CN103837848A - Radio frequency antenna device for magnetic resonance system and method - Google Patents

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

For radio frequency antenna apparatus and the method for magnetic resonance system

Technical field

The present invention relates to magnetic resonance imaging (MRI), relate in particular to parallel radio frequency transmitting and the radio frequency reception of hyperchannel or multiport.The invention still further relates to a kind of bearing calibration and multi-channel parallel radio-frequency transmissions/receiving coil group, for improving the picture quality of magnetic resonance imaging.

Background technology

Magnetic resonance imaging (MRI) is in the time of transmission/detecting radiofrequency signal, and the nuclear spin of imaging object is and B1 ⁺/ B1 ^-, rather than with radio-frequency coil in drive current/induction current, interact.Meanwhile follow the electric field (concomitant E field) that magnetic field produces to cause radio frequency loss, performance is with radio-frequency power consumption/noise.Electric current in coil has very important effect, serves as the contact tie between radio-frequency transmissions/reception (Tx/Rx) system and radio-frequency field, for controlling the radio frequency electromagnetic field of magnetic resonance imaging.

The feasible program that is used for radio-frequency transmissions/reception (Tx/Rx) of analyzing multiport system is as follows: a. is in radio-frequency transmissions (Tx) process, with the radio-frequency pulse of being scheduled to, by one group of radio-frequency power amplifier, drive the electric current in radio-frequency coil, electric current further excites B1 field, wherein, and B1 ⁺field excitation nuclear spin, and then produce precession.The radio frequency loss relevant to electric field (E field) 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+ω ε ") | E| ²dv.B. in radio frequency reception (Rx) process, the rotary magnetization that rotation precession causes makes to produce in radio-frequency coil electromotive force, this just produced with B1 field in B1 ^-the electric current meeting.Electric current is detected by radio frequency reception unit, obtains the clock signal for rebuilding magnetic resonance imaging.Noise in the clock signal that the radio frequency loss relevant to electric field causes receiving.While it is to be noted radio-frequency transmissions/radio frequency reception (Tx, Rx), electromagnetic field distributes and radio frequency loss is affected by imaging object.In radio-frequency transmissions/reception (Tx/Rx) process, gradient pulse carries out spatial modulation to the interaction of B1-nuclear spin.This spatial modulation is as the part control magnetic resonance excitation of radio-frequency transmissions/radio frequency reception scheme and the space orientation of detecting.

Size and phase place (magnitude/phase), time domain waveform and the space distribution of optimizing coil current are extremely important for improving magnetic resonance imaging performance.Promote that a key factor of optimizing is to grasp and utilize coil current pattern or the impact of source configuration (source configuration) on B1 space distribution and rf power dissipation.Promote that another key factor of optimizing is hardware structure.Except independently driver and receiver, can support that the loop construction of current path control versatile and flexible is also extremely important.Present patent application recorded considered the above factor for improving new system and the new method of magnetic resonance imaging performance.

Parallel radio frequency transmitting has outstanding capacity for control unit radio frequency absorptivity and realize high-quality radio-frequency (RF) excited simultaneously.But, never have a kind of practicable method for organic life entity of living, make full use of aforementioned capacity, be embodied as picture performance improvement, and reduce unit radio frequency absorptivity.In fact, parallel radio frequency is launched the degree of freedom of bringing and is significantly promoted (basis that this is also aforementioned capacity), usually cause on the contrary worry, because inappropriate radio-frequency pulse calculates or radio frequency shimming calculates, or hyperchannel hardware fault, not only indefinite reduction may worsen unit radio frequency absorptivity (SAR) on the contrary.There is a kind of power meter scheme can tackle to a certain extent this worry.This scheme monitors the radio-frequency power of different port, by power meter (powermeters) measurement different port forward direction and reflective power (forward and reflected power), calculate in real time clean through-put power, in the time that overall SAR reaches threshold value, stop scanning.Consider in order fully to tackle safety/performance, must further adopt aggressive schemes to supplement existing real-time monitoring, aggressive schemes should have following ability: first, carrying out the unit radio frequency absorptivity that before magnetic resonance imaging, predicted picture sequence causes imaging object, next is further to optimize radio-frequency pulse, realizes the excitation (target excitation profile) that will reach in reducing unit radio frequency absorptivity (SAR).

Generally speaking, in the urgent need to be practicable SAR quantitative prediction model, model is for any B1 shimming coefficient (shimming coefficients) or radio-frequency pulse excitation, the unit radio frequency absorptivity of predicted entire and relevant average (volumetric average), and/or unit radio frequency absorptivity and relevant average in different region-of-interests.

In principle, calculate (comprising B1 shimming and complete parallel transmission) for hyperchannel radio-frequency pulse, forecast model can be by following the trail of SAR and guide design, reduce clearly SAR, and model that can be based on same, by presetting a safe clearance (margin), reply hardware fault, avoids disadvantageous consequence to occur.In the time of magnetic resonance imaging, these models serve as SAR monitoring core, the ability that it has prediction and draws SAR, and the SAR that has expanded power meter scheme monitors capacity.

Existing evidence shows, except pulse calculating, the Tx of radio-frequency coil (antenna) geometric influence hyperchannel or multiport or Rx performance.Fundamentally, can support that the loop construction of current path control versatile and flexible is particularly important to promoting Tx or Rx performance to the limit.This and following identical of views: radio-frequency pulse adjust coil current, this coil current excites radio frequency electromagnetic field, final decision Tx or Rx performance.Needed is a radio-frequency coil structure, and this structure forms the intensive network structure of a multiport, can hold and realize complicated radio-frequency current distribution pattern.

Summary of the invention

The object of the present invention is to provide the radio frequency antenna apparatus for magnetic resonance system and the method for a kind of Tx of lifting or Rx performance.

For achieving the above object, the present invention adopts following technical scheme:

For a radio frequency antenna apparatus for magnetic resonance system, comprising:

Antenna structure, is roughly nettedly and for transmitting radio-frequency current, and described antenna structure comprises:

Conductor part, is dispersed on some layers;

Capacitive or inductive several johning knot chalaza, described johning knot chalaza is distributed in diverse location, is electrically connected conductor part and form reticulate texture roughly;

Interface device, for the Radio Frequency Subsystem of magnetic resonance system and described antenna structure are coordinated at least one locus, realizes the control that on antenna structure, radio-frequency current distributes; Wherein, described radio frequency antenna apparatus carries out radio frequency transmit and receive with continuous and various distribution of current pattern.

As further improved technical scheme of the present invention, described interface device comprises the some ports that are distributed on antenna structure.

As further improved technical scheme of the present invention, each impedance inverter circuit that comprises in described some ports.

As further improved technical scheme of the present invention, the control that described radio-frequency current distributes comprises the combination of the preposition radio-frequency pulse of corresponding magnetic resonance system emission mode and the preposition magnetic resonance signal/data of corresponding magnetic resonance system receiving mode.

As further improved technical scheme of the present invention, the combination of described preposition radio-frequency pulse and preposition magnetic resonance signal/data is to carry out preposition according to the packet of the power measurement values that includes prior acquisition, radio-frequency field measured value, noise measurement, magnetic resonance signal/data.

As further improved technical scheme of the present invention, described preposition be to have used multiple models, predict the different aspect of magnetic resonance imaging, described aspect is that the data group from including radio-frequency power transmitting/dissipation, flip angle, image comparison, signal to noise ratio (S/N ratio) is selected.

For achieving the above object, the present invention can also adopt following technical scheme:

One method, utilizes the change in time and space of a large amount of interconnective current delivery path implement electromagnetic fields, comprises the steps:

Step a: at least one antenna structure is provided, this antenna structure includes the conductor part of multilayer, conductor part clamps at least one plain film or the curved tabs that have non-conducting material to make, thereby forms the network of electrical connection path, for holding the change in time and space of radio-frequency current;

Step b: interface device is provided, for the Radio Frequency Subsystem of magnetic resonance system and described antenna structure are coordinated at least one locus, realizes the control that on antenna structure, radio-frequency current distributes;

Step c: current control device is provided, comprises the radio-frequency pulse for launching and the signal/data combination for receiving; Wherein,

Described method is beneficial to and produces various electromagnetic field change in time and space, comprises the variation that can promote radio frequency transmit and receive efficiency.

As further improved technical scheme of the present invention, described antenna structure is grid configuration, and grid configuration is enough intensive, for generation of accurate radio-frequency current change in time and space.

As further improved technical scheme of the present invention, described grid configuration has the conductor part that is distributed in different layers, and every layer is held the conductor piece of almost parallel.

As further improved technical scheme of the present invention, described non-conducting material is the insulating material with high-k.

As further improved technical scheme of the present invention, the combination of described radio-frequency pulse and signal/data is to carry out preposition according to the packet of the power measurement values that includes prior acquisition, radio-frequency field measured value, noise measurement, magnetic resonance signal/data.

As further improved technical scheme of the present invention, described preposition be to have used multiple models, predict the different aspect of magnetic resonance imaging, described aspect is that the data group from including radio-frequency (RF) energy transmission/dissipation, flip angle, image comparison, signal to noise ratio (S/N ratio) is selected.

As further improved technical scheme of the present invention, described multiple model comprises the functional unit that meets quadratic equation, for the definition prediction radio-frequency (RF) energy transmission based on radio-frequency pulse with dissipate, described functional unit has by use and has the information of power measurement values of prior acquisition and predetermined parameter.

As further improved technical scheme of the present invention, the rule of the combination of described signal/data is that rule is rebuild in magnetic resonance imaging.

For achieving the above object, the present invention can also adopt following technical scheme:

One method, utilizes the network with current delivery path to realize the change in time and space of electromagnetic field, comprises the following steps:

Step a: the measuring method that is provided for measuring radio-wave propagation effect;

Step b: obtain limited measured value by aforementioned measuring method;

Step c: provide a prediction mode based on aforementioned measurements, the radio-wave propagation effect of radio-frequency pulse is arbitrarily launched in this prediction mode prediction, and effect comprises Energy Transfer and dissipation;

Steps d: use aforementioned prediction mode to calculate radio-frequency pulse, radio-frequency pulse is used to the network with current delivery path that energy is provided;

Step e: radio-frequency pulse provides energy for the network with current delivery path, realizes electromagnetic field change in time and space; Wherein, before prediction mode and calculating radio-frequency pulse, take the photograph and manage radio-frequency (RF) energy transmission and dissipate.

As further improved technical scheme of the present invention, described prediction mode comprises use radio-wave propagation measurement and preposition numerical model.

As further improved technical scheme of the present invention, described numerical model comprises the functional unit that meets quadratic equation, for the definition prediction radio-frequency (RF) energy transmission based on radio-frequency pulse with dissipate, described functional unit has by use and has the information of power measurement values of prior acquisition and predetermined parameter.

As further improved technical scheme of the present invention, described calculating use at least one for predict radio-frequency (RF) energy dissipate quadratic equation as input, integrate described prediction mode by building and solve optimization problem, described optimization is using the definition of radio-frequency pulse as output.

As further improved technical scheme of the present invention, described conductor part comprises high conductivity material.

As further improved technical scheme of the present invention, described conductor part comprises high conductivity material.

The present invention is directed to parallel mode and carry out radio-frequency drive and magnetic resonance signal reception, promoted Tx or Rx performance, also can improve unit radio frequency absorptivity and signal to noise ratio (S/N ratio) (SNR), and then improve the picture quality of magnetic resonance imaging.

Accompanying drawing explanation

Below diagram has been shown and has been realized a preferred embodiment of the present invention.

Below diagram is respectively:

Fig. 1 is the principle schematic of implementing magnetic resonance imaging system of the present invention.

Fig. 2 arranges schematic diagram according to the parallel transmission system in one embodiment of the invention.

Fig. 3 A-3B is the schematic diagram of the many star coils according to another embodiment of the present invention.

Fig. 4 is the schematic diagram with many star coils (constellation coil) of additional port.

Fig. 5 is the schematic diagram with many star coils of N port.

Embodiment

Please refer to shown in Fig. 1, Fig. 1 has shown the critical piece that comprises magnetic resonance system 10 of the present invention, and this system is to control by operator's console 12, and control desk 12 comprises keyboard or other input equipments 13, control panel 14 and display screen 16.Control desk 12 is connected with the computer system 20 of a platform independent by link 18, computer system 20 can make operator can be on display screen 16 generation and the demonstration of control chart picture.This computer system 20 comprises some modules of communicating with each other by backboard 20a, these modules include image processor module 22, CPU module 24 and memory modules 26, and memory modules 26 can be the frame buffer for storing image data group that industry is known.Computer system 20 is connected with hard disk 28 and magnetic disc 30, storing image data and program, and connect 34 by high speed serialization and be connected with an autonomous control system 32.

Control system 32 comprises the one group of module interconnecting by a backboard 32a, the pulse producer module 38 that described module comprises CPU module 36, is connected with control desk 12 by (serial link) 40 connected in series.The instruction of the scanning sequence (scan sequence) that control system 32 is carried out from operator's needs by 40 receptions connected in series.Pulse producer module 38 operational system assemblies, carry out the scanning sequence of specifying, output data, for example: the timing of the radio-frequency pulse of radio-frequency transmissions, intensity, shape, the length of the timing of radio frequency reception and data acquisition window.Pulse producer module 38 is connected to a series of gradient amplifier systems 42, duration and the shape of the gradient pulse producing for control (indicate) scanning process.Pulse producer module 38 can receive patient information from physiology acquisition controller 44, and described physiology acquisition controller 44 by being connected to patient's some different sensor collection signal, for example, obtains ECG signal by the electrode that is arranged on patient.Pulse producer module 38 is finally connected to scan room interface circuit 46, the signal that the sensor that 46 receptions of scan room interface circuit are relevant to the state of an illness and magnetic system produces.By scan room interface circuit 46, patient positioning system 48 receives instruction, and removing patient is scanned to assigned address.

The gradient waveform that pulse producer module 38 produces be applied to there is Gx, the gradient amplifier system 42 of Gy, Gz, a gradient coil of correspondence in each gradient amplifier excite gradients coil groups 50, produces the magnetic field gradient for generating additional space coded signal.Gradient coils set 50 is a part for magnetic assembly 52, and magnetic assembly 52 also includes polarized magnet 54 and body radio-frequency coil 56.The pulse that transceiver module 58 in control system 32 produces is amplified by radio frequency amplifier 60, is coupled by sending/receiving switch 62 and radio-frequency coil 56.The signal that the atomic nucleus being excited in patient body sends is perceived by radio-frequency coil 56, then be transferred to prime amplifier 64 by sending/receiving switch 62, the magnetic resonance signal of amplification carries out demodulation, filtration, digitized processing through the acceptance division of transceiver module 58.Sending/receiving switch 62 can be by the signal controlling of pulse producer module 38, thereby under emission mode, is electrically connected radio frequency amplifier 60 and radio-frequency coil 56, under receiving mode, is electrically connected prime amplifier 64 and radio-frequency coil 56.Sending/receiving switch 62 can make independent radio-frequency coil (for example surface coils) use under the pattern transmitting and receiving.

The magnetic resonance signal that radio-frequency coil 56 is collected carries out digitized processing through transceiver module 58, is then transferred to the storage module 66 in control system 32.When storage module 66 obtains after one group of original k-spatial data, the end of scan.Original k-spatial data is rearranged into each independent k-space data set corresponding rebuilt image, each k-space data set is imported into array processor 68, carry out after Fourier transform in conjunction with magnetic resonance signal, form one group of view data, view data is transferred to computer system 20 by connected in series 34, and is kept at memory storage for example in hard disk 28.Corresponding with the instruction that control desk 12 sends, described view data can longer-term storage be got up, for example, be stored on magnetic disc 30, or be further processed and be sent to control desk 12 by image processor 22, and show on display screen 16.

The present invention be directed to parallel mode and carry out the method and system of radio-frequency drive and magnetic resonance signal reception, this parallel exciting with receive mode can reduce sweep time by accelerating radio-frequency pulse/accelerating magnetic resonance signal framing, also can improve unit radio frequency absorptivity and signal to noise ratio (S/N ratio) (SNR).

The exemplary method below describing in detail is about predict radio-frequency power transmission/dissipation and B1 field distribution by limited measurement data.

For arbitrary source configuration (source configuration), can control B1 space distribution and radio frequency loss by the system model with suitable and the measurement data obtaining from calibration process.Source configuration (source configuration) refer to one group in advance in transmitter (Tx case) the radio-frequency pulse of setting or one group in receiver (Rx case) for the weight to the image reconstruction that obtains signal.Very effective with multiport design analysis, in example as schematically shown in Figure 2, imageable target 78 and magnetic resonance radio-frequency coil 72 used can be considered as a multiport network 90, and this network cooperatively interacts by port 80 and some sources (source).In radio-frequency transmissions (Tx) process, port is connected to the output terminal of radio-frequency power amplifier 74.In radio frequency reception (Rx) process, port is connected to the input end of the prime amplifier of receiver.Obtain different paths by sending/receiving switch 62.

The design of core is the reaction that uses suitable one group of source configuration (source configuration) to carry out calibration experiments and record multiport system.In to radio-frequency transmissions (Tx) calibration process, result is used to determine the quantitative relation between system response and predetermined radio-frequency pulse, follow-up can be conversely for predicting the system response of the radio-frequency pulse predetermined for difference.

Multiport radio-frequency transmissions/reception (Tx/Rx) system hardware guarantees that the relative source of the electromagnetic field producing in imaging object (source) is for linear response conventionally.In radio-frequency transmissions (Tx) process, suppose that radio-frequency power amplifier (they amplify predetermined radio-frequency pulse and drive multiple ports) meets suitable linearity specifications (linearity specs), each amplifier is just shown as the voltage source with output terminal impedance to multiport network, this voltage source and the predetermined radio frequency pulse linear correlation of input end that offers amplifier.Under these circumstances, the present electromagnetic field of the linear body of Maxwell's formula is linear to the reaction of voltage source and radio-frequency pulse.Arbitrary electromagnetic field component in imaging object, as the function of time, shows as following formula 1:

b(t)=L(v ⁽¹⁾(t),v ⁽²⁾(t),...,v ^(N)(t)),

Wherein, L represents linear transformation, and b (t) represents this electromagnetic field component, v ⁽ⁿ⁾(t) represent predetermined radio-frequency pulse, N represents the quantity of Tx port.

In steady State Analysis, can use the arbitrary variations per hour of phasor mark, for example voltage source, by the electric current of conductors cross, a component of electromagnetic field vector.Particularly, can be by using complex variable to express variations per hour, this variations per hour can pass through complex variable and exp (j2 π f ₀t) multiplied result is got real part and is obtained.

Phasor has been simplified the description of the radio-frequency information in magnetic resonance.System electronic control is with the Δ t duration unit of being spaced apart in practice, and Δ t is equivalent to for example 2 microseconds.The realization of one radio-frequency pulse of subscribing is the result of a succession of control: when the each interval in the interval of a succession of coherent Δ t duration starts, system electronics is f to a frequency ₀sine wave apply a weight, this weight is a plural number

(n=port index, p=interval index), corresponding to one size-phase place pair.A whole set of weight is from so-called radio-frequency pulse design process.

Phasor mark is applicable to the steady State Analysis at each Δ t duration interval, for example, position r in vivo and at p Δ t duration interval, E field can be expressed as

the corresponding phasor mark in E field is complex vector:

for this interval, the phasor mark of the predetermined radio frequency pulse of n port is multiple scalar

For a Δ t duration interval, according to formula 1, use the linear system behavior of phasor mark can be expressed as matrix form, specifically as formula 2:

b=Aw，

Wherein, b=[b ⁽¹⁾b ⁽²⁾b ^(M)] ^t, b is an arrow phasor of collecting interested variations per hour, w=[w ⁽¹⁾w ⁽²⁾w ^(N)] ^t, w be one for collecting the arrow phasor (its n component is a multiple scalar, the size-phase place of this Δ of mark t duration interval and n port to) of predetermined radio frequency pulse definition, A is the M*N matrix of complex value.

Electromagnetic field calibration arranges (being source configuration) with one group of meticulously selected input and surveys multiport networking, and the electromagnetic field recording reaction adds a suitable system model and then the reaction for predicting that electromagnetic field arranges arbitrary input.

The magnetic resonance system linearity is convenient to the calibration of electromagnetic field, formula 2 shows, based on linearity, test the electromagnetic field reaction recording and can be used for predicting the electromagnetic field reaction under any input facilities for N that adopts Line independent input to arrange, because matrix A arranges decision by the electromagnetic field reaction and N the input that record completely, specifically as shown in Equation 3:

$\left[\begin{array}{cccc}{b}_1& b_2& ...& b_N\end{array}\right]=A\left[\begin{array}{cccc}{w}_1& w_2& ...& w_N\end{array}\right]\⇒A=\left[\begin{array}{cccc}{b}_1& b_2& ...& b_N\end{array}\right]{\left[\begin{array}{cccc}{w}_1& w_2& ...& w_N\end{array}\right]}^{-1}$

Formula 3 has collected formula 2, shown in the index number in experiment index ginseng formula.It is pointed out that the linear independence arranging according to input, the existence of inverse matrix is guaranteed.For a simple example, can calibrate Tx electromagnetic field by N experiment, wherein n experiment (n=1,2 ... N) relate to and drive n port with the rectangle radio-frequency pulse of unit amplitude and zero phase, other ports are used the radio-frequency pulse of zero amplitude.[w in this case ₁w ₂w _n] be a unit matrix, thus A=[b ₁b ₂b _n].

For multiport row energization, this comprises this special situation of multiport B1 shimming, and the principle of formula 3 can be as prediction B1 ⁺.Prediction B1 ⁺it is the prerequisite of radio-frequency pulse design process.B in this case _nto collect B1 in the n time test ⁺the vector of Spatial sampling.After the calibration program that A represents with formula 3 obtains, with regard to the B1 under measurable any one group of radio-frequency pulse excitation ⁺the change in time and space of field, and then, the spatial form of radio-frequency (RF) excited.This makes the spatial form control encouraging with suitable radio-frequency pulse design become feasible.

In the time producing the excitation space shape of target, must avoid producing too much rf power dissipation on the object to be imaged.This can by introducing in radio-frequency pulse design process, suitable Dilute multiple radio-frequency power consumption is loose to be solved.For example, design radio-frequency pulse can be considered as an affined minimization problem, and it is searching when radio-frequency pulse, to produce target excitation spatial form as constraint, and the unit radio frequency absorptivity that simultaneous minimization E field causes.

The thermal equilibrium of biological tissue can be described by Pennes bio-heat equation.Rf power dissipation, in the time existing, becomes the driving force that drives temperature rise, the formula of stating specific as follows:

Wherein, ρ, C and k represent respectively tissue density, thermal capacity and thermal conductivity, h _bthe heat flux transfer rate between blood and tissue, h _eit is fractional radio frequency's energy absorbing device.The increase of following radio-frequency (RF) energy to dissipate, organizes overheated may generation.

It is to be noted h _ebeing that Joule heating and polarization decay strength cause, is proportional with local E field strength, and specific formula for calculation is: h _e=1/2 σ | E| ², wherein σ=σ _tissue+ ω ε ".

Due to the difference of imageable target build and component, and interactive aggravation between source and imageable target under high-frequency, imageable target is depended in electric field and radio-frequency power loss to a great extent.In order to address this problem, there is method suggestion the test synthesis of the specific absorption ratio result of the Human Model Simulation acquisition based on average and actual human body profile and field.But what attract people's attention is that this integrated approach easily produces large error in high-field magnetic resonance, because the little difference between realistic model and reality often can cause considerable between SAR result and be difficult to the difference being in harmonious proportion.For Accurate Prediction unit's radio frequency absorptivity and improve magnetic resonance performance, need to use the measurement based on the concrete imaging object of reality to set up SAR forecast model.

From the angle of the development of magnetic resonance imaging, particularly at High field strenghth MRI, in order to manage SAR, inevitably need to, for the organism calibration SAR model of living, just as in order to manage excitation space shape, need to calibrate B1 distribution plan.For the result optimum under specific scan setting, can be based on each imageable target, use B1 and SAR calibration result to guide optimum pulse calculating or shimming to calculate as important input parameter.And be further to improve itself is set, can be comprehensively calibration result widely, using as important input parameter, the optimization of guiding radio system and coil.The present invention foundes and uses SAR to predict aspect two: overall SAR and any local SAR.This is consistent with following high-field magnetic resonance development trend.

As aforementioned, radio frequency transmit and receive (Tx/Rx) that can be from the magnetic resonance of network viewpoint, wherein imageable target and radio-frequency coil are considered as a multiport networking, and this network cooperatively interacts by port and some sources.In the time that MR scanner maintains the good linear needing for fine scanning, between electromagnetic field and source configuration, there is linear relationship, particularly, can be expressed as the weight stack of N the E field corresponding with N radio-frequency transmissions port with the E field in p Δ t duration interval, weight is respectively w _p ⁽¹⁾... w _p ^(N).Fractional radio frequency's power attenuation therefore computing formula is as follows:

Wherein, Λ is N row-N row positive definite Hermite Matrix, ^hrepresent conjugate transpose (conjugatetranspose), * represents complex conjugate (complex conjugate), and bottom line part is row or the row mark of vector or Input matrix component.

Above-mentioned formula shows, fractional radio frequency's power attenuation is w ⁽¹⁾... and w ^(N)quadratic equation.With matrix form statement, for p Δ t duration interval, h _e=w ^hΛ w, wherein w=[w ⁽¹⁾w ^(N)] ^tthat a vector is for collecting amplitude-phase place pair.These amplitude-phase places are to the definition for this Δ t duration interval from N parallel radio frequency pulse.Further, the overall radio-frequency power loss in this Δ t duration interval also can be calculated by quadratic equation, specific as follows:

Formula 4

Wherein Φ is N row-N row positive definite Hermitian matrix (an N-by-N positive definite Hermitianmatrix).

Λ and Φ are called to local and overall power incidence matrix, interaction and the impact of tissue conductivities on part and overall rf power dissipation that they have been summed up.The overall radio-frequency (RF) energy loss that whole radio-frequency (RF) excited process produces is ξ _ptime integral, be specifically expressed as follows:

Formula 5

Wherein W _fullbe a vector, collected a whole set of weight all amplitude-phase places of radio-frequency pulse (defined to).Similarly,

Formula 6

Formula 6 has calculated whole radio-frequency (RF) excited process and has resulted from the radio-frequency (RF) energy loss of local address x.

It is to be noted and describe unit radio frequency absorptivity, even if do not exist between element coil and be coupled, while considering local and overall radio-frequency (RF) energy loss, multiple sources can not be considered as isolating mutually and treat, this is overlapping owing to E field.When quantification, this is reflected in the continuous item component of common non-zero in Λ and Φ, and the continuous item component of these non-zeros has been summed up the feature that multi-source is interfered mutually, has comprised effective reduction SAR information needed.Under contrast, existing shimming calculating/radio-frequency pulse calculates the quadratic sum in the multiple sources that adopt simple or weighting, and the effect that while having ignored multiport transmitting, multi-source is interfered mutually, can exist serious deviation aspect tracing and managing SAR like this.

For the system that appropriate sensor has been installed, power sensor 82 as shown in Figure 2, Φ can infer with a calibration process.When sensor is power sensor when multiple port forward directions and reflective power reading can be provided, the method for a definite Φ is that the input setting (being source configuration) with one group of suitable preliminary election is tested, and then processes and tests the power reading obtaining.According to law of conservation of energy, Σ p _fwd-Σ p _rfl, the clean radio-frequency power of input N port network equals the total power dissipation of network.If with w _qthe clean rf power dissipation of calculating from sensor reading, i.e. Σ p are set as input _fwd-Σ p _rfl, with w _qrelevant, the formula of stating specific as follows:

Σp _fwd,q-Σp _rfl,q=w _q ^HΦw _q=∑w _q,i ^*w _q，j?Φ _ij,

Formula 7

Wherein w _q,iand w _{q, j}represent respectively w _qi and j component, formula 7 is Φ _ijlinear equation, the component of Φ is unknown number, product term w _q,i ^*w _{q, j}it is coefficient.

Easily draw the radio frequency loss feature of multiport network by some row experiments: the power sensor reading of each experiment and source setting (source configuration) are combined into the linear equation described in formula 7; The equation of combination sufficient amount, the institute that then just can calculate Φ is important.If with d _qrepresent all w that collect according to a definite sequence _q,i ^*w _q,jvector, need emphasis to note, input arrange selection should make one group of obtained d _q(q=1,2 ...) linear independence.From calculating Φ _ijthe angle of strong anti-interference power, preferably select in some way input setting, such mode makes matrix [d ₁d ₂] conditional number smaller (for example make this matrix orthogonal).

In the time that sensor is supported phase sensitivity detecting, an alternative method determining Φ is to use reciprocity principle (theprinciple of reciprocity), particularly, noise incidence matrix (covariance matrix) Ψ based on corresponding to multiport system, this matrix can obtain by the receiver that connects multiport, and the calculating of Φ can be used following formula:

Φ=L ₁ ^HΨ ^TL ₁,

In general, the prime amplifier in receiver front is different from power amplifier a series of impedances to multiport network performance in transmitting (Tx) process to a series of impedances of multiport network performance in (Rx) process of reception.Transformation matrix L ₁look after this factor.In particular cases all of the port is even in the process of Tx and Rx sees 50 Ω, at this moment L ₁it is unit matrix.

In addition, can not adopt and measure noise incidence matrix, and adopt the scattering matrix S at multiport networking and Bo Sima theorem to calculate Ψ:

Ψ=kT?L ₂ ^H(I-SS ^H)L ₂,

Next, the calculating of Φ can be used following formula:

Φ=L ₃ ^H(I-SS ^H) ^TL ₃=L ₃ ^H(I-S ^HS)L ₃.

L ₁l ₂or L ₃after different calibrations, can be determined.

It is feasible adopting the intravital radio-frequency (RF) energy of non-intruding mode spatial discrimination to dissipate.When magnetic resonance temperature measurement carries out with high precision, not only can record temperature, and provide the information that can be used for definite Λ (x) also therefore to make local SAR forecast model quantize.This can use the biological heat transfer equation of Penni (Pennes) to make an explanation, when radio-frequency transmissions test is that the rising of fractional radio frequency's energy dissipation and local temperature is proportional, i.e. Δ T ∝ h in the time enough carrying out in short time with respect to heat conduction _e=1/2 σ | E| ².Therefore position x in vivo, the Δ T measured value that magnetic resonance temperature measurement obtains can be used for determining Λ (x):

1/2σ|E| ²=w _q ^H?Λw _q=∑ _ij?w _q,i ^*w _q,j?Λ _ij

Formula 8

As shown in Equation 8, determine that the principle of Φ can be used for determining Λ (x) equally, difference is that the latter's serviceability temperature measured value Δ T solves the Λ in linear equation as sensing data _ij.

One of obstacle that utilizes magnetic resonance temperature measurement calibration local SAR forecast model is the temperature measurement accuracy/dynamic range in live body situation.But this is not basic restriction.Be different from diagram and the prediction of the local temperature rising of pursuing pin-point accuracy, a strategy is to avoid accident to violate the restriction of food and drug administration (FDA) to local SAR.Iff relying on overall SAR monitoring, prediction and management, such accident unlikely 100% is found or eliminates in violation of rules and regulations.By the grasp to local SAR model error, can set up the safe clearance that corresponding radio-frequency pulse calculates.The Accurate Prediction on live body, overall radio-frequency (RF) energy being dissipated and the reasonable prediction to heat distribution, combine and can provide one effectively to optimize the new tool of launching and reducing live body SAR.

Realize traditional method different of B1 homogenising from utilize body coil at large scale 3d space, the strong means of transmitting that walk abreast go to improve SAR problem.Intuitively, when imaging region is the sub-fraction of the imageable target of transmitting coil covering, optimize the utilization to loop construction, for example, make the coiler part of close imaging region more than other partial contribution, can avoid unnecessary high rf power dissipation.

In practice, an available affined optimization framework is clear and definite to be carried out and optimizes particularly.Based on the quantitative relationship of SAR and excitation space shape and radio-frequency pulse, it is by searching for a set of radio-frequency pulse that this framework reduces SAR, and this cover radio-frequency pulse produces target excitation spatial form, simultaneous minimization SAR.One free optimization framework can be used as alternative, and it provides numerical value solution faster.Excitation space form accuracy can appropriate reduction situation under, can search for a set of radio-frequency pulse, this cover radio-frequency pulse minimizes the weighted sum of shape error and SAR.The prerequisite of the search of above-mentioned arbitrary pattern is clearly know SAR and radio-frequency pulse quantitative associated.

The invention provides demonstration methods, the prediction of radio-frequency (RF) energy transmitting/dissipation is incorporated in the calculating of driving pulse.

Given forecast model, for example quadratic function w ^hΦ w (and is suitable for local w ^hΛ w), is associated SAR value with radio-frequency pulse, when design radio-frequency pulse, can from forecast model, obtain guidance.This extra degree of freedom that just makes parallel emission coefficient have can have been given play to advantage, accomplishes to adjust E field and reduces SAR, and following example has shown that the radio frequency loss tolerance based on quadratic function is integrated into constraint or unrestricted optimization framework by calibration gained.

In order to reduce overall SAR, described tolerance (metric) is the ξ of definition in formula 5, and in order to reduce local SAR, described tolerance is

Formula 9

ξ _locallocal rf power dissipation value (formula 6) weighted statistical to all points of interest, non-negative weight η _lspecify the relative importance that reduces each regional area SAR.The tolerance of whole and part SAR is integrated into constraint or unrestricted optimization (optimization) has the effect of the exomonental calculating of guide parallel, make the search of radio-frequency pulse shape be tending towards reducing the direction of SAR, this is because select other waveforms, can be increased and be paid larger cost by metric.The parallel driving pulse that design SAR optimizes is joined detailed description below.

The wide-angle category that encourages category or amplify out according to it at low-angle, to a given k-space tracking, can make to design with the following method parallel transponder pulse:

${\arg \min }_{w_{\mathrm{full}}}\{{(E_{\mathrm{full}}{w}_{\mathrm{full}}-u_{\mathrm{full}})}^H\mathrm{\Ω}(E_{\mathrm{full}}{w}_{\mathrm{full}}-u_{\mathrm{full}})+\mathrm{\α}{w}_{\mathrm{full}}^H{\mathrm{\Φ}}_{\mathrm{full}}{w}_{\mathrm{full}}+\mathrm{\β}{w}_{\mathrm{full}}^H{\mathrm{\Λ}}_{\mathrm{full}}{w}_{\mathrm{full}}\}$

Formula 10

Ω be one comprise in visual field the diagonal matrix of weight a little, these weight reflection important areas (for example, distribute respectively 1 and 0 for important area and non-region-of-interest, and/or pointedly difference in visual field is distributed to fractional value to specify the relative importance of accurate excitation to each point).α and β are positive parameter, for the reduction of balance SAR and the accurately excitation of spatial form.β and η _lthe increase of SAR of numerical value conference restriction point of interest.The present embodiment uses power correlation matrix, a rather than unit matrix, this has multiple spot advantage, not only help improve the reliability (regularization effect (regularizationeffect)) of Numerical Inversion, and important criteria when accurately following the trail of SAR and making to minimize SAR and become radio-frequency pulse design.This is important improvement: for example, for one group of parallel radio frequency pulse, can increase by 180 ° of phase places to one of them pulse, and not affect w ^hthe value of I w is for the change of the constructive or destruction interference of the E field by pulsed drive and the SAR that causes thereof, and this tolerance can not catch.The applying unit matrix I further each passage of supposition bears that same contribution-under same radio-frequency pulse drives, as long as different ports is different to SAR contribution, this supposition is just false.

The affined optimization relative with formula 10 is calculated as follows:

$\min \mathrm{imize}{w}_{\mathrm{full}}^H(\mathrm{\α}{\mathrm{\Φ}}_{\mathrm{full}}+\mathrm{\β}{\mathrm{\Λ}}_{\mathrm{full}})w_{\mathrm{full}}\mathrm{subjectto}{E}_{\mathrm{full}}{w}_{\mathrm{full}}-u_{\mathrm{full}}=0.$

Formula 11

Formula 11 emphasizes that excitation space shape is accurate, but numerical solution scheme is less efficiently.

Can and minimize SAR the technology of optimization k-spatial sampling (sampling) further integrates.To given transmitting setting and a target excitation spatial form, the Orthogonal Subspaces interworking searching method of before introducing is deleted E by selectivity a group by a group _fulleach column groups of matrix, significantly increases k-space and owes sampling and therefore shortened driving pulse.Better method is to use a criterion of revising, this criterion not only considers that column groups is to generating the contribution of target excitation spatial form, and consider the consequence that it produces SAR: iterate computing at j time and determine G group and corresponding pulsating wave sample w, choose and make the minimized G of following formula and w:

$w^H(\mathrm{\α\Φ}+\mathrm{\β}{\mathrm{\Σ}}_{l=1}^L{\mathrm{\η}}_l\mathrm{\Λ}\left(x_l\right))w+\mathrm{\λ}\left|\right|\left[E^{(j-1)}G\right]\left[\begin{array}{c}{w}^{(j-1)}\\ w\end{array}\right]-u_{\mathrm{full}}{\left|\right|}_{\mathrm{\Ω}}+\left|\right|\mathrm{projectionof}{\left(\mathrm{profileerror}\right)}^{(j-1)}\mathrm{ontospan}\left\{G\right\}{\left|\right|}^{-1}$

This has embodied a kind of improvement, because new Pulse Design is with controlled balance, optimizes the accuracy of excitation space shape, SAR and pulse length simultaneously.

For the parallel transponder pulse design of wide-angle, can amplify a method based on optimum control, minimize to reach effective SAR:

By express Bloch equation (Block equation) by control system, above-mentioned equation has reflected that magnetization spatial form (state vector M (t)) head for target spatial form D (dbjective state) encourages the requirement to radio frequency pulsating wave real part (u (t)) and imaginary part (v (t)).Need minimized tolerance to there is one and punish for end-state is deviated to dbjective state, separately there is one and punish for the increase to SAR.At wide-angle excitation category, it is especially to make us expecting that the SAR of accurate tracking and specific, concrete minimizes, because SAR management efficiently, by larger flip angle/compacter imaging sequence, for the application of MR brings new chance.

B1 shimming can use the formula 10 of reduction version.In order further to improve performance, can relax the requirement to phase place completely, for example to pursue the homogeneity of the amplitude of the spatial form finally motivating, but ignore the spatial variations of phase place, this problem is expressed as follows:

${\arg \min }_w\{{\left(\right|\mathrm{Ew}|-|u_{\mathrm{full}}\left|\right)}^H\mathrm{\Ω}\left(\right|\mathrm{Ew}|-|u_{\mathrm{full}}\left|\right)+w^H(\mathrm{\α\Φ}+\mathrm{\β}{\mathrm{\Σ}}_{l=1}^L{\mathrm{\η}}_l\mathrm{\Λ}\left(x_l\right))w\}$

Wherein w is the Nx1 vector of collecting shimming coefficient, and E comprises B1 ⁺sample (no longer comprising gradient encoding efficiency), u _fullrepresent the Uniform B 1+ field of target.

Size/phase place of optimizing radio-frequency coil electric current, time-modulation and space distribution are extremely important to magnetic resonance imaging performance.The important prerequisite of optimizing is to configuring the understanding of the radio frequency loss that relevant B1 space distribution and electric field cause to coil current pattern or source.The method solving is B1 mapping and the calibration of power correlation matrix.Another important prerequisite of optimizing is to provide the hardware structure that is conducive to optimization.Embodiment provides new radio-frequency coil structure, and this not only supports current path control the most versatile and flexible, allows on same conductor structure, to be suitable for different current-modes, and has significantly simplified the manufacture of radio-frequency coil.There is such structure and support the radio-frequency coil of hyperchannel or multiport Tx/Rx to be called many star coils.

Compare with traditional parallel radio frequency transmitting/receiving coil, the unnecessary mutual isolation of part of corresponding hyperchannel or multiport on many star coils, on the contrary, these parts have capacitive character or inductive coupling or direct interconnection each other, and the decoupling each other of these parts is less important.The structure of many star coils has been emphasized several characteristics, and described characteristic forms the basis of the parallel Tx/Rx running of high-quality.This has far reaching significance to manufacturing and using for the radio-frequency coil of magnetic resonance imaging, in following explanation, discusses.

Many star coils of example are grid, organize conductor more and are positioned at different Physical layers, and in lattice point position capacitive couplings.An effective coil manufacture method is in multilayer high dielectric constant substrate, to settle many group conductors, every layer of substrate is clamped between two groups of conductors. and Fig. 3 B has shown that is with two groups of conductors 101,102 plate originally, one group of 101 conductor of top layer is etched in substrate 103 end faces 104, and one group of conductor 102 of bottom is etched in substrate 103 bottom surfaces 105.Substrate has high dielectric constant, add other factors as substrate thickness and conductor near width and shape lattice point position, determined together a larger capacitive couplings, specifically as the electric capacity 106 in the equivalent electrical circuit in Fig. 3 A is illustrated.

The coil of structure preferably meets following requirement: electric capacity has little reactance in the time of Rameau frequency, has high reactance in the time of audio frequency.Such characteristic makes radio-frequency current can pass capacitive couplings, interval between substantially parallel conductor hour, intensive lattice structure, for radio-frequency current provides a kind of continuous conductor structure, makes such structure to a certain extent as radio frequency mask.This continuous performance is supported complicated radio-frequency current pattern, comprises the radio-frequency current pattern that can promote parallel Tx/Rx performance.Meanwhile, such structure is transparent to audio frequency gradient fields, because large electric current can not be responded in such field in grid.

Many star coils are expected to become the most effective parallel radio frequency antenna.This conception improves SNR and SAR performance based on electrodynamics principle: it payes attention to the optimization of distribution of current, and determines that B1 field and the E field of Tx/Rx performance derive from distribution of current.Several breakthroughs with respect to conventional coil are summarized as follows:

First, traditional loop construction too discrete and can not support the complicated current-mode that high-field magnetic resonance Tx/Rx needs versatile and flexiblely, and decoupling or mode configuration are to the additional a lot of restriction of electric current.The each several part of many star coils can be coupled well, similar netted radio frequency mask and maximize support complexity/wide band radio-frequency current-mode, and unnecessary processing decoupling or mode configuration.The current-mode needing can be driven or be received by the multiple ports with distributing in loop construction (many stars) to be realized, and this available Kirchhoff's current law (KCL) is analyzed.In fact, the B1+/B1-distribution plan and the power/noise incidence matrix that obtain based on calibration, parallel transmitting radio-frequency pulse/parallel receive image reconstruction that the current-mode of expectation can be scheduled to by use is realized.Concrete understanding to current-mode or special radio-frequency pulse design/image reconstruction are unwanted.

Secondly, many star coils can be tackled radio frequency loss better.The direct-coupling of E field and imaging object is an important radio frequency loss mechanism in high-field magnetic resonance, and now by large quantity and the high density of the distributed capacitance on coil, this loss meeting greatly reduces.The conductor cooperation conduction current of dense distribution, can help to reduce the suffered impedance of radio-frequency current.Many star coils and new conductor material, for example, carbon nano-tube, also more easily integrates, and this provides the chance of further minimizing conductor losses.

The 3rd, make conventional coil work effectively reliably, complicated design, manufacture, tuning and test are necessary.In reality, there is quite challenging example and be included in tuning these element coils under the state that multiple element coil complexity disturb mutually, integrate a large amount of parts (capacitor, inductor, and suppressing or enable/disable circuit), and the management of failure mode.Conventional coil is also in the face of this fact: a kind of structure can not be enough to be used in radio frequency transmit and receive, the different piece of health, and multiple frequency and different parallel MRs accelerate to arrange.This causes the too a large amount of demand to coil, and this means expensive operation and maintenance expense to clinical practice.

The SNR/SAR performance improvement of optimizing based on field has been followed in the design of many star coils.By contrast, attempt to allow gather together the classic method of work of multiple independent coils (unit) not only expensive, reliable not to the utmost, application category is excessively limited, under the parallel situation arranging of high channel number, especially face the challenge, and be too tied so that magnetic resonance signal excitation and detecting level cannot be brought up to new height, realize the limiting performance that electrodynamics allows.

As shown in Figure 4, in the time increasing port one 10 to many star coils, if needed, can introduce the network 111 of a coupling and realize coupling.For radio frequency reception, main target is for the prime amplifier before receiver provides suitable impedance, so that prime amplifier operates in low-noise factor situation.For radio-frequency transmissions, main target is for power amplifier provides suitable impedance, can Maximum Power Output.Fig. 5 has further shown the example of utilization with many star coils of N port one 10, and for n port, if needed, an extra electric capacity can increase, and parallel with Cn.Electric capacity and inductance L n have been composed in series matching network, and it has additional characteristic, the low output impedance of the low input impedance/power amplifier of prime amplifier can be changed into very high impedance.If there are further needs, general many inputs and many output interface/matching networks can be used, and make coupling more convenient.

Above the description of system and method is comprised to a lot of characteristics, these should not be interpreted as the limit to protection domain, and are only the explanations of preferred embodiment.Other conversion and result are also possible by the inspiration of different embodiment, and for example, foundation and the radio frequency loss forecast model of field can adopt other sensing datas, comprise field measurement, propagate and measure and different magnetic resonance signals.Further, many star coils are not limited to shown planar structure or two groups of conductors, and same design is also applicable to right cylinder, spherical structure and other warp architectures, or meet other complicated profiles of body shape.Build sandwich construction additional advantage can be provided.Hard or flexible/pliable material can be used, and realizes superperformance.Use carbon nano-tube or superconductor can make Performance optimization.

Claims (20)

1. for a radio frequency antenna apparatus for magnetic resonance system, comprising:

Antenna structure, is roughly nettedly and for transmitting radio-frequency current, and described antenna structure comprises:

Conductor part, is dispersed on some layers;

Capacitive or inductive several johning knot chalaza, described johning knot chalaza is distributed in diverse location, is electrically connected conductor part and form reticulate texture roughly;

Interface device, for the Radio Frequency Subsystem of magnetic resonance system and described antenna structure are coordinated at least one locus, realizes the control that on antenna structure, radio-frequency current distributes; Wherein, described radio frequency antenna apparatus carries out radio frequency transmit and receive with continuous and various distribution of current pattern.

2. radio frequency antenna apparatus as claimed in claim 1, is characterized in that: described interface device comprises the some ports that are distributed on antenna structure.

3. radio frequency antenna apparatus as claimed in claim 2, is characterized in that: each impedance inverter circuit that comprises in described some ports.

4. radio frequency antenna apparatus as claimed in claim 1, is characterized in that: the control that described radio-frequency current distributes comprises the combination of the preposition radio-frequency pulse of corresponding magnetic resonance system emission mode and the preposition magnetic resonance signal/data of corresponding magnetic resonance system receiving mode.

5. radio frequency antenna apparatus as claimed in claim 4, is characterized in that: the combination of described preposition radio-frequency pulse and preposition magnetic resonance signal/data is to carry out preposition according to the packet of the power measurement values that includes prior acquisition, radio-frequency field measured value, noise measurement, magnetic resonance signal/data.

6. radio frequency antenna apparatus as claimed in claim 5, it is characterized in that: described preposition be to have used multiple models, predict the different aspect of magnetic resonance imaging, described aspect is that the data group from including radio-frequency power transmitting/dissipation, flip angle, image comparison, signal to noise ratio (S/N ratio) is selected.

7. a method, utilizes the change in time and space of a large amount of interconnective current delivery path implement electromagnetic fields, comprises the steps:

Step a: at least one antenna structure is provided, this antenna structure includes the conductor part of multilayer, conductor part clamps at least one plain film or the curved tabs that have non-conducting material to make, thereby forms the network of electrical connection path, for holding the change in time and space of radio-frequency current;

Step b: interface device is provided, for the Radio Frequency Subsystem of magnetic resonance system and described antenna structure are coordinated at least one locus, realizes the control that on antenna structure, radio-frequency current distributes;

Step c: current control device is provided, comprises the radio-frequency pulse for launching and the signal/data combination for receiving; Wherein,

Described method is beneficial to and produces various electromagnetic field change in time and space, comprises the variation that can promote radio frequency transmit and receive efficiency.

8. method as claimed in claim 7, is characterized in that: described antenna structure is grid configuration, and grid configuration is enough intensive, for generation of accurate radio-frequency current change in time and space.

9. method as claimed in claim 8, is characterized in that: described grid configuration has the conductor part that is distributed in different layers, and every layer is held the conductor piece of almost parallel.

10. method as claimed in claim 7, is characterized in that: described non-conducting material is the insulating material with high-k.

11. methods as claimed in claim 7, is characterized in that: the combination of described radio-frequency pulse and signal/data is to carry out preposition according to the packet of the power measurement values that includes prior acquisition, radio-frequency field measured value, noise measurement, magnetic resonance signal/data.

12. methods as claimed in claim 11, it is characterized in that: described preposition be to have used multiple models, predict the different aspect of magnetic resonance imaging, described aspect is that the data group from including radio-frequency (RF) energy transmission/dissipation, flip angle, image comparison, signal to noise ratio (S/N ratio) is selected.

13. methods as claimed in claim 12, it is characterized in that: described multiple models comprise the functional unit that meets quadratic equation, for the definition prediction radio-frequency (RF) energy transmission based on radio-frequency pulse with dissipate, described functional unit has by use and has the information of power measurement values of prior acquisition and predetermined parameter.

14. methods as claimed in claim 7, is characterized in that: the rule of the combination of described signal/data is that rule is rebuild in magnetic resonance imaging.

15. 1 kinds of methods, utilize the network with current delivery path to realize the change in time and space of electromagnetic field, comprise the following steps:

Step a: the measuring method that is provided for measuring radio-wave propagation effect;

Step b: obtain limited measured value by aforementioned measuring method;

Step c: provide a prediction mode based on aforementioned measurements, the radio-wave propagation effect of radio-frequency pulse is arbitrarily launched in this prediction mode prediction, and effect comprises Energy Transfer and dissipation;

Steps d: use aforementioned prediction mode to calculate radio-frequency pulse, radio-frequency pulse is used to the network with current delivery path that energy is provided;

Step e: radio-frequency pulse provides energy for the network with current delivery path, realizes electromagnetic field change in time and space; Wherein,

Before prediction mode and calculating radio-frequency pulse, take the photograph and manage radio-frequency (RF) energy transmission and dissipate.

16. methods as claimed in claim 15, is characterized in that: described prediction mode comprises use radio-wave propagation measurement and preposition numerical model.

17. methods as claimed in claim 16, it is characterized in that: described numerical model comprises the functional unit that meets quadratic equation, for the definition prediction radio-frequency (RF) energy transmission based on radio-frequency pulse with dissipate, described functional unit has by use and has the information of power measurement values of prior acquisition and predetermined parameter.

18. methods as claimed in claim 15, it is characterized in that: described calculating use at least one for predict radio-frequency (RF) energy dissipate quadratic equation as input, integrate described prediction mode by building and solve optimization problem, described optimization is using the definition of radio-frequency pulse as output.

19. radio frequency antenna apparatus as claimed in claim 1, is characterized in that: described conductor part comprises high conductivity material.

20. methods as claimed in claim 7, is characterized in that: described conductor part comprises high conductivity material.

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