of the X-direction of component Y, the component Z of the Z-direction of level center, normal vectorx, normal vector Y direction
Component uy, normal vector Z-direction component uz, 7 data of level internal rotation angle degree.
It should be noted that through the above description of the embodiments, those skilled in the art can be understood that
It can be realized to some or all of the present invention by software and in conjunction with required general hardware platform.Based on this understanding,
Substantially the part that contributes to existing technology can embody technical solution of the present invention in the form of software products in other words
Out, which may include the one or more machine readable medias for being stored thereon with machine-executable instruction,
These instructions may make this when being executed by one or more machines such as computer, computer network or other electronic equipments
One or more machine embodiment according to the present invention execute operation.Machine readable media may include, but be not limited to, floppy disk,
CD, CD-ROM（Compact-disc-read-only memory）, magneto-optic disk, ROM（Read-only memory）,RAM（Random access memory）,
EPROM（Erasable Programmable Read Only Memory EPROM）,EEPROM（Electrically erasable programmable read-only memory）, magnetic or optical card, sudden strain of a muscle
Deposit or suitable for store machine-executable instruction other kinds of medium/machine readable media.
The present invention can be used in numerous general or special purpose computing system environments or configuration.Such as：Personal computer, service
Device computer, handheld device or portable device, laptop device, multicomputer system, microprocessor-based system, top set
Box, programmable consumer-elcetronics devices, network PC, minicomputer, mainframe computer, including any of the above system or equipment
Distributed computing environment etc..
The present invention can describe in the general context of computer-executable instructions executed by a computer, such as program
Module.Generally, program module includes routines performing specific tasks or implementing specific abstract data types, programs, objects, group
Part, data structure etc..The present invention can also be practiced in a distributed computing environment, in these distributed computing environments, by
Task is executed by the connected remote processing devices of communication network.In a distributed computing environment, program module can be with
In the local and remote computer storage media including storage equipment.
It should be noted that it will be understood by those skilled in the art that above-mentioned members can be programmable logic device,
Including：Programmable logic array（Programmable Array Logic, PAL）, Universal Array Logic（Generic Array
Logic, GAL）, field programmable gate array（Field-Programmable Gate Array, FPGA）, complex programmable patrols
One of volume device (Complex Programmable Logic Device, CPLD) or a variety of, the present invention, which does not do this, to be had
Body limitation.
Correspondingly, the present invention also provides a kind of magnetic resonance imaging equipments.Fig. 6 is magnetic resonance imaging equipment one of the invention
The structural schematic diagram of embodiment.As shown in fig. 6, the magnetic resonance imaging equipment of the present embodiment includes：Magnetic resonance chamber U1, hospital bed
U2, patient check interface U4, module U5, storage assembly（It is not shown）, sequence timing control unit U6, gradient unit U7 and
Radio-frequency unit U8.
Gradient coil is provided in the magnetic resonance chamber U1（It is not shown）And radio-frequency coil（It is not shown）.The gradient line
Circle is connected with the gradient unit U7, and is controlled by the gradient unit U7.The radio-frequency coil and the radio-frequency unit U8 phase
Even, and it is controlled by the radio-frequency unit U8.
Subject is lain on the hospital bed U2, and the hospital bed U2 can be moved forward and backward in the magnetic resonance chamber U1, is made described
The acquisition level of subject is located at the even magnetic field center in the magnetic resonance chamber U1.
The patient checks that interface U4 is connected with the sequence timing control unit U6, for determining acquisition level and presetting
Level.
The storage assembly（It is not shown）, the standard three-dimensional data and real-time three-dimensional number of the default level for storing subject
According to.The acquisition level of subject and the relative position of the default level are fixed.The standard three-dimensional data are located at physical coordinates system
Under, the standard three-dimensional data include at least：Level center, normal vector, level internal rotation angle degree.The real-time three-dimensional number
According to being located under physical coordinates system, the real-time three-dimensional data is included at least：Level center, normal vector, level internal rotation angle
Degree.The storage assembly, which can be located at, shows that the patient checks in the computer of interface U4, when can also be located at the sequence
In sequence control unit U6, this is not limited by the present invention.
The module U5 is connected with the sequence timing control unit U6, for generating sequence, is also used to described
Marker is added in sequence, when running the sequence to the marker, can trigger the sequence timing control unit U6 from institute
It states and obtains three-dimensional data in storage assembly.
The sequence timing control unit U6, for being based on the standard three-dimensional data and the real-time three-dimensional data, meter
The gradient modification amount and radio frequency correction amount for obtaining the acquisition level are calculated, and the gradient modification amount is sent to gradient unit
The radio frequency correction amount is sent to radio-frequency unit U8 by U7.
The gradient unit U7 generates gradient magnetic for being based on the gradient modification amount.
The radio-frequency unit U8, for being based on the radio frequency correction amount, transmitting signal and reception signal.
Correspondingly, the present invention also provides a kind of magnetic resonance scanning systems.Fig. 7 is magnetic resonance scanning system one of the invention
The structural schematic diagram of embodiment.As shown in fig. 7, the magnetic resonance scanning system of the present embodiment includes：Magnetic resonance imaging equipment and three
Tie up sensor U3.
The magnetic resonance imaging equipment refers to described previously, and details are not described herein.
The three-dimension sensor U3 is fixedly installed in the magnetic resonance chamber inner wall in the magnetic resonance imaging equipment, for obtaining
The standard three-dimensional data and real-time three-dimensional data for the default level that must be tested.
The data transmission rate of the three-dimension sensor is at least 30 frames/second, and the nuclear-magnetism precision of the three-dimension sensor is at least
For 1mm.The visual field of the three-dimension sensor is greater than or equal to 60 °, and the radius of sphericity of the three-dimension sensor is greater than or equal to
30cm。
The three-dimension sensor can be fixedly installed in the top of magnetic resonance chamber inner wall.When using 2 three-dimension sensors,
The three-dimension sensor can be fixedly installed in the two sides of magnetic resonance chamber inner wall.When using 3 three-dimension sensors, the three-dimensional
Sensor can be fixedly installed in magnetic resonance chamber inner wall, and the angle of adjacent three-dimensional sensor field of view overlapping is greater than or equal to 60 °.
Although the invention has been described by way of example and in terms of the preferred embodiments, but it is not for limiting the present invention, any this field
Technical staff without departing from the spirit and scope of the present invention, may be by the methods and technical content of the disclosure above to this hair
Bright technical solution makes possible variation and modification, therefore, anything that does not depart from the technical scheme of the invention, and according to the present invention
Technical spirit any simple modifications, equivalents, and modifications to the above embodiments, belong to technical solution of the present invention
Protection scope.
Claims (16)
1. a kind of magnetic resonance scanning method, which is characterized in that including：
It determines the default level of subject, obtains the standard three-dimensional data of the default level；The acquisition level of subject with it is described pre-
If the relative position of level is fixed；
Obtain the real-time three-dimensional data of the default level；
The standard three-dimensional data and the real-time three-dimensional data are fed back into sequence timing control unit；
The sequence timing control unit calculates the gradient modification amount and radio frequency correction amount for obtaining the acquisition level；
The gradient modification amount is sent to gradient unit by the sequence timing control unit, and the radio frequency correction amount is sent to
Radio-frequency unit；
The standard three-dimensional data are located under physical coordinates system, and the standard three-dimensional data include at least：Level center, method
Vector, level internal rotation angle degree；The real-time three-dimensional data is located under physical coordinates system, and the real-time three-dimensional data is at least wrapped
It includes：Level center, normal vector, level internal rotation angle degree；The gradient modification amount includes：Under physical coordinates system, gradient
Component GX, GY, GZ on three axis of x, y, z；The radio-frequency unit includes：Emission element and receiving part；The radio frequency is repaired
Positive quantity includes：The correction quantity of frequency TX_freq of the emission element, the phase error TX_phase of the emission element, institute
State the correction quantity of frequency RX_freq of receiving part, the phase error RX_phase of the receiving part；
The sequence timing control unit calculates the gradient modification amount for obtaining the acquisition level and radio frequency correction amount includes：
According to formula (1) obtain the current logical coordinates system of pulse train of the acquisition level to physical coordinates system spin matrix,
RotMatrix_log2phy_Current=RotMatrix_Tracking*RotMatrix_l og2phy (1)
Wherein, RotMatrix_log2phy_Current is the current logical coordinates system of pulse train of the acquisition level to physical coordinates system
Spin matrix, RotMatrix_Tracking be the corresponding default level of the real-time three-dimensional data spin matrix,
RotMatrix_Tracking is related to the normal vector of the real-time three-dimensional data and level internal rotation angle degree, RotMatrix_
Log2phy is spin matrix of the initial logical coordinates system of pulse train of the acquisition level to physical coordinates system；
Component GX, GY, GZ in physical coordinates system Gradient on tri- axis of X, Y, Z are obtained according to formula (2),
[GX, GY, GZ]T=RotMatrix_log2phy_Current* [GRO, GPE, GSS]T (2)
Wherein, [GX, GY, GZ] is component GX, GY, GZ in physical coordinates system Gradient on tri- axis of X, Y, Z,
RotMatrix_log2phy_Current is spin moment of the current logical coordinates system of pulse train of the acquisition level to physical coordinates system
Battle array, [GRO, GPE, GSS] be logical coordinates system of pulse train Gradient readout direction RO, phase directional PE, select on the SS of layer direction point
Measure GRO, GPE, GSS；
The current position of the acquisition level under physical coordinates system is obtained according to formula (3),
Shift_Phy_Current=Shift_Tracking+Shift_SlicePhy (3)
Wherein, Shift_Phy_Current is the current position of the acquisition level, Shift_ under physical coordinates system
Tracking is the displacement of the corresponding default level of the real-time three-dimensional data, Shift_Tracking and the real-time three-dimensional number
According to level center it is related to the level center of the standard three-dimensional data, Shift_SlicePhy be the acquisition
The initial position of level；
The current position of the acquisition level under logical coordinates system of pulse train is obtained according to formula (4),
Shift_Log_Current=(RotMatrix_log2phy_Current)-1* Shift_Phy_Current=
[Shift_RO, Shift_PE, Shift_SS]T (4)
Wherein, Shift_Log_Current is the current position of the acquisition level, RotMatrix_ under logical coordinates system of pulse train
Log2phy_Current is spin matrix of the current logical coordinates system of pulse train of the acquisition level to physical coordinates system, Shift_
Phy_Current is the current position of the acquisition level, [Shift_RO, Shift_PE, Shift_ under physical coordinates system
SS] be the acquisition layer currently logical coordinates system of pulse train bottom offset readout direction RO, phase directional PE, select on the SS of layer direction point
Measure Shift_RO, Shift_PE, Shift_SS；
The correction quantity of frequency of the emission element is obtained according to formula (5),
TX_freq=gamma*B0+freq_per_SS*Shift_SS (5)
Wherein, TX_freq is the correction quantity of frequency of emission element, and gamma is gyromagnet specific ray constant, and B0 is magnetic field strength, freq_
Per_SS is the frequency variation that logical coordinates system of pulse train lower edge selects layer direction SS per unit length to generate, and Shift_SS is the acquisition layer
Currently the component on the SS of layer direction is being selected in logical coordinates system of pulse train bottom offset；
The phase error of the emission element is obtained according to formula (6),
TX_phase=-gamma*GSS*Duration_RF*AsymmetricFactor_RF*Shif t_SS+phase_RF (6)
Wherein, gamma is gyromagnet specific ray constant, and GSS is to select the component on the SS of layer direction in logical coordinates system of pulse train Gradient,
Duration_RF is the duration of radio-frequency pulse, and AsymmetricFactor_RF is the asymmetric factor of radio-frequency pulse,
Shift_SS is that the acquisition layer is currently selecting the component on the SS of layer direction in logical coordinates system of pulse train bottom offset, and phase_RF is given
Phase；
The correction quantity of frequency of the receiving part is obtained according to formula (7),
RX_freq=gamma*B0+freq_per_RO*Shift_RO (7)
Wherein, RX_freq is the correction quantity of frequency of receiving part, and gamma is gyromagnet specific ray constant, and B0 is magnetic field strength, freq_
Per_RO is the frequency variation generated under logical coordinates system of pulse train along readout direction RO per unit length, and Shift_RO is the acquisition layer
The currently component in logical coordinates system of pulse train bottom offset on readout direction RO；
The phase error of the receiving part is obtained according to formula (8),
RX_phase=phase_RO+phase_per_PE*Shift_PE+phase_per_SPE*Sh ift_SPE (8)
Wherein, RX_phase is the phase error of receiving part, and phase_RO is to apply on the direction RO under logical coordinates system of pulse train
To phase bit, phase_per_PE is the phase change generated under logical coordinates system of pulse train along phase directional PE per unit length,
Shift_PE is the acquisition layer currently component in logical coordinates system of pulse train bottom offset on phase directional PE；phase_per_SPE
For the phase change generated under logical coordinates system of pulse train along the every element length of level phase-encoding direction SPE, Shift_SPE is described adopts
Collect the layer currently displacement under logical coordinates system of pulse train on level phase-encoding direction SPE.
2. magnetic resonance scanning method according to claim 1, which is characterized in that the standard for obtaining the default level
Three-dimensional data includes：It is acquired and is obtained using the three-dimension sensor of fixed installation；The real-time three-dimensional for obtaining the default level
Data include：It is acquired and is obtained using the three-dimension sensor of fixed installation.
3. magnetic resonance scanning method according to claim 2, which is characterized in that the data transmission rate of the three-dimension sensor
The nuclear-magnetism precision of at least 30 frames/second, the three-dimension sensor is at least 1mm.
4. magnetic resonance scanning method according to claim 3, which is characterized in that the visual field of the three-dimension sensor be greater than or
Equal to 60 °, the radius of investigation of the three-dimension sensor is greater than or equal to 30cm.
5. magnetic resonance scanning method according to claim 2, which is characterized in that the fixed peace of at least 1 three-dimension sensor
Top loaded on magnetic resonance chamber inner wall.
6. magnetic resonance scanning method according to claim 2, which is characterized in that the fixed peace of at least 2 three-dimension sensors
Two sides loaded on magnetic resonance chamber inner wall.
7. magnetic resonance scanning method according to claim 2, which is characterized in that the three-dimension sensor is at least 3, institute
It states three-dimension sensor and is fixedly installed in magnetic resonance chamber inner wall, the angle of adjacent three-dimensional sensor field of view overlapping is greater than or equal to
60°。
8. magnetic resonance scanning method according to claim 1, which is characterized in that the standard three-dimensional data and it is described in real time
Three-dimensional data storage is in predeterminated position；
The magnetic resonance scanning method further includes：Marker is added in magnetic resonance imaging sequence, runs the magnetic resonance imaging
When sequence to the marker, the sequence timing control unit is triggered from the predeterminated position and obtains the standard three-dimensional data
With the real-time three-dimensional data.
9. a kind of magnetic resonance imaging equipment, which is characterized in that including：
Storage assembly, the standard three-dimensional data and real-time three-dimensional data of the default level for storing subject；The acquisition layer of subject
Face and the relative position of the default level are fixed；
Sequence timing control unit calculates described in obtaining for being based on the standard three-dimensional data and the real-time three-dimensional data
The gradient modification amount and radio frequency correction amount of acquisition level, and the gradient modification amount is sent to gradient unit, by the radio frequency
Correction amount is sent to radio-frequency unit；
Gradient unit generates gradient magnetic for being based on the gradient modification amount；
Radio-frequency unit, for being based on the radio frequency correction amount, transmitting signal and reception signal；
The standard three-dimensional data are located under physical coordinates system, and the standard three-dimensional data include at least：Level center, method
Vector, level internal rotation angle degree；The real-time three-dimensional data is located under physical coordinates system, and the real-time three-dimensional data is at least wrapped
It includes：Level center, normal vector, level internal rotation angle degree；
The gradient modification amount includes：Under physical coordinates system, component GX, GY, the GZ of gradient on three axis of x, y, z；It is described
Radio-frequency unit includes：Emission element and receiving part；The radio frequency correction amount includes：The correction quantity of frequency of the emission element
TX_freq, the phase error TX_phase of the emission element, the receiving part correction quantity of frequency RX_freq, described
The phase error RX_phase of receiving part；
The sequence timing control unit calculates the gradient modification amount for obtaining the acquisition level and radio frequency correction amount includes：
According to formula (1) obtain the current logical coordinates system of pulse train of the acquisition level to physical coordinates system spin matrix,
RotMatrix_log2phy_Current=RotMatrix_Tracking*RotMatrix_l og2phy (1)
Wherein, RotMatrix_log2phy_Current is the current logical coordinates system of pulse train of the acquisition level to physical coordinates system
Spin matrix, RotMatrix_Tracking be the corresponding default level of the real-time three-dimensional data spin matrix,
RotMatrix_Tracking is related to the normal vector of the real-time three-dimensional data and level internal rotation angle degree, RotMatrix_
Log2phy is spin matrix of the initial logical coordinates system of pulse train of the acquisition level to physical coordinates system；
Component GX, GY, GZ in physical coordinates system Gradient on tri- axis of X, Y, Z are obtained according to formula (2),
[GX, GY, GZ]T=RotMatrix_log2phy_Current* [GRO, GPE, GSS]T (2)
Wherein, [GX, GY, GZ] is component GX, GY, GZ in physical coordinates system Gradient on tri- axis of X, Y, Z,
RotMatrix_log2phy_Current is spin moment of the current logical coordinates system of pulse train of the acquisition level to physical coordinates system
Battle array, [GRO, GPE, GSS] be logical coordinates system of pulse train Gradient readout direction RO, phase directional PE, select on the SS of layer direction point
Measure GRO, GPE, GSS；
The current position of the acquisition level under physical coordinates system is obtained according to formula (3),
Shift_Phy_Current=Shift_Tracking+Shift_SlicePhy (3)
Wherein, Shift_Phy_Current is the current position of the acquisition level, Shift_ under physical coordinates system
Tracking is the displacement of the corresponding default level of the real-time three-dimensional data, Shift_Tracking and the real-time three-dimensional number
According to level center it is related to the level center of the standard three-dimensional data, Shift_SlicePhy be the acquisition
The initial position of level；
The current position of the acquisition level under logical coordinates system of pulse train is obtained according to formula (4),
Shift_Log_Current=(RotMatrix_log2phy_Current)-1* Shift_Phy_Current=
[Shift_RO, Shift_PE, Shift_SS]T (4)
Wherein, Shift_Log_Current is the current position of the acquisition level, RotMatrix_ under logical coordinates system of pulse train
Log2phy_Current is spin matrix of the current logical coordinates system of pulse train of the acquisition level to physical coordinates system, Shift_
Phy_Current is the current position of the acquisition level, [Shift_RO, Shift_PE, Shift_ under physical coordinates system
SS] be the acquisition layer currently logical coordinates system of pulse train bottom offset readout direction RO, phase directional PE, select on the SS of layer direction point
Measure Shift_RO, Shift_PE, Shift_SS；
The correction quantity of frequency of the emission element is obtained according to formula (5),
TX_freq=gamma*B0+freq_per_SS*Shift_SS (5)
Wherein, TX_freq is the correction quantity of frequency of emission element, and gamma is gyromagnet specific ray constant, and B0 is magnetic field strength, freq_
Per_SS is the frequency variation that logical coordinates system of pulse train lower edge selects layer direction SS per unit length to generate, and Shift_SS is the acquisition layer
Currently the component on the SS of layer direction is being selected in logical coordinates system of pulse train bottom offset；
The phase error of the emission element is obtained according to formula (6),
TX_phase=-gamma*GSS*Duration_RF*AsymmetricFactor_RF*Shif t_SS+phase_RF (6)
Wherein, gamma is gyromagnet specific ray constant, and GSS is to select the component on the SS of layer direction in logical coordinates system of pulse train Gradient,
Duration_RF is the duration of radio-frequency pulse, and AsymmetricFactor_RF is the asymmetric factor of radio-frequency pulse,
Shift_SS is that the acquisition layer is currently selecting the component on the SS of layer direction in logical coordinates system of pulse train bottom offset, and phase_RF is given
Phase；
The correction quantity of frequency of the receiving part is obtained according to formula (7),
RX_freq=gamma*B0+freq_per_RO*Shift_RO (7)
Wherein, RX_freq is the correction quantity of frequency of receiving part, and gamma is gyromagnet specific ray constant, and B0 is magnetic field strength, freq_
Per_RO is the frequency variation generated under logical coordinates system of pulse train along readout direction RO per unit length, and Shift_RO is the acquisition layer
The currently component in logical coordinates system of pulse train bottom offset on readout direction RO；
The phase error of the receiving part is obtained according to formula (8),
RX_phase=phase_RO+phase_per_PE*Shift_PE+phase_per_SPE*Sh ift_SPE (8)
Wherein, RX_phase is the phase error of receiving part, and phase_RO is to apply on the direction RO under logical coordinates system of pulse train
To phase bit, phase_per_PE is the phase change generated under logical coordinates system of pulse train along phase directional PE per unit length,
Shift_PE is the acquisition layer currently component in logical coordinates system of pulse train bottom offset on phase directional PE；phase_per_SPE
For the phase change generated under logical coordinates system of pulse train along the every element length of level phase-encoding direction SPE, Shift_SPE is described adopts
Collect the layer currently displacement under logical coordinates system of pulse train on level phase-encoding direction SPE.
10. magnetic resonance imaging equipment according to claim 9, which is characterized in that further include：Module, in magnetic
Marker is added in resonance scan sequence, when running the magnetic resonance imaging sequence to the marker, triggers the sequence
Column timing control unit obtains the three-dimensional data from the storage assembly.
11. a kind of magnetic resonance scanning system, which is characterized in that including：As described in any claim in claim 9~10
Magnetic resonance imaging equipment；
The three-dimension sensor of fixed installation, the standard three-dimensional data and real-time three-dimensional data of the default level for obtaining subject.
12. magnetic resonance scanning system according to claim 11, which is characterized in that the data of the three-dimension sensor are transmitted
Rate is at least 30 frames/second, and the nuclear-magnetism precision of the three-dimension sensor is at least 1mm.
13. magnetic resonance scanning system according to claim 12, which is characterized in that the visual field of the three-dimension sensor is greater than
Or it is equal to 60 °, the radius of investigation of the three-dimension sensor is greater than or equal to 30cm.
14. magnetic resonance scanning system according to claim 11, which is characterized in that at least 1 three-dimension sensor is fixed
It is installed on magnetic resonance chamber inner wall.
15. magnetic resonance scanning system according to claim 11, which is characterized in that at least 2 three-dimension sensors are fixed
It is installed on the two sides of magnetic resonance chamber inner wall.
16. magnetic resonance scanning system according to claim 11, which is characterized in that the three-dimension sensor is at least 3,
The three-dimension sensor is fixedly installed in magnetic resonance chamber inner wall, and the angle of adjacent three-dimensional sensor field of view overlapping is greater than or equal to
60°。
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