CN103837848B - Radio frequency antenna device for magnetic resonance system and method - Google Patents
Radio frequency antenna device for magnetic resonance system and method Download PDFInfo
- Publication number
- CN103837848B CN103837848B CN201210491672.8A CN201210491672A CN103837848B CN 103837848 B CN103837848 B CN 103837848B CN 201210491672 A CN201210491672 A CN 201210491672A CN 103837848 B CN103837848 B CN 103837848B
- Authority
- CN
- China
- Prior art keywords
- radio
- frequency
- radio frequency
- magnetic resonance
- antenna structure
- 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.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
- G01R33/3607—RF waveform generators, e.g. frequency generators, amplitude-, frequency- or phase modulators or shifters, pulse programmers, digital to analog converters for the RF signal, means for filtering or attenuating of the RF signal
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/36—Electrical details, e.g. matching or coupling of the coil to the receiver
- G01R33/3621—NMR receivers or demodulators, e.g. preamplifiers, means for frequency modulation of the MR signal using a digital down converter, means for analog to digital conversion [ADC] or for filtering or processing of the MR signal such as bandpass filtering, resampling, decimation or interpolation
Abstract
The invention discloses a radio frequency antenna device for a magnetic resonance system and a method. The radio frequency antenna device comprises an antenna structure which is approximately in a net shape and is used for transmitting radio frequency current. The antenna structure comprises conductor parts and a plurality of capacitive or inductive connection points, wherein the conductor parts are scattered on a plurality of layers; the connection points are distributed at different positions and electrically connected with the conductor parts to form an approximate net shape. The radio frequency antenna device further comprises an interface device for enabling a radio frequency sub-system in the magnetic resonance system to be matched with the antenna structure in one or more space positions to control distribution of radio frequency current on the antenna structure. The radio frequency antenna device performs radio frequency transmission and reception in continuous and diverse current distribution modes. Therefore, Tx or Rx performance is improved, and image quality of magnetic resonance imaging is improved.
Description
Technical field
The present invention relates to nuclear magnetic resonance (MRI), more particularly to parallel radio frequency transmitting and the radio frequency of multichannel or multiport
Receive.The invention further relates to a kind of bearing calibration and multi-channel parallel radio-frequency transmissions/receiving coil group, for improve magnetic resonance into
The picture quality of picture.
Background technology
In transmission/detecting radiofrequency signal, the nuclear spin of imaging object is and B1 for nuclear magnetic resonance (MRI)+/B1-
, rather than with radio-frequency coil in driving current/faradic current, interact.At the same time the electric field for producing with magnetic field
(concomitant E field) causes radio frequency loss, shows with radio-frequency power consumption/noise.Electric current in coil have weigh very much
The effect wanted, serves as radio-frequency transmissions/reception（Tx/Rx）Contact tie between system and radio-frequency field, for control magnetic resonance into
Radio frequency electromagnetic field as in.
Radio-frequency transmissions/reception in for analyzing multiport system（Tx/Rx）Feasible program it is as follows：A. in radio-frequency transmissions
（Tx）During, with predetermined radio-frequency pulse, by one group of radio-frequency power amplifier, drive the electric current in radio-frequency coil, electric current
B1 fields are further excited, wherein, B1+Field excitation nuclear spin, and then produce precession.With electric field（E field）Related penetrates
Frequency loss causes imaging object to absorb radio-frequency (RF) energy, and radio frequency loss is weighed by Joule heat and polarization damping force mode, i.e. ∫ (σ+
ωε”)|E|2dv.B. in radio frequency reception（Rx）During, rotate the rotary magnetization that causes of precession make to be produced in radio-frequency coil it is electronic
Gesture, this generates and the B1 in B1 fields-The electric current for meeting.Electric current is detected by radio frequency reception unit, is obtained for rebuilding magnetic
The clock signal of resonance image-forming.The radio frequency loss related to electric field causes the noise in the clock signal for receiving.It may be noted that
Be radio-frequency transmissions/radio frequency reception（Tx、Rx）When, magnetic distribution and radio frequency loss are affected by imaging object.In radio frequency
Transmitting/receive（Tx/Rx）During, interaction of the gradient pulse to B1- nuclear spins carries out spatial modulation.This space
Modulate the part control magnetic resonance excitation as radio-frequency transmissions/radio frequency reception scheme and the space orientation of detecting.
The size and phase place of optimization coil current（magnitude/phase）, time domain waveform and spatial distribution be for improvement
Nuclear magnetic resonance performance is extremely important.A key factor for promoting optimization is to grasp and configured using coil current pattern or source
（source configuration）To B1 spatial distributions and the impact of rf power dissipation.Promote optimization another it is crucial because
Element is hardware structure.Except independent activator and receptor, it would be preferable to support the loop construction of current path control versatile and flexible
Also it is extremely important.Present patent application describes the new system for improving nuclear magnetic resonance performance for considering the above factor
And new method.
Parallel radio frequency transmitting is for control unit radio frequency absorbance and realizes that high-quality radio-frequency (RF) excited has outstanding appearance simultaneously
Amount.However, never a kind of practicable method makes full use of aforementioned capacity for organic life entity living, it is implemented as
As performance improvement, and reduce unit radio frequency absorbance.In fact, the degree of freedom that parallel radio frequency transmitting band is come is substantially improved (this
It is the basis of aforementioned capacity), worry is usually caused on the contrary, because inappropriate radio-frequency pulse is calculated or radio frequency shimming is calculated, or
Person's multichannel hardware fault, not only indefinite reduction may deteriorate on the contrary unit radio frequency absorbance (SAR).There is a kind of power meter scheme
This worry can to a certain extent be tackled.The program monitors the radio-frequency power of different port, uses power meter（powermeters）
Measurement different port forward and reflected power（forward and reflected power）, net through-put power is calculated in real time,
Overall SAR stops scanning when reaching threshold value.In order to fully tackle safety/performance considerations, it is necessary to further using aggressive schemes
The existing monitor in real time of supplement, aggressive schemes should have following ability：First, the prognostic chart picture sequence before magnetic resonance imaging is carried out
The unit radio frequency absorbance that row are caused to imaging object, next to that further optimizing radio-frequency pulse, is reducing unit radio frequency absorption
Rate（SAR）While realize the excitation to be reached（target excitation profile）.
Generally speaking, in the urgent need to be practicable SAR quantitative predictions model, model is directed to any B1 shimmings coefficient
（shimming coefficients）Or radio-frequency pulse excitation, predict the unit radio frequency absorbance and relevant average of entirety
（volumetric average）, and/or the unit radio frequency absorbance and relevant average in different interest regions.
In principle, for multi-channel radio frequency pulse calculates (including B1 shimmings and complete parallel transmission), forecast model can lead to
Tracking SAR and guide design are crossed, SAR is clearly reduced, it is possible to based on same model, by presetting a safety
Surplus（margin）, tackle hardware fault, it is to avoid unfavorable consequence occurs.In magnetic resonance imaging, these models serve as SAR prisons
Control core, its ability for having prediction and drawing SAR extends the SAR monitoring capacity of power meter scheme.
Existing evidence shows that, except pulse is calculated, radio-frequency coil (antenna) geometry affects multichannel or multiport
Tx or Rx performances.Fundamentally, it would be preferable to support the loop construction of current path control versatile and flexible is arrived to lifting Tx or Rx performances
The limit is particularly important.This is identical of views with following:Radio-frequency pulse adjusts coil current, and the coil current excites radio-frequency electromagnetic
, it is final to determine Tx or Rx performances.A radio-frequency coil structure is what is desired is that, the structure forms the intensive of multiport
Network structure, can accommodate and realize the radio-frequency current distribution pattern of complexity.
The content of the invention
It is an object of the invention to provide a kind of lifting Tx or Rx performances in magnetic resonance system radio-frequency antenna fill
Put and method.
For achieving the above object, the present invention is adopted the following technical scheme that：
A kind of radio frequency antenna apparatus in magnetic resonance system, including：
Antenna structure, substantially netted and for transmitting radio-frequency current, the antenna structure includes：
Conductor part, if being dispersed in dried layer；
Capacitive or inductive several connection binding sites, the connection binding site is distributed in diverse location, electricity
Property connecting conductor point and form network structure substantially；
Interface device, for by the Radio Frequency Subsystem in magnetic resonance system and the antenna structure at least one space bit
Put and coordinated, realize the control of radio-frequency current distribution on antenna structure；Wherein, the radio frequency antenna apparatus are with continuous and many
Sample current distribution pattern carries out radio-frequency transmissions and reception.
Used as further improved technical scheme of the present invention, the interface device is some on antenna structure including being distributed in
Port.
Used as further improved technical scheme of the present invention, each includes impedance inverter circuit in some ports.
Used as further improved technical scheme of the present invention, the control of the radio-frequency current distribution includes correspondence magnetic resonance system
The preceding radio frequency pulse of system emission mode and the combination of the preposition magnetic resonance signal/data of correspondence magnetic resonance system reception pattern.
As further improved technical scheme of the present invention, the preceding radio frequency pulse and preposition magnetic resonance signal/data
Combination be according to power measurement values, radio frequency field measure, noise measurement, the magnetic resonance signal/number for including prior acquisition
According to packet carry out it is preposition.
As further improved technical scheme of the present invention, it is described it is preposition be to have used multiple models, be predicted magnetic be total to
Shake the different aspect of imaging, and the aspect is from including radio-frequency power transmitting/dissipation, flip angle, image comparison, signal to noise ratio
Data set is selected.
For achieving the above object, the present invention can also be adopted the following technical scheme that：
A kind of method, using the electric current carrying pathway being connected with each other in a large number the change in time and space of electromagnetic field is realized, including as follows
Step：
Step a：An at least antenna structure is provided, the antenna structure includes the conductor part of multilamellar, conductor part clamping
There are made by non-conducting material at least a plain film or curved tabs, so as to be electrically connected the network in path, penetrate for accommodating
The change in time and space of frequency electric current；
Step b：There is provided interface device, for by the Radio Frequency Subsystem in magnetic resonance system and the antenna structure at least
One locus is coordinated, and realizes the control of radio-frequency current distribution on antenna structure；
Step c：Current control device is provided, including the radio-frequency pulse for transmitting and the signal/data set for receiving
Close；Wherein,
Methods described is beneficial to produce various electromagnetic field change in time and space, including the change that can lift radio-frequency transmissions and receiving efficiency
Change.
Used as further improved technical scheme of the present invention, the antenna structure is grid configuration, and grid configuration is enough
It is intensive, for produce precision radio-frequency current change in time and space.
Used as further improved technical scheme of the present invention, the grid configuration has the conductor portion for being distributed in different layers
Point, per layer accommodates almost parallel conductor piece.
Used as further improved technical scheme of the present invention, the non-conducting material is the insulation material with high-k
Material.
Used as further improved technical scheme of the present invention, the combination of the radio-frequency pulse and signal/data is according to bag
Including the prior power measurement values for obtaining, radio frequency field measure, noise measurement, the packet of magnetic resonance signal/data is carried out
Preposition.
As further improved technical scheme of the present invention, it is described it is preposition be to have used multiple models, be predicted magnetic be total to
Shake the different aspect of imaging, and the aspect is from including radio-frequency (RF) energy transmission/dissipation, flip angle, image comparison, signal to noise ratio
Data set is selected.
Used as further improved technical scheme of the present invention, the plurality of model includes meeting the function unit of quadratic equation
Part, for the definition prediction radio-frequency (RF) energy transmission based on radio-frequency pulse and dissipates, and the functional unit has by using having
The information of the power measurement values for obtaining in advance and predetermined parameter.
Used as further improved technical scheme of the present invention, the rule of the combination of the signal/data is nuclear magnetic resonance
Rebuild rule.
For achieving the above object, the present invention can also be adopted the following technical scheme that：
A kind of method, using the change in time and space of the real-time performance electromagnetic field with electric current carrying pathway, comprises the following steps：
Step a：Measuring method for measuring radio-wave propagation effect is provided；
Step b：Limited measured value is obtained by aforementioned measuring method；
Step c：A prediction mode is provided based on aforementioned measurements, the arbitrary radio-frequency pulse of prediction mode prediction transmitting
Radio-wave propagation effect, effect includes that energy is transmitted and dissipated；
Step d：Radio-frequency pulse is calculated with aforementioned prediction mode, it is the net with electric current carrying pathway that radio-frequency pulse is used for
Network provides energy；
Step e：Radio-frequency pulse provides energy for the network with electric current carrying pathway, realizes electromagnetic field change in time and space；Its
In, prediction mode manages radio-frequency (RF) energy transmission and dissipation proactively with radio-frequency pulse is calculated.
Used as further improved technical scheme of the present invention, the prediction mode includes front using radio-wave propagation measurement
The numerical model put.
Used as further improved technical scheme of the present invention, the numerical model includes meeting the function unit of quadratic equation
Part, for the definition prediction radio-frequency (RF) energy transmission based on radio-frequency pulse and dissipates, and the functional unit has by using having
The information of the power measurement values for obtaining in advance and predetermined parameter.
Used as further improved technical scheme of the present invention, the calculating is used to predict that radio-frequency (RF) energy consumes using at least one
Scattered quadratic equation integrates the prediction mode, the optimization as input by building and solving optimization problem
Output is defined as with radio-frequency pulse.
Used as further improved technical scheme of the present invention, the conductor part includes high conductivity material.
Used as further improved technical scheme of the present invention, the conductor part includes high conductivity material.
The present invention carries out radio-frequency drive for parallel mode and magnetic resonance signal is received, and improves Tx or Rx performances, also may be used
To improve unit radio frequency absorbance and signal to noise ratio (SNR), and then improve the picture quality of nuclear magnetic resonance.
Description of the drawings
It is illustrated below to illustrate a preferred embodiment for realizing the present invention.
It is illustrated below to be respectively：
Fig. 1 is the principle schematic of the magnetic resonance imaging system for implementing the present invention.
Fig. 2 is that the parallel transmission system in one embodiment of the invention arranges schematic diagram.
Fig. 3 A-3B are the schematic diagram of many star coils in another embodiment of the present invention.
Fig. 4 is the schematic diagram of many star coils (constellation coil) with additional port.
Fig. 5 is the schematic diagram of many star coils with N number of port.
Specific embodiment
Refer to shown in Fig. 1, Fig. 1 illustrates the critical piece of the magnetic resonance system 10 comprising the present invention, and the system is logical
Cross operator's console 12 to be controlled, control station 12 includes keyboard or other input equipments 13, control panel 14 and shows
Display screen 16.Control station 12 is connected by the computer system 20 independent with of connection member 18, and computer system 20 can make operation
Member can control the generation and display of image on display screen 16.The computer system 20 includes carrying out mutual ditch by backboard 20a
Logical some modules, these modules include image processor module 22, CPU modules 24 and memory modules 26, memory modules 26
Can be for the frame buffer of storage image data set known to industry.Computer system 20 is connected with hard disk 28 and magnetic disc 30,
Storage image data and program, and be connected with an autonomous control system 32 by high speed serialization connection 34.
Control system 32 includes the one group of module interconnected by a backboard 32a, and the module includes CPU moulds
Group 36, the pulse generator module 38 being connected with control station 12 by serial connection (serial link) 40.Control system 32 is led to
Cross serial connection 40 and receive the scanning sequence performed from the needs of operator（scan sequence）Instruction.Pulse generation
The runtime component of device module 38, the scanning sequence that execution is specified, output data, for example：The meter of the radio-frequency pulse of radio-frequency transmissions
When, intensity, shape, the timing of radio frequency reception and the length of data acquisition window.Pulse generator module 38 is connected to a series of
Gradient amplifier system 42, for controlling（indicate）The duration and shape of the gradient pulse produced in scanning process.Pulse
Generator module 38 can receive patient information from physiological acquisition controller 44, and the physiological acquisition controller 44 is by being connected to
The some different sensor acquisition signal of patient, for example, obtain ECG signal by the electrode with patient.Arteries and veins
Rush generator module 38 and be ultimately connected to scan room interface circuit 46, scan room interface circuit 46 is received and the state of an illness and magnetic system phase
The signal that the sensor of pass is produced.By scan room interface circuit 46, patient positioning system 48 receives instruction, and removing patient is to finger
Positioning is put and is scanned.
The gradient waveform that pulse generator module 38 is produced is applied to the gradient amplifier system 42 with Gx, Gy, Gz,
Each gradient amplifier excites a corresponding gradient coil in gradient coils set 50, produces for generating additional space coding letter
Number magnetic field gradient.Gradient coils set 50 is a part for magnetic assembly 52, and magnetic assembly 52 also includes polarized magnet 54 and body is penetrated
Frequency coil 56.The pulse that transceiver module 58 in control system 32 is produced is amplified by radio frequency amplifier 60, by sending/receiving
Switch 62 is coupled with radio-frequency coil 56.The signal that the atomic nucleus being excited in patient body send is perceived by radio-frequency coil 56
Arrive, be then transferred to preamplifier 64 by sending/receiving switch 62, the magnetic resonance signal of amplification is through transceiver module 58
Acceptance division be demodulated, filter, digitized processing.Send/receiving switch 62 can be by the signal of pulse generator module 38
Control, so as to be electrically connected with radio frequency amplifier 60 and radio-frequency coil 56 in the transmission mode, in the receiving mode, before electric connection
Put amplifier 64 and radio-frequency coil 56.Sending/receive switch 62 is sending out can single radio-frequency coil (such as surface coils)
Use under the pattern penetrated and receive.
The magnetic resonance signal that radio-frequency coil 56 is collected is digitized process through transceiver module 58, is then communicated to control
Storage module 66 in system processed 32.After the one group of original k- spatial data of acquisition of module 66 is stored, the end of scan.Original
K- spatial datas are rearranged into the corresponding single k- space data sets of reconstructed image, each k- space with each
Data set is imported into array processor 68, carries out combining magnetic resonance signal after Fourier transformation, forms one group of view data, figure
As data are transferred to computer system 20 by serial connection 34, and it is stored in storage device such as hard disk 28.With control station 12
The instruction for sending is corresponding, and described image data can be got up with longer-term storage, for example, be stored on magnetic disc 30, or by image
Processor 22 is further processed and is sent to control station 12, and shows on display screen 16.
The present invention be directed to parallel mode carries out the method and system that radio-frequency drive and magnetic resonance signal are received, it is this parallel
Excite and reception mode can be by accelerating radio-frequency pulse/accelerating magnetic resonance signal framing reducing sweep time, it is also possible to
Improve unit radio frequency absorbance and signal to noise ratio (SNR).
Exemplary method described below is with regard to predicting RF power/dissipation and B1 fields with limited measurement data
Distribution.
For the configuration of arbitrary source（source configuration）, can be by using appropriate system model and from school
The measurement data obtained during standard is controlling B1 spatial distributions and radio frequency loss.Source configures（source configuration）
One group is referred in advance in emitter（Tx case）The radio-frequency pulse of middle setting or one group are in receptor（Rx case）In for right
Obtain the weight of the image reconstruction of signal.It is highly effective with multiport design analysis, in example as schematically shown in Figure 2, it is imaged mesh
Radio-frequency coil 72 used by mark 78 and magnetic resonance can be considered as a multiport network 90, and the network is by port 80 and some sources
（source）Cooperated.In radio-frequency transmissions（Tx）During, port is connected to the outfan of radio-frequency power amplifier 74.
In radio frequency reception（Rx）During, port is connected to the input of the prime amplifier of receptor.Obtained by sending/receiving switch 62
Obtain different paths.
The design of core is to use one group of appropriate source to configure（source configuration）Carry out calibration experiments and
The reaction of record multiport system.To radio-frequency transmissions（Tx）In calibration process, as a result it is used for determining system response and makes a reservation for
Radio-frequency pulse between quantitative relation, subsequently can be used in turn predicting anti-for the system of different predetermined radio-frequency pulses
Should.
Multiport radio-frequency transmissions/reception（Tx/Rx）System hardware generally ensures the electromagnetic field phase produced in imaging object
To source（source）For linear response.In radio-frequency transmissions（Tx）During, it is assumed that radio-frequency power amplifier（They amplify predetermined
Radio-frequency pulse and the multiple ports of driving) meet appropriate linearity specifications (linearity specs), each amplifier is to multiport
Network is just shown as the voltage source with output terminal impedance, the predetermined radio frequency arteries and veins of the voltage source and the input for being supplied to amplifier
Rush linear correlation.In this case, Maxwell's formula is linearly embodied in electromagnetic field to voltage source and radio-frequency pulse
React for linear.Arbitrary electromagnetic field component in imaging object shows as equation below 1 as the function of time：
b(t)=L(v(1)(t),v(2)(t),...,v(N)(t)),
Wherein, L represents linear transformation, and b (t) represents the electromagnetic field component, v(n)T () represents predetermined radio-frequency pulse, N generations
The quantity of table Tx ports.
In steady State Analysis, it is possible to use the arbitrary variations per hour of phasor labelling, such as voltage source, by the electricity of conductors cross
Stream, a component of electromagnetic field vector.Specifically, variations per hour can be expressed by using complex variable, the variations per hour can be by multiple
Variable and exp (j2 π f0T) multiplied result treating excess syndrome portion obtains.
Phasor simplifies the description of the radio-frequency information in magnetic resonance.In practice system electronic control is with Δ t durations interval
For unit, Δ t is equivalent to such as 2 microseconds.The realization of one radio-frequency pulse subscribed is the result of a succession of control:In a succession of company
When each interval in the interval of the Δ t durations for passing through starts, system electronics are f to a frequency0Sine wave apply one weigh
Weight, the weight is one plural(n=ports index, p=interval index), corresponding to one size-phase place pair.A whole set of weight is come
From so-called RF pulse designs process.
Phasor labelling is adapted to the steady State Analysis at each Δ t durations interval, for example, position r in vivo and in p-th Δ t
Duration is spaced, and E fields can be expressed as The corresponding phasor labelling in E fields is complex vector： For the interval, the phasor mark of the predetermined radio frequency pulse of n-th port
Note is multiple scalar
For a Δ t durations interval, according to formula 1, square can be expressed as using the linear system behavior of phasor labelling
Configuration, it is concrete such as formula 2：
B=Aw,
Wherein, b=[b(1)b(2)…b(M)]T, b is an arrow phasor for collecting variations per hour interested, w=[w(1)w(2)…w(N)]T, w is that (its n-th component is one and answers scalar, the labelling Δ t arrow phasor for collecting predetermined radio frequency pulse definition
Duration be spaced and n-th port size-phase place to), A is the M*N matrixes of complex value.
Electromagnetism field calibration arranges (i.e. source configuration) to detect multiport networking with one group of meticulously selected input, the electricity for measuring
Magnetic field reaction is plus a suitable system model and then is used to predict the reaction that electromagnetic field arranges arbitrary input.
The magnetic resonance system linearity is easy to the calibration of electromagnetic field, formula 2 to show, based on linear, is input into using Line independent
The electromagnetic field reaction that the N number of experiment for arranging is measured can be used to predict the electromagnetic field reaction under arbitrarily input facilities, because of matrix A
Arranged and determined by the electromagnetic field reaction and N number of input that measure completely, specifically as shown in Equation 3：
Formula 3 summarizes formula 2, shown in the index number in experiment index ginseng formula.It is pointed out that according to input
The linear independence of setting, the presence of inverse matrix is guaranteed.A simply example is lifted, N number of test inhabitant area Tx can be passed through
Electromagnetic field, wherein n-th experiment (n=1,2 ... N) is related to n-th of the rectangular radio frequency pulsed drive of unit amplitude and zero phase
Port, other ports are then with the radio-frequency pulse of zero amplitude.In this case [w1w2…wN] it is a unit matrix, so as to A=
[b1b2…bN]。
For multiport parallel excitation, this includes this special situation of multiport B1 shimmings, and the principle of formula 3 can serve as
Prediction B1+.Prediction B1+It is the premise of RF pulse designs process.In this case bNIt is to collect B1 in n-th test+Take out in space
The vector of sample.After A is obtained with the calibration program that formula 3 is represented, so that it may predict the B1 under any one group of radio-frequency pulse excitation+
Change in time and space, and then, the spatial form of radio-frequency (RF) excited.This causes the space for entering row energization with appropriate RF pulse designs
Shape control becomes feasible.
When the excitation space shape of target is produced, it is necessary to avoid producing excessive radio-frequency power consumption on the object to be imaged
Dissipate.This can be dissipated solving by introducing appropriate Dilute multiple radio-frequency power consumption during RF pulse designs.For example, design is penetrated
Frequency pulse can be considered as an affined minimization problem, its search radio-frequency pulse when, to produce target excitation space shape
Shape is constraint, while minimizing the unit radio frequency absorbance that E fields cause.
The thermal balance of biological tissue can be described by Pennes bio-heat equations.Rf power dissipation, when it is present, into
It is the driving force risen with dynamic temperature, it is specific as follows to state formula：
Wherein, ρ, C and k represent respectively tissue density, thermal capacity and heat conductivity, hbIt is the heat flow biography between blood and tissue
Defeated rate, heIt is fractional radio frequency's energy absorbing device.With radio-frequency (RF) energy dissipate increase, organize it is overheated it may happen that.
It is to be noted that heIt is proportional with the E field intensities of local caused by being Joule heating and polarization decay strength
, specific formula for calculation is:he=1/2σ|E|2, wherein σ=σTissue+ωε”。
Due to interactive between the source under imageable target build and the difference of component, and altofrequency and imageable target plus
Play, electric field and radio-frequency power loss are heavily dependent on imageable target.In order to solve this problem, there is method to advise base
The specific absorption ratio result obtained in average Human Model Simulation is got up with the test synthesiss of actual human body profile and field.So
And, what is attracted people's attention is that this integrated approach easily produces big error in high-field magnetic resonance, because between phantom and reality
Little difference can often cause considerable between SAR results and be difficult to the difference for reconciling.For Accurate Prediction unit radio frequency absorbance
With improve magnetic resonance performance, need with based on actually specifically the measurement of imaging object setting up SAR forecast models.
From from the perspective of the development of nuclear magnetic resonance, particularly in High field strenghth MRI, in order to manage SAR, can not
What is avoided is needed for organism calibration SAR models living, just as managerial Incentives spatial form, needing to calibrate B1 distributions
Figure.In order to the result under specific scan setting is optimum, each imageable target can be based on, using B1 and SAR calibration results as weight
The optimum pulse calculating of |input paramete guiding or shimming is wanted to calculate.And be further to improve setting itself, can comprehensive extensive school
Quasi- result, using it as important |input paramete, guides the optimization of radio system and coil.The present invention is founded and made at two aspects
Predicted with SAR：Overall SAR and any local SAR.This is consistent with following high-field magnetic resonance development trend.
It has been observed that radio-frequency transmissions that can be from from the point of view of network point in magnetic resonance and reception (Tx/Rx), wherein imageable target
It is considered as a multiport networking with radio-frequency coil, the network is cooperated by port with some sources.Work as MR scanner
When maintaining the good linear for fine scanning needs, there is linear relationship between electromagnetic field and source configuration, particularly, with
E fields in p-th Δ t durations interval can be expressed as the weighted superposition of the N number of E field corresponding with N number of radio-frequency transmissions port, weight
Respectively wp (1),…wp (N).Therefore computing formula is as follows for fractional radio frequency's power attenuation:
Wherein, Λ is N row's-N row positive definite Hermite Matrixes,HRepresent conjugate transpose（conjugatetranspose）, * generations
Table complex conjugate（Complex conjugate), bottom line part is row or the row mark of vector or Input matrix component.
Above-mentioned formula shows that fractional radio frequency's power attenuation is w(1)... and w(N)Quadratic equation.Stated with matrix form, it is right
In p-th Δ t durations interval, he=wHΛ w, wherein w=[w(1)…w(N)]TIt is that a vector is used to collect amplitude-phase place pair.This
Definition of a little amplitude-phase places to being spaced for Δ t durations from N number of parallel radio frequency pulse.Further, between Δ t durations
Overall radio-frequency power loss in can also be calculated with quadratic equation, specific as follows：
Formula 4
Wherein Φ is N row's-N row positive definite Hermitian matrixs（an N-by-N positive definite
Hermitianmatrix）.
Λ and Φ are referred to as into local and overall power incidence matrix, they summarize the interaction of field and tissue electricity
Conductance is to local and the impact of overall rf power dissipation.The overall radio frequency energy loss that whole radio frequency excitation is produced is ξp
Time integral, be specifically expressed as follows:
Formula 5
Wherein WfullIt is a vector, have collected a whole set of weight and (define all amplitude-phase places of radio-frequency pulse
It is right).Similarly,
Formula 6
Formula 6 calculates the radio frequency energy loss that whole radio frequency excitation results from local address x.
It is to be noted that description unit radio frequency absorbance, couples even if there be no between element coil, it is contemplated that local and entirety
Multiple sources can not be considered as isolated mutually during radio frequency energy loss and be treated, this is attributed to the overlap of E fields.This reflection during quantization
The continuous item component of usual non-zero in Λ and Φ, the continuous item component of these non-zeros summarizes the feature that multi-source is interfered,
Contain and effectively reduce SAR information needed.Under control, existing shimming calculating/radio-frequency pulse calculate using simple or
The quadratic sum in multiple sources of weighting, have ignored the effect that multi-source is interfered when multiport is launched, and so track and managing SAR
Can there are severe deviations in aspect.
For the system for being mounted with appropriate sensor, power sensor as shown in Figure 2 82, Φ can use a calibration process
Infer.When sensor is power sensor and when can provide multiple port forward and reflected power readings, determination Φ's
Method is to arrange (i.e. source configuration) with the input of one group of appropriate pre-selection to test, and then processes the power reading that experiment is obtained.Root
According to law of conservation of energy, Σ pfwd-Σprfl, it is input into the total power dissipation of the net radio-frequency power equal to network of N-port network.If
With wqArrange as input, from the net rf power dissipation that sensor reading is calculated, i.e. Σ pfwd-Σprfl, with wqCorrelation,
It is specific as follows to state formula：
Σpfwd,q-Σprfl,q=wq HΦwq=∑wq,i *wQ, j Φij,
Formula 7
Wherein wq,iAnd wQ, jW is represented respectivelyqI-th and j-th component, formula 7 is ΦijLinear equation, Φ point
Amount is unknown number, product term wq,i *wQ, jIt is coefficient.
The radio frequency loss feature of multiport network is easily drawn by some row experiments:The power sensor of each experiment is read
Number and source are arranged（source configuration）The linear equation being combined into described in formula 7;Combination is sufficient amount of
Equation, the institute that then just can calculate Φ is important.If with dqRepresent all w collected according to certain orderq,i *wq,j's
Vector, it is important to note that the selection that input is arranged should cause obtained one group dq(q=1,2 ...) linear independence.From meter
Calculate ΦijStrong anti-interference power from the perspective of, preferably select input to arrange in some way, such mode causes matrix [d1
d2...] conditional number smaller (such as so that the matrix is orthogonal).
When sensor supports that phase sensitivity is detected, an alternative method for determining Φ is to use reciprocity principle
(theprinciple of reciprocity), specifically, based on noise correlation matrix (the association side corresponding to multiport system
Difference matrix) Ψ, the matrix can pass through the receptor of connection multiport and obtain, and the calculating of Φ can use equation below：
Φ=L1 HΨTL1,
In general, the preamplifier in front of receptor is being received（Rx）During one be to multiport network performance
Row impedance is different from power amplifier in transmitting（Tx）During to multiport network performance a series of impedances.Transformation matrix L1
Look after this factor.In particular cases all of the port is even during Tx and Rx sees 50 Ω, at this moment L1It is unit matrix.
In addition, measurement noise incidence matrix can not be adopted, and adopts the collision matrix S and Bo Simading at multiport networking
Reason calculates Ψ:
Ψ=kT L2 H(I-SSH)L2,
Next, the calculating of Φ can use equation below：
Φ=L3 H(I-SSH)TL3=L3 H(I-SHS)L3.
L1L2Or L3Can be determined after different calibrations.
It is feasible to be dissipated using the intravital radio-frequency (RF) energy of non-intruding mode spatial discrimination.Magnetic resonance temperature measurement is with high accuracy
When carrying out, temperature not only can be recorded, and offer can be used to determine the information of Λ (x) and therefore make local SAR forecast model
It is energetic.This can be explained using Penni (Pennes) bioheat equation, when radio-frequency transmissions test be relative to
When carrying out in the conduction of heat time short enough, fractional radio frequency's energy dissipation is proportional with the rising of local temperature, i.e. Δ T ∝
he=1/2σ|E|2.Therefore position x in vivo, the Δ T measured values that magnetic resonance temperature measurement is obtained can be used for determining Λ (x):
1/2σ|E|2=wq H Λwq=∑ij wq,i *wq,j Λij
Formula 8
As shown in Equation 8, determine that the principle of Φ may also used to determine Λ (x) that difference is that the latter is surveyed using temperature
Value Δ T as sensing data to solve linear equation in Λij。
One of the obstacle for calibrating local SAR forecast model using magnetic resonance temperature measurement be temperature measurement accuracy in the case of live body/
Dynamic range.But this is not basic restriction.Different from pursuing diagram and the prediction that the local temperature of pin-point accuracy rises, a plan
Slightly it is to avoid accident violation food and drug administration（FDA）Restriction to local SAR.It is overall iff relying on
SAR monitorings, prediction and management, such accident violation unlikely 100% is found or eliminates.By to local SAR model
The grasp of error, can set up the safe clearance that corresponding radio-frequency pulse is calculated.Overall radio-frequency (RF) energy is dissipated on live body
Accurate Prediction and the reasonable prediction to heat distribution, being combined together can provide an effective optimization transmitting and reduce live body SAR's
New tool.
Different from the traditional method for realizing B1 homogenization using body coil in large scale 3d space, giving transmitted in parallel has
The means of power go to improve SAR problems.Intuitively, it is excellent when imaging region is the sub-fraction of the imageable target that transmitting coil is covered
Change the utilization to loop construction, for example, make the coiler part near imaging region contribute more than other parts, can avoid not
Necessary high rf power dissipation.
In practice, optimization can be specifically performed with an affined optimization framework is clear and definite.Based on SAR and excitation space shape
The quantitative relationship of shape and radio-frequency pulse, it is that, by searching for a set of radio-frequency pulse, the set radio-frequency pulse produces mesh that the framework reduces SAR
Mark excitation space shape, while minimizing SAR.One free optimization framework can alternatively, and it is provided more
Fast numerical value solution.In the case of excitation space form accuracy can be reduced moderately, a set of radio-frequency pulse is may search for, the set is penetrated
Frequency pulse minimizes the weighted sum of form error and SAR.The premise of the search of any of the above-described pattern is clearly to know SAR and penetrate
The quantitative association of frequency pulse.
The invention provides demonstration methodses, the prediction that radio-frequency (RF) energy is launched/dissipated the calculating of driving pulse is incorporated into
In.
Given prediction model, such as quadratic function wHΦ w (and it is suitable for the w of localHΛ w), by SAR value and radio-frequency pulse phase
Association, can be instructed during design radio-frequency pulse from forecast model.It is extra that this allows for that transmitted in parallel system has
Degree of freedom can give play to advantage, accomplish to adjust E fields and reduce SAR, and following example is illustrated calibration gained based on secondary letter
Several radio frequency loss tolerance are integrated into constraint or unrestricted optimization framework.
In order to reduce overall SAR, the tolerance（metric）It is the ξ defined in formula 5, it is described in order to reduce local SAR
Tolerance is
Formula 9
ξlocalIt is rf power dissipation value (formula 6) weighted statistical of the local to all points of interest, nonnegative curvature ηlThen
Specifying reduces the relative importance of each regional area SAR.The tolerance of entirety and local SAR is integrated into constraint or unrestricted excellent
Change（optimization）Effect with the exomonental calculating of guide parallel, makes to tend to the search of radio-frequency pulse shape drop
The direction of low SAR, this is because selecting other waveforms, can be increased by metric and pay bigger cost.Design SAR optimization and
Detailed below is joined in row energization pulse.
In the wide-angle category that low-angle encourages category or amplifies out according to it, to a given k- space trackings, can make
Transmitted in parallel pulse is designed with the following method:
Formula 10
Ω be one comprising in visual field weight a little diagonal matrix, these weights reflect that important areas are (for example, right
1 and 0 is respectively allocated in important area and non-interesting region, and/or pointedly to difference distribution fractional value in visual field referring to
The fixed relative importance accurately encouraged to each point).α and β is positive parameter, for balancing reduction and the exact space shape of SAR
Excitation.β and ηlNumerical value conference limit point of interest SAR increase.The present embodiment uses power correlation matrix, rather than one
Unit matrix, this has multiple spot advantage, not only helps improve reliability (the regularization effect of Numerical Inversion
（regularizationeffect）), and accurately follow the trail of SAR and minimize important standard when SAR becomes RF pulse designs
Then.This is important improvement：For example, for one group of parallel radio frequency pulse, 180 ° of phase places can be increased to one of pulse,
And do not affect wHThe value of I w is for the constructive or destruction interference of E fields by pulsed drive and its changing for caused SAR
Become, the tolerance can not catch.Using unit matrix I it is further assumed that each passage undertakes same contribution-in same RF pulse-to-pulse
Under punching drives, as long as different ports is different to SAR contributions, this hypothesis is just false.
The affined optimization relative with formula 10 is calculated as follows：
Formula 11
Formula 11 emphasizes excitation space shape accurately, but efficiently numerical solution is less.
Can be the spatial sampling of optimization k-（sampling）Technology with minimize SAR further integrate.It is given to one
Transmitting setting and target excitation spatial form, the Orthogonal Subspaces interworking searching method introduced before is by selecting a group by a group
Selecting property deletes EfullEach column groups of matrix, dramatically increase k- spaces lack sampling and therefore shorten driving pulse.It is preferably square
Method is the criterion changed using, and the criterion not only considers column groups to generating the contribution of target excitation spatial form, and
It is also contemplated for its consequence produced to SAR:Computing is iterated at j time and determines G groups and corresponding impulse wave sample w, selection makes following formula most
The G and w of littleization:
This embodies a kind of improvement, because new Pulse Design is with controllable balance, while optimizing the standard of excitation space shape
True property, SAR and pulse length.
For wide-angle transmitted in parallel Pulse Design, a method based on optimum control can be amplified, to reach effectively
SAR is minimized：
By expressing Bloch equations with control system（Block equation), above-mentioned equation is reflected magnetization space
Shape (state vector M (t)) encourage to radio-frequency pulse ripple real part (u (t)) towards object space shape D (dbjective state) and
The requirement of imaginary part (v (t)).Need the tolerance for minimizing that there is one to be used for end-state at dbjective state
Penalize, it is another that there is one to be used to punish the increase of SAR.Category is encouraged in wide-angle, the SAR with specific, concrete is accurately followed the trail of
Minimum be especially it is desirable that because efficient SAR management, by bigger flip angle/greater compactness of imaging sequence, is
The application of MR brings new chance.
B1 shimmings can use the formula 10 of reduction version.In order to further improve performance, can relax completely to phase place
Require, for example, pursue the uniformity of the amplitude of the spatial form for finally motivating, but ignore the spatial variations of phase place, the problem
It is expressed as follows:
Wherein w is the Nx1 vectors for collecting shimming coefficient, and E includes B1+Sample (no longer comprising gradient encoding efficiency), ufullGeneration
Entry target Uniform B 1+ field.
Size/the phase place of optimization radio-frequency coil electric current, time-modulation and spatial distribution to nuclear magnetic resonance performance very
It is important.The important prerequisite of optimization is the radio frequency that pair B1 spatial distribution related to coil current pattern or source configuration and electric field cause
The understanding of loss.The method of solution is B1 mappings and the calibration of power correlation matrix.Another important prerequisite of optimization has been to provide
Beneficial to the hardware structure of optimization.Embodiment provides new radio-frequency coil structure, and this not only supports current path control most versatile and flexible
System, it is allowed to different current-modes are suitable on same conductor structure, and significantly simplify the manufacture of radio-frequency coil.With this
The structure of sample and the referred to as many star coils of the radio-frequency coil of support multichannel or multiport Tx/Rx.
Compare with traditional parallel radio frequency transmitting/receiving coil, the part of correspondence multichannel or multiport on many star coils
It is unnecessary mutually isolated, conversely, there is coupling capacitively or inductively or direct interconnection between these parts, these
Decoupling between part is secondary.The structure of many star coils highlights several characteristics, and the characteristic constitutes high-quality simultaneously
The basis of row Tx/Rx runnings.This is stated manufacturing and having far reaching significance using the radio-frequency coil for nuclear magnetic resonance under
Discuss in bright.
Many star coils of example are grid, and multigroup conductor is located at different physical layers, and in lattice site capacitive character
Coupling.One effective coil manufacture method is that multigroup conductor is disposed in multilamellar high dielectric constant substrate, every layer of substrate clamping
Between two groups of conductors. Fig. 3 B shows plate sheet of one band, two groups of conductors 101,102, one group of 101 conductor of top layer is etched
In the top surface 104 of substrate 103, one group of conductor 102 of bottom is etched in the bottom surface 105 of substrate 103.Substrate has higher dielectric normal
Number, adds the other factors such as width and shape of substrate thickness and conductor near lattice site, determines that one is larger together
Capacitive couplings, the electric capacity 106 in the concrete equivalent circuit as in Fig. 3 A is illustrated.
The coil of construction preferably meets following requirement：Electric capacity has low reactance in Rameau frequency, has height in audio frequency
Reactance.Such characteristic allows radio-frequency current through capacitive couplings, when the interval between substantially parallel conductor compared with
Hour, dense grid structure provides a kind of continuous conductor structure for radio-frequency current so that such structure is to a certain extent
As radio frequency mask.This continuous performance supports complicated radio-frequency current pattern, including the radio frequency electrical that can lift parallel Tx/Rx performances
Stream mode.Meanwhile, such structure is transparent to audio frequency gradient fields, because such field can not sense big electricity in grid
Stream.
Many star coils are expected to become maximally effective parallel radio frequency antenna.The conception based on electrodynamics principle improve SNR and
SAR performances:It payes attention to the optimization of CURRENT DISTRIBUTION, and determines that the B1 fields and E fields of Tx/Rx performances derive from CURRENT DISTRIBUTION.Relative to
Several breakthroughs of conventional coil are summarized as follows：
First, traditional loop construction it is excessively discrete and can not support versatile and flexiblely high-field magnetic resonance Tx/Rx need
Complicated current-mode, and decoupling or mode structure add many restrictions to electric current.The each several part of many star coils can be good
Coupled well, be similar to netted radio frequency mask and maximize support complexity/wide band radio-frequency current-mode, not necessarily processed
Decoupling or mode configuration.The current-mode of needs can be by being driven with the multiple ports (many stars) being distributed in loop construction
Move or receive to realize, this available Kirchhoff's current law (KCL) is analyzed.In fact, the B1+/B1- obtained based on calibration
Scattergram and power/noise correlation matrix, desired current-mode can by using predetermined transmitted in parallel radio-frequency pulse/and
Row receives image reconstruction to realize.Concrete understanding or special RF pulse designs/image reconstruction to current-mode is not
Need.
Secondly, many star coils can preferably tackle radio frequency loss.E fields are that High-Field magnetic is total to the direct-coupling of imaging object
The important radio frequency loss mechanism of center of percussion one, and now by the big quantity and high density of the distribution capacity on coil, this loss meeting
Greatly reduce.The conductor cooperation conduction electric current of dense distribution, can help reduce the impedance suffered by radio-frequency current.Many star coils with it is new
Conductor material, for example, CNT is also easier to integrate, and this provides the chance for further reducing conductor losses.
3rd, to make conventional coil effectively and reliably work, complicated design, manufacture, tuning and test is necessary.It is real
There is quite challenging example to be included in the state of multiple element coil complexity mutual interferences in border to tune these element coils, integrate big
The parts (capacitor, inducer, and suppress or enable/disable circuit) of amount, and the management of failure mode.Conventional coil also face
To the fact that:A kind of structure can not be enough to be used in radio-frequency transmissions and reception, the different piece of body, multiple frequency and different
Parallel MR accelerates to arrange.This causes the too substantial amounts of demand to coil, and this means the use of costliness to clinical practice
And maintenance cost.
The design of many star coils have followed the SNR/SAR performance improvements optimized based on field.By contrast, attempt to allow multiple lists
Only coil (unit) gather together work traditional method it is not only expensive, not to the utmost reliably, application category is excessively limited, in high channel
Especially face the challenge under the parallel arrangement of situations of number, and it is too constrained so that magnetic resonance signal cannot be encouraged and detected water
It is flat to bring up to new height, realize the limiting performance that electrodynamics are allowed.
As shown in figure 4, when a port 110 is increased to many star coils, if it is desired, the net of a matching can be introduced
Network 111 and realize matching.For radio frequency reception, main target be for receptor before preamplifier desired characteristic impedance is provided,
So that preamplifier is operated in low-noise factor situation.For radio-frequency transmissions, main target is provided for power amplifier
Desired characteristic impedance so as to being capable of Maximum Power Output.Fig. 5 further illustrates the example with many star coils with N number of port 110
Son, for n-th port, if it is desired, an extra electric capacity can increase, and parallel with Cn.Electric capacity and inductance Ln
Be composed in series matching network, it has additional characteristic, i.e., can be by the low input impedance/power amplifier of preamplifier
Low output impedance change into very high impedance.If needing further exist for, general multi input and multi output interface/matching
Network can be employed so that matching is more facilitated.
Description to system and method above includes many characteristics, and these are not necessarily to be construed as limiting protection domain,
And the only explanation of preferred embodiment.Other conversion and result by difference embodiments inspiration be also it is possible, for example, field
Foundation and radio frequency loss forecast model other sensors data, including field measurement can be adopted to propagate measurement and different magnetic
Resonance signal.Further, many star coils are not limited to shown planar structure or two groups of conductors, same design
Suitable for cylinder, spherical structure and other warp architectures, or other the complicated profiles for meeting body shape.Build multilamellar
Structure can provide additional advantage.Hard or flexible/pliable material can be used, and realize superperformance.Using carbon nanometer
Pipe or superconductor can make Performance optimization.
Claims (15)
1. a kind of radio frequency antenna apparatus in magnetic resonance system, including：Antenna structure, it is substantially netted and for transmission penetrate
Frequency electric current, the antenna structure includes：Conductor part, if being dispersed in dried layer；Capacitive or inductive several companies
Binding chalaza, the connection binding site is distributed in diverse location, is electrically connected with conductor part and forms network structure substantially；Boundary
Face device, for the Radio Frequency Subsystem in magnetic resonance system and the antenna structure to be matched somebody with somebody at least one locus
Close, realize the control of radio-frequency current distribution on antenna structure；The control of the radio-frequency current distribution includes correspondence magnetic resonance system
The preceding radio frequency pulse of emission mode and the combination of the preposition magnetic resonance signal/data of correspondence magnetic resonance system reception pattern, its
In, the radio frequency antenna apparatus carry out radio-frequency transmissions and reception with continuous and various current distribution pattern.
2. radio frequency antenna apparatus as claimed in claim 1, it is characterised in that：The interface device includes being distributed in antenna structure
On some ports.
3. radio frequency antenna apparatus as claimed in claim 2, it is characterised in that：Each includes impedance transformation in some ports
Circuit.
4. radio frequency antenna apparatus as claimed in claim 1, it is characterised in that：The preceding radio frequency pulse and preposition magnetic resonance are believed
Number/combination of data is according to power measurement values, radio frequency field measure, noise measurement, the magnetic resonance for including prior acquisition
The packet of signal/data carries out preposition.
5. radio frequency antenna apparatus as claimed in claim 4, it is characterised in that：It is described it is preposition be to have used multiple models, carry out
Prediction nuclear magnetic resonance different aspect, the aspect be from include radio-frequency power transmitting/dissipation, flip angle, image comparison,
The data set of signal to noise ratio is selected.
6. a kind of method, using the electric current carrying pathway being connected with each other in a large number the change in time and space of electromagnetic field is realized, including following step
Suddenly：
Step a：An at least antenna structure is provided, the antenna structure includes the conductor part of multilamellar, and conductor part is clamped with non-
At least a plain film or curved tabs made by conductive material, so as to be electrically connected the network in path, for accommodating radio frequency electrical
The change in time and space of stream；
Step b：There is provided interface device, for by the Radio Frequency Subsystem in magnetic resonance system and the antenna structure at least one
Locus are coordinated, and realize the control of radio-frequency current distribution on antenna structure；
Step c：Current control device is provided, including the radio-frequency pulse for transmitting and the signal/data combination for receiving；Its
In, methods described is beneficial to produce various electromagnetic field change in time and space, including the change that can lift radio-frequency transmissions and receiving efficiency.
7. method as claimed in claim 6, it is characterised in that：The antenna structure is grid configuration, and grid configuration is enough
It is intensive, for produce precision radio-frequency current change in time and space.
8. method as claimed in claim 7, it is characterised in that：The grid configuration has the conductor portion for being distributed in different layers
Point, per layer accommodates almost parallel conductor piece.
9. method as claimed in claim 6, it is characterised in that：The non-conducting material is the insulation material with high-k
Material.
10. method as claimed in claim 6, it is characterised in that：The combination of the radio-frequency pulse and signal/data is according to bag
Including the prior power measurement values for obtaining, radio frequency field measure, noise measurement, the packet of magnetic resonance signal/data is carried out
Preposition.
11. methods as claimed in claim 10, it is characterised in that：It is described it is preposition be to have used multiple models, be predicted magnetic
The different aspect of resonance image-forming, the aspect is from including radio-frequency (RF) energy transmission/dissipation, flip angle, image comparison, signal to noise ratio
Data set selected.
12. methods as claimed in claim 11, it is characterised in that：The plurality of model includes meeting the function of quadratic equation
Element, for definition prediction radio-frequency (RF) energy transmission and dissipation based on radio-frequency pulse, the functional unit has by using tool
Have the power measurement values of prior acquisition information and predetermined parameter.
13. methods as claimed in claim 6, it is characterised in that：The rule of the combination of the signal/data is nuclear magnetic resonance
Rebuild rule.
14. radio frequency antenna apparatus as claimed in claim 1, it is characterised in that：The conductor part includes high conductivity material.
15. methods as claimed in claim 6, it is characterised in that：The conductor part includes high conductivity material.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710195424.1A CN107092002A (en) | 2012-11-27 | 2012-11-27 | A kind of method of change in time and space using the real-time performance electromagnetic field with electric current carrying pathway |
| CN201210491672.8A CN103837848B (en) | 2012-11-27 | 2012-11-27 | Radio frequency antenna device for magnetic resonance system and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210491672.8A CN103837848B (en) | 2012-11-27 | 2012-11-27 | Radio frequency antenna device for magnetic resonance system and method |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710195424.1A Division CN107092002A (en) | 2012-11-27 | 2012-11-27 | A kind of method of change in time and space using the real-time performance electromagnetic field with electric current carrying pathway |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103837848A CN103837848A (en) | 2014-06-04 |
| CN103837848B true CN103837848B (en) | 2017-05-17 |
Family
ID=50801552
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210491672.8A Expired - Fee Related CN103837848B (en) | 2012-11-27 | 2012-11-27 | Radio frequency antenna device for magnetic resonance system and method |
| CN201710195424.1A Pending CN107092002A (en) | 2012-11-27 | 2012-11-27 | A kind of method of change in time and space using the real-time performance electromagnetic field with electric current carrying pathway |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710195424.1A Pending CN107092002A (en) | 2012-11-27 | 2012-11-27 | A kind of method of change in time and space using the real-time performance electromagnetic field with electric current carrying pathway |
Country Status (1)
| Country | Link |
|---|---|
| CN (2) | CN103837848B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP4028787A4 (en) * | 2019-09-13 | 2023-09-20 | Cedars-Sinai Medical Center | Systems and methods of deep learning for large-scale dynamic magnetic resonance image reconstruction |
| CN112763952B (en) * | 2019-11-06 | 2023-08-25 | 西门子(深圳)磁共振有限公司 | Method and apparatus for monitoring radio frequency transmit circuit of magnetic resonance imaging device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1306217A (en) * | 1999-12-06 | 2001-08-01 | 通用电气公司 | Radio frequency coil for opening magnetic resonance imaging system |
| CN1339703A (en) * | 2000-04-26 | 2002-03-13 | Ge医疗***环球技术有限公司 | Radio frequency coil and magnetic resonate imaging device |
| WO2005050239A1 (en) * | 2003-11-18 | 2005-06-02 | Koninklijke Philips Electronics, N.V. | Rf coil system for super high field (shf) mri |
| CN101900796A (en) * | 2009-05-26 | 2010-12-01 | Ge医疗***环球技术有限公司 | Radio frequency body coil and open type magnetic resonance imaging (MRI) system using same |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001258863A (en) * | 2000-03-10 | 2001-09-25 | Ge Medical Systems Global Technology Co Llc | Magnetic resonance imaging method and magnetic resonance imaging device |
| US20110012598A1 (en) * | 2007-11-30 | 2011-01-20 | Koninklijke Philips Electronics N.V. | Mr coils with an active electronic component having an indirect power connection |
| CN101556313B (en) * | 2008-04-08 | 2012-08-29 | 西门子（中国）有限公司 | Radio-frequency signal processing method and radio-frequency system |
| CN101339232B (en) * | 2008-08-13 | 2012-05-23 | 宁波鑫高益磁材有限公司 | Radio-frequency pulse synthesis method in magnetic resonance image-forming system |
| BRPI1006297A2 (en) * | 2009-04-01 | 2019-04-02 | Koninklijke Philips Electronics N.V. | imaging method, magnetic resonance system, computer readable medium and magnetic resonance system |
| JP5542591B2 (en) * | 2009-11-12 | 2014-07-09 | 株式会社東芝 | Magnetic resonance imaging apparatus and magnetic resonance imaging method |
| EP2367020A1 (en) * | 2010-03-04 | 2011-09-21 | Deutsches Krebsforschungszentrum (DKFZ) | Targeted traveling wave MRI |
| CN101856229B (en) * | 2010-04-22 | 2013-04-24 | 杜健军 | Radio-frequency coil device in magnetic resonance imaging system |
-
2012
- 2012-11-27 CN CN201210491672.8A patent/CN103837848B/en not_active Expired - Fee Related
- 2012-11-27 CN CN201710195424.1A patent/CN107092002A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1306217A (en) * | 1999-12-06 | 2001-08-01 | 通用电气公司 | Radio frequency coil for opening magnetic resonance imaging system |
| CN1339703A (en) * | 2000-04-26 | 2002-03-13 | Ge医疗***环球技术有限公司 | Radio frequency coil and magnetic resonate imaging device |
| WO2005050239A1 (en) * | 2003-11-18 | 2005-06-02 | Koninklijke Philips Electronics, N.V. | Rf coil system for super high field (shf) mri |
| CN101900796A (en) * | 2009-05-26 | 2010-12-01 | Ge医疗***环球技术有限公司 | Radio frequency body coil and open type magnetic resonance imaging (MRI) system using same |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103837848A (en) | 2014-06-04 |
| CN107092002A (en) | 2017-08-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102736045B (en) | Parallel transmission RF pulse design with local SAR constraints | |
| Wright et al. | Theory and application of array coils in MR spectroscopy | |
| US7800368B2 (en) | High field magnetic resonance | |
| Ohliger et al. | An introduction to coil array design for parallel MRI | |
| NL1033706C2 (en) | SAR reduction in MR image with parallel RF transmission. | |
| CN102866371B (en) | The Chemical Exchange saturation transfer imaging that magnetic field is insensitive | |
| US8102177B2 (en) | Using S-parameter measurements to manage SAR and transmit gain in MRI | |
| RU2582474C2 (en) | Virtual coil emulation in parallel transmission mri | |
| US8319495B1 (en) | Multi-port RF systems and methods for MRI | |
| RU2577254C2 (en) | Quasi-continuous rf magnetic resonance imaging | |
| CN102283649B (en) | Selective excitation sequential design method for magnetic resonance imaging in three-dimensional space | |
| Nehrke et al. | Eigenmode analysis of transmit coil array for tailored B1 mapping | |
| CN103782184A (en) | Dynamic modification of RF array coil/antenna impedance | |
| Giovannetti et al. | Hyperpolarized MRS surface coil: Design and signal‐to‐noise ratio estimation | |
| US9086446B2 (en) | Method and system for B1 field mapping in magnetic resonance imaging | |
| Keong Li et al. | Focused, eight‐element transceive phased array coil for parallel magnetic resonance imaging of the chest—theoretical considerations | |
| Giovannetti et al. | Radiofrequency coils for magnetic resonance applications: Theory, design, and evaluation | |
| CN103837848B (en) | Radio frequency antenna device for magnetic resonance system and method | |
| Kopanoglu et al. | Analytic expressions for the ultimate intrinsic signal‐to‐noise ratio and ultimate intrinsic specific absorption rate in MRI | |
| US8274283B2 (en) | Method and apparatus for diffusion tensor magnetic resonance imaging | |
| Collins | Numerical field calculations considering the human subject for engineering and safety assurance in MRI | |
| Katscher et al. | RF encoding using a multielement parallel transmit system | |
| CN102369452B (en) | Noise matching in couplet antenna arrays | |
| CN106872921B (en) | MR imaging method and device | |
| Horneff et al. | An EM simulation-based design flow for custom-built MR coils incorporating signal and noise |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20170517 Termination date: 20171127 |