Magnetic resonance volume coil with multiple independent transmit and receive channels

Abstract

An ultra-high field radio frequency (RF) transmission / reception device for a magnetic resonance (MR) system may include: a dipole array-based volume coil (2) having a plurality of straight dipole antennas (3); at least three circular conductive rings (4, 5, 6) radially surrounding the dipole array-based volume coil (2), the at least three circular conductive rings (4, 5, 6) being substantially parallel to each other and having a plurality of ports (9, 10) for receiving a set of orthogonal driving signals, the RF coil device also including at least two independent transmit / receive (T / R) RF channels (11, 12, 13, 14) for driving the dipole array-based volume coil (2) and the at least three circular conductive rings (4, 5, 6).

Description

Technical Field

[0001] The present invention relates to the field of radio frequency (RF) volume coils for magnetic resonance (MR) imaging (MRI) and spectroscopy (MRS) systems, and in particular to a radio frequency (RF) volume coil having an enhanced transverse RF magnetic field (B1 + ) uniformity and B1 + Ultra-high field RF volume coil with shimming capability. Background Art

[0002] Currently, ultra-high field MRI systems are commercially available for research purposes and clinical applications in confined anatomical structures. Unfortunately, at ultra-high fields such as 7T and above, the B1 generated by the RF transmit coil of a conventional MRI system increases due to the increased dielectric (wavelength) effect of the patient's tissue. + The field gradually becomes uneven. Although, in order to improve B1 + Field uniformity (e.g. B1 + To improve the uniformity of the volume of interest, a multi-element transmit / receive (T / R) surface coil with multiple T / R channels arranged to cover the volume of interest can be used, but this approach is technically complex and has limited B1 + Homogeneity. Accordingly, embodiments of the present system can overcome these and other shortcomings of conventional ultra-high field MRI and MRS systems.

[0003] A magnetic resonance (MR) system is known from US 2018 / 0246179 A1, comprising: a volume-type radio frequency (RF) coil assembly having a volume coil with multiple ports and a toroidal coil with multiple ports, and the toroidal coil is located around the volume-type coil; and at least one controller configured to selectively control a first transmit / receive (T / R) radio frequency (RF) channel to generate an output comprising an RF orthogonal signal for driving the volume-type coil, and selectively control a second T / R RF channel to generate an output comprising an RF orthogonal signal for driving the toroidal coil.

[0004] A magnetic resonance device is known from US 6,522,143 B1, which includes a main magnetic field source for providing a magnetic field (B0) along the main field axis. A transmitter and a transmitting coil excite nuclei of an object to produce resonance. The resonating nuclei produce a magnetic resonance signal, which is detected by a volume coil comprising a pair of end rings separated along the coil axis. The end rings are electrically interconnected by a plurality of crosspieces arranged around the ring. A conductive ring is concentrically arranged between the end rings and inductively coupled to the end rings. The ring includes an electrical conductor preferably surrounding the crosspiece and being positioned parallel to the end ring. A capacitive element electrically connected to the conductor is selected or adjusted to tune the ring to a signal of a selected frequency. In addition, the ring can be slidably positioned along the coil axis and has an adjustable capacitor to match or tune the ring to a signal of a selected frequency.

[0005] Furthermore, dipole antenna arrays are known from the prior art and are usually used to construct volumetric transmit / receive coils for ultra-high field MRI.

[0006] From US 2015 / 0130465 A1 a device is known, which comprises a plurality of electric dipole antenna devices, and a processing device configured to receive signals from the electric dipole antenna devices and to generate a magnetic resonance image based on the signals. Each of the electric dipole antenna devices may have at least two poles extending in mutually opposite directions. One of the poles may have a curved shape, which may fork and follow two mirror-symmetrical S-shapes.

[0007] The ISMRM-2016 (p. 2134) abstract “Hybrid 8channel TR-dipole and 8channel RX birdcage array with optimum SNR” by J. Paska et al. discloses a dipole array optimized for transmission performance and a birdcage array with optimum signal-to-noise ratio.

[0008] A dipole antenna array with a fixed number of independent transmit / receive channels improves B1 + There are limitations in field homogeneity and receive coil sensitivity. Summary of the invention

[0009] The object of the present invention is to provide a (RF) coil arrangement for a magnetic resonance (MR) system with improved transmit B1+ shimming and optimized receive signal-to-noise ratio (SNR) for MRI systems with a limited number of T / R channels.

[0010] According to the invention, this object is solved by the subject matter of the independent claims. Preferred embodiments of the invention are described in the dependent claims.

[0011] Therefore, according to the present invention, an ultra-high field radio frequency (RF) transmit / receive device for a magnetic resonance (MR) system is provided, the RF coil device comprising: a volume coil based on a dipole array, the volume coil based on the dipole array comprising a plurality of straight dipole antennas, wherein the straight dipole antennas are substantially parallel to each other and are located within a cylindrical RF shield, the RF coil device further comprising: at least three circular conductive rings radially surrounding the volume coil based on the dipole array, wherein a first circular conductive ring is located at one of the opposite axial ends of the volume coil based on the dipole array, a second circular conductive ring is located at the opposite end of the volume coil based on the dipole array, a third circular conductive ring is located between the first circular conductive ring and the second circular conductive ring, surrounding the center of the volume coil based on the dipole array, the first conductive ring, the second conductive ring and the third conductive ring are substantially parallel to each other, wherein at least the third circular conductive ring has a plurality of ports for receiving a set of orthogonal drive signals, the device further comprising at least two independent transmit / receive (T / R) RF channels for driving the volume coil based on the dipole array and the at least three circular conductive rings.

[0012] The main idea of ​​the present invention is to combine three conducting rings with a volume coil based on a dipole array. These three rings generate additional transverse B1 field components for improved B1 + Shimming and signal-to-noise ratio (SNR). Using the proposed (RF) coil arrangement, it is possible to transmit B1 + Field shimming and receive signal-to-noise ratio (SNR) optimization to improve MR imaging quality at ultra-high fields such as 7T and above.

[0013] The RF transmitting / receiving device of the present invention includes a volume coil based on a dipole array, which has straight dipole antennas arranged in parallel to each other in a cylindrical configuration along an axial direction. The axial direction is along the longitudinal axis of the cylindrical configuration. The first circular conductive ring and the second circular conductive ring are placed at opposite axial ends of the cylindrical configuration. The third circular conductive ring is placed axially between the first circular conductive ring and the second circular conductive ring. The conductive rings are arranged to surround the volume coil based on the dipole array. For example, the conductive ring is placed radially outside the straight dipole antenna of the volume coil based on the dipole array. Specifically, the circular conductive rings can be arranged transverse to the longitudinal axis. For example, the two circular conductive rings can be placed in radial planes at opposite axial ends, respectively, and the third circular conductive ring is placed axially in a radial plane between opposite axial ends.

[0014] At least two independent transmit / receive channels are provided for driving the volume coil and the circular conductive ring based on the dipole array. Specifically, the third (middle) circular conductive ring is provided with a port for receiving an orthogonal drive signal. To this end, the corresponding independent transmit / receive channels are coupled to the corresponding ports of the third (middle) circular conductive ring so as to drive the third (middle) circular conductive ring in an orthogonal mode.

[0015] In another disclosed aspect, at least one transmit / receive (T / R) RF channel is assigned to each straight dipole antenna, one channel is assigned to the first circular conductive ring and the second circular conductive ring, and one channel is assigned to the first port of the third circular conductive ring and the second port of the third circular conductive ring.

[0016] It is further contemplated that the device includes a power splitter and a 180° phase shifter, wherein the channels assigned to the first circular conductive ring and the second circular conductive ring are assigned to the first circular conductive ring and the second circular conductive ring via the power splitter and the 180° phase shifter.

[0017] According to an embodiment of the present device, the device includes an orthogonal hybrid coupler, wherein channels assigned to a first port of a third circular conductive ring and a second port of the third circular conductive ring are assigned to the first port of the third circular conductive ring and the second port of the third circular conductive ring through the orthogonal hybrid coupler, wherein the first port and the second port are separated by 90° in azimuth along the third circular conductive ring.

[0018] It is further contemplated that at least one transmit / receive (T / R) RF channel is assigned to each straight dipole, one channel is assigned to the first circular conductive ring, one channel is assigned to the second circular conductive ring, one channel is assigned to the first port of the third circular conductive ring, and one channel is assigned to the second port of the third circular conductive ring.

[0019] It is also contemplated that the straight dipole antenna and the circular conductive loop are tuned to the same MRI resonant frequency.

[0020] According to an embodiment of the present apparatus, a capacitor and / or an inductor is placed in each straight dipole antenna to tune the straight dipole antenna so that a maximum current flows in the middle of each straight dipole antenna.

[0021] It is further contemplated that capacitors and / or inductors are evenly distributed along the first circular conductive ring and along the second circular conductive ring for tuning the first circular conductive ring and the second circular conductive ring to a resonant mode having even current distribution along the first circular conductive ring and the second circular conductive ring.

[0022] According to an embodiment of the present device, the capacitors and / or inductors are uniformly distributed along the third circular conductive loop for tuning the third circular conductive loop to a resonant mode with a sinusoidal current distribution along the third circular conductive loop.

[0023] It is further contemplated that an ultra-high field radio frequency (RF) transmit / receive device includes an RF shield, wherein the RF shield is positioned around a dipole array-based volume coil and at least three circular conductive rings.

[0024] The present invention also provides a magnetic resonance (MR) system, which includes an ultra-high field radio frequency (RF) transmitting / receiving device according to the device described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] These and other aspects of the invention will become apparent and elucidated from the embodiments described below. However, such embodiments do not necessarily represent the full scope of the invention and reference is therefore made to the claims and this document to interpret the scope of the invention.

[0026] In the attached picture:

[0027] Figure 1 A partially cut-away front perspective view of an ultra-high field radio frequency (RF) transmit / receive device according to an embodiment of the present invention is shown;

[0028] 2 shows a schematic diagram of a power splitter and an orthogonal hybrid coupler for driving a dual-port type ultra-high field radio frequency (RF) transmission / reception device according to an embodiment of the present invention;

[0029] Figure 3 A front perspective side view of an ultra-high field radio frequency (RF) transmit / receive device having four electric dipole antennas and three circular conductive rings according to an embodiment of the present invention is shown;

[0030] Figure 4 A partially cut-away front perspective view of a finite-difference time-domain (FDTD) numerical model of an ultra-high-field radio frequency (RF) transmission / reception device according to an embodiment of the present invention is shown, wherein a model head is provided;

[0031] Figure 5 A diagram showing a central transverse slice (S) of a model head and ultra-high field radio frequency (RF) transmit / receive device taken along the third conductive ring of the model of FIG. 2 according to an embodiment of the present invention;

[0032] FIG. 6 shows normalized |B1 for central transverse, sagittal and coronal slices of a human head model acquired using an ultra-high field radio frequency (RF) transmission / reception device with six electric dipole antennas and three circular conductive rings according to an embodiment of the present invention. + |field (i.e., |B1 +| / |B1 + | avg ) of the graph, where |B1 + | avg is the average B1 on the central transverse, sagittal, and coronal slices + |;

[0033] FIG. 7 shows normalized |B1 for central transverse, sagittal and coronal slices of a human head model acquired using an ultra-high field radio frequency (RF) transmission / reception device with four electric dipole antennas and three circular conductive rings according to an embodiment of the present invention. + |Field (i.e. |B1 + | / |B1 + | avg ) of the graph, where |B1 + | avg is the average of the central transverse, sagittal, and coronal slices |B1 + |. DETAILED DESCRIPTION

[0034] Although the invention has been described and illustrated in detail in the drawings and the foregoing description, such description and illustration should be regarded as illustrative or exemplary rather than restrictive; the invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments can be understood and implemented by those skilled in the art in the practice of the invention through a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are described in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference numerals in the claims should not be construed as limiting the scope. Furthermore, for the sake of clarity, not all elements in the drawings have reference numerals.

[0035] Figure 1A partially cut-away front perspective view of an ultra-high field radio frequency (RF) transmit / receive device 1 according to an embodiment of the present invention is shown. The RF coil device 1 can be configured to operate as a transmit / receive volume coil that is compatible with various frequencies and / or field strengths, such as ultra-high field MRI and MRS. The RF coil 1 can include one or more dipole array-based volume coils 2, at least three circular conductive rings 4, 5, 6 radially surrounding the dipole array-based volume coil 2, and an RF shield that can surround the dipole array-based volume coil 2 and at least a portion of at least one of the at least three circular conductive rings 4, 5, 6. There is no physical contact or electronic connection between the dipole array-based volume coil 2 and the at least three circular conductive rings 4, 5, 6. The dipole array-based volume coil 2 includes several straight dipole antennas 3. The dipole array-based volume coil has a length L vc (e.g., the measured length of a straight dipole antenna) and the diameter d vc . The first circular conductive ring 4 is located at one of the opposite axial ends of the dipole array-based volume coil 2, and the second circular conductive ring 5 is located at the opposite end of the dipole array-based volume coil 2. The third circular conductive ring 6 is located between the first circular conductive ring 4 and the second circular conductive ring 5, surrounding the center of the dipole array-based volume coil 2. At least three circular conductive rings 4, 5, 6 are substantially parallel to each other. The three circular conductive rings 4, 5, 6 may include a diameter that may be larger than the diameter of the dipole array-based volume coil 2, so that the circular conductive rings 4, 5, 6 can surround the dipole array-based volume coil 2.

[0036] At least one of the circular conductive rings may include N (where N is an integer greater than 2) ports. For example, if N=4, then one of the circular conductive rings may include four ports, such as port-1, port-2, port-3, and port-4 (usually port-n). Each of these ports may be spatially arranged to be approximately 90° apart from an adjacent port. These ports (port-n) may be arranged so that they can be coupled at corresponding capacitances of corresponding circular conductive rings. The ports (port-n) may be identified by their angular positions with respect to the relative rings. Therefore, for N=4, port-1 to port-4 may be referred to as 0°, 90°, 180°, and 270° ports (p), respectively. For example, if one of the circular conductive rings includes 2 or 4 ports, then these ports may be spatially spaced 90° apart from one or more adjacent ports in azimuth. Each port (port-n) may be connected to an RF controller via a corresponding signal conductor. Therefore, the signal conductor can provide a driving / excitation signal to the corresponding port (port-x), which causes a magnetic resonance excitation effect, and the subsequent magnetic resonance signal is received by the circular conductive ring and provided to the RF controller or further processed, such as for reconstruction, etc.

[0037] The three circular conductive rings 4, 5, 6 can be tuned to the desired resonant frequency using any suitable method. For example, it is contemplated that the circular conductive rings 4, 5, 6 can be tuned by reactive elements, such as capacitive gaps and / or discrete and / or distributed capacitors (both may be referred to as capacitors hereinafter for clarity), by adjusting the width of the circular conductive rings 4, 5, 6, by filling the space between the circular conductive rings 4, 5, 6 and the RF shield 7 with a dielectric material to adjust the diameter of the circular conductive rings 4, 5, 6, by adding inductance in the capacitive gaps, and / or a suitable combination thereof. For example, the circular conductive rings 4, 5, 6 may include a plurality of conductive segments that are capacitively coupled together by capacitors (e.g., formed by capacitive gaps) located between the conductive segments.

[0038] According to embodiments of the present system, the capacitors may be placed at uniform intervals from one another along the circumference of the circular conductive rings 4, 5, 6 so as to be evenly spaced apart. For example, according to some embodiments, if the total number of capacitors M = 16, then the capacitors may be placed at intervals of 360 degrees / (M) = 360 degrees / 16 = 22.5 degrees. The total number of capacitors and / or the capacitance of each of the circular conductive rings 4, 5, 6 may be substantially equal to one another.

[0039] The RF shield 7 can be placed outside the dipole array-based volume coil 2 and at least three circular conductive rings 4, 5, 6, and surround them respectively. The shield can include any suitable RF shield 7, and can have any suitable shape, such as a cylindrical shape, and can be formed of any suitable material, such as thin copper or an equivalent type of shielding material or a material compatible with MRI applications. For example, according to some embodiments, the RF shield 7 can be formed of a conductive mesh, such as a copper mesh, a non-magnetic stainless steel mesh, a segmented copper in a printed circuit board type structure, etc. If necessary, the RF shield 7 can be grounded. According to an embodiment of the present system, the RF shield 7 can be uniformly assembled around the dipole array-based volume coil 2 and / or the at least three circular conductive rings 4, 5, 6, respectively. The main purpose of the RF shield 7 is to reduce the radiation loss of the dipole array-based volume coil 2 and / or the at least three circular conductive rings 4, 5, 6, and to isolate these components from external components of the aperture (such as gradient coils, etc.).

[0040] Figure 1The ultra-high field radio frequency (RF) transmission / reception device 1 proposed in the invention is a transmission / reception (T / R) volume coil for multi-channel ultra-high field MRI. In this example, the ultra-high field radio frequency (RF) transmission / reception device includes a total of eight independent T / R channels. In fact, all straight dipole antennas 3 and at least three circular conductive rings 4, 5, 6 of the dipole array-based volume coil 2 can independently transmit and receive RF signals for use with predefined independent RF T / R channels.

[0041] FIG. 2 shows a schematic diagram of a power splitter 15 and an orthogonal hybrid coupler 17 for driving a dual-port type ultra-high field radio frequency (RF) transmission / reception device 1 according to an embodiment of the present invention.

[0042] In one embodiment as shown in FIG. 2 , Figure 1 The eight-channel ultra-high field radio frequency (RF) coil device 1 in the embodiment includes six dipoles 3 and three circular conductive rings 4, 5, 6, wherein the six dipoles 6 are respectively assigned to the first six transmission channels CH1 to CH6. Transmission channel seven 13 is assigned to both the first circular conductive ring 4 and the second circular conductive ring 5 through a power splitter 15 and a 180° phase shifter, as shown in FIG2A. Channel eight 14 is assigned to the first port and the second port of the third circular conductive ring 6 through an orthogonal hybrid coupler, as shown in FIG2B. The first port and the second port are separated by 90° in azimuth along the third circular conductive ring.

[0043] Figure 3 A front perspective side view of an ultra-high field radio frequency (RF) transmission / reception device 1 having four electric dipole antennas 3 and three circular conductive rings 4, 5, 6 according to an embodiment of the present invention is shown.

[0044] In one embodiment of the device, Figure 1 The eight-channel ultra-high field radio frequency (RF) transmission / reception device in the embodiment includes four straight dipole antennas 3 and three circular conductive rings 4, 5, and 6. The four transmission channels are respectively assigned to the four straight dipole antennas 3. Channel five 19 and channel six 20 are assigned to the first circular conductive ring and the second circular conductive ring. Channel seven is assigned to the first port of the third circular conductive ring, and channel eight is assigned to the second port of the third circular conductive ring.

[0045] Now refer to Figure 4 7C to describe the test (simulation) results, wherein:

[0046] Figure 4 A partially cut-away front perspective view of a finite difference time domain (FDTD) numerical model of an ultra-high field radio frequency (RF) transmission / reception device 1 according to an embodiment of the present invention is shown, wherein a model head 8 is provided; Figure 5 The embodiment according to the present invention is shown along Figure 4 FIG. 6 shows a normalized image of the central transverse, sagittal and coronal slices of a human head model 8 obtained by using an ultra-high field radio frequency (RF) transmitting / receiving device 1 with six electric dipole antennas 3 and three circular conductive rings 4, 5, 6 according to an embodiment of the present invention; FIG. 7 shows a normalized image of the central transverse, sagittal and coronal slices of a human head model 8 obtained by using an ultra-high field radio frequency (RF) transmitting / receiving device 1 with six electric dipole antennas 3 and three circular conductive rings 4, 5, 6 according to an embodiment of the present invention; FIG. 8 shows a normalized image of the central transverse, sagittal and coronal slices of a human head model 8 obtained by using an ultra-high field radio frequency (RF) transmitting / receiving device 1 with six electric dipole antennas 3 and three circular conductive rings 4, 5, 6 according to an embodiment of the present invention; + |field (i.e., |B1 + | / |B1 + | avg ) of the graph, where |B1 + | avg is the average B1 on the central transverse, sagittal, and coronal slices + |; FIG. 7 shows normalized central transverse, sagittal and coronal slices of a human head model 8 acquired using an ultra-high field radio frequency (RF) transmitting / receiving device 1 with four electric dipole antennas 3 and three circular conductive rings 4, 5, 6 according to an embodiment of the present invention | B1 + |Field (i.e. |B1 + | / |B1 + | avg ) of the graph, where |B1 + | avg is the average of the central transverse, sagittal, and coronal slices |B1 + |.

[0047] refer to Figure 4 The RF coil includes a dipole array-based volume coil 2 composed of six dipoles 3, three circular conductive rings 4, 5, 6 radially surrounding the dipole array-based volume coil 2, and a cylindrical RF shield ( Figure 4 ). The RF coil may be carried by the phantom head 8. The six dipoles 3 are arranged in a circular form to form a dipole array-based volume coil 2. The dipole array-based volume coil 2 may have a diameter d of approximately 30 cm. vc , and a length L of approximately 21.5 cm vc Each dipole antenna 3 may have a length of 21.5 cm and a width of 2 cm. RF shield ( Figure 4) may have a diameter of 35 cm and a length of 27.5 cm. The three circular conductive rings 4, 5, 6 may have the same diameter of 31 cm and a width of 1.5 cm. With two inductors symmetrically placed on either side of the dipole antenna 3 and separated by 5.5 cm from each other, each dipole antenna 3 is tuned to have a maximum current in the middle of each dipole antenna 3. With uniformly distributed capacitors, the first conductive ring 4 and the conductive ring 5 are tuned to a resonant mode of uniform current distribution along the rings 4, 5. With uniformly distributed capacitors, the third conductive ring 6 is tuned to a resonant mode of sinusoidal current distribution. For 7 Tesla (7T) proton MRI, the dipole array-based volume coil 2 and the three circular rings 4, 5, 6 may be tuned to 298 MHz. However, other tuning values ​​are also contemplated and may be based on the main magnetic field value of the MRI system. Figure 4 The total number of independent RF transmit channels is limited to 8.

[0048] refer to Figure 5 , showing an embodiment of the present invention along Figure 4 The central transverse slice (S) of the model head and the ultra-high field radio frequency (RF) transmission / reception device 1 is cut out of the third conductive ring 6 of the model. The slice (S) may be located substantially at the middle plane of the dipole array-based volume coil 2. The central transverse slice (S) will now be discussed with reference to FIGS. 6A to 7C. + |Shimming and Figure 4 Slice positions shown. Best | B1 + |Shimming can be performed by independently changing the amplitude and / or phase difference between the eight transmission channels of the volume coil 2 based on the dipole array and the three circular conductive rings 4, 5, 6 to make the selected slice (such as the slice (S) in the current embodiment) |B1 + |This is achieved by minimizing the field standard deviation.

[0049] 6, there is shown the normalized |B1 of the central transverse, sagittal and coronal slices of the human head model obtained by using the ultra-high field radio frequency (RF) transmitting / receiving device 1 with six electric dipole antennas 3 and three circular conductive rings 4, 5, 6 according to an embodiment of the present invention. + |field (i.e., |B1 + | / |B1 + | avg ), where |B1 + | avg is the average of the central transverse, sagittal, and coronal slices |B1 + |. For the central transverse slice, |B1 + |(deviation) is 0.07, |B1 + | max / |B1+ | min is 1.6; for the central sagittal slice, |B1 + |(deviation) is 0.13, |B1 + | max / |B1 + | min is 2.3; for the central coronal slice, |B1 + |(deviation) is 0.12, |B1 + | max / |B1 + | min is 2.4. It can be seen that for improved MR imaging quality at ultra-high fields, |B1 + |B1 after shimming + |The uniformity is uniform enough.

[0050] 7, there is shown a normalized image of the central transverse, sagittal and coronal slices of a human head model acquired by using an ultra-high field radio frequency (RF) transmitting / receiving device 1 with four electric dipole antennas 3 and three circular conductive rings 4, 5, 6 according to an embodiment of the present invention. + |field (i.e., |B1 + | / |B1 + | avg ), where |B1 + | avg is the average of the central transverse, sagittal, and coronal slices |B1 + |. For the central transverse slice, |B1 + |(deviation) is 0.07, |B1 + | max / |B1 + | min is 1.7; for the central sagittal slice, |B1 + |(deviation) is 0.13, |B1 + | max / |B1 + | min is 2.1, and for the central coronal slice, |B1 + |(deviation) is 0.12, |B1 + | max / |B1 + | min In addition, for the ultra-high field radio frequency (RF) transmission / reception device 1 having four electric dipole antennas 3, for the improved MR imaging quality under ultra-high field, | B1 + |B1 after shimming + |The uniformity is uniform enough.

[0051] Reference numerals list

[0052] Radio frequency (RF) transmitting / receiving device 1

[0053] Volume coil based on dipole array 2

[0054] Straight dipole antenna 3

[0055] First conductive ring 4

[0056] Second conductive ring 5

[0057] The third conductive ring 6

[0058] RF Shielding 7

[0059] Check object 8

[0060] First Port 9

[0061] Second port 10

[0062] Channel 5 11

[0063] Channel 6 12

[0064] Channel 7 13

[0065] Channel 8 14

[0066] Power splitter 15

[0067] Phaser 16

[0068] Quadrature Hybrid Coupler 17

[0069] Load 18

[0070] Channel 5 19

[0071] Channel 6 20

[0072] Channel 7 21

[0073] Channel 8 22

Claims

1. An ultra-high field radio frequency transmitting / receiving device for a magnetic resonance system, the ultra-high field radio frequency transmitting / receiving device comprising: A dipole array-based volume coil (2), the dipole array-based volume coil (2) comprising a plurality of straight dipole antennas (3), wherein the straight dipole antennas (3) are parallel to each other; a cylindrical radio frequency shield (7) located around the dipole array-based volume coil and at least three circular conductive rings; The ultra-high field radio frequency transmitting / receiving device also includes: At least three circular conductive rings (4, 5, 6) radially surrounding the dipole array-based volume coil (2), wherein: A first circular conductive ring (4) is located at one of the opposite axial ends of the dipole array-based volume coil (2), A second circular conductive ring (5) is located at opposite axial ends of the dipole array-based volume coil (2), wherein a third circular conductive ring (6) is located between the first circular conductive ring (4) and the second circular conductive ring (5), surrounding the center of the dipole array-based volume coil (2), the first circular conductive ring (4), the second circular conductive ring (5) and the third circular conductive ring (6) being parallel to each other; A plurality of at least two independent transmit / receive RF channels (11, 12, 13, 14) are used to drive the dipole array-based volume coil (2) and the at least three circular conductive rings (4, 5, 6), wherein at least one transmit / receive RF channel is allocated to the dipole array-based volume coil, and corresponding transmit / receive RF channels are allocated to the first circular conductive ring and the second circular conductive ring, respectively, and at least the third circular conductive ring (6) has a plurality of ports (9, 10), wherein one of the transmit / receive RF channels is allocated to the first port and the second port of the third circular conductive ring for applying a set of orthogonal driving signals to the third circular conductive ring.

2. The ultra-high field radio frequency transmitting / receiving device according to claim 1, wherein: At least one transmit / receive radio frequency channel (11, 12, 13, 14) is allocated to each straight dipole antenna (3), one transmit / receive radio frequency channel is allocated to the first circular conductive ring (4) and the second circular conductive ring (5), and one transmit / receive radio frequency channel is allocated to the first port (9) of the third circular conductive ring (6) and the second port (10) of the third circular conductive ring (6).

3. The ultra-high field radio frequency transmitting / receiving device according to claim 2, wherein: The ultra-high field radio frequency transmission / reception device comprises a power splitter (15) and a 180° phase shifter (16), wherein a transmission / reception radio frequency channel (13) allocated to the first circular conductive ring (4) and the second circular conductive ring (5) is allocated to the first circular conductive ring (4) and the second circular conductive ring (5) through the power splitter (15) and the 180° phase shifter (16).

4. The ultra-high field radio frequency transmitting / receiving device according to claim 3, wherein: The ultra-high field radio frequency transmission / reception device comprises an orthogonal hybrid coupler (17), wherein a transmission / reception radio frequency channel (14) allocated to the first port (9) of the third circular conductive ring (6) and the second port (10) of the third circular conductive ring (6) is allocated to the first port (9) of the third circular conductive ring (6) and the second port (10) of the third circular conductive ring (6) through the orthogonal hybrid coupler (17), wherein the first port (9) and the second port (10) are separated by 90° in azimuth along the third circular conductive ring (6).

5. The ultra-high field radio frequency transmitting / receiving device according to claim 1, wherein: At least one transmit / receive RF channel (11, 12, 13, 14) is allocated to each straight dipole antenna (3), one transmit / receive RF channel (19) is allocated to the first circular conductive ring (4), one transmit / receive RF channel (20) is allocated to the second circular conductive ring (5), one transmit / receive RF channel (21) is allocated to the first port (9) of the third circular conductive ring (6), and one transmit / receive RF channel (22) is allocated to the second port (10) of the third circular conductive ring (6).

6. The ultra-high field radio frequency transmitting / receiving device according to any one of claims 1 to 5, wherein: The straight dipole antenna (3) and the circular conductive ring (4, 5, 6) are tuned to the same magnetic resonance imaging resonant frequency.

7. The ultra-high field radio frequency transmitting / receiving device according to any one of claims 1 to 5, wherein: Capacitors and / or inductors are placed in each straight dipole antenna (3) to tune the straight dipole antenna (3) so that a maximum current flows in the middle of each straight dipole antenna (3).

8. The ultra-high field radio frequency transmitting / receiving device according to any one of claims 1 to 5, wherein: Capacitors and / or inductors are evenly distributed along the first circular conductive ring (4) and along the second circular conductive ring (5) for tuning the first circular conductive ring (4) and the second circular conductive ring (5) to a resonant mode having an even current distribution along the first circular conductive ring (4) and along the second circular conductive ring (5).

9. The ultra-high field radio frequency transmitting / receiving device according to any one of claims 1 to 5, wherein: Capacitors and / or inductors are evenly distributed along the third circular conductive ring (6) for tuning the third circular conductive ring (6) to a resonant mode with a sinusoidal current distribution along the third circular conductive ring (6).

10. A magnetic resonance system, comprising the ultra-high field radio frequency transmitting / receiving device (1) according to any one of claims 1 to 9.

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