CN1313512A - Radio frequency coil, RF magnetic field generator, and magnetic resonance image method and apparatus - Google Patents
Radio frequency coil, RF magnetic field generator, and magnetic resonance image method and apparatus Download PDFInfo
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Abstract
In order to generate an RF magnetic field effectively, a current channel is used to generate said RF magnetic field in the space of object to be researched. An electric ring channel with a distance from said space greater than that of said current channel from said space is also used to connect to both ends of said current channel.
Description
The present invention relates to RF (radio frequency) coil, RF magnetic field generating apparatus and MR imaging method and equipment, relate in particular to a kind of a plurality of RF coil, a kind of RF magnetic field generating apparatus and a kind of MR imaging method and equipment that use this RF magnetic field generating apparatus that use this RF coil that carry the annular electro passage of the electric channel of the electric current that is used to produce RF magnetic field and the corresponding end that is connected a plurality of electric channels that have.
The static magnetic field direction is referred to as vertical magnetic field type MR imaging apparatus usually perpendicular to the axial MR imaging apparatus of the main body of research object, it produces the static magnetic field space of an opening, and uses its surface, loop to be parallel to the RF coil on pole shoe surface of static magnetic field generation unit as the RF coil that produces RF magnetic field.The direction in the RF magnetic field that such RF coil produces is parallel to the surface of wire loop, thereby can form the RF magnetic field perpendicular to the static magnetic field direction.This RF coil is disclosed in the applicant's United States Patent (USP) the 5760583rd.
On the other hand, the RF coil that also has another kind of type, be referred to as quadrature RF coil, it is constituted by a kind of of two RF coils, and the vector in the RF magnetic field by the correspondence that produced by two RF coils is synthetic, and the intensity in the RF magnetic field that is provided has been improved, and perhaps can reduce the RF magnetic field that the driving energy of each coil just can produce expectation strength.
Yet, in the RF of routine coil, can produce from the electric current that flows through the confined channel that is used to connect the main channel and not expect the RF magnetic field that occurs.Because the RF excitation field that is produced by the main channel of not expected the RF magnetic field cancellation that occurs has reduced to produce the efficient in RF magnetic field, the magnetic field intensity that obtain to expect just needs bigger excitation power.
Moreover the electric current that flows through main channel and confined channel has bigger corresponding relation, has therefore produced additional problem: the high-frequency electrical energy that has strengthened research object absorbs, and has promptly strengthened total SAR (than absorption rate) of research object.
And then, not only offset RF magnetic field by the RF magnetic field that occurs of not expecting that confined channel produces, but also increased the local high-frequency electric energy absorption of research object, promptly local SAL.
Therefore, an object of the present invention is to provide a kind of RF coil, a kind of RF magnetic field generating apparatus and a kind of MR imaging method and equipment that uses this RF magnetic field generating apparatus that can effectively produce RF magnetic field.
Another object of the present invention provides a kind of RF coil, a kind of RF magnetic field generating apparatus and a kind of MR imaging method and equipment that uses this RF magnetic field generating apparatus that the little SAL of research object is provided.
Press one aspect of the present invention, a kind of RF coil is provided, comprising: carry the electric channel that radially extends that is used for the electric current in a RF magnetic field of generation in comprising the space of research object; With, to a farther annular electro passage of the electric channel said space of distance that extends, be used to connect the respective end portions of the electric channel that radially extends apart from said space specific diameter.
By a second aspect of the present invention, a kind of RF coil is provided, comprising: carry a plurality of electric channels that are parallel to each other that are used in comprising the space of research object, producing the electric current in a RF magnetic field; With, be arranged on a plurality of electric channels two ends, apart from said space than a plurality of electric channels apart from the farther annular electro passage in said space, be used to connect the respective end portions of a plurality of electric channels.
By a third aspect of the present invention, a kind of RF magnetic field generating apparatus is provided, comprising: carry the electric channel that radially extends that is used for the electric current in a RF magnetic field of generation in comprising the space of research object; To a farther annular electro passage of the electric channel said space of distance that extends, be used to connect the respective end portions of the electric channel that radially extends apart from said space specific diameter; With, RF signal generator, being used for respectively two positions on the annular electro passage that direction to the center of distance annular electro passage differs 90 ° mutually, mutual phase differential is provided is 90 ° RF signal.
By a fourth aspect of the present invention, a kind of RF magnetic field generating apparatus is provided, comprising: carry a plurality of electric channels that are parallel to each other that are used in comprising the space of research object, producing the electric current in a RF magnetic field; The said space of two end distances that is arranged on a plurality of electric channels is used to connect the respective end portions of a plurality of electric channels than the farther annular electro passage in a plurality of electric channels said space of distance; With, RF signal generator, being used for respectively two positions that direction to the center of distance annular electro passage differs one of two annular electro passages of 90 ° mutually, mutual phase differential is provided is 90 ° RF signal.
According to the present invention, increased the distance between annular electro passage and research object, thereby reduced of the negative function of annular electro passage, and reduced the SAR of research object the RF excitation field.
Therefore, the present invention can provide RF magnetic field generating apparatus and a kind of MR imaging method and equipment that uses this RF magnetic field generating apparatus in a kind of RF coil, a kind of effective generation RF magnetic field.
And the present invention can provide a kind of RF coil, a kind of RF magnetic field generating apparatus and a kind of MR imaging method and equipment that uses this RF magnetic field generating apparatus that the little SAL of research object is provided.
In the description below the preferred embodiments of the present invention of representing from accompanying drawing, some other purpose of the present invention and advantage all will become apparent.
Fig. 1 is the calcspar by an equipment of one embodiment of the present of invention.
Fig. 2 is the synoptic diagram of the structure of a transmitting coil part in presentation graphs 1 equipment.
Fig. 3 is the synoptic diagram of the structure of the transmitting coil part in presentation graphs 1 equipment.
A circuit of transmitting coil part in Fig. 4 presentation graphs 1 equipment.
Fig. 5 is illustrated in the distribution of the electricity in the transmitting coil part of Fig. 1 equipment.
Fig. 6 represents a RF magnetic field partly being produced by the transmitting coil in the equipment of Fig. 1.
Fig. 7 is illustrated in the distribution of the electricity in the transmitting coil part of Fig. 1 equipment.
Fig. 8 represents a RF magnetic field partly being produced by the transmitting coil in the equipment of Fig. 1.
Fig. 9 represents an intensity distributions in a RF magnetic field partly being produced by the transmitting coil in the equipment of Fig. 1
Figure 10 is illustrated in a typical electric channel figure in the transmitting coil part of Fig. 1 equipment.
Figure 11 is a sectional view of getting along the A-A line of electric channel figure shown in Figure 10.
Figure 12 is a sectional view of getting along the A-A line of electric channel figure shown in Figure 10, and combines with the sectional view of a RF shielding.
Figure 13 is a calcspar according to the equipment of an alternative embodiment of the invention.
Figure 14 is the synoptic diagram of the structure of main coil part in the equipment of expression Figure 13.
Figure 15 is the synoptic diagram of the structure that main coil part and RF shield in the equipment of expression Figure 13.
Figure 16 is the synoptic diagram that expression is used for a typical pulse train of magnetic resonance imaging.
Describe embodiments of the invention in detail referring now to accompanying drawing.Fig. 1 represents the calcspar of a MR imaging apparatus, and it is one embodiment of the present of invention.The structure representative of this equipment is according to an embodiment of equipment of the present invention, and the operation representative of this equipment is according to an embodiment of method of the present invention.
As shown in Figure 1, this equipment comprises that a static magnetic field produces part 2, is used for producing a uniform static magnetic field in the inner space of equipment.Static magnetic field produces part 2 and comprises pair of magnetic generation device (not shown), as permanent magnet, they the vertical direction of accompanying drawing mutually in the face of and keep certain distance, be used in the space of inserting, producing static magnetic field (vertical magnetic field).Finding out that easily the magnetic generation device is not limited to permanent magnet, can be superconducting electromagnet, normal conductor electromagnet or analog.
In static magnetic field produces the inner space of part 2, be provided with respectively gradient coil part 4,4 vertically opposed facing and separated by a distance in a similar manner ' and transmitting coil part 6,6 '.Gradient coil part 4,4 ' and transmitting coil part 6,6 ' between a RF shielding (not shown in Fig. 1) is provided.The RF coil is to be made of the conductive material such as Copper Foil.Transmitting coil part 6,6 ' is together represented an embodiment of RF coil of the present invention.The back is again to transmitting coil part 6,6 ' be described in detail.
A research object 8 is placed on one becomes on the entablement 10, and by the carrying device (not shown) with this research object bring into or take out of relative transmitting coil part 6,6 ' between the space of inserting.The body shaft of research object 8 is perpendicular to the static magnetic field direction.Become entablement 10 to be fixed with a receiving coil part 106, receiving coil part 106 is surrounded a position of the research object 8 of wanting imaging.Receiving coil part 106 for example is the part that is used for the lumbar spine imaging, and be fixed to research object 8 hip joint around.Should be noted that receiving coil part 106 not only can be placed on lumbar spine around, and any one position that can be placed on and want the desired site correspondence of imaging.
Gradient coil part 4,4 ' be connected with gradient-driven part 16.Gradient-driven part 16 to gradient coil part 4,4 ' provide drive signal to produce gradient magnetic.The gradient magnetic that produces has following 3: amplitude limit gradient magnetic, readout gradient magnetic field and phase encoding gradient magnetic field.
Transmitting coil part 6,6 ' be connected with a transmitter portion 18.Transmitter portion 18 to a drive signal of transmitting coil part 6,6 ' provide to produce RF magnetic field, whereby in spin of internal excitation of research object 8.
Receiving coil part 106 receives a magnetic resonance signal that is produced by the spin that excites in research object 8.Receiving coil part 106 is connected to the input end of receiver part 20, to the signal of receiver part 20 input receptions.The output of receiver part 20 is connected to the input end of an analog to digital (A-D) converter part 22.A-D converter part 22 converts the output signal of receiver part 20 to digital signal.The output of A-D converter part 22 is connected to a computing machine 24.
So, in storer, forming a data space, this data space has constituted a Fourier space.Computing machine 24 carries out inverse Fourier transform to these data in this Fourier space, with the image of reconstruct research object 8.
Fig. 2 schematically represent transmitting coil part 6,6 ' structure.What Fig. 2 represented is the three-dimensional structure of a RF coil, it constituted transmitting coil part 6,6 ' major part.3 orthogonal directions in three dimensions are represented by x, y, z.The z direction is corresponding to the static magnetic field direction.As shown in the figure, the electric channel of a transmitting coil part 6 is located on the x-y plane, another transmitting coil part 6 ' electric channel be located at previous x-y plane and separate on another x-y plane of certain distance in the z direction.
Transmitting coil part 6 has an annular electro passage 602, an embodiment of annular electro passage 602 representatives annular electro passage of the present invention.A plurality of electric channels 604 that divide beginning radially to extend from central division are provided in the inside of annular electro passage 602.An embodiment of the electric channel 604 representatives electric channel that radially extends of the present invention.Radially the number of the electric channel 604 of Yan Shening for example is 8.Yet the number of electric channel 604 is not limited to 8, and can be any one integral multiple of 4.The label that should be noted that electric channel 604 is by representing at the reference number of a position in the accompanying drawings.One end of each electric channel 604 is connected to electric channel 602, and its other end is connected on the central annular electric channel 606.
Two positions of respective direction apart from inside center differs 90 degree on electric channel 602 provide the corresponding RF that comes from transmitter portion 18 signal.The corresponding phase that offers the RF signal of these two positions differs 90 degree.
An annular electro passage 602 of transmitting coil part 6 ' have ', an embodiment of annular electro passage 602 ' representative annular electro passage of the present invention.Annular electro passage 602 ' inside provide a plurality of electric channels 604 that divide beginning radially to extend from central division '.An embodiment of electric channel 604 ' representative electric channel that radially extends of the present invention.Radially the electric channel 604 of Yan Shening ' number for example be 8.Yet, electric channel 604 ' number also be to be not limited to 8, and can be any one integral multiple of 4.Should be noted that electric channel 604 ' label be by representing in the accompanying drawings at the reference number of a position.Each electric channel 604 ' an end be connected to electric channel 602 ', its other end be connected to a central annular electric channel 606 ' on.
Electric channel 602 ' on two positions of respective direction apart from inside center differs 90 degree provide the corresponding RF that comes from transmitter portion 18 signal.The corresponding phase that offers the RF signal of these two positions differs 90 degree.
Such transmitting coil part 6 and 6 ' face mutually by mirror has constituted the RF coil of apparatus of the present invention.By sending two RF signals that differ 90 degree from the respective phase each other of transmitter portion 18 outputs, and divide equally the power of RF signal with corresponding power beam splitter 182,184, just can be to transmitting coil part 6 and 6 ' provide RF signal, shown in Fig. 3 gives an example.In the scheme that under the condition that is equal to fully transmitting coil part 6 and 6 ' carry out RF is driven, it is preferred scheme that the RF signal is provided in this wise.Should be noted that corresponding RF power amplifier can be arranged on as required beam splitter 182,184 and emission line chart part 6,6 ' between.
Offer two opposite wire loops owing to have the RF signal of equal-wattage and same phase simultaneously from a common signal source, therefore the electromagnetic coupled between coil just becomes inessential.In addition, because enough big distance is arranged between the coil, so the electrostatic coupling between the coil also is unessential.Therefore can obtain the fabulous RF coil of frequency characteristic.
Provide the signal wire of RF signal to be made by the suitable signal wire such as concentric cable to coil, signal wire can infinitely prolong.Therefore, the processing of wire size line is easy to, and can not hinder the research object 8 that enters magnetic field space, and can not stop the opening of magnetic field space.
What represent in Fig. 4 is the circuit of transmitting coil part 6.As shown in the figure, be divided in the annular electro passage 602 of a plurality of segmentations by the electric channel 604 that radially extends, corresponding capacitor 608 is connected in series.Should illustrate that the label of capacitor 608 is in the accompanying drawings by representing at the reference number of a position.Some capacitor corresponding variable condenser that is connected in parallel is used for control capacittance.Variable condenser is used for the perpendicularity of minute adjustment between 0 ° of phase place and 90 ° of phase places.
Apply the RF signal that phase place is 0 ° and 90 ° from transmitter portion 18 to the two ends that are arranged on two respective electrical containers 608 the segmentation, these two segmentations differ 90 ° mutually with respect to the respective direction at center.
Consider that now phase place is 0 ° a RF signal.In Fig. 5, express the ratio of the electric current that flows through electric channel.Specifically, externally in the annular electro passage 602, the segmentation that provides the RF signal is 0 with the current ratio of the segmentation relative with it, and the current ratio that leaves two segmentations of 90 ° of directions of above-mentioned two segmentations is 1, and the current ratio of remaining segmentation is 0.7.The current ratio of the segmentation in inner annular electric channel 606 is similar to the current ratio of the segmentation in the corresponding external electric passage 602.
In the electric channel 604 that radially extends, 4 its current ratios of electric channel that for the current ratio that is arranged in annular electro passage 602 are the both sides of two segmentations of 0 are 0.7, are that 4 its current ratios of electric channel of the both sides of two segmentations of 1 are 0.3 for the current ratio that is arranged in annular electro passage 602.
At the RF signal is a polarity chron, and the direction of current in the electric channel is the direction of the arrow indication among Fig. 5.Specifically, externally in the annular electro passage 602, electric current is respectively to be that counter clockwise direction is carried out in 0 segmentation and clockwise direction flows with respect to current ratio in the right side of accompanying drawing and left side; But in inner annular electric channel 606, the direction of current flow of direction of current flow and outside annular electric channel 602 is opposite.In the electric channel 604 that radially extends,, mobile along opposite direction from the electric current of above-mentioned shunt current for each electric channel 604 to coming into line with respect to the center symmetry.
Such electric current produces a magnetic field in the diametric(al) that perpendicular to current ratio is 1 electric channel, as among Fig. 6 by the direction of dotted arrow indication, this the action of a magnetic field is the opposition side of inner annular electric channel 606 in the accompanying drawings, promptly in the face of transmitting coil part 6 ' that side.
At the RF signal is another polarity chron, and sense of current and above-mentioned direction are opposite fully, thereby make magnetic direction opposite.Therefore, 6 generations of transmitting coil part are corresponding to the RF magnetic field of this RF signal.
The electric current that consideration now has 90 ° of phase places, at a polarity chron of RF signal, Fig. 7 expresses the current ratio of electric channel at this moment.Because the RF signal when the RF signal provides the position spatially to depart from phase place for 0 ° provides 90 ° of positions, so Fig. 7 is equal to the Fig. 5 that has counterclockwise rotated 90 °.Therefore, the RF magnetic direction has counterclockwise rotated 90 ° from situation shown in Figure 6, shown in the dotted arrow among Fig. 8.
Transmitting coil part 6 has produced a RF magnetic field, and it is the resultant magnetic field in above-mentioned two RF magnetic fields.Because there is one 90 ° phase differential in two RF magnetic fields, so synthetic RF magnetic field becomes a rotating magnetic field with the frequency rotation of RF signal.So the effect of transmitting coil part 6 is quadrature RF coils.
Transmitting coil part 6 ' have identical circuit structure, and produce similar rotating magnetic field.Yet, transmitting coil part 6 ' electric channel in direction of current with respect to the transmitting coil part 6 of transmitting coil part 6 ' be mirror in this direction of current opposite fully.This oppositely being easy to of direction of current realize, for example by oppositely with being connected of the signal link at capacitor 608 two ends.In this case, inner annular electric channel 606 ' on the direction in produced simultaneously RF magnetic field, promptly in the direction in the RF magnetic field that produces in the face of a side of transmitting coil part 6, identical with the direction in the above-mentioned magnetic field that produces by transmitting coil part 6, form the RF magnetic field in these two magnetic fields of stack thus.
Therefore, transmitting coil part 6 and 6 ' between a space in, produced a RF magnetic field that in a plane, rotates perpendicular to the z direction.Shown in Fig. 9 was exemplary, the RF magnetic field that is produced by two coils by addition can be so that (Z/2) be uniform in the family curve of the intensity in the RF magnetic field of z direction comprises the wide scope at static magnetic field center therein.
Transmitting coil part 6 and 6 ' electric channel for example can constitute by conductive foil.In Figure 10, express a typical circuitous pattern of the transmitting coil part 6 that constitutes by conductive foil.As shown in the figure, all electric channels 602,604,606 all are made of a kind of conductive material such as Copper Foil.The thickness of Copper Foil for example is in the scope of about 10-100 micron. Electric channel 602 and 604 width for example are about several centimetres or 10 centimetres or bigger.Should illustrate that circuitous pattern constitutes on a support component (not shown).
Make electric channel by the electric channel 604 that will radially extend, compare, can obviously reduce not carry between the adjacent electric channel 604 this part shared ratio of electric current with the electric channel 604 that constitutes by single line with big width.This can alleviate reducing of magnetic field intensity that the center section between adjacent electric channel 604 takes place, thereby has alleviated the unevenness of magnetic field distribution.
Between the electric channel 604 of annular electro passage 602 and radially extension, provide shoulder.Specifically, shown in the sectional view of the Figure 11 that gets as A-A along the line, the shoulder that provides should make annular electro passage 602 farther apart from the center of static magnetic field to the electric channel 604 that extends apart from the center specific diameter of static magnetic field.Thereby, increase the research object 8 of in static magnetic field, placing and the distance between the annular electro passage 602, thereby reduced the cancellation effect of 602 pairs of RF excitation fields of annular electro passage.
Therefore, can reduce to obtain a predetermined required electric power of RF magnetic field intensity, produce effective RF excitation.Moreover, owing to can correspondingly reduce to flow through the RF electric current of electric channel, so can reduce total SAR of research object 8.And then, by increasing the distance between research object 8 and the annular electro passage 602, can reduce the local SAR of research object 8 along with reducing of electric current.
Transmitting coil part 6 ' circuitous pattern construct to such an extent that form mirror with the circuit diagram of transmitting coil part 6.Therefore, research object 8 and annular electro passage 602 ' between distance also strengthened, thereby reduced annular electro passage 602 ' for the cancellation effect of RF excitation field.Thereby and above-described mode similar, can realize effective RF excitation, reduced total SAR and local SAR simultaneously again.
By shoulder is provided, reduced the distance between a RF shielding 700 and the electric channel 602, said RF shielding 700 is arranged between gradient coil part 4 and the transmitting coil part 6, shown in Figure 12 is exemplary.Therefore, the RF electric current that flows through electric channel 602 has bigger mirror effect.The state that mirror effect causes is equivalent to and produces an electric current (image current), the polarity of image current and to flow through the polarity of RF electric current of electric channel 602 opposite, and the position of image current is symmetrical with respect to RF shielding 700 electric channel 602 of mediating a settlement.Therefore, the negative function of image current has been strengthened in the increase of mirror effect, and has offset the RF magnetic field that is caused by the electric current that flows through electric channel 602.Therefore, improve the efficient of RF excitation more, and reduced the total SAR and the local SAR of research object 8 more.
Figure 13 represents another typical MR imaging apparatus, and it is an alternative embodiment of the invention.The structure of this equipment is represented the embodiment of equipment of the present invention, and the embodiment of method of the present invention is represented in the operation of this equipment.
In Figure 13, be similar to parts shown in Figure 1 by identical label representative, and saved explanation them.As shown in figure 13, this equipment has a columniform substantially static magnetic field and produces part 21, and on behalf of static magnetic field of the present invention, it produce an embodiment of part.Static magnetic field produces part 21 and for example is made of a superconducting electromagnet.Static magnetic field produces part 21 and produces a static magnetic field in its inner space.The static magnetic field direction is parallel to the main body axis of research object 8 substantially, so this static magnetic field forms a so-called horizontal magnetic field.
In the inner space of static magnetic field generation part 21, a columniform substantially gradient coil part 41 is set, people's body coil part 61 is set in the inside of gradient coil part 41.A RF shielding (not shown) is set between gradient coil part 41 and human body coiler part 61.Research object 8 just is placed in the inner space of human body coiler part 61.
Human body coiler part 61 is driven by transmitter portion 18, to produce a RF magnetic field.Human body coiler part 61 also detects the magnetic resonance signal that is produced by research object 8, and this signal is offered receiver part 20.In other words, human body coiler part 61 is used for transmitting and receives the RF signal.
Figure 14 schematically represents the structure of human body coiler part 61.As shown in the figure, human body coiler part 61 has a plurality of electric channels that are parallel to each other 612.It should be noted that the label of electric channel 612 is by representing at the reference number of a position.An embodiment of electric channel 612 representatives a plurality of electric channels that are parallel to each other of the present invention.The two ends of a plurality of electric channels 612 are by annular electro passage 614 and 614 ' be connected.An embodiment of annular electro passage 614 and 614 ' representative annular electro passage of the present invention.
The position of the segmentation of each annular electro passage 614 and 614 ' form at the tie point by a plurality of electric channels 612 all is provided with the capacitor (not shown).Annular electro passage 614 or 614 ' in any one electric channel on two positions all be provided with RF signal power source part (not shown), these two positions with respect to the counterparty at center of ring to differing 90 °.Power unit also is used to pick up the RF signal.Such RF coil is referred to as birdcage coil sometimes.
In a kind of like this birdcage coil, a plurality of just electric channels 612 are made contributions to the generation of RF excitation field.And annular electro passage 614 and 614 ' the two generation for excitation field at its two ends does not all have contribution, but is used as the backward channel of RF electric current.
Annular electro passage 614 and 614 ' the diameter of the cylindrical space that forms greater than array of diameter by a plurality of electric channels 612, and the two ends of electric channel 612 are to the outer bend of cylindrical space, so as to be connected to annular electro passage 614 and 614 '.Therefore, it is more farther apart from the distance of research object 8 than electric channel 612 that annular electro passage 614 and 614 ' distance is placed on the distance of the research object 8 in the cylindrical space.Therefore, reduced annular electro passage 614 and 614 ', improved launching efficiency to the negative function of excitation field.In addition, the total SAR and the local SAR of research object 8 have been reduced.These effects by come from annular electro passage 614 and 614 ' the increase of mirror effect strengthened further, said electric channel 614 and 614 ' close RF shielding 700 ', and RF shielding 700 ' be located between human body coiler part 61 and the gradient coil part 41, as shown in figure 15.
The operating process of equipment of the present invention is described now.Though describe is to carry out with reference to equipment shown in Figure 1, and this description also is applicable to the equipment of Figure 13.The operation of equipment is to carry out under the control of control section 30.As a kind of typical MR imaging method, the imaging process of utilizing the gtadient echo technology is described below.It should be noted that magnetic resonance imaging is not limited to utilize the gtadient echo technology to realize, but can utilize any other suitable technology to go to realize, as spin echo technique or EPI (echo-planar imaging) technology.
In the imaging process of utilizing the gtadient echo technology, for example use a pulse train shown in exemplary in Figure 16.This pulse train along time shaft " t " from the left front right side that enters.The implementation of pulse train is by control section 30 controls.
As shown in Figure 16 (1), the RF excitation is realized by a α ° of pulse.Because the structure of this RF coil and above-mentioned mirror effect allow to carry out effective RF excitation, also keep the low total SAR and the local SAR of research object 8 simultaneously, so can reduce the total temperature rise and the local temperature rise of research object 8.
In a wide scope, realized the RF excitation with good homogeneity.In the RF process of motivation, as shown in (2), apply an amplitude limit gradient magnetic Gs.Therefore, encouraged the spin of a predetermined position in the research object 8 selectively.After excitation selectively, redefine the phase place of spin by gradient magnetic Gs.
Below, realize phase encoding by the phase encoding gradient magnetic field Gp shown in (4).Then, make spin redefine phase place by readout gradient magnetic field Gr, the reverse polarity of this gradient magnetic subsequently is to read magnetic resonance signal (gtadient echo).
By repeating this pulse train, just can obtain each corresponding gtadient echo at a predetermined repetition time TR.For each TR, change the amplitude of phase encoding gradient magnetic field Gp, and in a storer, collect the magnetic resonance signal that is used for a plurality of views.Computing machine 24 carries out the bidimensional inverse Fourier transform for the data that are collected in the storer, and produces the x-ray tomography images at imaging position.32 show this x-ray tomography images in the display part.
Under the condition that does not depart from design of the present invention and scope, can design the very big embodiment of many difference of the present invention.Should be appreciated that the specific embodiment that the invention is not restricted to describe is limited by the scope of appending claims definition only in instructions.
Claims (16)
1. RF coil comprises:
Carry the electric channel that radially extends of electric current, be used in the space that comprises a research object, producing RF magnetic field; With
An annular electro passage, it is more farther apart from the position in said space than the said electric channel that radially extends apart from the position in said space, is used to connect the respective end portions of the said electric channel that radially extends.
2. RF coil comprises:
Carry a plurality of electric channels that are parallel to each other of electric current, be used in the space that comprises a research object, producing RF magnetic field; With
The annular electro passage, they are located at the two ends of said a plurality of electric channels, and they are more farther apart from the position in said space than said a plurality of electric channels apart from the position in said space, are used to connect the respective end portions of said a plurality of electric channels.
3. RF magnetic field generating apparatus comprises:
Carry the electric channel that radially extends of electric current, be used in the space that comprises a research object, producing RF magnetic field;
An annular electro passage, it is more farther apart from the position in said space than the said electric channel that radially extends apart from the position in said space, is used to connect the respective end portions of the said electric channel that radially extends; With
RF signal generator is used for respectively that two positions on said annular electro passage provide respective phase to differ 90 ° RF signal, and these two positions differ 90 ° with respect to the direction at the center of said annular electro passage.
4. RF magnetic field generating apparatus comprises:
Carry a plurality of electric channels that are parallel to each other of electric current, be used in the space that comprises a research object, producing RF magnetic field;
The annular electro passage, they are located at the two ends of said a plurality of electric channels, and they are more farther apart from the position in said space than said a plurality of electric channels apart from the position in said space, are used to connect the respective end portions of said a plurality of electric channels; With
RF signal generator is used for respectively that two positions on said any one electric channel of annular electro passage provide respective phase to differ 90 ° RF signal, and these two positions differ 90 ° with respect to the direction at the center of said annular electro passage.
5. MR imaging method, comprise the steps: in the space that comprises a research object, to produce a static magnetic field, in said space, produce gradient magnetic, in said space, produce a RF magnetic field, measurement comes from the magnetic resonance signal in said space, and the magnetic resonance signal according to said measurement produces an image, wherein:
The step that produces RF magnetic field is finished by the described RF magnetic field generating apparatus of claim 3.
6. MR imaging method, comprise the steps: in the space that comprises a research object, to produce a static magnetic field, in said space, produce gradient magnetic, in said space, produce a RF magnetic field, measurement comes from the magnetic resonance signal in said space, and the magnetic resonance signal according to said measurement produces an image, wherein:
The step that produces RF magnetic field is finished by the described RF magnetic field generating apparatus of claim 4.
7. MR imaging apparatus comprises:
The static magnetic field generation device is used for producing a static magnetic field in the space that comprises a research object;
The gradient magnetic generation device is used for producing gradient magnetic in said space;
The RF magnetic field generating apparatus is used for producing a RF magnetic field in said space;
Measurement mechanism is used to measure the magnetic resonance signal that comes from said space; With
Image forming appts is used for producing an image according to the magnetic resonance signal of being measured by said measurement mechanism, wherein:
Said RF magnetic field generation device is a RF magnetic field generating apparatus as claimed in claim 3.
8. MR imaging apparatus comprises:
The static magnetic field generation device is used for producing a static magnetic field in the space that comprises a research object;
The gradient magnetic generation device is used for producing gradient magnetic in said space;
The RF magnetic field generating apparatus is used for producing a RF magnetic field in said space;
Measurement mechanism is used to measure the magnetic resonance signal that comes from said space; With
Image forming appts is used for producing an image according to the magnetic resonance signal of being measured by said measurement mechanism, wherein:
Said RF magnetic field generation device is a RF magnetic field generating apparatus as claimed in claim 4.
9. claim 1 or 2 RF coil, it is characterized in that: further comprise a RF shielding, the RF shielding is near said annular electro passage.
10. claim 3 or 4 RF magnetic field generating apparatus, it is characterized in that: further comprise a RF shielding, the RF shielding is near said annular electro passage.
11. the MR imaging method of claim 5 or 6 is characterized in that: further comprise a RF shielding, the RF shielding is near said annular electro passage.
12. the MR imaging apparatus of claim 7 or 8 is characterized in that: further comprise a RF shielding, the RF shielding is near said annular electro passage.
13. the RF coil of claim 1 is characterized in that: a pair of said electric channel group of radially extending is mutually in the face of ground is provided with, and said space is between them.
14. the RF coil of claim 2 is characterized in that: said a plurality of electric channels are provided with in the face of ground mutually, and said space is between them.
15. the RF magnetic field generating apparatus of claim 3 is characterized in that: a pair of said electric channel group of radially extending is mutually in the face of ground is provided with, and said space is between them.
16. the RF magnetic field generating apparatus of claim 4 is characterized in that: said a plurality of electric channels are provided with in the face of ground mutually, and said space is between them.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB001041304A CN1327238C (en) | 2000-03-14 | 2000-03-14 | Radio frequency coil, RF magnetic field generator, and magnetic resonance image method and apparatus |
Applications Claiming Priority (1)
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| CNB001041304A CN1327238C (en) | 2000-03-14 | 2000-03-14 | Radio frequency coil, RF magnetic field generator, and magnetic resonance image method and apparatus |
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| CN1313512A true CN1313512A (en) | 2001-09-19 |
| CN1327238C CN1327238C (en) | 2007-07-18 |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100416294C (en) * | 2002-06-21 | 2008-09-03 | 皇家飞利浦电子股份有限公司 | Magnetic resonance imaging apparatus and method |
| CN103777160A (en) * | 2012-10-25 | 2014-05-07 | 西门子股份有限公司 | Body coil of magnetic resonance imaging device and magnetic resonance imaging device using same |
| CN105301533A (en) * | 2015-12-08 | 2016-02-03 | 上海辰光医疗科技股份有限公司 | Mouse experiment radiofrequency coil device used for magnetic resonance imaging |
| CN107076812A (en) * | 2014-10-16 | 2017-08-18 | 皇家飞利浦有限公司 | MRI birdcage coils with distribution excitation |
| CN107533115A (en) * | 2015-04-30 | 2018-01-02 | 皇家飞利浦有限公司 | There is improved space and the radio frequency volume coil accessed for what is used in magnetic resonance examination system |
| CN108627783A (en) * | 2017-03-23 | 2018-10-09 | 通用电气公司 | Radio frequency coil arrays and magnetic resonance imaging emission array |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3133432A1 (en) * | 1981-08-24 | 1983-03-03 | Siemens AG, 1000 Berlin und 8000 München | HIGH-FREQUENCY FIELD DEVICE IN A NUCLEAR RESONANCE APPARATUS |
| US5696449A (en) * | 1996-06-03 | 1997-12-09 | General Electric Company | RF coil for open MR magnet |
| US5777474A (en) * | 1996-11-08 | 1998-07-07 | Advanced Imaging Research, Inc. | Radio-frequency coil and method for resonance imaging/analysis |
-
2000
- 2000-03-14 CN CNB001041304A patent/CN1327238C/en not_active Expired - Fee Related
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100416294C (en) * | 2002-06-21 | 2008-09-03 | 皇家飞利浦电子股份有限公司 | Magnetic resonance imaging apparatus and method |
| CN103777160A (en) * | 2012-10-25 | 2014-05-07 | 西门子股份有限公司 | Body coil of magnetic resonance imaging device and magnetic resonance imaging device using same |
| US9568570B2 (en) | 2012-10-25 | 2017-02-14 | Siemens Aktiengesellschaft | Body coil for magnetic resonance imaging |
| CN103777160B (en) * | 2012-10-25 | 2017-03-01 | 西门子股份有限公司 | The body coil of MR imaging apparatus and use its MR imaging apparatus |
| CN107076812A (en) * | 2014-10-16 | 2017-08-18 | 皇家飞利浦有限公司 | MRI birdcage coils with distribution excitation |
| CN107076812B (en) * | 2014-10-16 | 2019-11-01 | 皇家飞利浦有限公司 | MRI birdcage coil with distribution excitation |
| CN107533115A (en) * | 2015-04-30 | 2018-01-02 | 皇家飞利浦有限公司 | There is improved space and the radio frequency volume coil accessed for what is used in magnetic resonance examination system |
| CN107533115B (en) * | 2015-04-30 | 2020-07-14 | 皇家飞利浦有限公司 | Radio frequency volume coil for use in a magnetic resonance examination system |
| CN105301533A (en) * | 2015-12-08 | 2016-02-03 | 上海辰光医疗科技股份有限公司 | Mouse experiment radiofrequency coil device used for magnetic resonance imaging |
| CN108627783A (en) * | 2017-03-23 | 2018-10-09 | 通用电气公司 | Radio frequency coil arrays and magnetic resonance imaging emission array |
| CN108627783B (en) * | 2017-03-23 | 2022-01-14 | 通用电气公司 | Radio frequency coil array and magnetic resonance imaging transmitting array |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1327238C (en) | 2007-07-18 |
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