RF coil

Abstract

To provide an RF coil having an excellent high frequency characteristic and flexibility.SOLUTION: RF coils comprise three or more electrical conductors that form an RF coil element. The electrical conductors are spatially in parallel with one another. Along a length of the RF coil element, the electrical conductors are separated from one another by respective distances and by one or more dielectric materials. Each of the electrical conductors has a cross section perpendicular to a direction of the length, the cross section having a shape isotropic with respect to an axial center of the electrical conductor.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] The embodiments disclosed in this specification and in the drawings relate to RF coils. [Background technology]

[0002] MRI is an imaging modality that uses magnetic fields and RF energy to create images of the interior of an object (e.g., a human patient) without the use of X-rays or other ionizing radiation. MRI scanners include a main magnet that generates a static magnetic field (B0 field) that polarizes the object. As pulses of RF energy are transmitted through the object, the RF pulses may also produce other magnetic fields (B1 field). MRI scanners may use B0 shimming coils to improve the static magnetic field homogeneity and B1 shimming techniques to improve the homogeneity of the RF transmit field. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 6,980,000 [Patent Document 2] U.S. Patent No. 9,678,180 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to provide an RF coil having good high frequency characteristics and flexibility. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0005] An RF coil according to an embodiment comprises three or more conductors forming an RF coil element, the conductors being spatially parallel to one another, the conductors being electrically separated from one another by discrete distances and one or more dielectric materials along the length of the RF coil element, and the shape of a cross section perpendicular to the length of each of the conductors being isotropic with respect to the axis of each of the conductors. [Brief description of the drawings]

[0006] [Figure 1A] FIG. 1A illustrates an exemplary embodiment of a medical imaging system. [Figure 1B] FIG. 1B shows a schematic cross-sectional view of the exemplary embodiment of the MRI apparatus shown in FIG. 1A along line AA. [Figure 2A] FIG. 2A illustrates an exemplary embodiment of a radio frequency ("RF") coil. [Figure 2B] FIG. 2B shows a cross-sectional view of the RF coil shown in FIG. 2A taken along line AA. [Figure 2C] FIG. 2C shows one area of ​​overlapping capacitance of the RF coil of FIG. 2A. [Figure 2D] FIG. 2D illustrates connections between members of the RF coil of FIG. 2A in another exemplary embodiment. [Figure 3A] FIG. 3A illustrates an exemplary embodiment of an RF coil. [Figure 3B] FIG. 3B shows a cross-sectional view of the RF coil shown in FIG. 3A taken along line AA. [Figure 3C] FIG. 3C illustrates an exemplary embodiment of a circuit for an RF coil. [Figure 4A] FIG. 4A illustrates an exemplary embodiment of an RF coil. [Figure 4B] FIG. 4B shows a cross-sectional view of the RF coil shown in FIG. 4A taken along line AA. [Figure 4C] FIG. 4C shows a cross-sectional view along line AA of the RF coil shown in FIG. 4A in another embodiment. [Figure 5A]FIG. 5A illustrates an exemplary embodiment of an RF coil. [Figure 5B] FIG. 5B shows a cross-sectional view of the RF coil shown in FIG. 5A taken along line AA. [Figure 6] FIG. 6 shows an exemplary embodiment of an RF coil. [Figure 7A] FIG. 7A illustrates an exemplary embodiment of an RF coil. [Figure 7B] FIG. 7B shows a cross-sectional view of the RF coil shown in FIG. 7A taken along line AA. [Figure 8A] FIG. 8A illustrates an exemplary embodiment of an RF coil. [Figure 8B] FIG. 8B shows a cross-sectional view of the RF coil shown in FIG. 8A taken along line AA. [Figure 9A] FIG. 9A illustrates an exemplary embodiment of an RF coil. [Figure 9B] FIG. 9B shows a cross-sectional view of the RF coil shown in FIG. 9A taken along line AA. [Figure 9C] FIG. 9C shows a cross-sectional view of the RF coil of the alternative embodiment of FIG. 9A taken along line AA. [Figure 9D] FIG. 9D shows a cross-sectional view of the RF coil along line AA in the alternative embodiment of FIG. 9A. [Figure 10A] FIG. 10A illustrates an exemplary embodiment of an RF coil. [Figure 10B] FIG. 10B shows a cross-sectional view of the RF coil shown in FIG. 10A taken along line AA. [Figure 10C] FIG. 10C shows a cross-sectional view of the RF coil shown in FIG. 10A taken along line BB. [Figure 11A] FIG. 11A illustrates an exemplary embodiment of an RF coil. [Figure 11B] FIG. 11B shows a cross-sectional view of the RF coil shown in FIG. 11A taken along line AA. [Figure 11C] FIG. 11C shows a cross-sectional view of the RF coil shown in FIG. 11A taken along line BB. [Figure 12A] FIG. 12A illustrates an exemplary embodiment of an RF coil. [Figure 12B] FIG. 12B shows a cross-sectional view of the RF coil shown in FIG. 12A taken along line AA. [Figure 12C] FIG. 12C shows a cross-sectional view of the RF coil shown in FIG. 12A taken along line BB. [Figure 13A] FIG. 13A illustrates an exemplary embodiment of an RF coil. [Figure 13B] FIG. 13B shows a cross-sectional view of the RF coil shown in FIG. 13A taken along line AA. [Figure 13C] FIG. 13C shows a cross-sectional view of the RF coil shown in FIG. 13A taken along line BB. [Figure 14A] FIG. 14A shows an exemplary embodiment of an RF coil shape. [Figure 14B] FIG. 14B illustrates an exemplary embodiment of an RF coil shape. [Figure 14C] FIG. 14C illustrates an exemplary embodiment of an RF coil shape. [Figure 14D] FIG. 14D illustrates an exemplary embodiment of an RF coil shape. [Figure 14E] FIG. 14E illustrates an exemplary embodiment of an RF coil shape. [Figure 14F] FIG. 14F illustrates an exemplary embodiment of an RF coil shape. [Figure 14G] FIG. 14G illustrates an exemplary embodiment of an RF coil shape. [Figure 14H] FIG. 14H shows an exemplary embodiment of an RF coil shape. [Figure 14I] FIG. 14I illustrates an exemplary embodiment of an RF coil shape. [Figure 15A] FIG. 15A illustrates an exemplary embodiment of an RF coil array. [Figure 15B] FIG. 15B illustrates an exemplary embodiment of an RF coil array. [Figure 15C] FIG. 15C illustrates an exemplary embodiment of an RF coil array. [Figure 15D] FIG. 15D illustrates an exemplary embodiment of an RF coil array. [Figure 15E]FIG. 15E illustrates an exemplary embodiment of an RF coil array. [Figure 15F] FIG. 15F illustrates an exemplary embodiment of an RF coil array. [Figure 15G] FIG. 15G illustrates an exemplary embodiment of an RF coil array. [Figure 15H] FIG. 15H illustrates an exemplary embodiment of an RF coil array. [Figure 16A] FIG. 16A illustrates an exemplary embodiment of an RF coil. [Figure 16B] FIG. 16B shows the capacitance between the conductors shown in FIG. 16A. [Figure 17A] FIG. 17A illustrates an exemplary embodiment of an RF coil. [Figure 17B] FIG. 17B shows the capacitance between the conductors shown in FIG. 17A. [Figure 18A] FIG. 18A illustrates an exemplary embodiment of an RF coil. [Figure 18B] FIG. 18B illustrates an exemplary embodiment of an RF coil. [Figure 19A] FIG. 19A illustrates an exemplary embodiment of an RF coil. [Figure 19B] FIG. 19B illustrates an exemplary embodiment of an RF coil. [Figure 20] FIG. 20 shows an exemplary embodiment of an RF coil. [Figure 21A] FIG. 21A illustrates an exemplary embodiment of an RF coil. [Figure 21B] FIG. 21B illustrates an exemplary embodiment of a matching and decoupling circuit. [Figure 22A] FIG. 22A shows an exemplary embodiment of an RF coil. [Figure 22B] FIG. 22B illustrates an exemplary embodiment of a matching and decoupling circuit. [Diagram 23] FIG. 23 shows an exemplary embodiment of an RF coil. [Figure 24] FIG. 24 shows an exemplary embodiment of an RF coil. [Diagram 25] FIG. 25 shows an exemplary embodiment of an RF coil. [Figure 26A] FIG. 26A illustrates an exemplary embodiment of a cross-sectional view of an RF coil. [Figure 26B] FIG. 26B illustrates an exemplary embodiment of a cross-sectional view of an RF coil. [Figure 26C] FIG. 26C illustrates an exemplary embodiment of a cross-sectional view of an RF coil. [Figure 26D] FIG. 26D illustrates an exemplary embodiment of a cross-sectional view of an RF coil. [Figure 26E] FIG. 26E illustrates an exemplary embodiment of a cross-sectional view of an RF coil. [Figure 26F] FIG. 26F illustrates an exemplary embodiment of a cross-sectional view of an RF coil. [Figure 26G] FIG. 26G illustrates an exemplary embodiment of a cross-sectional view of an RF coil. [Fig. 26H] FIG. 26H illustrates an exemplary embodiment of a cross-sectional view of an RF coil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The following paragraphs describe embodiments. Other embodiments may include alternatives, equivalents, and variations. Also, the illustrated embodiments may include some novel features, and certain features may not be required in some embodiments of the devices, systems, and methods described herein.

[0008] 1A illustrates an exemplary embodiment of a medical imaging system 10. The medical imaging system 10 includes at least one magnetic resonance imaging (MRI) device 100, one or more image generating devices 110, each of which is a specially configured computing device (e.g., a specially configured desktop computer, a specially configured laptop computer, a specially configured server), and a display device 120.

[0009] The MRI device 100 is configured to scan a region (e.g., an area, volume, slice) of an object (e.g., a patient) using magnetic resonance imaging to obtain scan data. One or more image generating devices 110 obtain the scan data from the MRI device 100 and generate an image of the region of the object based on the scan data. After the one or more image generating devices 110 generate the images, the one or more image generating devices 110 send the images to a display device 120 that displays the images.

[0010] FIG. 1B shows a schematic cross-sectional view of an exemplary embodiment of the MRI device 100 shown in FIG. 1A along line AA. The MRI device 100 contains a main magnet 102 that generates a static magnetic field (B0 field). The main magnet 102 is hollow and cylindrical. The MRI device 100 also contains a gradient coil 103 and may contain one or more RF whole-body coils 104. The MRI device 100 may contain the gradient coil 103 and the RF whole-body coil 104 (e.g., on the inner circumference of the main magnet 102). In addition to the RF whole-body coil 104 included in the MRI device 100, one or more RF coils 130 (e.g., phased array coils, surface coils) may be contained in a separate coil containment device 105 or a housing such as a blanket, cover, or shield placed on the patient. The MRI device 100 or another specially configured computing device may act as a control device for the RF coils 130.

[0011] The RF coil includes an RF transmit coil, an RF receive coil, and an RF transmit / receive coil. The RF transmit coil generates RF pulses that generate a B1 magnetic field perpendicular to the B0 magnetic field, rotating the net magnetization away from alignment with the B0 magnetic field, resulting in a transverse precessing magnetization. The RF transmit coil generates a pulse at a Larmor frequency ω r The B1 field may be oscillated at a Larmor frequency ω resulting in a precessing magnetization that generates a transverse magnetic field. rdepends on the mass of the precessing system (e.g., the atomic nuclei of the material that makes up the object being scanned) and on the strength of the B0 magnetic field.

[0012] The RF receive coil detects the precessional magnetization by the B1 magnetic field via electromagnetic induction which generates an induced electromotive force (EMF). The detected induced EMF may be used as the scan data or the scan data may be different based on the detected induced EMF. Also, the RF transmit / receive coil combines the functions of the RF transmit coil and the RF receive coil.

[0013] RF receive coils, RF transmit coils, and RF transmit / receive coils are resonant circuits (e.g., LC resonant circuits) with tuned electrical components. A tuned RF coil has a capacitance (C) (and sometimes an inductance (L) as well as a capacitance) such that the resonant frequency of the RF coil matches a desired frequency (e.g., the frequency of nuclear magnetic resonance of spins in the material that makes up the patient's tissue). At that resonant frequency, small external perturbations due to precessional magnetization produce a large response from the RF coil. RF coils include three or more electrical conductors that form an RF coil element.

[0014] FIG. 2A shows an exemplary embodiment of an RF coil. The RF coil 230 comprises three dielectric coated conductors 231A-C (e.g., coated conductors) that constitute an RF coil element. Each dielectric coated conductor 231A-C comprises an individual electrical conductor (e.g., a transmission line). Thus, the RF coil 230 comprises three electrical conductors 232A-C (collectively referred to as "conductors 232") that are arranged to be locally parallel (or such that the distance between the two closest parts of two conductors is constant or nearly constant over the length of the conductors 232) and to form a closed RF loop. That is, the conductors 232 are spatially parallel to each other. For example, the conductors 232 may be copper wires, one or more copper layers on the top or bottom surface of a flexible PCB substrate, one or more copper layers sandwiched between thin layers of polyimide or dielectric material, copper wiring, or other conductive materials. In this and other embodiments described herein, at least some of the gauges (cross-sectional diameters) of the conductors 232 may be the same, or the gauges may all be different from one another, and the conductors 232 may be composed of multiple smaller conductors (e.g., multiple wires twisted together).

[0015] In this embodiment, each conductor 232 is covered (e.g., jacketed or surrounded) by a respective dielectric material 234A-C (collectively referred to as "dielectric material 234"). That is, the conductors 232 are electrically separated from each other by a respective plurality of distances and one or more dielectric materials along the length (length direction) of the RF coil element. At least some of the first dielectric material 234A, the second dielectric material 234B, and the third dielectric material 234C may be the same dielectric material, or may all be different from each other. FIG. 2B shows a cross-sectional view of the RF coil 230 shown in FIG. 2A taken along line AA. As shown in FIG. 2B, the shape of the cross section perpendicular to the length direction of each conductor is isotropic with respect to the axis of each conductor. That is, the RF coil element is formed by a structure that is isotropic with respect to its own axis. Therefore, the RF coil element having the conductor has flexibility that allows it to be bent in any direction. In other words, the RF coil element is formed by a structure that can tolerate bending in any direction.

[0016] The ends of the conductor 232 are coupled (e.g., connected) to one or more of the B0 shimming circuit 241, the B1 shimming circuit 242, the matching and decoupling circuit 243, and the at least one capacitor 244. For example, in an RF coil, when the three or more conductors include a first conductor, a second conductor, and a third conductor, the RF coil includes a first shimming circuit connected to the first conductor and a second shimming circuit connected to the second conductor. For example, when the first shimming circuit is the B0 shimming circuit 241, the second shimming circuit is the B1 shimming circuit 242. An exemplary embodiment of the RF coil 230 has only a single breakpoint capacitor 244. In this embodiment, the first conductor 232A has (i) a first end that connects to the capacitor 244 and the matching and decoupling circuit 243, and (ii) a second end that connects to the B1 shimming circuit 242. The second conductor 232B has (i) a first end that connects to the B0 shimming circuit 241 and (ii) a second end that connects to the B0 shimming circuit 241. The third conductor 232C has (i) a first end that connects to the B1 shimming circuit 242 and (ii) a second end that connects to the capacitor 244 and the matching and decoupling circuit 243.

[0017] The dielectric material 234 maintains electrical separation of the conductors 232 along the length of the RF coil 230, but the conductors 232 have overlapping capacitance. For example, FIG. 2C shows one area of ​​overlapping capacitance of the RF coil 230 of FIG. 2A. The first conductor 232A is separated from the second conductor 232B by the dielectric material and overlaps the second conductor 232B along the length of the RF coil 230 (e.g., the circumference of the RF coil 230, the outer periphery of the RF coil 230), so that the first conductor 232A and the second conductor 232B create overlapping capacitance in the overlapping area 239. The overlapping capacitance between the conductors 232 can act as one or more additional breakpoint capacitors along the length of the RF coil 230.

[0018] radius r a of wire A and radius r bIf wire A and wire B are parallel and separated by a distance D, then the capacitance C between wire A and wire B can be written as:

number

number

[0019] Parameters of the RF coil 230, the first conductor 232A, the second conductor 232B, and the dielectric material 234 may be selected to tune the RF coil 230 by configuring the overlap capacitance between the conductors 232. The parameters may include, for example, the size (e.g., diameter) of the RF coil 230, the shape of the RF coil 230, the distance between the conductors 232, the material from which the conductors 232 are made, the cross-sectional diameter (gauge) of the conductors 232, the length of the conductors 232, the length of the overlap of the conductors 232, the material from which the dielectric material 234 is made, the thickness of the dielectric material 234, and the capacitance of the capacitor 244.

[0020] A switching circuit (e.g., a switching circuit of a controller) can enable or otherwise activate the B0 shimming circuit 241, the B1 shimming circuit 242, and the matching and decoupling circuit 243. When active (e.g., when providing a current or voltage to the RF coil 230), the B0 shimming circuit 241 causes the RF coil 230 to generate a magnetic field that compensates for variances in the B0 magnetic field. When active, the B1 shimming circuit 242 causes the RF coil 230 to perform a B1 shim. Additionally, some embodiments of the RF coil 230 and other RF coils described herein do not include the B0 shimming circuit 241, do not include the B1 shimming circuit 242, or do not include either the B0 shimming circuit 241 or the B1 shimming circuit 242.

[0021] Also, when active, some embodiments of the matching and decoupling circuitry 243 cause the RF coil to function as one or more of an RF transmit coil, an RF receive coil, and an RF transmit / receive coil. Furthermore, some embodiments of the RF coil 230 and other RF coils described herein are configured to function only as a transmit coil, and some embodiments of the RF coil 230 and other RF coils described herein are configured to function only as a receive coil. The matching and decoupling circuitry 243 may be used for impedance matching or noise matching of the RF coil 230 to other circuits (e.g., amplifiers such as low noise amplifiers). Also, in an array of RF coils 230 (e.g., the arrays shown in Figs. 15A-15H), the matching and decoupling circuitry 243 decouples (e.g., reduces coupling due to mutual inductance) the RF coils 230 of the array.

[0022] Figure 2D shows the connections between the members of the RF coil of Figure 2A in another exemplary embodiment, in which one side of the capacitor 244 connects to both the first conductor 232A and the second conductor 232B, and the other side of the capacitor 244 connects only to the third conductor 232C.

[0023] The RF coil may also have other configurations as shown in the following embodiments.

[0024] Figure 3A shows an exemplary embodiment of an RF coil. Figure 3B shows a cross-sectional view of the RF coil shown in Figure 3A along line AA. The RF coil 330 forms a loop (like the RF coil 23 in Figure 2A), but in Figure 3A the opposite half of the RF coil 330 from the capacitor 344 is not shown.

[0025] This embodiment is similar to the embodiment shown in Figure 2A, but the dielectric covered conductors 331A-C are twisted (e.g., triple helix) or otherwise twisted, resulting in a different cross-sectional view of the RF coil 330. In some embodiments of the RF coil shown in Figure 3A, the dielectric covered conductors 331A-C are not twisted, but have a cross-sectional view similar or the same as the cross-sectional view shown in Figure 3B.

[0026] The twisting of the dielectric covered conductors 331A-C is also a parameter that can be adjusted to tune the RF coil 330. The dielectric covered conductors 331A-C comprise conductors 332A-C and dielectric materials 334A-C, respectively. At least some of the dielectric materials 334A-C may be the same, or all may be different. Although the conductors 332A-C are twisted together, the distance between the two closest portions of any two of the conductors 332A-C may be constant or approximately constant over the length of the conductors 332A-C.

[0027] The ends of the conductors 332A-C are connected to one or more of the B0 shimming circuit 341, the B1 shimming circuit 342, the matching and decoupling circuit 343, and the capacitor 344. In this embodiment, the first conductor 332A has (i) a first end connected to the capacitor 344 and the matching and decoupling circuit 343, and (ii) a second end connected to the B1 shimming circuit 342. The second conductor 332B has (i) a first end connected to the B1 shimming circuit 342, and (ii) a second end connected to the capacitor 344 and the matching and decoupling circuit 343. The third conductor 332C has (i) a first end connected to the B0 shimming circuit 341, and (ii) a second end connected to the B0 shimming circuit 341.

[0028] Also, other embodiments of the RF coil 330 may have different configurations of the capacitor 344 and the matching and decoupling circuit 343, as shown in box 349. Figure 3C shows an exemplary embodiment of the circuitry of an RF coil. This circuitry shows another embodiment of the circuitry shown in box 349. This embodiment includes a decoupling or tuning circuit 345 that is separate from the matching network 346 that includes the matching circuit. This embodiment also includes two capacitors 344A-B. Moreover, this embodiment of the circuitry shown in box 349 may be used with other embodiments of the RF coil 330 (e.g., other embodiments described herein).

[0029] Additionally, in this and other embodiments described herein, the B0 shimming circuit 341, the B1 shimming circuit 342, and the matching and decoupling circuit 343 are coupled to a controller (e.g., an MRI device, a specially configured computing device) that controls their operation.

[0030] FIG. 4A shows an exemplary embodiment of an RF coil, and FIG. 4B shows a cross-sectional view of the RF coil shown in FIG. 4A along line AA. The RF coil 430 includes two dielectric covered conductors 431B-C and another conductor 432A that is not covered by a dielectric. The two dielectric covered conductors 431B-C and the other conductor 432A form an RF coil element. Each of the dielectric covered conductors 431B-C includes conductors 432B-C and dielectric materials 434B-C, respectively. The dielectric materials 434B-C may be the same or different from each other. Thus, the RF coil 430 includes three conductors 432A-C that form a closed RF loop.

[0031] One of the conductors 432B has an unconnected end 433B (eg, a floating end). The length of the conductor 432B with the unconnected end 433B is adjustable, and this adjustment can be used to tune the RF coil 430.

[0032] The other ends of the conductors 432A-C are connected to one or more of the B0 shimming circuit 441, the B1 shimming circuit 442, the matching and decoupling circuit 443, and the capacitor 444. In this embodiment, the first conductor 432A has (i) a first end connected to the B1 shimming circuit 442, and (ii) a second end connected to the capacitor 444 and the matching and decoupling circuit 443. The second conductor 432B has (i) a first end connected to the capacitor 444 and the matching and decoupling circuit 443, and (ii) a non-connected end 433B. The third conductor 432C has (i) a first end connected to the B0 shimming circuit 441, and (ii) a second end connected to the B0 shimming circuit 441 and the B1 shimming circuit 442.

[0033] Fig. 4C shows a cross-sectional view of the RF coil shown in Fig. 4A along line AA in another embodiment, in which the conductor 432 not covered by a dielectric is positioned at the same distance or approximately the same distance as the other two conductors 432.

[0034] FIG. 5A shows an exemplary embodiment of an RF coil, and FIG. 5B shows a cross-sectional view of the RF coil shown in FIG. 5A along line AA. The RF coil 530 includes three dielectric covered conductors including a first dielectric covered conductor 531A, a second dielectric covered conductor 531B, and a third dielectric covered conductor 531C (collectively referred to as "dielectric covered conductor 531") constituting an RF coil element. The dielectric covered conductor 531 is arranged in a twinax structure. For example, one of the three or more conductors (conductor 532A) is formed by braiding a linear conductor such as copper wire, iron wire, or aluminum wire into a mesh shape, and the braid surrounds a dielectric material (second dielectric covered conductor 531B, third dielectric covered conductor 531C) that covers the non-braided conductors (conductor 532B, conductor 532C) among the three or more conductors. Thus, the first dielectric covered conductor 531A includes a conductor 532A (for example, a braided weave) surrounding the second dielectric covered conductor 531B and the third dielectric covered conductor 531C. The second dielectric covered conductor 531B and the third dielectric covered conductor 531C also include conductors 532B-C surrounded by dielectric materials 534B-C, respectively. At least some of the first dielectric material 534A, the second dielectric material 534B, and the third dielectric material 534C may be the same dielectric material, or all may be different. Thus, the RF coil 530 includes conductors 532A-C forming a closed RF loop.

[0035] The ends of the conductors 532A-C are connected to one or more of the B0 shimming circuit 541, the B1 shimming circuit 542, the matching and decoupling circuit 543, and the capacitor 544. In this embodiment, the first conductor 532A has (i) a first end connected to the B0 shimming circuit 541, and (ii) a second end connected to the B0 shimming circuit 541. The second conductor 532B has (i) a first end connected to the B1 shimming circuit 542, and (ii) a second end connected to the capacitor 544 and the matching and decoupling circuit 543. The third conductor 532C has (i) a first end connected to the capacitor 544 and the matching and decoupling circuit 543, and (ii) a second end connected to the B1 shimming circuit 542.

[0036] FIG. 6 shows an exemplary embodiment of an RF coil. As shown in FIG. 5A, the RF coil 630 includes three dielectric covered conductors 631 including a first dielectric covered conductor 631A, a second dielectric covered conductor 631B, and a third dielectric covered conductor 631C arranged in a biaxial configuration to configure an RF coil element. Thus, the first dielectric covered conductor 631A includes a conductor 632A surrounding the second dielectric covered conductor 631B and the third dielectric covered conductor 631C. That is, the conductor 632A is configured with a braid, and the braid surrounds the second dielectric covered conductor 631B and the third dielectric covered conductor 631C, which respectively cover two non-formed conductors (632B, 632C). In addition, the second dielectric covered conductor 631B and the third dielectric covered conductor 631C include conductors 632B-C, respectively. However, two of the conductors 632B-C have non-contact ends 633B-C, respectively.

[0037] The other ends of the conductors 632A-C are respectively connected to one or more of the B0 shimming circuit 641, the B1 shimming circuit 642, the matching and decoupling circuit 643, and the capacitor 644. In this embodiment, the first conductor 632A has (i) a first end connected to the B0 shimming circuit 641, and (ii) a second end connected to the B0 shimming circuit 641, the B1 shimming circuit 642, the capacitor 644, and the matching and decoupling circuit 643. The second conductor 632B has (i) a first end connected to the B1 shimming circuit 642, and (ii) a non-connected end 633B. The third conductor 632C has (i) a first end connected to the capacitor 644 and the matching and decoupling circuit 643, and (ii) a non-connected end 633C.

[0038] FIG. 7A shows an exemplary embodiment of an RF coil, and FIG. 7B shows a cross-sectional view of the RF coil shown in FIG. 7A along line AA. The RF coil 730 includes three dielectric covered conductors (collectively referred to as "dielectric covered conductors 731") including a first dielectric covered conductor 731A, a second dielectric covered conductor 731B, and a third dielectric covered conductor 731C. The dielectric covered conductors 731 are arranged in a triaxial configuration to form an RF coil element. For example, two of the three or more conductors (the first conductor 732A and the second conductor 732B) are formed by braiding a wire-shaped conductor such as a copper wire, an iron wire, or an aluminum wire into a mesh shape. At this time, one of the two conductors formed by braiding (the second conductor 732B) surrounds a dielectric material (the third dielectric material 734C) that covers the conductor (the third conductor 732C) among the three or more conductors that is not braided. The other of the two conductors formed by braiding (first conductor 732A) surrounds the dielectric material (second dielectric material 734B) that covers the one conductor (second conductor 732B). Thus, the first dielectric covered conductor 731A includes the first conductor 732A that surrounds the second dielectric covered conductor 731B and the third dielectric covered conductor 731C, and the second dielectric covered conductor 731B includes the second conductor 732B that surrounds the third dielectric covered conductor 731C. Thus, the RF coil 730 includes three conductors 732A-C that form a closed RF loop, and the three conductors 732A-C are directly surrounded by the dielectric materials 734A-C, respectively. At least some of the first dielectric material 734A, the second dielectric material 734B, and the third dielectric material 734C may be the same dielectric material, or all may be different.

[0039] In this embodiment, the second conductor 732B has a non-connected end 733B, and the third conductor 732C has a non-connected end 733C. The other ends of the conductors 732A-C are respectively connected to one or more of the B0 shimming circuit 741, the B1 shimming circuit 742, the matching and decoupling circuit 743, and the capacitor 744. In this embodiment, the first conductor 732A has (i) a first end connected to the B0 shimming circuit 741, the capacitor 744, and the matching and decoupling circuit 743, and (ii) a second end connected to the B0 shimming circuit 741 and the B1 shimming circuit 742. The second conductor 732B has (i) a first end connected to the capacitor 744 and the matching and decoupling circuit 743, and (ii) a non-contact end 733B. The third electrical conductor 732C has (i) a first end that connects to the B1 shimming circuit 742, and (ii) a non-contact end 733C.

[0040] FIG. 8A shows an exemplary embodiment of an RF coil, and FIG. 8B shows a cross-sectional view of the RF coil shown in FIG. 8A along line AA. The RF coil 830 comprises three dielectric covered conductors (collectively referred to as "dielectric covered conductors 831"), including a first dielectric covered conductor 831A, a second dielectric covered conductor 831B, and a third dielectric covered conductor 831C, constituting an RF coil element. The second dielectric covered conductor 831B and the third dielectric covered conductor 831C are arranged in a coaxial configuration. The first dielectric covered conductor 831A comprises a first conductor 832A, and the second dielectric covered conductor 831B comprises a second conductor 832B surrounding the third dielectric covered conductor 831C. Also, the third dielectric covered conductor 831C comprises a third conductor 832C. Thus, the RF coil 830 comprises three conductors 832A-C, and the three conductors 832A-C are directly surrounded by dielectric materials 834A-C, respectively. At least some of the first dielectric material 834A, the second dielectric material 834B, and the third dielectric material 834C may be the same dielectric material, or all may be different.

[0041] In this embodiment, the first conductor 832A has an unconnected end 833A, and the third conductor 832C has an unconnected end 833C. The other ends of the conductors 832A-C are respectively connected to one or more of a B0 shimming circuit 841, a B1 shimming circuit 842, a matching and decoupling circuit 843, and a capacitor 844. In this embodiment, the first conductor 832A has (i) a first end connected to the capacitor 844 and the matching and decoupling circuit 843, and (ii) an unconnected end 833A. The second conductor 832B has (i) a first end connected to the B0 shimming circuit 841, the capacitor 844, and the matching and decoupling circuit 843, and (ii) a second end connected to the B0 shimming circuit 841 and the B1 shimming circuit 842. The third electrical conductor 832C has (i) a first end that connects to the B1 shimming circuit 842 and (ii) a non-contact end 833C.

[0042] Some embodiments of the RF coil include more than three conductors. For example, FIG. 9A shows an exemplary embodiment of an RF coil, and FIG. 9B shows a cross-sectional view of the RF coil shown in FIG. 9A along line AA. The RF coil 930 includes four dielectric covered conductors (collectively referred to as "dielectric covered conductors 931"), including a first dielectric covered conductor 931A, a second dielectric covered conductor 931B, a third dielectric covered conductor 931C, and a fourth dielectric covered conductor 931D, constituting an RF coil element. The first dielectric covered conductor 931A includes a first conductor 932A, the second dielectric covered conductor 931B includes a second conductor 932B, the third dielectric covered conductor 931C includes a third conductor 932C, and the fourth dielectric covered conductor 931D includes a fourth conductor 932D. Thus, the RF coil 930 includes four conductors 932A-D, and the four conductors 932A-D are covered by dielectric materials 934A-D, respectively. At least some of the first dielectric material 934A, the second dielectric material 934B, the third dielectric material 934C, and the fourth dielectric material 934D may be the same dielectric material or may all be different.

[0043] In this embodiment, one end of the second conductor 932B is connected to one end of the fourth conductor 932D. The other ends of the conductors 932A-D are connected to one or more of the B0 shimming circuit 941, the B1 shimming circuit 942, the matching and decoupling circuit 943, and the capacitor 944. In this embodiment, the first conductor 932A has (i) a first end that is connected to the B1 shimming circuit 942, and (ii) a second end that is connected to the capacitor 944 and the matching and decoupling circuit 943. The second conductor 932B has (i) a first end that is connected to the second end of the fourth conductor 932D, and (ii) a second end that is connected to the B0 shimming circuit 941. The third conductor 932C has (i) a first end that is connected to the capacitor 944 and the matching and decoupling circuit 943, and (ii) a second end that is connected to the B1 shimming circuit 942. The fourth conductor 932D has (i) a first end that connects to the B0 shimming circuit 941 and (ii) a second end that connects to the first end of the second conductor 932B.

[0044] 9B, the dielectric covered conductors 931 are locally parallel and are arranged in a line in cross section.

[0045] Figure 9C shows a cross-sectional view of an alternative embodiment of an RF coil of Figure 9A along line AA. In this embodiment, the four dielectric covered conductors 931 are arranged such that the first conductor 932A and the fourth conductor 932D are closer together than the first conductor 932A and the fourth conductor 932D in Figure 9B. Also, in the cross-sectional view, the dielectric covered conductors 931 are arranged to form a diamond shape.

[0046] The four dielectric covered conductors 931A-D may be arranged in other ways. For example, FIG. 9D shows a cross-sectional view of the RF coil according to another embodiment of FIG. 9A taken along line AA. In the cross-sectional view, the dielectric covered conductors 931 are arranged such that the second dielectric covered conductor 931B, the third dielectric covered conductor 931C, and the fourth dielectric covered conductor 931D form a triangle. Also, the second dielectric covered conductor 931B is closest to the first dielectric covered conductor 931A. Thus, in the cross-sectional view, the dielectric covered conductors 931 are arranged in a manner such that the second dielectric covered conductor 931B, the third dielectric covered conductor 931C, and the fourth dielectric covered conductor 931D form a triangle.

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[0047] FIG. 10A shows an exemplary embodiment of an RF coil, FIG. 10B shows a cross-sectional view of the RF coil shown in FIG. 10A taken along line AA, and FIG. 10C shows a cross-sectional view of the RF coil shown in FIG. 10A taken along line BB. The RF coil 1030 includes three dielectric covered conductors, including a first dielectric covered conductor 1031A, a second dielectric covered conductor 1031B, and a third dielectric covered conductor 1031C, constituting an RF coil. The first dielectric covered conductor 1031A includes a first conductor 1032A, the second dielectric covered conductor 1031B includes a second conductor 1032B, and the third dielectric covered conductor 1031C includes a third conductor 1032C. Thus, the RF coil 1030 includes three conductors 1032A-C, and the three conductors 1032A-C are covered by dielectric materials 1034A-C, respectively. At least some of the first dielectric material 1034A, the second dielectric material 1034B, and the third dielectric material 1034C may be the same dielectric material, or all may be different.

[0048] In this embodiment, the second conductors 1032B and the third conductors 1032C do not extend across the entire length (e.g., circumference, perimeter) of the RF coil 1030 and do not overlap one another. Instead, in this embodiment, the second conductors 1032B and the third conductors 1032C each extend across approximately half the length of the RF coil 1030. However, in some embodiments, the second conductors 1032B and the third conductors 1032C are not symmetrical, such that one of the second conductors 1032B and the third conductors 1032C extends beyond half of the RF coil 1030, or at least one of the second conductors 1032B and the third conductors 1032C does not extend substantially halfway through the RF coil 1030. The lengths of the second conductor 1032B and the third conductor 1032C—and the length of their overlap with the first conductor 1032A—are adjustable, and this adjustment can be used to tune the RF coil 1030.

[0049] Additionally, the second conductor 1032B has an unconnected end 1033B and an end that connects to the matching and decoupling circuit 1043 and the capacitor 1044. The third conductor 1032C has an unconnected end 1033C and an end that connects to the matching and decoupling circuit 1043 and the capacitor 1044. The first conductor 1032A has two ends that connect to the B0 shimming circuit 1041. Additionally, some embodiments include a B1 shimming circuit in addition to or instead of the B0 shimming circuit 1041.

[0050] FIG. 11A shows an exemplary embodiment of an RF coil, FIG. 11B shows a cross-sectional view of the RF coil shown in FIG. 11A along line AA, and FIG. 11C shows a cross-sectional view of the RF coil shown in FIG. 11A along line BB. The RF coil 1130 comprises three dielectric covered conductors including a first dielectric covered conductor 1131A, a second dielectric covered conductor 1131B, and a third dielectric covered conductor 1131C. The first dielectric covered conductor 1131A comprises a first conductor 1132A, the second dielectric covered conductor 1131B comprises a second conductor 1132B, and the third dielectric covered conductor 1131C comprises a third conductor 1132C. Thus, the RF coil 1130 comprises three conductors 1132A-C, and the three conductors 1132A-C are covered by dielectric materials 1134A-C, respectively. At least some of the first dielectric material 1134A, the second dielectric material 1134B, and the third dielectric material 1134C may be the same dielectric material, or all may be different.

[0051] In this embodiment, the first dielectric covered conductor 1131A and the second dielectric covered conductor 1131B are arranged on a concentric axis, and the first dielectric covered conductor 1131A and the third dielectric covered conductor 1131C are arranged on a concentric axis. Also, in this example, the second conductor 1132B and the third conductor 1132C each extend only for a portion of the length of the RF coil 1130 and are inside the first dielectric covered conductor 1131A. The second conductor 1132B and the third conductor 1132C do not overlap each other. The second conductor 1132B has an unconnected end 1133B and an end that connects to the matching and decoupling circuit 1143 and the capacitor 1144. The third conductor 1132C has an unconnected end 1133C and an end that connects to the matching and decoupling circuit 1143 and the capacitor 1144. The first conductor 1132A has an end that connects to the B0 shimming circuit 1141. Further, some embodiments include a B1 shimming circuit in addition to or instead of the B0 shimming circuit 1141.

[0052] Fig. 12A shows an exemplary embodiment of an RF coil, Fig. 12B shows a cross-sectional view of the RF coil shown in Fig. 12A along line AA, and Fig. 12C shows a cross-sectional view of the RF coil shown in Fig. 12A along line BB. The RF coil 1230 comprises four dielectric covered conductors including a first dielectric covered conductor 1231A, a second dielectric covered conductor 1231B, a third dielectric covered conductor 1231C, and a fourth dielectric covered conductor 1231D. The first dielectric covered conductor 1231A and the second dielectric covered conductor 1231B are arranged on a concentric axis, and the third dielectric covered conductor 1231C and the fourth dielectric covered conductor 1231D are arranged on a concentric axis. The first dielectric covered conductor 1231A comprises a first conductor 1232A, the second dielectric covered conductor 1231B comprises a second conductor 1232B, the third dielectric covered conductor 1231C comprises a third conductor 1232C, and the fourth dielectric covered conductor 1231D comprises a fourth conductor 1232D. The conductors 1232A-D are covered by dielectric materials 1234A-D, respectively. At least some of the first dielectric material 1234A, the second dielectric material 1234B, the third dielectric material 1234C, and the fourth dielectric material 1234D may be the same dielectric material, or they may all be different.

[0053] Also, in this embodiment, the first conductor 1232A and the second conductor 1232B each extend over approximately half the length of the RF coil 1230. The third conductor 1232C and the fourth conductor 1232D extend over approximately the other half of the length of the RF coil 1230. Neither the first conductor 1232A nor the second conductor 1232B overlaps either the third conductor 1232C or the fourth conductor 1232D along the length of the RF coil 1230. Furthermore, neither the third conductor 1232C nor the fourth conductor 1232D overlaps either the first conductor 1232A or the second conductor 1232B along the length of the RF coil 1230.

[0054] Conductors 1232A-D have non-contact ends 1233A-D, respectively. Additionally, first conductor 1232A has an end that connects to first capacitor 1244A, and second conductor 1232B has an end that connects to matching and decoupling network 1243 and second capacitor 1244B. Third conductor 1232C has an end that connects to first capacitor 1244A, and fourth conductor 1232D has an end that connects to matching and decoupling network 1243 and second capacitor 1244B. Additionally, depending on the embodiment, the capacitance of first capacitor 1244A may be equal to the capacitance of second capacitor 1244B, or the capacitance of first capacitor 1244A may be different from the capacitance of second capacitor 1244B.

[0055] FIG. 13A shows an exemplary embodiment of an RF coil, FIG. 13B shows a cross-sectional view of the RF coil shown in FIG. 13A along line AA, and FIG. 13C shows a cross-sectional view of the RF coil shown in FIG. 13A along line BB. The RF coil 1330 comprises four dielectric covered conductors including a first dielectric covered conductor 1331A, a second dielectric covered conductor 1331B, a third dielectric covered conductor 1331C, and a fourth dielectric covered conductor 1331D. The first dielectric covered conductor 1331A comprises a first conductor 1332A, the second dielectric covered conductor 1331B comprises a second conductor 1332B, the third dielectric covered conductor 1331C comprises a third conductor 1332C, and the fourth dielectric covered conductor 1331D comprises a fourth conductor 1332D. The conductors 1332A-D are covered by dielectric materials 1334A-D, respectively. At least some of the first dielectric material 1334A, the second dielectric material 1334B, the third dielectric material 1334C, and the fourth dielectric material 1334D may be the same dielectric material or may all be different.

[0056] In this embodiment, the first conductor 1332A and the second conductor 1332B each extend over approximately half the length of the RF coil 1330. The third conductor 1332C and the fourth conductor 1332D extend over approximately the other half of the length of the RF coil 1330. Neither the first conductor 1332A nor the second conductor 1332B overlaps either the third conductor 1332C or the fourth conductor 1332D along the length of the RF coil 1330. Additionally, neither the third conductor 1332C nor the fourth conductor 1332D overlaps either the first conductor 1332A or the second conductor 1332B along the length of the RF coil 1330. However, in some embodiments, the first conductor 1332A and the third conductor 1332C are not symmetrical, the second conductor 1332B and the fourth conductor 1332D are not symmetrical, or at least one of the conductors 1332A-D does not extend substantially halfway through the length of the RF coil 1330.

[0057] Conductors 1332A-D have unconnected ends 1333A-D, respectively. Additionally, first conductor 1332A has an end that connects to first capacitor 1344A and matching and decoupling network 1343, and second conductor 1332B has an end that connects to second capacitor 1344B. Third conductor 1332C has an end that connects to first capacitor 1344A and matching and decoupling network 1343, and fourth conductor 1332D has an end that connects to second capacitor 1344B. Additionally, depending on the embodiment, the capacitance of first capacitor 1344A may be equal to the capacitance of second capacitor 1344B, or the capacitance of first capacitor 1344A may be different from the capacitance of second capacitor 1344B.

[0058] Some embodiments of the RF coil have a different shape than that of Figures 2A, 3A, 4A, 5A, 6, 7A, 8A, 9A, 10A, 11A, 12A, 13A. For example, Figures 14A-I show an exemplary embodiment of the shape of the RF coil 1430. As shown in Figures 14A-I, the shape of the RF coil 1430 is, for example, one of a butterfly shape, a rectangle, a solenoid shape, a square shape, an ellipse, a parallelogram shape, a trapezoid shape, a polygon shape, and a circle shape. The shape of the RF coil, as well as other parameters, can be selected and configured for a particular application (e.g., an RF transmit coil, an RF receive coil, an RF transmit / receive coil).

[0059] Also, multiple RF coils may be arranged in an RF coil array. Figures 15A-H show exemplary embodiments of RF coil arrays. As shown by the exemplary embodiment of Figure 15A, some RF coil arrays include non-overlapping RF coils 1530. And as shown by Figures 15B-H, some RF coil arrays include overlapping RF coils 1530 with various overlap amounts and arrangements. The shimming circuits, matching and decoupling circuits, and control methods used to operate the RF coil array may be configured for different applications. For example, the shimming circuits, matching and decoupling circuits, and control methods may be configured based on one or more of the following: parameters of the MRI device, the scanning pattern, the anatomy of the patient or object being scanned, the material (e.g., tissue) being scanned, and the position and orientation of the RF coil 1530 within the RF coil array (including the position and orientation when the RF coil array is disposed around the object (e.g., patient) being scanned).

[0060] FIG 16A shows an example embodiment of an RF coil, and FIG 16B shows the capacitance between the conductors shown in FIG 16A. The RF coil 1630 comprises three dielectric covered conductors including a first dielectric covered conductor 1631A, a second dielectric covered conductor 1631B, and a third dielectric covered conductor 1631C. The first dielectric covered conductor 1631A comprises a first conductor 1632A, the second dielectric covered conductor 1631B comprises a second conductor 1632B, and the third dielectric covered conductor 1631C comprises a third conductor 1632C. One end of the capacitor 1644 is connected to both the first conductor 1632A and the second conductor 1632B, and the other end of the capacitor 1644 is connected to the third conductor 1632C.

[0061] 16A, the first conductor 1632A, the second conductor 1632B, and the third conductor 1632C each have an unconnected end 1633A-C. However, in some embodiments, at least one of the unconnected ends 1633A-C connects to one or more other circuits (e.g., a matching and decoupling circuit, a B0 shimming circuit, a B1 shimming circuit). Similarly, at least one of the ends of the first conductor 1632A, the second conductor 1632B, and the third conductor 1632C that connects to the capacitor 1644 may also connect to one or more other circuits.

[0062] The distributed capacitance between the first conductor 1632A and the third conductor 1632C is C AC Also, the distributed capacitance between the second conductor 1632B and the third conductor 1632C is C BC Therefore, the total distributed capacitance C T is C T =C AC +C BC Because two conductors are connected to one end of the capacitor 1644 and one conductor is connected to the other end of the capacitor 1644, this embodiment of the RF coil 1630 has a wider tuning range or higher Q than other embodiments. This also applies to RF coils with more than three conductors, such as the RF coil embodiment of FIG. 17A.

[0063] FIG. 17A shows an exemplary embodiment of an RF coil, and FIG. 17B shows the capacitance between the conductors shown in FIG. 17A. The RF coil 1730 includes four dielectric covered conductors including a first dielectric covered conductor 1731A, a second dielectric covered conductor 1731B, a third dielectric covered conductor 1731C, and a fourth dielectric covered conductor 1731D. The first dielectric covered conductor 1731A includes a first conductor 1732A, the second dielectric covered conductor 1731B includes a second conductor 1732B, the third dielectric covered conductor 1731C includes a third conductor 1732C, and the fourth dielectric covered conductor 1731D includes a fourth conductor 1732D. Additionally, the conductors 1732A-D have unconnected ends 1733A-D, respectively.

[0064] One end of the capacitor 1744 is connected to both the first conductor 1732A and the second conductor 1732B, and the other end of the capacitor 1744 is connected to both the third conductor 1732C and the fourth conductor 1732D.

[0065] 17A, conductors 1732A-D have unconnected ends 1733A-D, respectively, but in some embodiments, at least one of unconnected ends 1733A-D connects to one or more other circuits (e.g., matching and decoupling circuit, B0 shimming circuit, B1 shimming circuit). Similarly, at least one of the ends of first conductor 1732A, second conductor 1732B, third conductor 1732C, fourth conductor 1732D that connects to capacitor 1744 may also connect to one or more other circuits.

[0066] The distributed capacitance between the first conductor 1732A and the third conductor 1732C is C AC Also, the distributed capacitance between the first conductor 1732A and the fourth conductor 1732D is C AD Also, the distributed capacitance between the second conductor 1732B and the third conductor 1732C is C BC The distributed capacitance between the second conductor 1732B and the fourth conductor 1732D is C BD Therefore, the total distributed capacitance C T is C T =C AC +CAD +C BC +C BD It is.

[0067] Additionally, Table 1 shows parameters from an exemplary embodiment of the RF coil. [Table 1] *One side of the capacitor connects to two of the three conductors, and the other side of the capacitor connects to only one of the three conductors (e.g., as shown in Figure 2D). **One side of the capacitor connects to only one of the three conductors, and the other side of the capacitor connects to only one of the three conductors (e.g., as shown in Figure 2A). ***Some conductors are composed of multiple smaller conductors and the cross-sectional diameter is the combined diameter of the multiple smaller conductors.

[0068] As mentioned above, the length and overlap of the conductors can be adjusted to tune the RF coil, for example as shown in Figures 18A, 18B, 19A and 19B.

[0069] 18A shows an exemplary embodiment of an RF coil. The RF coil 1830 includes three dielectric covered conductors including a first dielectric covered conductor 1831A, a second dielectric covered conductor 1831B, and a third dielectric covered conductor 1831C. The first dielectric covered conductor 1831A includes a first conductor 1832A, the second dielectric covered conductor 1831B includes a second conductor 1832B, and the third dielectric covered conductor 1831C includes a third conductor 1832C. One end of a capacitor 1844 is connected to both the first conductor 1832A and the second conductor 1832B, and the other end of the capacitor 1844 is connected to the third conductor 1832C. Additionally, the conductors 1832A-C each have an unconnected end 1833A-C.

[0070] In this embodiment, the extension of conductors 1832A-C relative to the length (e.g., circumference, perimeter) of RF coil 1830 is less than conductors 1632A-C in Figure 16A. Additionally, the overlap of conductors 1832A-C along the length of RF coil 1830 is less than the overlap of conductors 1632A-C in Figure 16A.

[0071] 18A, electrical conductors 1832A-C have non-contact ends 1833A-C, respectively, however, in some embodiments, at least one of non-connected ends 1833A-C connects to one or more other circuits (e.g., matching and decoupling circuit, B0 shimming circuit, B1 shimming circuit). Similarly, at least one of the ends of first electrical conductor 1832A, second electrical conductor 1832B, third electrical conductor 1832C that connects to capacitor 1844 may also connect to one or more other circuits.

[0072] 18B shows an exemplary embodiment of an RF coil. The RF coil 1830 comprises three dielectric covered conductors including a first dielectric covered conductor 1831A, a second dielectric covered conductor 1831B, and a third dielectric covered conductor 1831C. The first dielectric covered conductor 1831A comprises a first conductor 1832A, the second dielectric covered conductor 1831B comprises a second conductor 1832B, and the third dielectric covered conductor 1831C comprises a third conductor 1832C.

[0073] Second conductor 1832B has non-contact end 1833B. The other ends of conductors 1832A-C connect to one or more of B0 shimming circuit 1841, B1 shimming circuit 1842, matching and decoupling circuit 1843, and capacitor 1844. In this embodiment, first conductor 1832A has (i) a first end connecting to B0 shimming circuit 1841, and (ii) a second end connecting to B0 shimming circuit 1841 and B1 shimming circuit 1842. Second conductor 1832B has (i) a first end connecting to capacitor 1844 and matching and decoupling circuit 1843, and (ii) non-contact end 1833B. The third conductor 1832C has (i) a first end that connects to the B1 shimming circuit 1842 and (ii) a second end that connects to the capacitor 1844 and the matching and decoupling circuit 1843.

[0074] In this embodiment, second electrical conductor 1832B having non-contact end 1833B has a shorter extension relative to the length of RF coil 1830 than electrical conductor 432 having non-contact end 433 of FIG. 4A.

[0075] 19A shows an exemplary embodiment of an RF coil. RF coil 1930 comprises three dielectric covered conductors including a first dielectric covered conductor 1931A, a second dielectric covered conductor 1931B, and a third dielectric covered conductor 1931C. The first dielectric covered conductor 1931A comprises a first conductor 1932A, the second dielectric covered conductor 1931B comprises a second conductor 1932B, and the third dielectric covered conductor 1931C comprises a third conductor 1932C.

[0076] Second conductor 1932B and third conductor 1932C have unconnected ends 1933B-C, respectively. Each end of second conductor 1932B and third conductor 1932C connects to capacitor 1944. Additionally, an end of first conductor 1932A connects to one or more other circuits (e.g., matching and decoupling circuit, B0 shimming circuit, B1 shimming circuit) (not shown in FIG. 19A). Similarly, at least one of the ends of second conductor 1932B and third conductor 1932C that connects to capacitor 1944 may also connect to one or more other circuits.

[0077] 10A, in this embodiment the second conductor 1932B and the third conductor 1932C are not symmetrical or nearly symmetrical. Instead, the second conductor 1932B is substantially shorter than the third conductor 1932C, and the third conductor 1932C extends more than half the length of the RF coil 1930. Also, the overlap of the third conductor 1932C and the first conductor 1932A along the length of the RF coil 1930 is greater than the overlap of the second conductor 1932B and the first conductor 1932A.

[0078] 19B illustrates an exemplary embodiment of an RF coil. RF coil 1930 comprises four dielectric covered conductors including a first dielectric covered conductor 1931A, a second dielectric covered conductor 1931B, a third dielectric covered conductor 1931C, and a fourth dielectric covered conductor 1931D. The first dielectric covered conductor 1931A comprises a first conductor 1932A, the second dielectric covered conductor 1931B comprises a second conductor 1932B, the third dielectric covered conductor 1931C comprises a third conductor 1932C, and the fourth dielectric covered conductor 1931D comprises a fourth conductor 1932D.

[0079] The conductors 1932A-D have non-contact ends 1933A-D, respectively. The ends of the first conductor 1932A and the third conductor 1932C connect to the first capacitor 1944A. The ends of the second conductor 1932B and the fourth conductor 1932D connect to the second capacitor 1944B. At least one of the ends of the first conductor 1932A and the third conductor 1932C that connect to the first capacitor 1944A may also be connected to one or more other circuits (e.g., a matching and decoupling circuit, a B0 shimming circuit, a B1 shimming circuit) (not shown in FIG. 19B). At least one of the ends of the second conductor 1932B and the fourth conductor 1932D that connect to the second capacitor 1944B may also be connected to one or more other circuits.

[0080] In contrast to the RF coil 1330 of Fig. 13A, in Fig. 19B the first conductor 1932A and the third conductor 1932C are not symmetrical or nearly symmetrical, and the second conductor 1932B and the fourth conductor 1932D are not symmetrical or nearly symmetrical, and the overlap of the first conductor 1932A and the second conductor 1932B along the length of the RF coil 1930 is greater than the overlap of the third conductor 1932C and the fourth conductor 1932D.

[0081] FIG. 20 shows an exemplary embodiment of an RF coil. The RF coil 2030 comprises three dielectric covered conductors including a first dielectric covered conductor 2031A, a second dielectric covered conductor 2031B, and a third dielectric covered conductor 2031C. The first dielectric covered conductor 2031A comprises a first conductor 2032A, the second dielectric covered conductor 2031B comprises a second conductor 2032B, and the third dielectric covered conductor 2031C comprises a third conductor 2032C. The ends of the conductors 2032A-C connect to one or more of a B0 shimming circuit 2041, a B1 shimming circuit 2042, a transmit / receive circuit 2048, and a capacitor 2044. The transmit / receive circuit 2048, which may also implement a matching and decoupling circuit, comprises circuitry that provides voltages or currents that cause the RF coil 2030 to function as one of a transmit coil, a receive coil, or a transmit / receive coil. In addition, the switching circuit 2049 activates and deactivates the B0 shimming circuit 2041, the B1 shimming circuit 2042, and the transmit / receive circuit 2048.

[0082] 21 shows an exemplary embodiment of an RF coil. The RF coil 2130 comprises three dielectric covered conductors including a first dielectric covered conductor 2131A, a second dielectric covered conductor 2131B, and a third dielectric covered conductor 2131C. The first dielectric covered conductor 2131A comprises a first conductor 2132A, the second dielectric covered conductor 2131B comprises a second conductor 2132B, and the third dielectric covered conductor 2131C comprises a third conductor 2132C. Each end of the conductors 2132A-C connects to one or more of a B0 shimming circuit 2141, a B1 shimming circuit 2142, a first capacitor 2144A, and a second capacitor 2144. In this embodiment, the matching and decoupling circuit 2143 connects to the RF coil 2130 via two capacitors 2144A-B, one capacitor for each connection to the RF coil 2130. This embodiment of the connection between the RF coil 2130 and the matching and decoupling circuit 2143 can be used for other RF coils, such as, for example, the RF coils shown in Figures 3A, 4A, 5A, 6, 7A, 8A, 9A, 10A, 11A, 12A, 13A, 16A, 17A, 18A, and 18B.

[0083] 21B shows an exemplary embodiment of the matching and decoupling circuit. In this embodiment, the matching and decoupling circuit 2143 comprises a first capacitor 2144A and a second capacitor 2144B. Some embodiments of the matching and decoupling circuit 2143 comprise only one of the first capacitor 2144A and the second capacitor 2144B. And, at least one of the first capacitor 2144A and the second capacitor 2144B may be a tuning capacitor.

[0084] 22A shows an exemplary embodiment of an RF coil. The RF coil 2230 comprises three dielectric covered conductors including a first dielectric covered conductor 2231A, a second dielectric covered conductor 2231B, and a third dielectric covered conductor 2231C. The first dielectric covered conductor 2231A comprises a first conductor 2232A, the second dielectric covered conductor 2231B comprises a second conductor 2232B, and the third dielectric covered conductor 2231C comprises a third conductor 2232C. Each end of the conductors 2232A-C connects to one of a B0 shimming circuit 2241, a B1 shimming circuit 2242, a matching and decoupling circuit 2243, and a capacitor 2244. In this embodiment, in one connection of the matching and decoupling circuit 2243 to the RF coil 2230, there is a capacitor 2244 between the matching and decoupling circuit 2243 and the RF coil 2230. This embodiment of the connection between the RF coil 2230 and the matching and decoupling circuit 2243 can be used for other RF coils, such as, for example, the RF coils shown in Figures 3A, 4A, 5A, 6, 7A, 8A, 9A, 10A, 11A, 12A, 13A, 16A, 17A, 18A, and 18B.

[0085] 22B shows an exemplary embodiment of a matching and decoupling circuit. In this embodiment, the matching and decoupling circuit 2243 includes a capacitor 2244. And, the capacitor 2244 may be a tuning capacitor.

[0086] FIG. 23 shows an exemplary embodiment of an RF coil. The RF coil 2330 comprises three conductors including a first conductor 2332A, a second conductor 2332B, and a third conductor 2332C. The second conductor 2332B is a member of the first dielectric covered conductor 2331B, and the third conductor 2332C is a member of the second dielectric covered conductor 2331C. The ends of the conductors 2332A-C connect to one or more of a B0 shimming circuit 2341, a B1 shimming circuit 2342, a matching and decoupling circuit 2343, and a capacitor 2344. Also, unlike the embodiment of the RF coil in FIG. 4A, this embodiment does not comprise an unconnected end.

[0087] FIG. 24 shows an exemplary embodiment of an RF coil. The RF coil 2430 comprises three dielectric covered conductors including a first dielectric covered conductor 2431A, a second dielectric covered conductor 2431B, and a third dielectric covered conductor 2431C. The dielectric covered conductors 2431A-C are arranged in a concentric triaxial configuration. Thus, the first dielectric covered conductor 2431A comprises a first conductor 2432A surrounding the second dielectric covered conductor 2431B and the third dielectric covered conductor 2431C, and the second dielectric covered conductor 2431B comprises a second conductor 2432B surrounding the third dielectric covered conductor 2431C. Thus, the three conductors 2432A-C are directly surrounded by respective dielectric materials. The ends of the conductors 2432A-C are connected to one or more of the B0 shimming circuit 2441, the B1 shimming circuit 2442, the matching and decoupling circuit 2443, and the capacitor 2444. Unlike the RF coil embodiment of FIG. 7A, this embodiment does not have any unconnected ends.

[0088] FIG. 25 shows an exemplary embodiment of an RF coil. The RF coil 2530 comprises three dielectric covered conductors including a first dielectric covered conductor 2531A, a second dielectric covered conductor 2531B, and a third dielectric covered conductor 2531C. The second dielectric covered conductor 2531B and the third dielectric covered conductor 2531C are arranged in a concentric axial configuration. The first dielectric covered conductor 2531A comprises a first conductor 2532A, and the second dielectric covered conductor 2531B comprises a second conductor 2532B surrounding the third dielectric covered conductor 2531C. The third dielectric covered conductor 2531C comprises a third conductor 2532C. The ends of the conductors 2532A-C are connected to one or more of a B0 shimming circuit 2541, a B1 shimming circuit 2542, a matching and decoupling circuit 2543, and a capacitor 2544, respectively. Unlike the embodiment of the RF coil in FIG. 8A, this embodiment does not comprise an unconnected end.

[0089] Figures 26A-H show an example embodiment of a cross-sectional view of an RF coil. As shown in Figures 26A-H, multiple conductors may be encased in the same body of dielectric material. This may help to maintain a desired distance between the conductors.

[0090] 26A shows a cross-sectional view of a dielectric covered conductor group 2631 comprising three conductors 2632A-C surrounded by a dielectric material 2634. In this embodiment, in the cross-sectional view, the three conductors 2632A-C form the vertices of an equilateral triangle or approximately an equilateral triangle.

[0091] 26B shows a cross-sectional view of a dielectric covered conductor group 2631 comprising three conductors 2632A-C surrounded by a dielectric material 2634. In this embodiment, the cross-sectional view shows that the three conductors 2632A-C are aligned in a row, with the second conductor 2632B closer to the first conductor 2632A than the third conductor 2632C. And, in this cross-sectional view, the dielectric material 2634 is approximately stadium shaped (i.e., discorectangle, elongated oval).

[0092] 26C shows a cross-sectional view of a dielectric covered conductor group 2631 comprising three conductors 2632A-C surrounded by a dielectric material 2634. In this embodiment, in the cross-sectional view, the three conductors 2632A-C form the points of an isosceles triangle or approximately an isosceles triangle.

[0093] 26D shows a cross-sectional view of a dielectric covered conductor group 2631 comprising two conductors 2632A-B surrounded by dielectric material 2634. In this embodiment, in the cross-sectional view, dielectric material 2634 is approximately stadium shaped.

[0094] 26E shows a cross-sectional view of a dielectric covered conductor group 2631 including four conductors 2632A-D surrounded by dielectric material 2634. In this embodiment of the cross-sectional view, the four conductors 2632A-D are aligned in a row, the four conductors 2632A-D are equally or nearly equally spaced apart, and the dielectric material 2634 is approximately stadium shaped in this cross-sectional view.

[0095] 26F shows a cross-sectional view of a dielectric coated conductor group 2631 comprising four conductors 2632A-D surrounded by dielectric material 2634. In this embodiment of the cross-sectional view, the four conductors 2632A-D form a diamond shaped point, and in this cross-sectional view, the dielectric material 2634 is approximately diamond shaped.

[0096] FIG. 26G shows a cross-sectional view of a dielectric covered conductor group 2631 comprising four conductors 2632A-D surrounded by a dielectric material 2634. In this embodiment, the cross-sectional view shows the four conductors 2632A-D are approximately

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[0097] 26H shows a cross-sectional view of a dielectric coated conductor group 2631 comprising four conductors 2632A-D surrounded by dielectric material 2634. In this embodiment of the cross-sectional view, three conductors 2632A-C form a diamond shaped point, and one conductor 2632D is located between two conductors 2632B-C on the base of a triangle. And in this cross-sectional view, the dielectric material 2634 is approximately triangular in shape.

[0098] As used herein, the conjunction "or" generally means an inclusive "or." When an exclusive "or" is expressly stated or the context requires, "or" means an exclusive "or."

[0099] In the RF coil according to the above-mentioned embodiment, the RF coil elements are composed of three or more thin flexible conductors, which are arranged closely side by side. Furthermore, in the RF coil, the conductors are electrically separated by a dielectric material arranged between the conductors, which creates a wide range of distributed capacitance. As a result, the RF coil can be manufactured with more flexibility, light weight, low cost, and easy adjustment.

[0100] According to at least one of the embodiments described above, it is possible to provide an RF coil having good high frequency characteristics and flexibility.

[0101] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0102] 10 Medical Imaging Systems 100 MRI machine 102 Main magnet 103 Gradient magnetic field coil 104 RF whole body coil 105 Coil storage device 110 Image generating device 120 Display device 130, 230, 330, 430, 530, 630, 730, 830, 930, 1030, 1130, 1230, 1330, 1430, 1530, 1630, 1730, 1830, 1930, 2030, 2130, 2230, 2330, 2430, 2530 RF Coil 239 Area 241, 341, 441, 541, 641, 741, 841, 941, 1041, 1141, 1841, 2041, 2141, 2241, 2341, 2441, 2541 B0 shimming circuit 242, 342, 442, 542, 642, 742, 842, 942, 1042, 1142, 1842, 2042, 2142, 2242, 2342, 2442, 2542 B1 shimming circuit 243, 343, 443, 543, 643, 743, 843, 943, 1043, 1143, 1243, 1343, 1843, 2143, 2243, 2343, 2443, 2543 Matching and decoupling circuits 244, 344, 444, 544, 644, 744, 844, 944, 1044, 1144, 1644, 1744, 1844, 1944, 2044, 2244, 2344, 2444, 2544 Capacitors 345 Tuning Circuit 346 Matching Network 349 Box 2048 transmit / receive circuit 2049 Switching Circuit 2631 Dielectric Coated Conductors 2634 Dielectric materials

Claims

1. Three or more conductors forming an RF coil element; The conductors are spatially parallel to one another, the conductors are electrically separated from one another by one or more dielectric materials along an axial length of the RF coil element with a distance between two of the three or more conductors; One end of at least one of the three or more conductors is connected to a B0 shimming circuit or a B1 shimming circuit; the lengths, the distances, and the dielectric material of the RF coil elements are configured such that the RF coil elements function as B0 shimming and / or B1 shimming; RF coil.

2. The shape of a cross section perpendicular to the direction of the length of each of the conductors is isotropic with respect to an axis of each of the conductors. The RF coil according to claim 1 .

3. along at least a portion of said length, the three or more conductors are locally parallel to one another. An RF coil according to claim 1 or 2.

4. the three or more conductors include a first conductor, a second conductor, and a third conductor; the first conductor is connected to the B0 shimming circuit; the second conductor is connected to the B1 shimming circuit; An RF coil according to any one of claims 1 to 3.

5. At least one of the three or more conductors has an unconnected end. An RF coil according to any one of claims 1 to 4.

6. The three or more conductors function as one of a transmitting coil, a receiving coil, and a transmitting / receiving coil. An RF coil according to any one of claims 1 to 5.

7. The RF coil element is flexible. An RF coil according to any one of the preceding claims.

8. the three or more conductors include a first conductor, a second conductor, and a third conductor; One end of the first conductor is connected to one end of the second conductor, a distributed capacitance along at least a portion of the length of the RF coil element is the sum of a distributed capacitance between the first conductor and the third conductor along at least a portion of the length of the RF coil element and a distributed capacitance between the second conductor and the third conductor along at least a portion of the length of the RF coil element. An RF coil according to any one of the preceding claims.

9. The three or more conductors are twisted together. An RF coil according to any one of the preceding claims.

10. One of the three or more conductors is formed with a braid and surrounds the dielectric material covering the other conductor of the three or more conductors that is not formed with the braid. An RF coil according to any one of the preceding claims.

11. Two of the three or more conductors are formed by braiding; One of the two braided conductors surrounds the dielectric material that covers the one of the three or more conductors that is not braided; The other of the two conductors formed by the braid surrounds a dielectric material covering the one of the conductors. An RF coil according to any one of the preceding claims.

12. At least two of the three or more conductors are disposed in a coaxial cable; At least one of the three or more conductors is not disposed in the coaxial cable. An RF coil according to any one of the preceding claims.

13. each of the three or more electrical conductors has a length along an axial length of the RF coil element; the lengths, the distances, and the one or more dielectric materials of the three or more conductors are configured such that the RF coil element functions as both a B0 shimming and a B1 shimming and as a transmit / receive coil. An RF coil according to any one of the preceding claims.

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