CN100449327C - RF coil system for magnetic resonance image forming device - Google Patents
RF coil system for magnetic resonance image forming device Download PDFInfo
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- CN100449327C CN100449327C CNB021584362A CN02158436A CN100449327C CN 100449327 C CN100449327 C CN 100449327C CN B021584362 A CNB021584362 A CN B021584362A CN 02158436 A CN02158436 A CN 02158436A CN 100449327 C CN100449327 C CN 100449327C
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Abstract
An RF coil system for a magnetic resonance imaging apparatus whereby a substantially computer-aided and hence automatically optimized image quality in respect of signal-to-noise ratio and resolution can be achieved in dependence on the type and size of the object to be imaged, without time-consuming replacement or manual positioning of the RF coil system being necessary. To this end, the coil system (A) includes a plurality of single RF coils (Sx) which are essentially decoupled from one another and have a different size and/or different position, as well as a control device with a plurality of transmission units which are associated with a respective RF coil and whereby one or more RF coils can be selected and supplied with an RF pulse having an independently adjustable amplitude and/or phase and/or pulse shape. The invention also relates to a magnetic resonance imaging apparatus provided with such an RF coil system.
Description
Technical field
The present invention relates to a kind of radio frequency (RF) coil system that is used for MR imaging apparatus, and this MR imaging apparatus.
Background technology
Magnetic resonance imaging (MRI) device is used in particular for checking and the treatment patient.The RF pulse excitation is arranged and is subjected in the nuclear spin of checked tissue thus by basic magnetic field.So the RF relaxation process that causes like this stands the gradient magnetic induction, thereby receive and handle the image that it forms surveyed area.
There are certain difference in so-called open MR system (perpendicular system) and MR system, in the open MR system, patient is placed in the surveyed area that forms between the C type support two ends, like this, in inspection or therapeutic process, can be from each side near patient, and the MR system comprises a tubular detection area (axial system), patient is placed on wherein.These differences also need equipment to have diverse layout and structure, so that produce and receive basic magnetic field, gradient magnetic and RF signal.
The transmission of RF signal and reception need to use the RF coil system, and its structure and position especially play a decisive role to signal to noise ratio (S/N ratio) and resolution to image quality.Except forever being installed in intrasystem RF coil system, also need to use so-called RF body coil, it can be arranged in around the tested zone or on it, for example as sleeve pipe or liner neatly.
The type of MR device not only, and especially various patient datas for example patient's size and tested zone (organ) type, position, the degree of depth and size, also have all motions in this zone or the like, all be the deciding factor of optimizing or select the RF coil system.Therefore, in the beginning that detects, the user generally must carry out test exposure by the RF coil of different sizes and diverse location, thereby obtains the optimum image in tested zone.This step is time-consuming very, and must repeatedly shift out patient from the MR device, will be more consuming time.This is a special problem deserving of attention in the axial system.
For fear of this problem, for example disclose among the DE4030878 and utilized duolateral coil with two independent coils, these two independent coils can be individually or are jointly passed through switch activator, thereby obtain optimum image quality.
Summary of the invention
The purpose of this invention is to provide a kind of the above-mentioned type the RF coil system it can be applicable to fairly simple and better that thereby given exposure position improves image quality.
Another object of the present invention provides a kind of RF coil system of the above-mentioned type, and it can as signal to noise ratio (S/N ratio) or time or spatial resolution, be controlled the optimization of image quality with regard to given parameter.
A further object of the invention provides a kind of RF coil system, and its effective dimensions and position can change, and needn't replace coil system and patient is shifted out from the MR device.
Last purpose of the present invention provides a kind of MR imaging device, owing to it has utilized according to RF coil system of the present invention, and the speed of therefore can relatively determining ground imaging, and can not reduce image quality.
According to design of the present invention, can reach goal of the invention by the RF coil system, this coil system comprises a plurality of basic each other decouplings and varies in size or the mutually different independent RF coil in position, and these transmitting elements of a plurality of transmitting elements are associated with separately RF coil, thereby can select one or more RF coils, and providing RF to send pulse to selected RF coil, the amplitude of this pulse and/or phase place and/or pulse waveform can be regulated separately.
This scheme has many advantages, and allows height computer auxiliary, therefore can the Automatic Optimal image quality and need not carry out replacement consuming time or the RF coil system is manuallyd locate.Patient particularly under the situation of axial system, this means and to save time significantly, because needn't shift out from this MR imaging device again.
RF coil (coil) is suitably selected to change the active position and the size (being used for determining the penetration depth of magnetic field) thereof of coil system at tissue.The magnetic field structure of coil system mainly is homogeneity and symmetry, can be optimized by amplitude, phase place and/or the waveform that changes RF transmission pulse.
According to the preferred embodiment, when the RF coil system operates with reception RF signal, obtained above-mentioned advantage.
Can optimize the structure that sends or receive magnetic field according to preferred embodiment.
Can regulate above-mentioned parameter especially neatly according to preferred embodiment.
Be particularly related to the MR imaging device that comprises tubulose detection space (axial system) according to an embodiment, and can be used as the body coil, that is to say with the type of MR imaging device irrelevant according to another embodiment.
Description of drawings
Below by example and with reference to accompanying drawing preferred embodiment is carried out further detailed description, the features and advantages of the present invention will show.Wherein:
Fig. 1 is the longitudinal profile synoptic diagram of MR imaging device,
Fig. 2 has shown the circuit diagram with basic module in the MR imaging device,
Fig. 3 has shown the block scheme of the control circuit of coil,
Fig. 4 is the synoptic diagram of first coil system,
Fig. 5 is the synoptic diagram of coil system first combination,
Fig. 6 a, 6b are the synoptic diagram of coil system second and the 3rd combination,
Fig. 7 is the synoptic diagram of second coil system,
Fig. 8 is first synoptic diagram of the magnetic field structure of independent coil,
Fig. 9 is second synoptic diagram of the magnetic field structure of independent coil,
Figure 10 has shown the block scheme of the equipment that is used for the control coil system,
Figure 11 is the synoptic diagram of tertiary coil system,
Figure 12 is the synoptic diagram of the 4th coil system,
Figure 13 is the synoptic diagram of the 5th coil system,
Figure 14 is the synoptic diagram of six-coil array system,
Figure 15 is the synoptic diagram of coil system the 4th combination,
Figure 16 is the sectional view of coil system the 4th combination.
Embodiment
Fig. 1 comprises that tubulose detects the longitudinal profile synoptic diagram of the MR imaging apparatus (MR pick-up unit) in space (axial system).Measured target 1, for example patient is positioned at and detects the space.Detect the space and surrounded by solenoid 2, it is used to produce even, stable basic magnetic field (B
0Magnetic field or main field are used to magnetize measured target, promptly adjust nuclear spin), basic magnetic field in axial direction (z direction) is run through and is detected the space, the order of magnitude of magnetic flux density (magnetic induction density) from tens teslas to several teslas.
For the signal that measured target 1 is sent carries out space identification and resolution, surround the detection space by three gradient magnetic field coils 3,4,5 (showing in detail), these coils produce along three gradient magnetics of z direction of principal axis extension.First gradient magnetic is linear change substantially on the x direction of principal axis, and second gradient magnetic is linear change substantially on the y direction of principal axis, and the 3rd gradient magnetic is linear change substantially on the z direction of principal axis.
In order to encourage the nuclear magnetisation (spin resonance) in the measured target, the RF that can conduct the RF pulse sends coil system 30 (RF surface resonator) and is placed in the target top, thereby makes RF magnetic field (B
1Magnetic field) can cross target.In order to gather after excitation and cause the relaxation of the further variation of magnetized state in the target, provide the RF receiving coil system 40 (the surperficial resonator of RF) that is installed in the target below and goes out relevant voltage according to variation sensing.If use suitable conversion, then a common RF coil system also can be used for sending and receiving, and maybe can select one from two RF coil systems and be used for common transmission, and another is used for receiving.Between RF coil system 30,40 and adjacent separately gradient magnetic field coil 3,4,5, provide the shielding 12,13 that RF coil system and gradient magnetic field coil are isolated.
In addition, for given detection, RF body coil system 45 can also be used as receiving coil, is directly used in patient 1 or tested zone.In general, this RF body coil is very soft and constitute with liner or sleeve pipe form.
The signal that RF coil system 40,45 receives is estimated,, gradient magnetic is located foment to be used for the MR imaging.
Schematically shown this MR imaging device essential critical elements in service among Fig. 2, comprised the control module 17 of control gradient waveform generator 20, the output terminal of this generator is connected respectively to first, second and the 3rd gradient amplifier 21,22,23.These amplifiers produce electric current to gradient coil 3,4,5 respectively.These Amplifier Gain coefficients can be regulated independently of one another, and coil is producing the selection of cutting into slices in known manner on gradient magnetic and three the corresponding space directions in tested zone on x direction of principal axis, y direction of principal axis and the z direction of principal axis then.
In addition, send coil for each of RF coil system, the transmission path by control module 7 controls all is provided, it mainly comprises RF generator 18 separately, thereby the frequency adjustment that makes the RF pulse is to the Larmor frequency that depends on gradient magnetic.The RF pulse is applied to the amplifier of being controlled by control module 17 19, thereby regulates its amplitude, phase place and pulse waveform; Their final arrival send RF coil system 30.
The MR signal that causes by the relaxation of excitation magnetized state at RF coil system 40,45 (will be used for receive), mix mutually with two carrier oscillations (having definite Larmor or MR frequency) that are offset 90 ° mutually of oscillator 24 by quadrature demodulator 13 by the local strength of stabilizing magnetic field, with reception path that each coil is associated in demodulation, so cause the real part that can be considered to complex signal and two signals of imaginary part.These signals are applied to analog to digital converter 14.At last, the MR image produces again in known manner by image processing unit 15 and shows on monitor 16.
RF coil system according to the present invention can be used in above-mentioned axial system, and has in the perpendicular system (open MR imaging system) that vertically runs through the basic magnetic field of detecting the space.
And, can be according to RF coil system of the present invention as sending coil 30 and receiving coil 40,45; For blocked operation, each coil will be connected to (for example passing through diode) transmission/reception path S/R that can do corresponding switching of merging.
Fig. 3 has shown the block scheme of the device of the transmission/reception path S/R of each independent coil in the control RF coil system.For each RF coil, this device all comprises transmitting element and the receiving element of combining as shown in Figure 3, thereby forms dispensing device 100 with z path and the receiving trap 110 (z=RF coil number) with z path respectively.The output of dispensing device 100 follows the adjustable phase place of the independence of each RF coil, amplitude and pulse waveform to carry RF voltage T.The input of receiving trap 110 carries the RF received signal R of each RF coil.At last, MR spectrometer 120 is two-way to be connected to two devices 100,110, and described spectrometer can be regulated the signal that dispensing device 100 and assessment receive.
If hereinafter described RF coil system will be used as the body coil, they should be placed in the propping material of suitable softness, if necessary, can be connected to prime amplifier by suitable network, thereby proofread and correct the change in electrical characteristics that may be caused by bending.
Fig. 4 has shown first embodiment according to RF coil system of the present invention, and it comprises three independent surface coils S1, S2, the S3 (generally being represented by mark Sx) of arranged concentric.The magnetic decoupling each other of these coils.For this purpose, between each coil, provide three decoupling capacitor C
K1, C
K2, C
K3Thereby the current phase that influences in the coil system distributes, and it all is decoupling that described electric capacity is tuned to each pattern.
For decoupling, can also use (additional or alternatively) little mutual inductor, for example comprise that annular core (little stray magnetic field) and two inductance are wrapped in the type on the common iron core.This is applicable to hereinafter described all embodiment.
Therefore reception path and/or transmission path that each coil is connected respectively to prime amplifier V1, V2, V3 (generally being represented by mark Vx) and is associated can produce or obtain three different images simultaneously.And, a plurality of tuning capacity C
rConnect with each conductor part of separately RF coil.Therefore, thus relevant RF coil resonates can cause in the conductor circuit (network) that this conductor part forms that electric current changes.
This RF coil system can be by selecting one or more independent coil S1, S2, S3, and electricity is applicable to tested zone, therefore according to its type, size, the degree of depth, motion or the like, can produce corresponding to signal to noise ratio (S/N ratio), resolution and/or corresponding to the Optimal Signals of minimum movement ambiguity.
For example, the penetration depth of the transmission field of RF coil or received field is in proportion with it substantially.Under toroidal situation shown in Figure 4, Effective depth penetration equals its radius substantially.Therefore, in the time will being positioned at body surface, should select coil S2 or S3 to send and receive by the tissue of imaging.
Can improve signal to noise ratio (S/N ratio) partly by image in conjunction with two coils.Therefore, under the situation of Fig. 4, for example use first and when tertiary coil S1, S3 simultaneously, the whole integrated noise voltage in this composite image comprises the effects of two different amounts.The mutual relationship of noise depends on overall dimensions, shape, conductivity and the position of coil imaging region.Therefore, the noise component that is produced by two coils each other can not be related fully.Notice shown in situation under obtained association less than 30%.Therefore, in the zone that two coil S1, S3 cover, just the zone below being located immediately at body surface obtains signal to noise ratio (S/N ratio), and it is than from being arranged in the signal to noise ratio (S/N ratio) height that health obtains than the zone that is only covered by the first bigger coil S1 of position, deep.
At last, body coil that can also RF coil system and other is independent is used in combination, by they suitably are placed in the both sides of tested zone (or health of patient 1) relative to one another, to form the optimum image of moving region (for example heart).This purpose realized in the short as far as possible time, so that obtain suitable temporal resolution.Special under known SENSE (sensitivity encoding) imaging situation, can select short acquisition time and obtain enough visual fields, therefore can form more substantial corresponding image.Then can avoid any slight disadvantageous signal to noise ratio (S/N ratio) by the cluster coil of forming by a plurality of independent coils or coil system.
Fig. 5 has shown this embodiment that is used for coil system first combination of coronary artery detection, and at this moment two suitable R F coil system A1, A2 and three independent surface coils B1, B2, B3 arrange around patient 1 trunk.So realized optimum cluster coil system.Various loop A 1, A2, B1, B2, B3 are can be by the part overlapping or keep suitable distance and/or carry out decoupling each other by the L/C circuit is adaptive between these coils.
Except the described adjustability of RF coil system effective dimensions, for given detection, its relative patient's active position can be tried one's best, and to change simply also be very important.For this purpose, thereby can arrange that a large amount of described RF coil system A1, A2, A3 are overlapping and press close to tested zone with its ground that differs from one another.Fig. 6 a shown the RF coil system this second the combination and Fig. 6 b has shown its 3rd combination.
So can be by overlapping or between the RF coil system, keep suitable distance to obtain each other magnetic decoupling.The operator of this system can select to have RF coil system A1, A2, the A3 of optimal location by suitable switch.The independent coil S1 of each coil system, S2, S3 also transmission/reception path V1, V2, the V3 (generally being represented by mark Vx) by separately operate.
The one or more butterfly shaped coils system that increases or replace can be used in these and other combination; The example embodiment that has shown this butterfly shaped coils among Fig. 7.This coil system is by two staggered capacitor C of passing through each other
KIndependent butterfly shaped coils S1, the S2 of decoupling forms.Also have a plurality of tuning capacity C in each conductor part of each RF coil
TTo do tuning usefulness.Each coil is also connected to the transmission/reception path S/R1 or the S/R2 of merging.
At last, because the effect of dielectric resonance, the field intensity that independent RF coil may occur changes distortion or uneven problem.Then can cause the convergence of Biot-savart low frequency rule and to compare too much deviation with actual measured value.Described RF system can proofread and correct and tuning these dielectric resonance effects, this is owing to phase change or amplitude variations according to the electric current I 1 on coil S1, the S3 of two individual interleavings of Fig. 8, I3 can suitably change also combination, thereby obtains more balanced promptly more uniform variation I
ResFor this purpose, for example, can suppose a decoupling capacitor C
KThereby, utilize di-cap or switch-capacitor to switch, so the operator of this system can change the variation of magnetic field intensity effectively.Under the very high situation of magnetic field intensity, effectively the even variation of controlling magnetic field intensity can further improve image quality greatly.
The inhomogeneity left-right symmetric of RF coil magnetic field is subjected to the interference of known LISA (local strength's skew illusion) and dielectric resonance effect, that is, and especially under the situation of RF frequency and magnetic field intensity all relative higher (for example 128MHz, 3Tesla).These influences and cause thereof are illustrated in p.1175 " medical magnetic resonance " 1989.Disturb in order to eliminate these, select the structure according to Fig. 9, wherein coil is subdivided into two independent, coils of decoupling each other, or uses two independent coil S1, S2 of the RF coil system that forms the independent coil that comprises two adjacent layouts.For the effective inhomogeneity left-right symmetric of controlling magnetic field, and for the main field that obtains to expect changes, provide as shown in Figure 10 device 50 to be used for controlling tuning and change coupling between independent coil S1, the S2.These coils especially can be responded to each other by inductance L and are coupled to a certain degree, and by tuning capacity C
TCome the RF electric current in the control coil, thereby obtain the left-right symmetric of height at least.
The RF coil magnetic field is carried out the control of described homogeneity, and especially to use advantage under so-called SENSE (sensitivity encoding) imaging situation more outstanding.This method is 2000, and " the international association of medical magnetic resonance journal " and 1999 p.152 was described in detail in " medical magnetic resonance " p.952 and the more article.Wherein said geometry factor g can be optimized by coil is suitably controlled the magnetic field homogeneity of regulating the RF coil system; Under the situation of a plurality of coil systems (for example according to Fig. 5), then can correspondingly regulate one of them of suitable R F coil system A1, A2.
If described RF coil system is used for sending then can finds further application.In RF coil system shown in Figure 4, be desirably in the magnetic decoupling that realizes about 20dB between three nested independent RF surface coils S1, S2, the S3.This layout local omnidistance send can or by homogenising effectively, or the phase place by electric current in the independent coil of suitable adjusting or amplitude are to form described SENSE imaging.In this case, when allowing to have the pulse transmission of different wave, utilize space encoding or recodification function, thereby the image that acquisition time and spatial resolution improve is significant.A plurality of suitable R F coil system A1, A2 ... can also make up in this case.
These methods are specially adapted to heart and head imaging, and the coil system that the latter adopts generally comprises one and has larger-diameter coil, and a plurality ofly have than minor diameter and along the coil of big coil circumferential arrangement.
Figure 11 has shown the 3rd RF coil system.Two at this moment independent RF coil system A1, the A2 of type arrange adjacent to each other that and the external coil S1 of two coil systems has public part as shown in Figure 4.Decoupling between each coil is by decoupling capacitor C
KRealize.A plurality of tuning capacity C
TBe inserted in each conductor part of independent RF coil.The transmission of merging separately/reception path S/R is connected to each of whole six independent coil S1, S2, S3, S1`, S2`, S3`; Under sending mode, provide the RF electric current that amplitude is different with phase place and the pulse waveform possibility is different by the transmission/reception path that merges to each independent coil, thereby obtain according to desirable symmetry recited above, even or the characteristic of radiation or the effective dimensions and the active position of integral arrangement.
According to top described,, also can obtain afore-mentioned characteristics by independent coil or coil system suitably being selected and being made up.
Figure 12 has shown the 4th RF coil system, and wherein the RF coil S1 of four adjacent layouts, S2, S3, S4 are surrounded by the 5th RF coil S5.Pass through decoupling capacitor C between the coil
KDecoupling each other, and with a plurality of tuning capacity C
TInsert the different conductor part of independent RF coil.Each independent coil is connected with separately controllable transmission/reception path S/R.Utilize this RF coil system, the magnetic field that first to fourth coil S1 to S4 can produce less penetration depth, the magnetic field that stack the 5th coil S5 produces on this magnetic field with big penetration depth.According to top described with these coils select the combination, thereby can obtain optimum signal to noise ratio (S/N ratio) at the desired locations of surveyed area.
The third and fourth RF coil system is particularly suitable for being used with the SENSE imaging method.
Figure 13 has shown the 5th RF coil system, wherein first, external coil S1 surrounds second, Inside coil S2.Operate the first coil S1 by the first transmission/reception path S/R1.Two two conductor Lt1, Lt2 that are perpendicular to one another and extend and be connected to the second coil S2 with the angular distance of 90 degree are provided in the second coil S2.Each transmission/reception path S/R2, the S/R3 that is used to operate the second coil S2 links to each other with each conductor.Two coil S1, S2 are by decoupling capacitor C
K1, C
K2Decoupling each other, and tuning capacity C
TIn the different conductor part of independent RF coil, work.
The 5th RF coil system is used in advantageous particularly in HFO (highfield the is open) system (open MR system).The use of this coil system is irrelevant with a location, activates suitable R F coil because select a total energy from three transmission/reception path S/R1, S/R2, S/R3.
Figure 14 has shown the 6th RF coil system, and wherein tertiary coil S3 is superimposed upon adjacent layout and passes through first capacitor C
K1Public branch each other on the first and second coil S1, the S2 of decoupling.Tertiary coil is by second capacitor C
K2With the first coil S1 decoupling, by the 3rd capacitor C
K2With the second coil S2 decoupling.In these three coils each all has tuning capacity C equally
T, and the transmission/reception path S/R1, S/R2, the S/R3 that pass through separately operate at every turn.
The peculiar advantage of the 6th RF coil system is: by switching or selecting coil S1, S2 and/or S3 can simplify the procedure of adaptation to the patient of different size.
Detect the MR imaging device in space for as shown in Figure 1 the tubulose that comprises, it is advantageous that (the 4th) combination of having used the RF coil system, it comprises so-called saddle coil, as three-dimensional representation among Figure 15 a with shown in Figure 15 b midplane figure.
The RF saddle coil A1 of system, A2 extend also toward each other along detecting the space.In these systems each all by separately first, long loop S1, S1` and stack thereon second, short coil S2, S2` constitute.Coil S1, S2, S1`, S2` equally also have tuning capacity C separately
T, and by decoupling capacitor C
KDecoupling each other, and the transmission/reception path S/R1, S/R2, S/R1`, the S/R2` that pass through separately operate.The magnetic field of each coil is represented by different shades in Figure 15 b.The magnetic field that the figure illustrates two coils is in the regional addition of short coil S2 (S2`), therefore the signal to noise ratio (S/N ratio) of the RF coil system that can obtain to improve in this zone with reference to the explanation of Fig. 4.
Figure 16 is the schematic cross-section with tubulose detection space of coil shown in Figure 15 a.Essential coil 2, the 3-5 that produces main field and gradient magnetic be arranged in this space around and isolated by RF shielding 12 and inner space.Patient 1 schematically represents in the inner space and by two pairs of all two RF coil system A1 of positioned opposite, A2, A3, A4 encirclements at every turn, each coil system all has three independent RF coils at every turn.These RF coil systems setover mutually in a circumferential direction about 90 the degree.Each independent RF coil is all being taken the transmission/reception path S/R that sends signal T and received signal R by carrying separately and to operate.
One or more RF coil systems according to the present invention preferably are used in the MR imaging apparatus, so RF coil or coil system can be by computer control, for example, wait according to type, size, the position of measured target and to select the line height of going forward side by side control.
Claims (14)
1. coil device, it is adaptable about its effective size and/or the homogeneity and/or the symmetry of the radio-frequency field of generation, and it is used for MR imaging apparatus especially, this coil device comprises:
At least one rf coil system (A; A1, A2, A3), it comprises a plurality of independent radio-frequency coil (S
X), the basic each other decoupling of this independent radio-frequency coil and have different sizes and/or the position and
Transmitting element (100), it comprises a plurality of paths, each path is related with radio-frequency coil (Sx) separately, is used for by selecting one or more independent radio-frequency coils to adjust effective size of described coil device, and/or is used for by to one or more selected radio-frequency coil (S
X) each provides the radio frequency with independently adjustable amplitude and/or phase place and/or pulse waveform to send the homogeneity and/or the symmetry of the radio-frequency field of pulse adjustment generation.
2. coil device as claimed in claim 1 comprises:
Receiving element (110) with a plurality of paths, each is associated described path with separately radio-frequency coil (Sx) and can be activated or cancels activation separately, is used for by selecting one or more independent radio-frequency coils (Sx) to adjust effective size of described coil device.
3. coil device as claimed in claim 1 comprises
Several rf coil system (A; A1, A2, A3), it comprises a plurality of independent radio-frequency coil (S
X), wherein said rf coil system (A1, A2, A3) by overlay structure or the structure that has distance each other come decoupling each other, be used for by select at least one described rf coil system (A1, A2, A3) to adjust the active position of described coil device by switch.
4. coil device as claimed in claim 1, wherein said radio-frequency coil (S
X) be the surface coils of arranging with one heart.
5. coil device as claimed in claim 1,
Provide therein by a plurality of independent radio-frequency coil (S
X) first and second rf coil systems (A1, A2) that constitute, wherein first and second rf coil systems (A1, A2) are arranged adjacent to each other, and the external radio frequency coil (S1, S1 ') of wherein said first and second rf coil systems (A1, A2) comprises common part.
6. coil device as claimed in claim 1 wherein provides the radio-frequency coil (S1-S4) of four adjacent layouts, and it is surrounded by the 5th radio-frequency coil (S5).
7. coil device as claimed in claim 1,
Therein by first external coil (S1) and second Inside coil (S2) provide described at least one by a plurality of independent radio-frequency coil (S
X) rf coil system that constitutes, this second Inside coil (S2) is surrounded by described first external coil (S1), wherein two conductors (Lt1, Lt2) are connected to described second Inside coil (S2), these two conductors are perpendicular to one another and are connected with described second coil (S2) with the angular distances of 90 degree, are used for operating described coil device by one of selection or two conductors (Lt1, Lt2) of described first coil (S1) or described second coil (S2).
8. coil device as claimed in claim 1,
First and second radio-frequency coils (S1, S2) are provided therein, and it is arranged and adjacent to each other by having the first electric capacity (CK
1) common branch uncoupling each other, and the 3rd radio frequency coil (S3), it is superimposed upon on described first and second coils (S1, S2), wherein said tertiary coil (S3) is by the second electric capacity (CK
2) with described first coil (S1) uncoupling and by the 3rd electric capacity (CK
3) and described second coil (S2) uncoupling.
9. coil device as claimed in claim 1 comprises
At least the first and second rf coil systems (A1, A2, A3; A1, A2; A1 ', A2 '), it is by a plurality of independent radio-frequency coil (S of the uncoupling each other with different size
X) constitute wherein said rf coil system (A1, A2, A3; A1, A2; A1 ', A2 ') all center on surveyed area layout, and wherein said rf coil system (A1, A2, A3; A1, A2; A1 ', A2 ') by partly overlapping or certain distance is arranged each other and/or by coming uncoupling each other by means of the coupling of L/C circuit.
10. coil device as claimed in claim 9 comprises
Three independent radio frequency surface coil (B1, B2, B3), it is arranged around described surveyed area.
11. coil device as claimed in claim 1,
Two independent insertion radio-frequency coils (S1, S3) are by means of decoupling capacitance (C therein
K) uncoupling each other, this decoupling capacitance (C
K) be disposable by utilizing di-cap or switching capacity, to revise the dielectric resonance effect by the phase change or the changes in amplitude that change and make up the electric current on described two independent radio-frequency coils (S1, S3).
12. coil device as claimed in claim 1,
Radio-frequency coil (S therein
X) be subdivided into two independent, radio-frequency coils of uncoupling mutually, or provide two radio-frequency coils independent, adjacent setting (S1, S2), wherein respectively in order to control an inhomogeneity left side/right side symmetry and the radio-frequency field structure of the radio-frequency field that described two radio-frequency coils produce in order need to obtain, can be by means of the coupling between described two radio-frequency coils of the device that is used for tuning control (50) change.
13. a MR imaging apparatus, it comprises the described coil device of at least one arbitrary as described above claim.
14. MR imaging apparatus as claimed in claim 13, this equipment comprise an arithmetic element, are used to select the path of the transmitting element (100) of radio-frequency coil (Sx), thereby and are used to control selected path to described radio-frequency coil (S
X) provide the radio frequency with independently adjustable amplitude and/or phase place and/or pulse waveform to send pulse.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16747196A JP3327507B2 (en) | 1996-06-27 | 1996-06-27 | Wireless paging method |
| JP20500596A JP3400252B2 (en) | 1996-08-02 | 1996-08-02 | Wireless paging method |
| DE10157039A DE10157039A1 (en) | 2001-11-21 | 2001-11-21 | RF coil arrangement for magnetic resonance imaging device |
| DE10157039.2 | 2001-11-21 |
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| CN1420363A CN1420363A (en) | 2003-05-28 |
| CN100449327C true CN100449327C (en) | 2009-01-07 |
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| CNB021584362A Expired - Fee Related CN100449327C (en) | 1996-06-27 | 2002-11-18 | RF coil system for magnetic resonance image forming device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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