CN109765512A - Magnetic resonance gradient system and its eddy current compensation method and device - Google Patents
Magnetic resonance gradient system and its eddy current compensation method and device Download PDFInfo
- Publication number
- CN109765512A CN109765512A CN201910049406.1A CN201910049406A CN109765512A CN 109765512 A CN109765512 A CN 109765512A CN 201910049406 A CN201910049406 A CN 201910049406A CN 109765512 A CN109765512 A CN 109765512A
- Authority
- CN
- China
- Prior art keywords
- waveform data
- function
- gradient waveform
- gradient
- preemphasis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
The invention discloses a kind of magnetic resonance gradient system and its eddy current compensation method and devices.This method comprises: obtaining test gradient waveform data and reality output gradient waveform data at least one target axis direction；Non-linear vorticity-stream function is determined by the test gradient waveform data and reality output gradient waveform data, the vortex preemphasis function at least one described target axis direction is determined by test gradient waveform data, the reality output gradient waveform data and the non-linear vorticity-stream function, to carry out eddy current compensation to gradient current.The technical solution of the embodiment of the present invention realizes better eddy current compensation effect, improves picture quality.
Description
Technical field
The present embodiments relate to mr imaging technique field more particularly to a kind of magnetic resonance gradient systems and its vortex
Compensation method and device.
Background technique
Magnetic resonance imaging is a kind of imaging technique of non-intrusion type, and room and time abundant can be provided for clinical diagnosis
Information.In magnetic resonance imaging, vortex is to influence a key factor of picture quality, and the presence of vortex can seriously affect gradient
The variation in magnetic field, gradient magnetic can generate vortex in high-speed switch, gradient waveform caused to be distorted, and this distortion will cause
Image artifacts reduce picture quality.Therefore, it is necessary to compensate to vortex.
It can be compensated in the prior art by design self-shielded gradient coils, using eddy plate, gradient current preemphasis
Etc. modes eliminate or reduce vortex.The mode of design self-shielded gradient coils needs two groups of reverse windings to replace conventional single line
Circle, required electric current is big, space is more, significantly increases system cost.By the way of eddy plate, due to the limit by processing technology
System, it is still very big in edges of boards edge and the place vortex not covered, it causes preferably reduce vortex.Using gradient current pre-add
The mode compensated again makes gradient magnetic reach desired output effect, but is counted in real time by the size of regulating gradient electric current
The limitation of calculation has that accumulated error is gradually amplified with increasing for the number of iterations.
Summary of the invention
The embodiment of the invention provides a kind of magnetic resonance gradient system and its eddy current compensation method and devices, more preferable to realize
Eddy current compensation effect, improve picture quality.
In a first aspect, the embodiment of the invention provides a kind of eddy current compensation methods, this method comprises:
Obtain test gradient waveform data and reality output gradient waveform data at least one target axis direction；
Non-linear vorticity-stream function is determined by the test gradient waveform data and reality output gradient waveform data, is passed through
The test gradient waveform data, the reality output gradient waveform data and non-linear vorticity-stream function determine at least one
Vortex preemphasis function in the target axis direction, to carry out eddy current compensation to gradient current.
Second aspect, the embodiment of the invention also provides a kind of eddy current compensation device, which includes:
Wave data obtains module, for obtaining test gradient waveform data and reality at least one target axis direction
Border exports gradient waveform data；
It is vortexed preemphasis function determination module, for passing through the test gradient waveform data and reality output gradient waveform
Data determine non-linear vorticity-stream function, by the test gradient waveform data, the reality output gradient waveform data and
Non-linear vorticity-stream function determines the vortex preemphasis function at least one described target axis direction, to carry out to gradient current
Eddy current compensation.
The third aspect, the embodiment of the invention also provides a kind of magnetic resonance gradient system, the magnetic resonance gradient system packet
The gradient generator being sequentially connected, gradient power amplifier and gradient coil are included, further includes being connected to gradient generator
With the gradient pre-emphasis module of gradient power amplifier, the gradient pre-emphasis module is according to first axle to the coaxial whirlpool of first axle
It flows preemphasis function, the second axis and intersects axial eddy preemphasis function and third axis to the second of first axle to the first of first axle
Intersect axial eddy preemphasis function and eddy current compensation is carried out to magnetic resonance gradient system.
The technical solution of the embodiment of the present invention is by obtaining the test gradient waveform number at least one target axis direction
According to reality output gradient waveform data.Then, pass through the test gradient waveform data and reality output gradient waveform data
It determines non-linear vorticity-stream function, passes through the test gradient waveform data, reality output gradient waveform data and non-thread
Property vorticity-stream function determines the vortex preemphasis function at least one described target axis direction, to be vortexed to gradient current
Compensation.The technical solution of the embodiment of the present invention solve using the methods of self-shielded gradient coils higher cost, can not be preferably
Reduce vortex, is gradually amplified there are accumulated error with increasing for the number of iterations by the way of the compensation of gradient current preemphasis
The problem of, it realizes and eddy current compensation is carried out to gradient current in real time, save debug time and cost, the effect of eddy current compensation is very
It is good, improve picture quality.
Detailed description of the invention
A kind of flow chart of the eddy current compensation method provided in Fig. 1 a embodiment of the present invention one；
Fig. 1 b is a kind of structural schematic diagram of the vortex mathematical model provided in the embodiment of the present invention one；
Fig. 1 c is a kind of frame of the eddy current compensation mathematical model that joined eddy current compensation provided in the embodiment of the present invention one
Figure；
Fig. 1 d is that the one kind provided in the embodiment of the present invention one does not carry out the effect diagram of eddy current compensation；
Fig. 1 e is a kind of effect diagram by eddy current compensation method provided in the embodiment of the present invention one；
A kind of flow chart of the eddy current compensation method provided in Fig. 2 a embodiment of the present invention two；
A kind of computing block diagram of the preemphasis filter provided in Fig. 2 b embodiment of the present invention two；
Fig. 2 c is the hardware composition schematic diagram of MRI system eddy current measurement system；
Fig. 3 is a kind of flow chart of the eddy current compensation device provided in the embodiment of the present invention three；
Fig. 4 is a kind of structural schematic diagram of magnetic resonance gradient system of the offer in the embodiment of the present invention four.
Specific embodiment
The present invention is described in further detail with reference to the accompanying drawings and examples.It is understood that this place is retouched
The specific embodiment stated is used only for explaining the present invention rather than limiting the invention.It also should be noted that in order to just
Only the parts related to the present invention are shown in description, attached drawing rather than entire infrastructure.
Embodiment one
Fig. 1 a is the flow chart for the eddy current compensation method that the embodiment of the present invention one provides, and the present embodiment is applicable to vortex and mends
The case where repaying, the case where being particularly suitable for the eddy current compensation of gradient current in magnetic resonance imaging.This method can be by eddy current compensation
Device executes, which can be realized by hardware and/or software, which can be integrated in equipment (such as computer)
It executes, specifically comprises the following steps:
Step 101, the test gradient waveform data and reality output gradient wave obtained at least one target axis direction
Graphic data.
Wherein, target axis includes x-axis, y-axis and z-axis.Magnetic resonance system has three groups of coils, is passed through the electric current of predefined size
The gradient fields in three directions of x, y, z are generated afterwards.
Test gradient waveform data refer to the gradient waveform data of input, that is, give the gradient current of gradient coil, real
Border output gradient waveform data refer to the test gradient waveform data of input without the collected output gradient wave of eddy current compensation
Graphic data, that is, the gradient current of collected gradient coil.
Step 102 determines non-linear vortex by the test gradient waveform data and reality output gradient waveform data
Function passes through the test gradient waveform data, the reality output gradient waveform data and the non-linear vorticity-stream function
The vortex preemphasis function at least one described target axis direction is determined, to carry out eddy current compensation to gradient current.
The method of the embodiment of the present invention can be indicated by preset vortex mathematical model.Wherein, it is vortexed mathematical modulo
Type can be expressed as follows.Fig. 1 b is the structural schematic diagram for being vortexed mathematical model.It includes linear for being vortexed the system function of mathematical model
Function model δ (t) and non-linear vorticity-stream function heddy(t), linear function model δ (t) and non-linear vorticity-stream function heddy(t) into
Row superposition.Gin(t) test gradient waveform data, G are indicatedout(t) reality output gradient waveform data are indicated, t indicates the time.With x
For axis line compensation, then tests gradient waveform data and be expressed as Gxin(t), reality output gradient waveform data are Gxout(t)；
By taking y-axis as an example, then tests gradient waveform data and be expressed as Gyin(t), reality output gradient waveform data are Gyout(t)；With z-axis
For, then it tests gradient waveform data and is expressed as Gzin(t), reality output gradient waveform data are Gzout(t)。
It should be noted that eddy current compensation and gradient pre-emphasis indicate same meaning, the ladder issued to pulse train is indicated
Degree waveform is corrected, so that the gradient waveform of reality output, close to test gradient waveform data, which, which is known as being vortexed, mends
It repays.
Optionally, described to determine non-linear whirlpool by the test gradient waveform data and reality output gradient waveform data
Stream function, comprising:
Eddy axis is obtained by the test gradient waveform data and reality output gradient waveform data；
The parameter that the non-linear vorticity-stream function is determined by way of the nonlinear fitting to the eddy axis, obtains
Non-linear vorticity-stream function in the transform domain of Lars.
Nonlinear fitting is carried out by the test gradient waveform data and reality output gradient waveform data to be vortexed
Curve, eddy axis are non-linear vorticity-stream function, determine the parameter of the non-linear vorticity-stream function, obtain Lars transform domain
In non-linear vorticity-stream function.
Optionally, described to obtain vortex song by the test gradient waveform data and reality output gradient waveform data
Line is determined the parameter of the non-linear vorticity-stream function by way of the nonlinear fitting to the eddy axis, obtains Lars
Non-linear vorticity-stream function in transform domain, comprising:
When establishing first according to the test gradient waveform data, system function and the reality output gradient waveform data
Domain system equation, wherein system function includes linear function model δ (t) and non-linear vorticity-stream function heddy(t)；
Laplace transform is carried out to first time domain system equation, by by the first time domain after Laplace transform
System equation deforms to obtain the first system expression of the non-linear vorticity-stream function in Lars transform domain described in the system function
Formula；
Laplace transform is carried out to the predefined time-domain function model of the non-linear vorticity-stream function and obtains frequency-domain function
Model；
The non-linear vorticity-stream function is carried out according to the first system expression formula and the frequency-domain function model non-
Linear fit finds out parameter of the non-linear vorticity-stream function in the transform domain of Lars, obtains non-linear in the transform domain of Lars
Vorticity-stream function, wherein the parameter includes frequency constant and amplitude constant.By taking the coaxial item eddy current compensation of x-axis as an example, survey at this time
Examination gradient waveform data are Gxin(t), the reality output gradient waveform data measured are Gxout(t).Wherein, x-axis is coaxial
Item eddy current compensation, which refers to, emits gradient current in x-axis, and acquires corresponding reality output gradient waveform data in x-axis.
First time domain system equation is expressed as follows:
Wherein, heddy(t) indicate that non-linear vorticity-stream function, δ (t) indicate linear function model,Indicate convolution algorithm.
Laplace transform is carried out to formula (1) to obtain:
Gout(s)=Gin(s)·(1+Heddy(s))(2)
Wherein, multiplying is indicated.
Deformation is arranged to formula (2) to obtain:
Formula (3) indicates the first system expression formula of the non-linear vorticity-stream function in the transform domain of Lars, and the data of the formula can
To be calculated according to test gradient waveform data and reality output gradient waveform data.
GinIt (s) is test gradient, GoutIt (s) is collected measurement gradient.
In MRI system, Heddy(s) nonlinear transformations of vortex are contained.Vortex is with a kind of a variety of time constants of approximation
E index series decay, can be approached with following function model, formula (4) is the pre- of non-linear vorticity-stream function
Define time-domain function model.
Wherein, jump functionModel in Time Domain parameter alphalFor amplitude constant, τlFor when
Between constant, do not need directly to find out.
It carries out Laplace transform to the derivative of Model in Time Domain formula (4) above to obtain formula (5), formula (5) is frequency
Domain function model:
Wherein, N is positive integer, and L indicates Laplace transform, and formula (5) is indicated to heddy(t) derivation carries out La Pula again
This transformation.The purpose differentiated is to indicate vortex field.
Since formula (3) is equal with formula (5):
Pass through Gin(s) and Gout(s) data obtain eddy axis by way of nonlinear fitting, carry out parameter Estimation,
The amplitude constant η in the transform domain of Lars can be found outlWith frequency constant τl, obtain Heddy(s) function to get arrive Lars transform domain
In non-linear vorticity-stream function, the non-linear vorticity-stream function as in frequency domain.The Lars that eddy axis is namely fitted becomes
Change the non-linear vorticity-stream function in domain.
Optionally, pass through the test gradient waveform data, the reality output gradient waveform data and non-linear whirlpool
Stream function determines the vortex preemphasis function at least one described target axis direction, comprising:
According to predefined vortex preemphasis function, the test gradient waveform data, the system function and the reality
Border output gradient waveform data establish the second time domain system equation；
Laplace transform is carried out to second time domain system equation, when the reality output gradient waveform data are institute
When stating test gradient waveform data, the second system expression formula of the vortex preemphasis function in the transform domain of Lars is determined；
It is determined according to the vortex preemphasis function model of the second system expression formula and the vortex preemphasis function
Vortex preemphasis function at least one described target axis direction out.
In order to find out vortex preemphasis function, Fig. 1 c is the block diagram that joined the eddy current compensation mathematical model of eddy current compensation.
Its second time domain system equation are as follows:
hpre(t) predefined vortex preemphasis function is indicated.
Laplace transform is carried out to formula (6):
Gout(s)=Gin(s)·(Hpre(s))·(1+Heddy(s)) (7)
It is expected that the reality output gradient waveform data are the test gradient waveform data, then after eddy current compensation
Have:
Gout(s)=Gin(s)
I.e. preferably test gradient waveform data are consistent with the reality output gradient waveform data waveform.
Substituting into formula (7) then has following formula:
Formula (8) indicates the Laplace domain expression formula of vortex preemphasis function, the whirlpool in the as described Lars transform domain
Flow the second system expression formula of preemphasis function.
Then, Digital Signal Processing realization is carried out to vortex preemphasis function, needs to transform to Laplace domain into the domain z.
Enable Hpre(s) function model are as follows:
Formula (9) is the vortex preemphasis function model for being vortexed preemphasis function, wherein N is positive integer, indicates rank
Number.
It is equal with formula (9) according to formula (8), then have:
It is approached by series nonlinear fitting, parameter Estimation can find out multiple groups series parameter alphak、ξk, finally establish function
Hpre(s), as it is vortexed preemphasis function.
Eddy current compensation is carried out to gradient current according to the vortex preemphasis function.
Optionally, the method for the present embodiment further include: preemphasis filter is generated according to the vortex preemphasis function；
Compensating parameter is determined by the preemphasis filter, and vortex benefit is carried out to gradient current based on the compensating parameter
It repays.
It is optionally, described that preemphasis filter is generated according to the vortex preemphasis function, comprising:
The vortex preemphasis function is transformed into discrete-time system by Lars transform domain, obtains preemphasis filter.
Obtain vortex preemphasis function Hpre(s) after, by Hpre(s) domain z is transformed to from the domain s, the change in the domain z is transformed to from the domain s
The method of changing is the mature prior art, including shock response not political reform, step response not political reform, Bilinear transformation method etc..
It is illustrated with Bilinear transformation method, it can be by carrying out vortex preemphasis function by bilinear transformation, it will
It is vortexed preemphasis function and transforms to the domain z from the domain s, convert preemphasis filter for vortex preemphasis function.Such as it can be by whirlpool
Stream preemphasis function is converted into achievable infinite-duration impulse response iir filter, by achievable iir filter coefficient to ladder
It spends electric current and carries out eddy current compensation.
During magnetic resonance imaging, since gradient magnetic can generate vortex in high-speed switch, gradient current wave is caused
The distortion of shape is as shown in Figure 1 d, indicates the effect diagram for not carrying out eddy current compensation.
This gradient current wave distortion makes image, and there are the distortion phenomenons such as geometric deformation, artifact.Eddy current decay needs simultaneously
It wants for a long time, even if using the method for multiple stacking, it is also difficult to resolution ratio, signal-to-noise ratio and the good Characteristic Contrast obtained
Degree.So vortex elimination is one of the key technology in magnetic resonance imaging.The method of the embodiment of the present invention can carry out vortex
Compensation, the effect of eddy current compensation as shown in fig. le, show that the eddy current compensation method of the present embodiment can be preferably to the ladder of input
Degree electric current compensates.
The technical solution of the embodiment of the present invention is by obtaining the test gradient waveform number at least one target axis direction
According to reality output gradient waveform data.Then, pass through the test gradient waveform data and reality output gradient waveform data
It determines non-linear vorticity-stream function, passes through the test gradient waveform data, reality output gradient waveform data and non-thread
Property vorticity-stream function determines the vortex preemphasis function at least one described target axis direction, to be vortexed to gradient current
Compensation.The technical solution of the embodiment of the present invention solve using the methods of self-shielded gradient coils higher cost, can not be preferably
Reduce vortex, is gradually amplified there are accumulated error with increasing for the number of iterations by the way of the compensation of gradient current preemphasis
The problem of, it realizes and eddy current compensation is carried out to gradient current in real time, save debug time and cost, the effect of eddy current compensation is very
It is good, improve picture quality.
Embodiment two
Fig. 2 a is a kind of flow chart of eddy current compensation method provided by Embodiment 2 of the present invention, and the present embodiment is in above-mentioned implementation
On the basis of example, test gradient waveform data and reality output of the optionally described acquisition at least one target axis direction
Gradient waveform data, comprising:
Close the second test gradient waveform data in the second axis direction and the third test gradient in third axis direction
Wave data, obtains the first test gradient waveform data in the first axis direction and the first reality in the first axis direction is defeated
Gradient waveform data out；
The third closed in third axis direction tests gradient waveform data, obtains the second test ladder in the second axis direction
Spend Wave data and the second reality output gradient waveform data in the first axis direction；
The second test gradient waveform data in the second axis direction are closed, the third obtained in third axis direction tests ladder
Spend Wave data and the third reality output gradient waveform data in the first axis direction；
Correspondingly, described to pass through the test gradient waveform data, reality output gradient waveform data and non-thread
Property vorticity-stream function determine vortex preemphasis function, comprising:
According to the first test gradient waveform data, the first reality output gradient waveform data and non-linear whirlpool
Stream function is determined with axial eddy preemphasis function；
According to the second test gradient waveform data, the second reality output gradient waveform data and non-linear whirlpool
Stream function determines the first intersection axial eddy preemphasis function；
Gradient waveform data, the third reality output gradient waveform data and non-linear whirlpool are tested according to the third
Stream function determines the second intersection axial eddy preemphasis function；
Intersect axial eddy preemphasis function and the second intersection axial eddy according to the same axial eddy preemphasis function, first
Preemphasis function determines the vortex preemphasis function in first axis direction.
If Fig. 2 a is indicated, the method for the embodiment of the present invention specifically comprises the following steps:
Step 201 closes the second test gradient waveform data in the second axis direction and the third in third axis direction
Gradient waveform data are tested, the first test gradient waveform data in the first axis direction and the in the first axis direction are obtained
One reality output gradient waveform data.
The step indicates that first axle measures the coaxial item of the vortex of first axle.
Step 202, the third closed in third axis direction test gradient waveform data, obtain the in the second axis direction
Two test gradient waveform data and the second reality output gradient waveform data in the first axis direction.
The step indicates that the second axis measures the vortex cross term of first axle.
Step 203 closes the second test gradient waveform data in the second axis direction, obtains the in third axis direction
Three test gradient waveform data and the third reality output gradient waveform data in the first axis direction.
The step indicates that third axis measures the vortex cross term of first axle.
By taking x-axis as an example, first axle can be x-axis, and the second axis is y-axis, and third axis is z-axis.In step first, second with
Third does not have special meaning, merely to distinguishing.For example, first axle, the second axis indicate that these three axis are different from third axis
Axis.First test gradient waveform data correspond to the test gradient waveform data of x-axis, the first reality output gradient waveform data pair
Answer the reality output gradient waveform data of x-axis.Second test gradient waveform data correspond to the test gradient waveform data of y-axis, the
Two reality output gradient waveform data correspond to the reality output gradient waveform data of y-axis.Third test gradient waveform data correspond to z
The test gradient waveform data of axis, third reality output gradient waveform data correspond to the reality output gradient waveform data of z-axis.
By taking x-axis as an example, the second test gradient waveform data in the second axis direction and the in third axis direction are closed
Three test gradient waveform data obtain first in the first axis direction and test gradient waveform data and in the first axis direction
First reality output gradient waveform data, refer to coaxial item compensation, need to close the gradient of y-axis and z-axis, emit gradient in x-axis,
And reality output gradient waveform data are acquired in x-axis.The third closed in third axis direction tests gradient waveform data, obtains
The second test gradient waveform data in second axis direction and the second reality output gradient waveform data in the first axis direction,
Refer to that the second axis compensates the cross term of first axle, refers to and emit gradient in y-axis, acquisition y-axis transmitting gradient is in the corresponding reality of x-axis
Border exports gradient waveform data.The second test gradient waveform data in the second axis direction are closed, are obtained in third axis direction
Third test gradient waveform data and the third reality output gradient waveform data in the first axis direction refer to third axis pair
The cross term of first axle compensates, and refers to and emits gradient in z-axis, acquisition z-axis transmitting gradient is in the corresponding reality output gradient wave of x-axis
Graphic data.
Equally, the coaxial item compensation of y-axis and z-axis can also be determined as procedure described above with cross term compensation.
It is understood that the test gradient waveform data and reality output gradient wave in the same axis direction can be obtained
Graphic data carries out coaxial item compensation.Wherein, the same axis direction refers to coaxial item compensation, such as the coaxial item compensation of x, need to be by y, z
The gradient of axis is turned off, and tests gradient waveform data and reality output gradient waveform data are the data of x-axis, fitting obtains x-axis
To the eddy axis of x-axis.Similarly the coaxial item compensation of y obtains y-axis to the eddy axis of y-axis for fitting, and the compensation of z-axis item is to be fitted
To z-axis to the eddy axis of z-axis.
It is understood that input test gradient waveform data and reality output in the same axis direction can be obtained
Gradient waveform data carry out coaxial item compensation, can also carry out cross term compensation.When measuring cross term compensation, third axis is closed
Gradient, such as when measurement y-axis compensates the cross term of x-axis, close z-axis gradient, need to emit gradient current in y-axis, be adopted in x-axis
Collect reality output gradient waveform data.
It is understood that only carrying out coaxial item compensation also may be implemented eddy current compensation.
Eddy current compensation effect is better achieved in order to realize, needs to measure coaxial item compensation, it is also desirable to cross term compensation.
By taking x-axis as an example, when measurement, needs to obtain vortex x-axis to the eddy axis of x-axis, it is also desirable to measure y-axis to the whirlpool of x-axis
The eddy axis of flow curve and z-axis to x-axis.
Eddy current compensation method contain x, y, z it is coaxial between compensation, while can be for the cross term shadow between each axis
Sound compensates, and eddy current compensation precision is higher, and image goes artifact effect to become apparent from.
Step 204, according to it is described first test gradient waveform data, the first reality output gradient waveform data and
The non-linear vorticity-stream function of frequency domain is determined with axial eddy preemphasis function.
Step 205, according to it is described second test gradient waveform data, the second reality output gradient waveform data and
The non-linear vorticity-stream function of frequency domain determines the first intersection axial eddy preemphasis function.
Step 206, according to the third test gradient waveform data, the third reality output gradient waveform data and
The non-linear vorticity-stream function of frequency domain determines the second intersection axial eddy preemphasis function.
The determination method that preemphasis function is vortexed in step 204- step 206 can be true according to formula (1) to formula (13)
Fixed, difference is that test gradient waveform data are different from the reference axis of reality output gradient waveform data, the vortex calculated separately
The parameter of preemphasis function is different therewith, and the eddy axis of fitting is different accordingly, but calculation method is identical.
Step 207 intersects axial eddy preemphasis function and the second friendship according to the same axial eddy preemphasis function, first
Fork shaft vortex preemphasis function determines the vortex preemphasis function in first axis direction.
The present embodiment carries out the explanation of coaxial item compensation and cross term compensation by taking x-axis as an example, it is to be understood that y-axis, z
The method that axis method is similar to x-axis.
Step 208 generates preemphasis filter according to the vortex preemphasis function.
It is pre- according to axial eddy is intersected with axial eddy preemphasis function, the first intersection axial eddy preemphasis function and second respectively
Emphasis function determines corresponding preemphasis filter.
It is optionally, described that infinite-duration impulse response preemphasis filter is generated according to the vortex preemphasis function, comprising:
By the vortex preemphasis function by bilinear transformation, discrete-time system is transformed to by Lars transform domain, is obtained
To infinite-duration impulse response preemphasis filter.
By to Hpre(s) bilinear transformation is carried out, the domain z, available infinite-duration impulse response preemphasis are transformed to by the domain s
Filter, the technology due to obtaining infinite-duration impulse response preemphasis filter is the prior art, and details are not described herein.
Step 209 determines compensating parameter by the preemphasis filter, based on the compensating parameter to gradient current into
Row eddy current compensation.
After the test gradient waveform data of input are by the corresponding output eddy current compensation of infinite-duration impulse response preemphasis filter
Gradient waveform data.
Wherein, compensating parameter is the coefficient of preemphasis filter.
By taking infinite-duration impulse response preemphasis filter as an example, if Hpre(s) order N=12, it should be noted that order N with
Required models fitting precision is related, and the value of N is without limitation, it is only necessary to be positive integer.
The infinite-duration impulse response preemphasis filter of 12 ranks is expressed as follows:
In order to realize that eddy current compensation preemphasis accelerates to calculate, needs to become preemphasis function achievable unlimited impulse and ring
Preemphasis filter is answered, by bilinear transformation, the domain s is transformed into the domain z.
It enablesWherein, TsFor the sampling period, can be configured according to actual needs.
Bring H intopre(s) equation (10):
It obtains:
Wherein bl=αlTs,
Illustratively, the eddy current compensation method that the embodiment of the present invention proposes may include coaxial item eddy current compensation and cross term
Eddy current compensation.(for y-axis to x-axis, z-axis is to x-axis, and x-axis is to y-axis, and z-axis is to y-axis, and x-axis is to z-axis, and y-axis is to z for the compensation of vortex cross term
Axis) it is the same with coaxial item (for x-axis to x-axis, y-axis is to y-axis, and z-axis is to z-axis) compensation method, measure the mutual of two intersecting axle between centers
When influence, third axis needs are turned off, and when measuring coaxial item influences, close other two axis.
Such as x-axis line compensation, the gradient of y, z-axis need to be turned off, obtain vortex x-axis to the eddy axis of x-axis.X-axis
Cross term compensation includes that y-axis compensates the cross term of x-axis the cross term compensation of x-axis and z-axis, measures y-axis to the vortex of x-axis
The eddy axis of curve and z-axis to x-axis.
Cross term compensation is carried out to three axis respectively, fitting obtains being vortexed preemphasis function: H accordinglyx→y(z), Hx→z
(z), Hy→x(z), Hy→z(z), Hz→x(z), Hz→y(z)。
Hx→y(z) indicate x-axis to the z-transform of the vortex preemphasis function of y-axis as a result, Hx→z(z) indicate x-axis to the whirlpool of z-axis
The z-transform of preemphasis function is flowed as a result, since meaning is similar, repeats no more Hy→x(z), Hy→z(z), Hz→x(z), Hz→y(z) contain
Justice.
It is understood that Hx→y(z), Hx→z(z), Hy→x(z), Hy→z(z), Hz→x(z), Hz→y(z) calculation method is
It is identical, derivation calculating can be carried out to formula (12) by formula (1).
After obtaining the result of the transformation of the vortex preemphasis function, discrete-time system is transformed to by Lars transform domain,
Obtain preemphasis filter.
Consider that coaxial item compensation is compensated with cross term simultaneously, then have:
For the eddy current compensation in the direction x: x-axis to gradient waveform Gx(n) coaxial item preemphasis H is carried outx→x(z), it subtracts pre-
Accentuation filter Hy→x(z) to y direction gradient waveform Gy(n) preemphasis output, then subtract preemphasis filter Hz→x(z) to z
Direction gradient waveform Gz(n) preemphasis output, the result of final output are the gradient waveform G after x-axis preemphasisprex(n), n is
Integer indicates that the signal is digital signal.
The compensation of the vortex cross term in other directions equally uses the above calculation method, is as shown in Figure 2 b unlimited impulse
Respond the computing block diagram of preemphasis filter.
Finally obtain the gradient pre-emphasis functional equation to x-axis:
Wherein, Gx(n) it indicates in the progress discrete sampling to time domain gradient continuous signal G (t) as a result, usually A/
D chip is completed.
Wherein, subscript x, y, z indicates x-axis, y-axis, z-axis.
Gprex(n) knot for the corresponding test gradient waveform data of x-axis after preemphasis filter carries out eddy current compensation
Fruit, i.e. gradient waveform after x-axis preemphasis.
hpre(n)x→xIndicate Hx→x(z) result of inverse z-transform is carried out.Each function meaning of formula (13) is similar, and difference only exists
In the difference of reference axis.
To the gradient pre-emphasis of y-axis, comprising coaxial preemphasis, x-axis to the preemphasis of y-axis and z-axis to the preemphasis of y-axis:
The gradient pre-emphasis functional equation such as following formula of y-axis:
Gprey(n) knot for the corresponding test gradient waveform data of y-axis after preemphasis filter carries out eddy current compensation
Fruit.
To the gradient pre-emphasis of z-axis, comprising same axial eddy preemphasis, x-axis to the preemphasis of z-axis and y-axis to the pre-add of z-axis
Weight:
The gradient pre-emphasis functional equation such as following formula of z-axis:
Gprez(n) knot for the corresponding test gradient waveform data of z-axis after preemphasis filter carries out eddy current compensation
Fruit.
The embodiment of the present invention propose method can be realized in the programming devices such as high speed processor FPGA, DSP, GPU,
Can the eddy current compensation method of the embodiment of the present invention is comprehensive at logic circuit, for accelerating and real-time perfoming eddy current compensation vortex
The parameter of preemphasis function has just been generated when system installs debugging calibration, and clinical scanning is needed before starting by preemphasis filtering
Device is issued to sequence timing control unit.Command analysis module parses instruction, is sent to gradient waveform generator, while will be pre-
Accentuation filter parameter is sent to preemphasis filter module and is calculated, and finally exports final preemphasis gradient waveform.
It is understood that eddy current compensation method is the measurement vortex mathematical model in system installation and debugging, pre-add is generated
Weight filter coefficient (compensating parameter) is deposited in system files as system parameter.System no longer needs when doing clinical application scanning
Real-time measurement vortex, reduces System trace time, to achieve the purpose that high speed real-time compensation.When gradient unit damages, it is only necessary to
Try again system debug, regenerates preemphasis filter coefficient.
Fig. 2 c is the hardware composition schematic diagram of MRI system eddy current measurement system, and eddy current measurement system is for realizing the present invention
The eddy current compensation method of embodiment.Eddy current measurement system is by industrial personal computer, gradient timing control unit, gradient amplifier and gradient line
Circle is constituted.Industrial personal computer emits scan instruction sequence, generates gradient waveform (i.e. G through gradient generator after parsingin(t)), gradient wave
Shape sends the gradient magnetic that gradient amplifier is finally switched at high speed in gradient coil generation to after carrying out preemphasis, passes through vortex and feels
Eddy current data (the i.e. G for answering device that back production is arrived to the gradient current back production of induction to gradient timing control unit, industrial personal computerout(t))
Carry out parameter Estimation.Vortex is acquired when system initialization, is generated preemphasis filter coefficient and is issued to gradient timing control unit,
It is calculated for gradient pre-emphasis, the preemphasis gradient waveform after generating eddy current compensation.Wherein, gradient pre-emphasis module in figure
Implementation method is eddy current compensation method provided in an embodiment of the present invention, the preemphasis filter of corresponding diagram 2b.Pre-add in figure
Weight coefficient is preemphasis filter coefficient.
It should be noted that being carried out clearly just for the sake of convenient to each technical characteristic in this implementation to the number of step
The explanation of Chu, not to the considered critical of execution sequence.Illustratively, in the present embodiment, to step 201, step 202 and step
With no restrictions, step 201, step 202 and step 203 can execute 203 sequence parallel, can also serially execute, similarly, step
Rapid 204, step 205, the sequence of step 206 with no restriction, for example, step 204, step 205, step 206 can execute parallel,
It can serially execute.
The technical solution of the present embodiment determines compensating parameter by the preemphasis filter, is based on the compensating parameter pair
Gradient current carries out eddy current compensation.In turn, the vortex preemphasis function is transformed into discrete-time system by Lars transform domain,
Preemphasis filter is obtained, can be compensated in real time by preemphasis filter, while preemphasis filter can be increased
Order, can more precisely compensate for being vortexed.In turn, the test gradient waveform data at least one target axis direction are obtained
With reality output gradient waveform data, comprising: close the second test gradient waveform data and the third axis in the second axis direction
Third on direction tests gradient waveform data, obtains first in the first axis direction and tests gradient waveform data and first
The first reality output gradient waveform data in axis direction；The third closed in third axis direction tests gradient waveform data, obtains
Second in the second axis direction is taken to test gradient waveform data and the second reality output gradient waveform in the first axis direction
Data；The second test gradient waveform data in the second axis direction are closed, the third obtained in third axis direction tests gradient
Wave data and the third reality output gradient waveform data in the first axis direction；Correspondingly, described to pass through the test ladder
It spends Wave data, the reality output gradient waveform data and non-linear vorticity-stream function and determines vortex preemphasis function, comprising:
It is true according to the first test gradient waveform data, the first reality output gradient waveform data and non-linear vorticity-stream function
Determine with axial eddy preemphasis function；According to the second test the gradient waveform data, the second reality output gradient waveform number
Accordingly and non-linear vorticity-stream function determines the first intersection axial eddy preemphasis function；Gradient waveform number is tested according to the third
The second intersection axial eddy preemphasis letter is determined according to, third reality output gradient waveform data and non-linear vorticity-stream function
Number；Intersect axial eddy preemphasis function and the second intersection axial eddy pre-add according to the same axial eddy preemphasis function, first
Weight function determines the vortex preemphasis function in first axis direction, both considers the compensation of coaxial item, it is also considered that intersection
The influence of item more accurately can carry out eddy current compensation by gradient waveform.
Embodiment three
Fig. 3 is a kind of structural schematic diagram of the eddy current compensation device provided in the embodiment of the present invention three.The embodiment of the present invention
Eddy current compensation method provided by any embodiment of the invention, the specific knot of the device can be performed in provided eddy current compensation device
Structure is as follows: Wave data obtains module 31 and vortex preemphasis function determination module 32.
Wherein, Wave data obtains module 31, for obtaining the test gradient waveform at least one target axis direction
Data and reality output gradient waveform data；
It is vortexed preemphasis function determination module 32, for passing through the test gradient waveform data and reality output gradient wave
Graphic data determines non-linear vorticity-stream function, by the test gradient waveform data, the reality output gradient waveform data with
And non-linear vorticity-stream function determines the vortex preemphasis function at least one described target axis direction, with to gradient current into
Row eddy current compensation.
The technical solution of the embodiment of the present invention is by obtaining the test gradient waveform number at least one target axis direction
According to reality output gradient waveform data.Then, pass through the test gradient waveform data and reality output gradient waveform data
It determines non-linear vorticity-stream function, passes through the test gradient waveform data, reality output gradient waveform data and non-thread
Property vorticity-stream function determines the vortex preemphasis function at least one described target axis direction, to be vortexed to gradient current
Compensation.The technical solution of the embodiment of the present invention solve using the methods of self-shielded gradient coils higher cost, can not be preferably
Reduce vortex, is gradually amplified there are accumulated error with increasing for the number of iterations by the way of the compensation of gradient current preemphasis
The problem of, it realizes and eddy current compensation is carried out to gradient current in real time, save debug time and cost, the effect of eddy current compensation is very
It is good, improve picture quality.
Based on the above technical solution, device provided in an embodiment of the present invention further include: compensating parameter determining module.
Compensating parameter determining module, is used for:
Preemphasis filter is generated according to the vortex preemphasis function；
Compensating parameter is determined by the preemphasis filter, gradient current can be vortexed based on the compensating parameter
Compensation.
Based on the above technical solution, compensating parameter determining module is particularly used in: by the vortex preemphasis letter
Number transforms to discrete-time system by Lars transform domain, obtains preemphasis filter.
Based on the above technical solution, it is vortexed preemphasis function determination module 32, is particularly used in:
Eddy axis is obtained by the test gradient waveform data and reality output gradient waveform data；
The parameter that the non-linear vorticity-stream function is determined by way of the nonlinear fitting to the eddy axis, obtains
Non-linear vorticity-stream function in the transform domain of Lars.
Based on the above technical solution, it is vortexed preemphasis function determination module 32, is particularly used in:
When establishing first according to the test gradient waveform data, system function and the reality output gradient waveform data
Domain system equation；
Laplace transform is carried out to first time domain system equation, by by the first time domain after Laplace transform
System equation deforms to obtain the first system expression of the non-linear vorticity-stream function in Lars transform domain described in the system function
Formula；
Laplace transform is carried out to the predefined time-domain function model of the non-linear vorticity-stream function and obtains frequency-domain function
Model；
The non-linear vorticity-stream function is carried out according to the first system expression formula and the frequency-domain function model non-
Linear fit finds out parameter of the non-linear vorticity-stream function in the transform domain of Lars, obtains non-linear in the transform domain of Lars
Vorticity-stream function, wherein the parameter includes frequency constant and amplitude constant.
Based on the above technical solution, it is vortexed preemphasis function determination module 32, is particularly used in:
According to predefined vortex preemphasis function, the test gradient waveform data, the system function and the reality
Border output gradient waveform data establish the second time domain system equation；
Laplace transform is carried out to second time domain system equation, when the reality output gradient waveform data are institute
When stating test gradient waveform data, the second system expression formula of the vortex preemphasis function in the transform domain of Lars is determined；
It is determined according to the vortex preemphasis function model of the second system expression formula and the vortex preemphasis function
Vortex preemphasis function at least one described target axis direction out.
Based on the above technical solution, Wave data obtains module 31, is particularly used in:
Close the second test gradient waveform data in the second axis direction and the third test gradient in third axis direction
Wave data, obtains the first test gradient waveform data in the first axis direction and the first reality in the first axis direction is defeated
Gradient waveform data out；
The third closed in third axis direction tests gradient waveform data, obtains the second test ladder in the second axis direction
Spend Wave data and the second reality output gradient waveform data in the first axis direction；
The second test gradient waveform data in the second axis direction are closed, the third obtained in third axis direction tests ladder
Spend Wave data and the third reality output gradient waveform data in the first axis direction；
Correspondingly, vortex preemphasis function determination module 32 is particularly used in: according to the first test gradient waveform number
It determines according to, the first reality output gradient waveform data and non-linear vorticity-stream function with axial eddy preemphasis function；
According to the second test gradient waveform data, the second reality output gradient waveform data and non-linear whirlpool
Stream function determines the first intersection axial eddy preemphasis function；
Gradient waveform data, the third reality output gradient waveform data and non-linear whirlpool are tested according to the third
Stream function determines the second intersection axial eddy preemphasis function；
Intersect axial eddy preemphasis function and the second intersection axial eddy according to the same axial eddy preemphasis function, first
Preemphasis function determines the vortex preemphasis function in first axis direction.
Eddy current compensation device provided by the embodiment of the present invention can be performed vortex provided by any embodiment of the invention and mend
Compensation method has the corresponding functional module of execution method and beneficial effect.
Example IV
Fig. 4 is a kind of structural schematic diagram for magnetic resonance gradient system that the embodiment of the present invention four provides.The magnetic resonance ladder
Degree system includes the gradient generator 41, gradient power amplifier 42 and gradient coil 43 being sequentially connected.The magnetic that Fig. 4 is shown is total
The gradient system that shakes is only an example, should not function to the embodiment of the present invention and use scope bring any restrictions.
The magnetic resonance gradient system further includes the ladder for being connected to gradient generator 41 and gradient power amplifier 42
Spend pre-emphasis module 44, the gradient pre-emphasis module 44 is according to first axle to the same axial eddy preemphasis function of first axle, the
Two axis intersect axial eddy preemphasis function and third axis to the first of first axle and intersect axial eddy pre-add to the second of first axle
Weight function carries out eddy current compensation to magnetic resonance gradient system.
Wherein, for gradient generator for generating gradient waveform, it is pre- that gradient waveform carries out gradient pre-emphasis module progress gradient
It sends gradient amplifier after exacerbation to and finally generates the gradient magnetic switched at high speed in gradient coil.
Eddy current compensation method provided by the embodiment of the present invention one and embodiment two can be applied to the ladder in the present embodiment
Spend pre-emphasis module.
The gradient pre-emphasis module of the present embodiment can be realized in the chips such as FPGA, DSP, GPU.FPGA, DSP, GPU etc.
Chip can be comprehensive at logic circuit eddy current compensation method provided by embodiment one and embodiment two, for accelerating and in real time
Eddy current compensation is calculated, until preemphasis filter parameter generates, last preemphasis filter is in chips such as FPGA, DSP, GPU
It is interior to be realized by logic circuit.
The technical solution of the embodiment of the present invention carries out ladder for generating gradient waveform, gradient waveform by gradient generator
Degree pre-emphasis module sends the gradient that gradient amplifier is finally switched at high speed in gradient coil generation to after carrying out gradient pre-emphasis
Magnetic field realizes realization and carries out eddy current compensation to gradient current in real time, saves debug time and cost, the effect of eddy current compensation
Very well, picture quality is improved.
It is worth noting that, included each unit and module are only pressed in the embodiment of above-mentioned eddy current compensation device
It is divided, but is not limited to the above division according to function logic, as long as corresponding functions can be realized；In addition,
The specific name of each functional unit is also only for convenience of distinguishing each other, the protection scope being not intended to restrict the invention.
Note that the above is only a better embodiment of the present invention and the applied technical principle.It will be appreciated by those skilled in the art that
The invention is not limited to the specific embodiments described herein, be able to carry out for a person skilled in the art it is various it is apparent variation,
It readjusts and substitutes without departing from protection scope of the present invention.Therefore, although being carried out by above embodiments to the present invention
It is described in further detail, but the present invention is not limited to the above embodiments only, without departing from the inventive concept, also
It may include more other equivalent embodiments, and the scope of the invention is determined by the scope of the appended claims.
Claims (10)
1. a kind of eddy current compensation method characterized by comprising
Obtain test gradient waveform data and reality output gradient waveform data at least one target axis direction；
Non-linear vorticity-stream function is determined by the test gradient waveform data and reality output gradient waveform data, by described
Test gradient waveform data, the reality output gradient waveform data and the non-linear vorticity-stream function determine at least one
Vortex preemphasis function in the target axis direction, to carry out eddy current compensation to gradient current.
2. the method according to claim 1, wherein further include: it is generated according to the vortex preemphasis function pre-
Accentuation filter；
Compensating parameter is determined by the preemphasis filter, and eddy current compensation is carried out to gradient current based on the compensating parameter.
3. according to the method described in claim 2, it is characterized in that, described generate preemphasis according to the vortex preemphasis function
Filter, comprising:
The vortex preemphasis function is transformed into discrete-time system by Lars transform domain, obtains preemphasis filter.
4. the method according to claim 1, wherein described by the test gradient waveform data and practical defeated
Gradient waveform data determine non-linear vorticity-stream function out, comprising:
Eddy axis is obtained by the test gradient waveform data and reality output gradient waveform data；
The parameter that the non-linear vorticity-stream function is determined by way of the nonlinear fitting to the eddy axis, obtains Lars
Non-linear vorticity-stream function in transform domain.
5. according to the method described in claim 4, it is characterized in that, described by the test gradient waveform data and practical defeated
Gradient waveform data obtain eddy axis out, are determined by way of the nonlinear fitting to the eddy axis described non-linear
The parameter of vorticity-stream function obtains the non-linear vorticity-stream function in the transform domain of Lars, comprising:
The first time domain system is established according to the test gradient waveform data, system function and the reality output gradient waveform data
System equation；
Laplace transform is carried out to first time domain system equation, by by the first time domain system after Laplace transform
Equation deforms to obtain the first system expression formula of the non-linear vorticity-stream function in Lars transform domain described in the system function；
Laplace transform is carried out to the predefined time-domain function model of the non-linear vorticity-stream function and obtains frequency-domain function model；
The non-linear vorticity-stream function is carried out according to the first system expression formula and the frequency-domain function model non-linear
Fitting, finds out parameter of the non-linear vorticity-stream function in the transform domain of Lars, obtains the non-linear vortex in the transform domain of Lars
Function, wherein the parameter includes frequency constant and amplitude constant.
6. the method according to claim 1, wherein defeated by the test gradient waveform data, the reality
Gradient waveform data and non-linear vorticity-stream function determine the vortex preemphasis letter at least one described target axis direction out
Number, comprising:
It is defeated according to predefined vortex preemphasis function, the test gradient waveform data, the system function and the reality
Gradient waveform data establish the second time domain system equation out；
Laplace transform is carried out to second time domain system equation, when the reality output gradient waveform data are the survey
When trying gradient waveform data, the second system expression formula of the vortex preemphasis function in the transform domain of Lars is determined；
According to the second system expression formula and it is described vortex preemphasis function vortex preemphasis function model determine to
Vortex preemphasis function in a few target axis direction.
7. the method according to claim 1, wherein test of the acquisition at least one target axis direction
Gradient waveform data and reality output gradient waveform data, comprising:
Close the second test gradient waveform data in the second axis direction and the third test gradient waveform in third axis direction
Data obtain the first test gradient waveform data in the first axis direction and the first reality output ladder in the first axis direction
Spend Wave data；
The third closed in third axis direction tests gradient waveform data, obtains the second test gradient wave in the second axis direction
Graphic data and the second reality output gradient waveform data in the first axis direction；
The second test gradient waveform data in the second axis direction are closed, the third obtained in third axis direction tests gradient wave
Graphic data and the third reality output gradient waveform data in the first axis direction；
Correspondingly, described to pass through the test gradient waveform data, the reality output gradient waveform data and non-linear whirlpool
Stream function determines vortex preemphasis function, comprising:
According to the first test gradient waveform data, the first reality output gradient waveform data and non-linear vortex letter
Number is determined with axial eddy preemphasis function；
According to the second test gradient waveform data, the second reality output gradient waveform data and non-linear vortex letter
Number determines that first intersects axial eddy preemphasis function；
Gradient waveform data, the third reality output gradient waveform data and non-linear vortex letter are tested according to the third
Number determines that second intersects axial eddy preemphasis function；
Intersect axial eddy preemphasis function and the second intersection axial eddy pre-add according to the same axial eddy preemphasis function, first
Weight function determines the vortex preemphasis function in first axis direction.
8. a kind of magnetic resonance gradient system, the magnetic resonance gradient system includes the gradient generator being sequentially connected, gradient power
Amplifier and gradient coil, which is characterized in that further include the ladder for being connected to gradient generator and gradient power amplifier
Pre-emphasis module is spent, the gradient pre-emphasis module is according to first axle to same axial eddy preemphasis function, the second axis of first axle
Intersect axial eddy preemphasis function and third axis to the first of first axle and intersects axial eddy preemphasis letter to the second of first axle
Several pairs of magnetic resonance gradient systems carry out eddy current compensation.
9. a kind of eddy current compensation device characterized by comprising
Wave data obtains module, defeated for obtaining the test gradient waveform data at least one target axis direction and reality
Gradient waveform data out；
It is vortexed preemphasis function determination module, for passing through the test gradient waveform data and reality output gradient waveform data
It determines non-linear vorticity-stream function, passes through the test gradient waveform data, reality output gradient waveform data and non-thread
Property vorticity-stream function determines the vortex preemphasis function at least one described target axis direction, to be vortexed to gradient current
Compensation.
10. device according to claim 9, which is characterized in that described device further include:
Compensating parameter determining module, for generating preemphasis filter according to the vortex preemphasis function；
Compensating parameter is determined by the preemphasis filter, and eddy current compensation is carried out to gradient current based on the compensating parameter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910049406.1A CN109765512B (en) | 2019-01-18 | 2019-01-18 | Magnetic resonance gradient system and eddy current compensation method and device thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910049406.1A CN109765512B (en) | 2019-01-18 | 2019-01-18 | Magnetic resonance gradient system and eddy current compensation method and device thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109765512A true CN109765512A (en) | 2019-05-17 |
| CN109765512B CN109765512B (en) | 2021-09-17 |
Family
ID=66454257
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910049406.1A Active CN109765512B (en) | 2019-01-18 | 2019-01-18 | Magnetic resonance gradient system and eddy current compensation method and device thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109765512B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111551883A (en) * | 2020-04-29 | 2020-08-18 | 中国科学院苏州生物医学工程技术研究所 | Magnetic field compensation method and equipment based on array coil |
| CN112630712A (en) * | 2020-11-25 | 2021-04-09 | 哈尔滨医科大学 | Simple and convenient nuclear magnetic resonance gradient waveform distortion pre-correction method |
| CN112881959A (en) * | 2020-06-10 | 2021-06-01 | 苏州纽迈分析仪器股份有限公司 | Gradient eddy current compensation method and system for magnetic resonance imaging |
| CN112885202A (en) * | 2021-01-13 | 2021-06-01 | 陕西师范大学 | Method for evolving wave model waveform process based on bilinear construction function method |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0647014A (en) * | 1992-07-31 | 1994-02-22 | Yokogawa Medical Syst Ltd | Imaging method by mr |
| US5864233A (en) * | 1997-02-22 | 1999-01-26 | General Electric Company | Method to reduce eddy current effects in diffusion-weighted echo planar imaging |
| CN1518949A (en) * | 2003-02-06 | 2004-08-11 | Ge医疗系统环球技术有限公司 | Eddy current corrention method and magnetic resonance imaging appts. |
| US20070159168A1 (en) * | 2006-01-10 | 2007-07-12 | Bruker Biospin Gmbh | Automatic digital preemphasis for dynamic NMR-magnetic fields by means of a digital IIR filter |
| CN103654787A (en) * | 2012-09-24 | 2014-03-26 | 三星电子株式会社 | Magnetic resonance imaging (MRI) apparatus and manufacturing method thereof |
| CN103961101A (en) * | 2013-02-05 | 2014-08-06 | 三星电子株式会社 | Magnetic resonance imaging apparatus and control method thereof |
| CN104181479A (en) * | 2013-05-23 | 2014-12-03 | 上海联影医疗科技有限公司 | Eddy current compensation method for magnetic resonance imaging system |
| CN106291423A (en) * | 2016-09-07 | 2017-01-04 | 厦门大学 | Nuclear magnetic resonance analyser gradient pre-emphasis adjusting means |
| CN106483482A (en) * | 2015-08-25 | 2017-03-08 | 上海联影医疗科技有限公司 | Gradient eddy bearing calibration for magnetic resonance imaging system and device |
| CN107677976A (en) * | 2017-09-26 | 2018-02-09 | 中国科学院武汉物理与数学研究所 | A kind of self-adaptive kernel magnetic resonance gradient preemphasis Waveform generating apparatus and method |
| US20180329010A1 (en) * | 2017-05-10 | 2018-11-15 | Siemens Healthcare Gmbh | Method and magnetic resonance apparatus for acquiring a magnetic resonance dataset with correction of gradient impulse response functions |
-
2019
- 2019-01-18 CN CN201910049406.1A patent/CN109765512B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0647014A (en) * | 1992-07-31 | 1994-02-22 | Yokogawa Medical Syst Ltd | Imaging method by mr |
| US5864233A (en) * | 1997-02-22 | 1999-01-26 | General Electric Company | Method to reduce eddy current effects in diffusion-weighted echo planar imaging |
| CN1518949A (en) * | 2003-02-06 | 2004-08-11 | Ge医疗系统环球技术有限公司 | Eddy current corrention method and magnetic resonance imaging appts. |
| US20070159168A1 (en) * | 2006-01-10 | 2007-07-12 | Bruker Biospin Gmbh | Automatic digital preemphasis for dynamic NMR-magnetic fields by means of a digital IIR filter |
| CN103654787A (en) * | 2012-09-24 | 2014-03-26 | 三星电子株式会社 | Magnetic resonance imaging (MRI) apparatus and manufacturing method thereof |
| CN103961101A (en) * | 2013-02-05 | 2014-08-06 | 三星电子株式会社 | Magnetic resonance imaging apparatus and control method thereof |
| CN104181479A (en) * | 2013-05-23 | 2014-12-03 | 上海联影医疗科技有限公司 | Eddy current compensation method for magnetic resonance imaging system |
| CN106483482A (en) * | 2015-08-25 | 2017-03-08 | 上海联影医疗科技有限公司 | Gradient eddy bearing calibration for magnetic resonance imaging system and device |
| CN106291423A (en) * | 2016-09-07 | 2017-01-04 | 厦门大学 | Nuclear magnetic resonance analyser gradient pre-emphasis adjusting means |
| US20180329010A1 (en) * | 2017-05-10 | 2018-11-15 | Siemens Healthcare Gmbh | Method and magnetic resonance apparatus for acquiring a magnetic resonance dataset with correction of gradient impulse response functions |
| CN107677976A (en) * | 2017-09-26 | 2018-02-09 | 中国科学院武汉物理与数学研究所 | A kind of self-adaptive kernel magnetic resonance gradient preemphasis Waveform generating apparatus and method |
Non-Patent Citations (6)
| Title |
|---|
| A. V. NETREBA: "Influence of the transverse gradient magnetic fields instability to reconstruction in MR imaging", 《2017 IEEE INTERNATIONAL YOUNG SCIENTISTS FORUM ON APPLIED PHYSICS AND ENGINEERING (YSF)》 * |
| A.O. KOMAROV: "Compensation of the Magnetic Gradient Instability in MRI by Measurements Data for Several Angular Orientations", 《 2018 IEEE 38TH INTERNATIONAL CONFERENCE ON ELECTRONICS AND NANOTECHNOLOGY (ELNANO)》 * |
| C. CHU: "3-dimensional rendering of MR (magnetic resonance) images", <IEEE WESCANEX 93 COMMUNICATIONS, COMPUTERS AND POWER IN THE MODERN ENVIRONMENT - CONFERENCE PROCEEDINGS> * |
| 谢晨: "核磁共振成像仪梯度预加重和数字下变频调节", 《中国优秀硕士学位论文全文数据库 信息科技II辑》 * |
| 郑海荣: "基于高场磁共振的快速高分辨成像", 《生命仪器科学》 * |
| 郭亚平: "磁共振谱仪的通信模块设计和涡流补偿方法研究", 《中国优秀硕士学位论文全文数据库 信息科技II辑》 * |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111551883A (en) * | 2020-04-29 | 2020-08-18 | 中国科学院苏州生物医学工程技术研究所 | Magnetic field compensation method and equipment based on array coil |
| CN111551883B (en) * | 2020-04-29 | 2022-05-20 | 中国科学院苏州生物医学工程技术研究所 | Magnetic field compensation method and equipment based on array coil |
| CN112881959A (en) * | 2020-06-10 | 2021-06-01 | 苏州纽迈分析仪器股份有限公司 | Gradient eddy current compensation method and system for magnetic resonance imaging |
| WO2021248752A1 (en) * | 2020-06-10 | 2021-12-16 | 苏州纽迈分析仪器股份有限公司 | Gradient eddy current compensation method and system for magnetic resonance imaging |
| CN112881959B (en) * | 2020-06-10 | 2021-12-21 | 苏州纽迈分析仪器股份有限公司 | Gradient eddy current compensation method and system for magnetic resonance imaging |
| CN112630712A (en) * | 2020-11-25 | 2021-04-09 | 哈尔滨医科大学 | Simple and convenient nuclear magnetic resonance gradient waveform distortion pre-correction method |
| CN112630712B (en) * | 2020-11-25 | 2024-01-02 | 哈尔滨医科大学 | Simple nuclear magnetic resonance gradient waveform distortion predistortion method |
| CN112885202A (en) * | 2021-01-13 | 2021-06-01 | 陕西师范大学 | Method for evolving wave model waveform process based on bilinear construction function method |
| CN112885202B (en) * | 2021-01-13 | 2022-07-22 | 陕西师范大学 | Method for evolving wave model waveform process based on bilinear construction function method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109765512B (en) | 2021-09-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109765512A (en) | Magnetic resonance gradient system and its eddy current compensation method and device | |
| US11698430B2 (en) | Eddy current mitigation systems and methods | |
| US7626387B2 (en) | MRI apparatus and method using sample filtering based on time shifts caused by temporal variations in magnetic field strength | |
| WO2012020720A1 (en) | Magnetic resonance imaging device and magnetic resonance imaging method | |
| JP2009502281A (en) | Method for processing 2D or 3D reconstructed image photographed by magnetic resonance apparatus and corrected for distortion | |
| JP5865785B2 (en) | Magnetic resonance imaging apparatus and gradient magnetic field generation system load calculation method | |
| JP6038654B2 (en) | Magnetic resonance imaging apparatus and vibration error magnetic field reduction method | |
| JPH0228713A (en) | Device and method for acquiring signal | |
| Chen et al. | First measurement and SNR results of a 3D magnetic particle spectrometer | |
| JP5189361B2 (en) | Magnetic resonance imaging apparatus and method | |
| CN101711671B (en) | Magnetic resonance diagnostic apparatus and magnetic resonance diagnostic method | |
| Dillinger et al. | Direct comparison of gradient Fidelity and acoustic noise of the same MRI system at 3 T and 0. 75 T | |
| JP6109508B2 (en) | Magnetic resonance imaging system | |
| JP4481591B2 (en) | Method, system and computer product for gradient nonlinearity k-space correction | |
| JPH1189817A (en) | Magnetic resonance imaging equipment | |
| DE19753093A1 (en) | MR procedure | |
| JP2013017811A (en) | Magnetic resonance imaging apparatus | |
| JPH02211124A (en) | Magnetic resonance imaging device | |
| Sierra et al. | Acoustic fMRI noise: linear time-invariant system model | |
| JPH1176191A (en) | Magnetic resonance imaging | |
| JP3842607B2 (en) | Spectral estimation method and magnetic resonance imaging apparatus | |
| JP5013357B2 (en) | Image processing program and image processing apparatus in magnetic resonance imaging | |
| CN110954853B (en) | Method and device for improving digital resolution of gradient precompensation waveform | |
| US20230358839A1 (en) | Reducing and correcting magnetic field gradient deviations | |
| JPH01218439A (en) | Magnetic resonance imaging device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| CB02 | Change of applicant information |
Address after: 201807 Shanghai City, north of the city of Jiading District Road No. 2258 Applicant after: Shanghai Lianying Medical Technology Co., Ltd Address before: 201807 Shanghai City, north of the city of Jiading District Road No. 2258 Applicant before: SHANGHAI UNITED IMAGING HEALTHCARE Co.,Ltd. |
|
| CB02 | Change of applicant information | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |