Radiofrequency coils for medical imaging equipment

Abstract

A method and system for a radio frequency (RF) coil for a magnetic resonance imaging (MRI) system is provided. In one embodiment, a radio frequency (RF) coil for a medical imaging device includes: a first conductive portion having a first end and an opposite second end; and a first plurality of notches of the first conductive portion extending from the first end to the second end across a centerline of the first conductive portion. In this manner, the amount of eddy currents generated within the conductive surface of the RF coil is reduced, thereby reducing the temperature and vibration of the RF coil.

Description

Technical Field

[0001] Embodiments of the subject matter disclosed herein relate to magnetic resonance imaging (MRI), and more particularly, to radio frequency (RF) coils for MRI systems. Background Art

[0002] Magnetic resonance imaging (MRI) is a medical imaging modality that can produce images of the interior of a patient without the use of X-ray radiation or other types of ionizing radiation. An MRI system is a medical imaging device that utilizes a superconducting magnet to generate a strong and uniform static magnetic field within a specified region (e.g., within a channel shaped to receive a patient). When the patient's body (or a portion of the patient's body) is located within the magnetic field, the nuclear spins associated with the hydrogen nuclei that form water within the patient's tissue become polarized. The magnetic moments associated with these spins align along the direction of the magnetic field and cause a small net tissue magnetization in the direction of the magnetic field. The MRI system additionally includes a magnetic gradient coil that generates a spatially varying magnetic field that is small in magnitude relative to the uniform magnetic field generated by the superconducting magnet. The spatially varying magnetic fields are configured to be orthogonal to each other so as to spatially encode the region by generating characteristic resonant frequencies of the hydrogen nuclei at different locations within the patient's body. A radio frequency (RF) coil assembly is then used to generate pulses of RF energy at or near the resonant frequency of the hydrogen nuclei. The pulses of RF energy are absorbed by the hydrogen nuclei, thereby adding energy to the nuclear spin system and modulating the hydrogen nuclei from a rest state to an excited state. When the hydrogen nuclei relax from the excited state back to the rest state, they release the absorbed energy in the form of an RF signal. This signal is detected by the MRI system and converted into an image by a computer using known reconstruction algorithms. Summary of the invention

[0003] In one embodiment, a radio frequency (RF) coil for a medical imaging device includes: a first conductive portion having a first end and an opposite second end; and a first plurality of notches of the first conductive portion extending from the first end to the second end across a centerline of the first conductive portion. In this manner, the plurality of notches reduce the amount of eddy currents flowing through the first conductive segment and reduce the operating temperature of the RF coil during imaging of a patient.

[0004] It should be understood that the above brief description is provided to introduce in a simplified form selected concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The present invention will be better understood by reading the following description of non-limiting embodiments with reference to the accompanying drawings, in which:

[0006] Figure 1 A schematic diagram of an example magnetic resonance imaging (MRI) system including a radio frequency (RF) coil is shown in accordance with an embodiment.

[0007] Figure 2 A perspective view showing a bore of a gantry of an MRI system including an RF coil having segmented end rings according to an embodiment;

[0008] Figure 3 According to an embodiment Figure 2 A front perspective view of an RF coil;

[0009] Figure 4A According to an embodiment Figure 2 A flat view of the exterior of the RF coil, and Figure 4B According to the embodiment Figure 2 A flat view of the interior of the RF coil;

[0010] Figure 5A According to one embodiment, a Figure 2 A magnified view of the conductive portion of the RF coil exterior, and Figure 5B According to one embodiment, a Figure 2 An enlarged view of the conductive part inside the RF coil;

[0011] Fig. 6A According to one embodiment, Figure 5A The relative temperature of the conductive parts shown, and Figure 6B According to one embodiment, Figure 5B the relative temperature of the conductive parts shown; and

[0012] Figure 7 According to an embodiment Figure 2 The hole in Figure 2 A graph of the temperature during operation of the RF coil.

[0013] Although other relative dimensions may be used, Figures 2 to 6B Shown approximately to scale. DETAILED DESCRIPTION

[0014] The following description relates to various embodiments of magnetic resonance imaging (MRI). In particular, systems and methods are provided for radio frequency (RF) coils for MRI systems. MRI systems, such as Figure 1The MRI system shown includes a gantry having a bore with an imaging space located therein. An RF coil including two opposing end rings and a plurality of crosspieces is coupled around the perimeter of the bore to image a patient located in the imaging space. Figures 3 to 5B As shown, the RF coil includes a plurality of conductive portions coupled to the inner and outer surfaces of the end ring. FIG. 5A to FIG. 5B As shown, each conductive portion includes a plurality of notches extending in a transverse direction relative to a centerline of the conductive portion. The notches of each conductive portion reduce the amount of eddy current within the conductive portion during operation of the MRI system. The reduction in eddy current reduces the temperature of the conductive portion, such as FIG. 6A to FIG. 6B As shown, the amount of vibration of the RF coil can be reduced. The reduced temperature of the conductive portion leads to a reduced temperature of the hole of the gantry, such as Figure 7 The reduction in temperature and vibration due to reduced eddy currents can result in increased patient comfort and reduced power consumption by the RF coil.

[0015] Although an MRI system is described by way of example, it should be appreciated that the present technology may also be useful when applied to images acquired using other imaging modalities, such as tomosynthesis, computed tomography, C-arm angiography, etc. The present discussion of the MRI imaging modality is provided merely as an example of one suitable imaging modality.

[0016] Figure 1 An MRI system 10 is shown, which includes a static magnetic field magnet unit 12 (e.g., a superconducting magnet), a magnetic gradient generator 13, a local RF coil 14, a volume RF coil 15 (which may be referred to herein as a body RF coil), a transmit / receive (T / R) switch 20, an RF signal driver 22, a gradient driver 23, a data acquisition unit 24, a controller unit 25, a patient table 26 (which may be referred to herein as a bed), a data processing unit 31, an operation console unit 32, and a display unit 33. The local RF coil 14 is a surface coil configured to be placed close to the surface of an anatomical structure of an object 16 (e.g., a patient) to be scanned by the MRI system 10. The volume RF coil 15 is a coil configured to transmit RF signals (e.g., electromagnetic waves of radio frequency), and the local RF coil 14 is configured to receive RF signals. Thus, the volume RF coil 15 and the local RF coil 14 are spatially separated from each other, but may be electromagnetically coupled to each other. In some examples, the local RF coil 14 and / or the volume RF coil 15 may transmit and receive RF signals. Example modes of operation of the coils (eg, the local RF coil 14 and the volume RF coil 15 ) are described further below.

[0017] The MRI system 10 includes a patient table 26 for placing an object 16 (e.g., a patient) thereon. By moving the patient table 26, the object 16 can be moved inside and outside the imaging space 18. The imaging space 18 can be positioned within the bore 19 of the gantry 17 of the MRI system 10. In some examples, the controller unit 25 can send a control signal (e.g., an electrical signal) to the operation console unit 32 and / or the display unit 33 to indicate the position of the patient table 26 within the imaging space 18 to an operator (e.g., a user, a technician, etc.) of the MRI system 10.

[0018] The operation console unit 32 includes a user input device such as a keyboard and a mouse. The operation console unit 32 is used by the operator to, for example, input an imaging protocol (e.g., a parallel imaging protocol) and set an area to be executed for an imaging sequence. Data on the imaging protocol is input to the operation console unit 32 by the operator, and the imaging sequence execution area is output to the controller unit 25.

[0019] The display unit 33 includes a graphic display device (e.g., a computer screen), and displays an image on the graphic display device based on a control signal received from the controller unit 25. The display unit 33 displays, for example, an image regarding an input item on which operation data regarding the input item is input by the operator from the operation console unit 32. The display unit 33 also displays a slice image of the object 16 generated by the data processing unit 31.

[0020] The data processing unit 31 includes a computer and a recording medium (e.g., a hard disk drive) on which a program executed by the computer to perform predetermined data processing is recorded. The data processing unit 31 is electrically coupled to the controller unit 25, and performs data processing based on a control signal received from the controller unit 25. The data processing unit 31 is also connected to the data acquisition unit 24, and generates spectrum data by applying various image processing operations to magnetic resonance (MR) signals output from the data acquisition unit 24 (described in more detail below).

[0021] The static magnetic field magnet unit 12 includes a toroidal superconducting electromagnet coupled to and positioned inside an annular vacuum container (e.g., gantry 17). The electromagnet defines a cylindrical space (e.g., hole 19) surrounding the object 16, and generates a static magnetic field of substantially constant magnitude and direction within the cylindrical space (e.g., in the direction of the y-axis within the cylindrical space, as shown by reference axis 199). The static magnetic field generated by the electromagnet may be referred to herein as a uniform magnetic field.

[0022] The MRI system 10 further includes a magnetic gradient generator 13 that generates an additional magnetic field (which may be referred to herein as a gradient magnetic field) in an imaging space 18 so as to associate the MR signals received by the local RF coil 14 with three-dimensional position information. For example, the gradient magnetic field generated by the magnetic gradient generator 13 may have different magnitudes (e.g., different field strengths) at different locations within the imaging space 18. The magnetic gradient generator 13 includes three gradient coil systems. Each gradient coil system adjusts the magnitude of the gradient magnetic field along one of three perpendicular directions. For example, the first gradient coil system adjusts the magnitude of the gradient magnetic field in the frequency encoding direction, the second gradient coil system adjusts the magnitude of the gradient magnetic field in the phase encoding direction, and the third gradient coil system adjusts the magnitude of the gradient magnetic field in the slice selection direction. The frequency encoding direction, the phase encoding direction, and the slice selection direction may be defined based on input from a user (e.g., an operator) of the MRI system 10 (e.g., via the operation console unit 32). More specifically, the magnetic gradient generator 13 adjusts the magnitude of the gradient magnetic field in the slice selection direction of the object 16 in response to input from the operator. Then, the local RF coil 14 transmits RF pulses to the selected slice of the object 16 and excites the slice (for example, excites the nuclear spins of hydrogen atoms in the selected slice of the object 16). The magnetic gradient generator 13 adjusts the magnitude of the gradient magnetic field in the phase encoding direction of the object 16 to phase-encode the MR signal emitted by the slice excited by the RF pulse. Then, the magnetic gradient generator 13 adjusts the magnitude of the gradient magnetic field in the frequency encoding direction of the object 16 to frequency-encode the MR signal emitted by the slice excited by the RF pulse.

[0023] The gradient driver 23 drives the magnetic gradient generator 13 based on a control signal received from the controller unit 25, thereby generating a gradient magnetic field in the imaging space 18. The gradient driver 23 includes three driver circuit systems (not shown) corresponding to the three gradient coil systems included in the magnetic gradient generator 13 (described above).

[0024] The RF coils (e.g., the local RF coil 14 and / or the volume RF coil 15) of the MRI system 10 may transmit electromagnetic pulse signals to an object 16 located within an imaging space 18, wherein a uniform magnetic field and a gradient magnetic field extend through the imaging space 18. The local RF coil 14 is shaped, for example, to surround a region to be imaged of the object 16. In some examples, the local RF coil 14 may be referred to as a surface coil or a receiver coil. The MRI system 10 receives MR signals from the object 16 (e.g., via a data acquisition unit 24 coupled to the RF coils) and processes the MR signals (e.g., via a data processing unit 31) so as to construct an image of a slice of the object 16 based on the received MR signals.

[0025] For example, during a state in which the object 16 is positioned to be scanned by the MRI system 10 (e.g., during a state in which the object 16 is within the imaging space 18), the spins of the hydrogen nuclei within the tissue of the object 16 may be consistent with the initial magnetization vector generated by the combination of the uniform magnetic field and the gradient magnetic field. The local RF coil 14 may transmit RF pulses as electromagnetic waves to the object 16 based on a control signal from the controller unit 25. The RF pulses transmitted to the object 16 generate a high-frequency magnetic field within a slice of the object 16 to be imaged (e.g., selected by an operator of the MRI system 10). The high-frequency magnetic field excites the spins of the hydrogen nuclei in the slice of the object 16 and causes the spins to be consistent with the magnetization vector that has changed compared to the initial magnetization vector. As the spins of the excited hydrogen nuclei in the slice of the object 16 relax and return to be consistent with the initial magnetization vector, the local RF coil 14 receives the electromagnetic waves generated from the tissue of the object 16 as MR signals.

[0026] The volume RF coil 15 may be used alternately (or additionally) to generate a high frequency magnetic field similar to that described above with reference to the local RF coil 14. For example, the volume RF coil 15 is positioned to surround the imaging space 18 and may generate RF pulses in a direction orthogonal to the direction of the uniform magnetic field generated by the static magnetic field magnet unit 12 within the imaging space 18 so as to excite hydrogen nuclei of the subject 16. Unlike the local RF coil 14, which may be disconnected from the MRI system 10 and replaced by a different local RF coil, the volume RF coil 15 is fixedly attached and coupled to the MRI system 10. Furthermore, local coils such as those including the local RF coil 14 may send signals to and / or receive signals (e.g., send RF signals and / or receive MR signals) from a local region of the subject 16 (e.g., a specific anatomical structure or slice of the subject 16), while the volume RF coil 15 may send signals to and / or receive signals from a larger portion of the subject 16 (e.g., the entire body of the subject 16).

[0027] The RF signal driver 22 electrically coupled to the coil (e.g., the volume RF coil 15 and / or the local RF coil 14) via the T / R switch 20 includes a gate modulator (not shown), an RF power amplifier (not shown), and an RF oscillator (not shown) for driving the local RF coil 14 and / or the volume RF coil 15 to form a high-frequency magnetic field (as described above) in the imaging space 18. The RF signal driver 22 modulates the RF signal received from the RF oscillator into a signal having a predetermined timing and a predetermined envelope via the gate modulator, wherein the RF signal is based on a control signal from the controller unit 25. The RF signal modulated by the gate modulator is amplified by the RF power amplifier, and then output to the local RF coil 14 and / or the volume RF coil 15.

[0028] The T / R switch 20 may selectively electrically couple the local RF coil 14 and / or the volume RF coil 15 to the data acquisition unit 24 when operating in the receive mode, and may selectively electrically couple the local RF coil 14 and / or the volume RF coil 15 to the RF signal driver 22 when operating in the transmit mode. During a state in which both the local RF coil 14 and the volume RF coil 15 are used for a single scan (e.g., during a state in which the local RF coil 14 is configured to receive MR signals and the volume RF coil 15 is configured to transmit RF signals), the T / R switch 20 may direct a control signal from the RF signal driver 22 to the volume RF coil 15 while directing received MR signals from the local RF coil 14 to the data acquisition unit 24. As described above, the volume RF coil 15 may be configured to operate in a transmit-only mode, a receive-only mode, or a transmit-and-receive mode. The local RF coil 14 may be configured to operate in a transmit-and-receive mode or a receive-only mode.

[0029] The data acquisition unit 24 includes a preamplifier (not shown), a phase detector (not shown) and an analog / digital converter (not shown), and is used to acquire magnetic resonance signals received by the local RF coil 14 and / or the volume RF coil 15. In the data acquisition unit 24, the phase detector uses the output of the RF oscillator from the RF signal driver 22 as a reference signal to phase-detect the MR signal received by the local RF coil 14 and / or the volume RF coil 15 (where the MR signal is amplified by the preamplifier), and outputs the phase-detected analog MR signal to the analog / digital converter for conversion into a digital signal. The digital signal thus obtained is output to the data processing unit 31 electrically coupled to the controller unit 25.

[0030] The controller unit 25 includes a computer and a recording medium recording a program to be executed by the computer. The program, when executed by the computer, causes the various parts of the system to perform operations corresponding to a predetermined scan. The recording medium may include, for example, a read-only memory (ROM), a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, or a non-volatile memory card. The controller unit 25 is connected to the operation console unit 32 and processes an operation signal (for example, input by an operator of the MRI system 10) input to the operation console unit 32, and further controls the patient table 26, the RF signal driver 22, the gradient driver 23, and the data acquisition unit 24 by outputting a control signal to the patient table 26, the RF signal driver 22, the gradient driver 23, and the data acquisition unit 24. The controller unit 25 also controls the data processing unit 31 and the display unit 33 based on the operation signal received from the operation console unit 32 to obtain a desired image.

[0031] During scanning (e.g., imaging the object 16 according to the above examples), a coil interface cable (not shown) may be used to transmit signals between the RF coils (e.g., the local RF coil 14 and the volume RF coil 15) and other aspects of the processing system (e.g., the data acquisition unit 24, the controller unit 25, etc.), for example, to control the RF coils and / or receive information from the RF coils. As previously described, in one example, the volume RF coil 15 may transmit RF signals and the local RF coil 14 may receive MR signals. The local RF coil 14 and / or the volume RF coil 15 may include a coil for transmitting RF excitation signals (a "transmitter coil") and a coil for receiving MR signals transmitted by the imaging object (a "receive coil"). In some examples, the transmitter coil and the receive coil may be the same coil (e.g., configured to both transmit RF excitation signals and receive MR signals), such that the coil is a single mechanical structure or array of structures, wherein the transmit / receive mode of the coil may be switched by auxiliary circuitry (e.g., the T / R switch 20). In other examples, the volume RF coil 15 and the local RF coil 14 may be separate structures that are physically coupled to each other via a data acquisition unit or other processing unit.

[0032] In some examples (e.g., examples where the transmitter coil and the receive coil are not the same coil), it may be desirable to configure the receive coil to be mechanically and electrically isolated from the transmitter coil in order to obtain improved image quality. In one example, the receive coil (e.g., the local RF coil 14) may be configured to receive MR signals for a duration after an RF signal is transmitted from a transmitter coil (e.g., the volume RF coil 15). However, during the duration that the transmitter coil transmits the RF signal, it may be desirable to electromagnetically decouple the receive coil from the transmitter coil so that the receive coil does not resonate with the transmitter coil (e.g., so that the receive coil does not receive the RF signal from the transmitter coil). Electromechanically decoupling (e.g., deactivating) the receive coil during the transmission of the RF signal by the transmitter coil may reduce the amount of noise generated within auxiliary circuits coupled to the receive coil, and may result in improved image quality.

[0033] In some examples (as described below, Figure 2 6 ), the volume RF coil 15 may be positioned in a birdcage arrangement (which may be referred to herein as a birdcage coil assembly) that is coupled to an outer surface of a bore 19 of a gantry 17 and surrounds an imaging space 18 .

[0034] Figure 2 A bore 200 of a gantry of an MRI system is shown including an RF coil 206 (similar to Figure 1 An imaging space is formed within the interior 202 of the bore 200 for a subject (e.g., a patient positioned on a table such as a Figure 1The imaging of the stage 26) as shown and described above. Figure 2 In the example shown, the hole 200 is cylindrical in shape, having a central axis 204. In other examples, the hole 200 may have a different shape (eg, a shape having a rectangular cross-section).

[0035] The RF coil 206 is similar to Figure 1 The volume RF coil 206 is a volume RF coil of the volume coil 15 shown and described above. The RF coil 206 is coupled to the outer surface 208 of the bore 200 circumferentially around the central axis 204 and includes a first end ring 210 and a second end ring 212 coupled together via a plurality of rungs 214 (which may be referred to herein as legs). The first end ring 210 and the second end ring 212 are annular and are shaped to surround the perimeter of the bore 200 to image a patient within the interior 202 (e.g., as described above with reference to Figure 1 The imaging is described). Each of the first end ring 210 and the second end ring 212 can be formed of a non-conductive material (e.g., an electrical insulator) and include a plurality of conductive portions 216. In one example, the first end ring 210 and the second end ring 212 can be formed of glass-reinforced epoxy, and the conductive portions can be a copper layer directly bonded to the surface of the end ring (e.g., directly adhered to the surface without other components in between). In other examples, the end rings can be formed of different materials (e.g., silicon dioxide) and / or the conductive portions can be formed of different conductive materials (e.g., gold, platinum, etc.). For example, the end rings can each include one or more printed circuit boards, wherein the conductive portions are a copper layer permanently adhered to the surface of the circuit board. Each conductive portion includes a plurality of notches that are positioned to reduce the amount of eddy current within the conductive portion, such as Figure 3 The first inset 300 and the second inset 302 are shown in further detail.

[0036] Figure 3 A perspective view of an RF coil 206 decoupled from an outer surface 208 of a bore 200 of an MRI system is shown. A first end ring 210 and a second end ring 212 of the RF coil 206 each include a first surface and an opposing second surface (which may be referred to herein as an outer surface and an inner surface, respectively). For example, the first end ring 210 includes an inner surface 304 and an outer surface 306, and the second end ring 212 includes an inner surface 308 and an outer surface 310. Although the first end ring 210 is described below as an example, the second end ring 212 is similarly configured relative to the first end ring 210.

[0037] The first end ring 210 includes a first plurality of conductive portions 312 (which may be referred to herein as outer portions) positioned along the outer surface 306. As described above, each conductive portion of the outer portion 312 may be formed of a conductive metal (e.g., copper) that is directly bonded to the outer surface 306 of the first end ring 210. As shown in the first inset 300, the outer portion 312 includes a first conductive portion 314 having a first configuration and a second conductive portion 316 having a second configuration. Specifically, the first conductive portion 314 includes a plurality of notches 318 that extend from a first end 320 and a second end 322 of the first conductive portion 314 toward the centerline 324 in a transverse direction relative to the centerline 324 of the first conductive portion 314. However, the notches 318 do not extend across the centerline 324 of the first conductive portion 314. The second conductive portion 316 includes a plurality of notches 328 extending from a first end 330 of the second conductive portion 316 to a second end 332 of the second conductive portion 316 in a transverse direction relative to the centerline 326 of the second conductive portion 316 and straddling the centerline 326. The shapes of the first conductive portion 314 and the second conductive portion 316 are as follows: FIG. 5A to FIG. 5B Further details are shown and described below.

[0038] The outer portion 312 includes a plurality of conductive portions similar to the first conductive portion 314 and the second conductive portion 316 described above (e.g., having the same shape), wherein portions similar to the first conductive portion 314 are disposed in an arrangement alternating with portions similar to the second conductive portion 316 along the entire circumference of the outer surface 306. Each portion similar to the first conductive portion 314 is located between two corresponding portions similar to the second conductive portion 316. In other words, each portion similar to the first conductive portion 314 is positioned such that one portion similar to the second conductive portion 316 is positioned adjacent to the first end 320, and another portion similar to the second conductive portion 316 is positioned adjacent to the second end 322. This arrangement is repeated along the entire circumference of the outer surface 306, such that no two portions similar to the first conductive portion 314 are positioned adjacent to each other along the outer surface 306. Similarly, no two portions similar to the second conductive portion 316 are positioned adjacent to each other along the outer surface 306. In this arrangement, the number of portions similar to the first conductive portion 314 included in the outer portion 312 is the same as the number of portions similar to the second conductive portion 316 included in the outer portion 312. For example, outer portion 312 may include 16 portions similar to first conductive portion 314 (including first conductive portion 314) and 16 portions similar to second conductive portion 316 (including second conductive portion 316), wherein each portion similar to first conductive portion 314 is adjacent to two corresponding portions similar to second conductive portion 316. In other examples, outer portion 312 may include a different number of portions (e.g., 32 portions similar to first conductive portion 314 and 32 portions similar to second conductive portion 316).

[0039] In the above alternating arrangement, each portion similar to the first conductive portion 314 is located at a corresponding crosspiece of the plurality of crosspieces 214. For example, the conductive portion 334 located at the outer surface 306 of the first end ring 210 is located at a first end 340 of the crosspiece 338, and the conductive portion 336 located at the outer surface 310 of the second end ring 212 is located at a second end 342 of the crosspiece 338, wherein the first end 340 is opposite to the second end 342 in the direction of the central axis 344 of the RF coil 206, and the crosspiece 338 extends between the conductive portion 334 and the conductive portion 336 (e.g., between the first end ring 210 and the second end ring 212) in a direction parallel to the central axis 344. The conductive portion 334 of the outer surface 306 of the first end ring 210 is mechanically and electrically coupled (e.g., welded, fused, etc.) to the rung 338 at a first end 340, and the conductive portion 336 of the outer surface 310 of the second end ring 212 is similarly mechanically and electrically coupled to the rung 338 at a second end 342. In this configuration, current can flow between the conductive portion 334 of the first end ring 210 and the conductive portion 336 of the second end ring 212 via the rung 338. Although the conductive portions 334 and 336 are described above as being coupled to the rung 338 as an example, each portion of the first end ring 210 that is similar to the first conductive portion 314 is similarly coupled to a corresponding portion of the second end ring 212 (where the corresponding portion is similar to the first conductive portion 314) through a corresponding rung of the plurality of rungs 214.

[0040] No portion similar to the second conductive portion 316 is directly coupled to the plurality of rungs 214 at the outer surface 306 or the outer surface 310. However, each portion similar to the second conductive portion 316 is mechanically and electrically coupled to each adjacent conductive portion. For example, the conductive portion 346 (similar to the second conductive portion 316) is mechanically and electrically coupled to two adjacent conductive portions 348 (each similar to the first conductive portion 314) along the outer surface 306 of the first end ring 210. In this configuration, the conductive portions at the outer surface 306 of the first end ring 210 are electrically coupled to each other so that current can flow through each portion (e.g., during a state in which the MRI system is operated to image a patient, as described above with reference to FIG. 1 ). Figure 1 described above).

[0041] The first end ring 210 additionally includes a second plurality of conductive portions 352 (which may be referred to herein as inner portions) positioned along the inner surface 304. As described above (and similar to the outer portion 312), each conductive portion of the inner portion 352 may be formed of a conductive metal (e.g., copper) that is directly bonded to the inner surface 304 of the first end ring 210. As shown in the second inset 302, each conductive portion of the inner portion 352 has a shape similar to the second conductive portion 316 described above. For example, the conductive portion 354 includes a plurality of notches 360 that extend from the first end 320 to the second end 322 across the centerline 362 in a transverse direction relative to the centerline 362 of the conductive portion 354.

[0042] Although the conductive portions located at the outer surface 306 are positioned in an alternating arrangement as described above, the conductive portions located at the inner surface 304 do not have an alternating arrangement. Each conductive portion of the inner portion 352 is shaped in the same manner relative to each other conductive portion of the inner portion 352 (e.g., similar to the second conductive portion 316). Each conductive portion of the inner portion 352 is electrically coupled and mechanically coupled (e.g., welded, fused, etc.) to each adjacent conductive portion of the inner portion 352 so that current can flow through each portion (e.g., during a state in which the MRI system is operated to image a patient, as described above with reference to Figure 1 In addition, one or more conductive portions of the inner portion 352 may be electrically coupled to one or more conductive portions of the outer portion 312 such that current may flow to portions located at both the inner surface 304 and the outer surface 306. Although the configuration (e.g., shape, position, etc.) of the conductive portions of the first end ring 210 is described above as an example, the second end ring 212 includes a similar configuration.

[0043] By shaping the conductive portions at the inner surface 304 and the inner surface 308 to include a notch extending across the centerline of each conductive portion, the amount of eddy current within each conductive portion can be reduced. For example, during operation of the MRI system, due to eddy currents generated in the conductive portions of the first end ring 210 and the second end ring 212, the hole 200 (formed by Figure 2 The temperature of the eddy currents generated by the gradient coils (e.g., Figure 1The eddy currents are generated by the interaction between the magnetic field generated by the magnetic gradient generator 13 described above and the conductive portion of the end ring. The eddy currents, combined with the static magnetic field (e.g., the B0 field generated by the static magnetic field magnet unit, such as the static magnetic field magnet unit 12 described above), can additionally cause vibrations of the RF coil 206, thereby causing an increase in the acoustic noise level within the interior 202 of the bore 200. By increasing the number of conductive portions that include notches, the eddy currents are interrupted, thereby causing a decrease in the temperature of the bore 200 and / or a decrease in the amount of acoustic noise within the interior 202. In particular, increasing the number of conductive portions that include notches extending across the centerline of each portion further reduces the generation of eddy currents relative to the number of conductive portions that include notches that do not extend across the centerline of each portion.

[0044] FIG. 4A to FIG. 4B Each shows a plan view of a different side of the RF coil 206. FIG. 4A to FIG. 4B The illustrated views are included for illustrative purposes to indicate the relative positions, quantities, and arrangements of the conductive portions of the inner portion 352 and the outer portion 312. For example, Figure 4A A plan view of the exterior of the RF coil 206 is shown (eg, a side of the RF coil 206 that includes the exterior portion 312 and is positioned away from the exterior surface 208 of the aperture 200 during a state where the RF coil 206 is coupled to the aperture 200), while Figure 4B A plan view of the interior of the RF coil 206 is shown (e.g., a side of the RF coil 206 that includes the interior portion 352 and that is positioned in coplanar contact with the outer surface 208 of the bore 200 during a state where the RF coil 206 is coupled to the bore 200). Reference axis 499 is included for comparison of FIGS. Figure 4B View shown.

[0045] like FIG. 4A to FIG. 4B As shown, configuring the inner portion 352 to include only conductive portions having a notch extending across the centerline of each portion increases the number of conductive portions of the RF coil 206 that are similar to the second conductive portion 316 relative to the number of conductive portions that are similar to the first conductive portion 314. Because the second conductive portion 316 includes the notch 328 that extends across the centerline 326, the amount of eddy currents within the second conductive portion 316 during operation of the RF coil 206 is reduced relative to the first conductive portion 314. Similarly, because the RF coil 206 includes a greater number of conductive portions that are similar to the second conductive portion 316 relative to portions that are similar to the first conductive portion 314, the amount and / or magnitude of eddy currents within the RF coil 206 is reduced, thereby reducing the temperature and vibration of the RF coil 206.

[0046] Figure 4AThe bracket 400 shown shows the location of the first conductive portion 314 and the second conductive portion 316 at the outer surface 306, and Figure 4B The bracket 402 shown shows that the conductive portion 354 and the adjacent similar conductive portion 355 are located at the inner surface 308 (eg, Figure 3 The first conductive portion 314, the second conductive portion 316, the conductive portion 354 and the conductive portion 355 are each formed by FIG. 5A to FIG. 5B Shown in more detail.

[0047] FIG. 5A to FIG. 5B Shown around Figure 3 The axis 500 is positioned about the center axis 344 of the RF coil 206 shown. As shown, the axis 500 extends in a direction parallel to each of the recesses (e.g., the recess 318 of the first conductive portion 314, the recess 328 of the second conductive portion 316, the recess 504 of the conductive portion 355, and the recess 360 of the conductive portion 354). The axis 500 (and the center axis 344) extends in a transverse direction relative to each center line of each conductive portion (e.g., the center line 324 of the first conductive portion 314, the center line 326 of the second conductive portion 316, the center line 362 of the conductive portion 354, and the center line 502 of the conductive portion 355). Figures 2 to 6B As shown and in the examples described herein, each conductive portion includes four notches. However, in alternative embodiments, one or more of the conductive portions may include a different number of notches (e.g., three, five, six, etc.). In addition, in the examples described herein, each notch is positioned the same distance from each adjacent notch in the direction of the corresponding centerline (e.g., such as the length 506 between the notches 318 of the first conductive portion 314 is the same as the length 508 between the notches 328 of the second conductive portion 316). In alternative embodiments, one or more lengths between adjacent notches may be different from other lengths between adjacent notches. For example, at least one length between the notches 318 of the first conductive portion 314 may be different from the length between other adjacent notches 318 and / or the length between the notches 328 of the second conductive portion 316.

[0048] As described above, the notches in the conductive portion reduce the temperature of the conductive portion during operation of the MRI system. FIG. 6A to FIG. 6B6 shows the relative temperatures at various regions of the conductive portion during an operating state. Specifically, a region operating at a first temperature is indicated by a first stippled shading 600, a region operating at a second temperature lower than the first temperature is indicated by a second stippled shading 602, and a region operating at a third temperature lower than each of the first and second temperatures is indicated by a third stippled shading 604. The temperature near the centerline 324 of the first conductive portion 314 (e.g., at region 606) is increased relative to the temperature near the centerline 326 of the second conductive portion 316 (e.g., at region 608). The reduced temperature of region 608 of the second conductive portion 316 relative to region 606 of the first conductive portion 314 is a result of the notch 328 extending across the centerline 326.

[0049] As described above, because the RF coil 206 includes an increased number of portions similar to the second conductive portion 316 relative to the number of portions similar to the first conductive portion 314 , the temperature of the RF coil 206 is reduced during operation of the MRI system relative to RF coils that do not include such a configuration. Figure 7 Graph 700 is shown illustrating the difference in operating temperature of a standard RF coil that does not include a notch extending across the centerline of the conductive portion relative to the RF coil 206 described herein. Specifically, graph 702 illustrates the aperture (e.g., Figure 2 200) with respect to time, and curve 704 shows the temperature with respect to time of the aperture coupled with the RF coil 206 in the same state instead. In one example, the peak temperature indicated by curve 702 may be 58 degrees Celsius, and the peak temperature indicated by curve 704 may be 52 degrees Celsius. By reducing the temperature of the aperture and the amount of vibration noise generated by the operation of the MRI system via the RF coil 206, patient comfort may be increased.

[0050] Figures 2 to 6BAn example configuration with relative positioning of various components is shown. If shown to be in direct contact or direct coupling with each other, these elements may be referred to as direct contact or direct coupling, respectively, at least in one example. Similarly, at least in one example, the elements shown as being adjacent or adjacent to each other may be adjacent or adjacent to each other, respectively. As an example, components in coplanar contact with each other may be referred to as being in coplanar contact. As another example, in at least one example, there is only one space between the elements positioned separately from each other, and no other elements may be referred to as such. As another example, the elements shown above / below each other, on opposite sides or on the left / right side of each other may be referred to as such. Further, as shown in the figure, in at least one example, the topmost element or point of the element may be referred to as the "top" of the component, and the bottommost element or point of the element may be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the accompanying drawings and used to describe the positioning of the elements in the accompanying drawings relative to each other. Thus, in one example, the elements shown above other elements are vertically positioned above other elements. As yet another example, the shapes of elements depicted in the drawings may be referred to as having those shapes (e.g., round, straight, flat, curved, enclosed, chamfered, angled, etc.). Further, in at least one example, elements shown as crossing each other may be referred to as crossing elements or crossing each other. Still further, in one example, an element shown as being within another element or an element shown as being outside another element may be referred to as such.

[0051] The technical effect of the present disclosure is to reduce the amount and size of eddy currents within the conductive portion of the RF coil via a plurality of notches extending toward the center line of each conductive portion. By reducing the amount of eddy currents, the temperature of the RF coil is reduced, and the amount of vibration of the RF coil is reduced. The reduced temperature and vibration result in a reduced temperature of the bore of the MRI system and a reduced acoustic noise level within the bore, thereby increasing patient comfort. Another technical effect of the present disclosure is to increase the electrical power efficiency of the RF coil. By reducing the eddy currents, the reduced electrical energy is converted into heat energy within the conductive portion of the RF coil, thereby generating an RF signal more efficiently.

[0052] In one embodiment, a radio frequency (RF) coil for a medical imaging device includes: a first conductive portion having a first end and an opposite second end; and a first plurality of notches of the first conductive portion extending from the first end to the second end across a center line of the first conductive portion. In the first example of the RF coil, the RF coil further includes: a second conductive portion having a third end and an opposite fourth end; a second plurality of notches formed at the third end, wherein each notch of the second plurality of notches extends toward the fourth end and does not cross the center line of the second conductive portion; and a third plurality of notches formed at the fourth end, wherein each notch of the third plurality of notches extends toward the third end and does not cross the center line of the second conductive portion. The second example of the RF coil optionally includes the first example, and further includes wherein the center line of the first conductive portion and the center line of the second conductive portion are positioned parallel to each other. The third example of the RF coil optionally includes one or both of the first example and the second example, and further includes wherein the first conductive portion is one of the first plurality of conductive portions positioned along a first circumferential surface of an end ring of the RF coil. The fourth example of the RF coil optionally includes one or more or each of the first to third examples, and further includes a second plurality of conductive portions positioned along a second circumferential surface of the end ring, the second circumferential surface being opposite to the first circumferential surface in a radial direction of the end ring. The fifth example of the RF coil optionally includes one or more or each of the first to fourth examples, and further includes wherein the first plurality of conductive portions includes a second conductive portion positioned adjacent to the first conductive portion along the first circumferential surface, the second conductive portion including a second plurality of notches and a third plurality of notches positioned opposite to each other across a center line of the second conductive portion. The sixth example of the RF coil optionally includes one or more or each of the first to fifth examples, and further includes wherein each conductive portion of the second plurality of conductive portions has the same shape as the first conductive portion. The seventh example of the RF coil optionally includes one or more or each of the first to sixth examples, and further includes wherein the first circumferential surface forms an outer perimeter of the end ring and the second circumferential surface forms an inner perimeter of the end ring. An eighth example of the RF coil optionally includes one or more or each of the first to seventh examples, and further includes wherein the first circumferential surface and the second circumferential surface are each formed of a dielectric material, wherein each of the first plurality of conductive portions is directly bonded to the first circumferential surface, and wherein each of the second plurality of conductive portions is directly bonded to the second circumferential surface.

[0053] In another embodiment, a radio frequency (RF) coil for a medical imaging device includes: a first plurality of conductive portions located along a first surface of a first end ring; and a plurality of notches formed by a first conductive portion of the first plurality of conductive portions and extending across a center line of the first conductive portion. In the first example of the RF coil, the RF coil further includes a second plurality of conductive portions located at the first surface, wherein each conductive portion of the second plurality of conductive portions includes a second plurality of notches that do not extend across a center line of any of the conductive portions of the second plurality of conductive portions, and wherein each conductive portion of the second plurality of conductive portions is positioned in an alternating arrangement with each conductive portion of the first plurality of conductive portions. The second example of the RF coil optionally includes the first example, and further includes wherein the first end ring is one of a plurality of end rings of the RF coil. The third example of the RF coil optionally includes one or both of the first example and the second example, and further includes wherein the plurality of end rings includes exactly a first end ring and a second end ring, wherein the first end ring and the second end ring are coupled together by a plurality of crosspieces. A fourth example of an RF coil optionally includes one or more or each of the first to third examples, and further includes a second plurality of conductive portions positioned along a second surface of the first end ring, the second surface being opposite to the first surface, and wherein each conductive portion of the second plurality of conductive portions includes a second plurality of notches extending across a centerline of each conductive portion of the second plurality of conductive portions. A fifth example of an RF coil optionally includes one or more or each of the first to fourth examples, and further includes wherein the first plurality of conductive portions includes a different second conductive portion, the second conductive portion including a second plurality of notches that do not extend across a centerline of the second conductive portion. A sixth example of an RF coil optionally includes one or more or each of the first to fifth examples, and further includes wherein the first conductive portion and the second conductive portion are positioned adjacent to each other along the first surface.

[0054] In another embodiment, a radio frequency (RF) coil for a medical imaging device includes: a first annular end ring coupled to a second annular end ring by a plurality of rungs, each of the first annular end ring and the second annular end ring including a first plurality of conductive portions; and a first plurality of notches formed by the first plurality of conductive portions and extending along the entire width of each of the first plurality of conductive portions. In the first example of the RF coil, each of the plurality of rungs extends from the first annular end ring to the second annular end ring in a direction parallel to a central axis of the coil, and each of the first plurality of notches extends in a circumferential direction around the central axis. The second example of the RF coil optionally includes the first example, and further includes wherein the first plurality of conductive portions are positioned along a first perimeter and a second perimeter of each of the first annular end ring and the second annular end ring. A third example of an RF coil optionally includes one or both of the first example and the second example, and further includes: a second plurality of conductive portions positioned along a first perimeter of each of the first end ring and the second end ring, wherein each portion of the first plurality of conductive portions is positioned in an alternating arrangement with each portion of the second plurality of conductive portions; and a second plurality of notches formed by the second plurality of conductive portions and extending partially along an entire width of each portion of the second plurality of conductive portions.

[0055] As used herein, the elements or steps cited in the singular and beginning with the word "one" or "an" should be understood as not excluding a plurality of the elements or steps, unless such exclusion is explicitly stated. In addition, the reference to "one embodiment" of the present invention is not intended to be interpreted as excluding the existence of other embodiments that also include the features. In addition, unless there is a clear statement to the contrary, the embodiments of "including", "comprising" or "having" one or more elements with a specific attribute may include other such elements that do not have the attribute. The terms "including (including)" and "in which (in which)" are used as the simple language equivalents of the corresponding terms "comprising (comprising)" and "wherein (wherein)". In addition, the terms "first", "second" and "third" etc. are only used as labels and are not intended to impose numerical requirements or specific positional order on their objects.

[0056] This written description uses examples to disclose the invention, including the best mode, and also to enable a person skilled in the relevant art to practice the invention, including making and using any device or system and performing any combined methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to a person skilled in the art. These other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

[0057] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed to be included within the subject matter of the present disclosure.

Claims

1. A radio frequency (RF) coil for medical imaging equipment, comprising: a first conductive portion extending along a centerline and having a first end and an opposing second end on either side of the centerline of the first conductive portion; as well as a second conductive portion extending along a centerline and having a third end and an opposing fourth end on either side of the centerline of the second conductive portion; The first conductive portion includes a first plurality of notches extending from the first end to the second end across the centerline of the first conductive portion, The second conductive portion includes a second plurality of notches formed at the third end and a third plurality of notches formed at the fourth end, wherein each notch in the second plurality of notches extends toward the fourth end and does not cross the center line of the second conductive portion, and each notch in the third plurality of notches extends toward the third end and does not cross the center line of the second conductive portion. 2 . The RF coil of claim 1 , wherein a centerline of the first conductive portion and a centerline of the second conductive portion are positioned parallel to each other. 3 . The RF coil of claim 1 , wherein the first conductive portion is one of a first plurality of conductive portions positioned along a first circumferential surface of an end ring of the RF coil. 4 . The RF coil of claim 3 , further comprising a second plurality of conductive portions positioned along a second circumferential surface of the end ring, the second circumferential surface being opposite to the first circumferential surface in a radial direction of the end ring.

5. The RF coil of claim 4, wherein the first plurality of conductive portions includes the second conductive portion positioned adjacent to the first conductive portion along the first circumferential surface, the second plurality of notches and the third plurality of notches being positioned opposite each other across a centerline of the second conductive portion. The RF coil of claim 5 , wherein each conductive portion of the second plurality of conductive portions has the same shape as the first conductive portion. 7 . The RF coil of claim 6 , wherein the first circumferential surface forms an outer perimeter of the end ring, and the second circumferential surface forms an inner perimeter of the end ring.

8. The RF coil of claim 7, wherein the first circumferential surface and the second circumferential surface are each formed of a dielectric material, wherein each of the first plurality of conductive portions is directly bonded to the first circumferential surface, and wherein each of the second plurality of conductive portions is directly bonded to the second circumferential surface.

9. A radio frequency (RF) coil for medical imaging equipment, comprising: a first plurality of conductive portions positioned along a first surface of a first end ring; as well as a second plurality of conductive portions, the second plurality of conductive portions being positioned along the first surface of the first end ring, the first plurality of conductive portions comprises a first plurality of notches, the first plurality of notches being formed by a first conductive portion of the first plurality of conductive portions, the first conductive portion of the first plurality of conductive portions extending along a centerline, and the first plurality of notches extending across the centerline of the first conductive portion, Each second conductive portion of the second plurality of conductive portions includes a second plurality of notches that extend across a center line of any second conductive portion of the second plurality of conductive portions, and wherein each second conductive portion of the second plurality of conductive portions is positioned in an alternating arrangement with each first conductive portion of the first plurality of conductive portions. 10 . The RF coil of claim 9 , wherein the first end ring is one of a plurality of end rings of the RF coil. 11 . The RF coil of claim 10 , wherein the plurality of end rings include the first end ring and the second end ring, wherein the first end ring and the second end ring are coupled together by a plurality of rungs.

12. The RF coil of claim 9, further comprising a third plurality of conductive portions positioned along a second surface of the first end ring, the second surface being opposite the first surface, and wherein each conductive portion of the third plurality of conductive portions comprises a third plurality of notches extending across a centerline of each conductive portion of the third plurality of conductive portions. 13 . The RF coil of claim 12 , wherein the first conductive portion and the second conductive portion are positioned adjacent to each other along the first surface.

14. A radio frequency (RF) coil for medical imaging equipment, comprising: a first annular end ring coupled to a second annular end ring via a plurality of rungs, each of the first annular end ring and the second annular end ring comprising a first plurality of conductive portions; as well as a second plurality of conductive segments positioned along a first perimeter of each of the first annular end ring and the second annular end ring, wherein each segment of the first plurality of conductive segments is positioned in an alternating arrangement with each segment of the second plurality of conductive segments; a first plurality of notches formed by the first plurality of conductive portions and extending along an entire width of each of the first plurality of conductive portions, A second plurality of notches is formed by the second plurality of conductive segments and extends partially along the entire width of each of the second plurality of conductive segments.

15. The RF coil of claim 14, wherein each of the plurality of rungs extends from the first annular end ring to the second annular end ring in a direction parallel to a central axis of the coil, and wherein each of the first plurality of notches extends in a circumferential direction around the central axis. 16 . The RF coil of claim 15 , wherein the first plurality of conductive portions are positioned along a first perimeter and a second perimeter of each of the first and second annular end rings.

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