阅读说明：本技术 用于磁共振成像的具有压力贮存器的射频线圈单元 (Radio frequency coil unit with pressure reservoir for magnetic resonance imaging ) 是由 冯利民 陈培勋 阿列克谢·泽姆斯科夫 杰森·李·菲尔普斯 克里斯汀·弗雷德里克 加齐·穆斯 于 2020-08-11 设计创作，主要内容包括：本发明题为“用于磁共振成像的具有压力贮存器的射频线圈单元”。本发明提供了用于磁共振成像的射频线圈单元的各种方法和系统。在一个示例中,一种用于磁共振成像(MRI)的射频(RF)线圈单元包括：外层,该外层形成RF线圈单元的外部；压力贮存器,该压力贮存器由外层包封,其中压力贮存器形成密封室；和RF线圈元件阵列,该RF线圈元件阵列由外层包封,其中RF线圈元件阵列设置在压力贮存器的密封室的外部。(The invention relates to a radio frequency coil unit with a pressure reservoir for magnetic resonance imaging. Various methods and systems are provided for a radio frequency coil unit for magnetic resonance imaging. In one example, a Radio Frequency (RF) coil unit for Magnetic Resonance Imaging (MRI) includes: an outer layer forming an exterior of the RF coil unit; a pressure reservoir enclosed by the outer layer, wherein the pressure reservoir forms a sealed chamber; and an array of RF coil elements enclosed by the outer layer, wherein the array of RF coil elements is disposed outside of the sealed chamber of the pressure reservoir.)

1. A Radio Frequency (RF) coil unit for Magnetic Resonance Imaging (MRI), comprising:

an outer layer forming an exterior of the RF coil unit;

a pressure reservoir enclosed by the outer layer, wherein the pressure reservoir forms a sealed chamber; and

an array of RF coil elements enclosed by the outer layer, wherein the array of RF coil elements is disposed outside of the sealed chamber of the pressure reservoir.

2. The RF coil unit of claim 1, wherein the pressure reservoir includes a plurality of openings extending therethrough, and each RF coil element includes:

a ring portion disposed on one side of the pressure reservoir; and

a coupling electronics portion disposed at a corresponding opening of the plurality of openings of the pressure reservoir.

3. The RF coil unit according to claim 2, further comprising a layer of cloth disposed between said pressure reservoir and said ring portion, wherein said ring portion is secured to said layer of cloth.

4. The RF coil unit according to claim 2, further comprising a layer of cloth to which said ring portion is secured, wherein said ring portion is disposed between said pressure reservoir and said layer of cloth.

5. The RF coil unit of claim 1, further comprising a fluid channel fluidly coupling the sealed chamber to ambient atmosphere.

6. The RF coil unit of claim 5 wherein the pressure inside the pressure reservoir is reduced by flowing gas out of the pressure reservoir into the ambient atmosphere, the pressure being increased by flowing gas into the pressure reservoir from the ambient atmosphere.

7. The RF coil unit of claim 1, wherein the pressure reservoir further comprises a plurality of particles within the sealed chamber.

8. The RF coil unit of claim 1, further comprising a coil interface cable electrically coupling the array of RF coil elements to an MRI system.

9. The RF coil unit of claim 8 further comprising an output board electrically coupling the array of RF coil elements to the coil interface cable.

10. The RF coil unit of claim 1, further comprising a plurality of spacers disposed between the outer layer and the pressure reservoir.

11. A Radio Frequency (RF) coil unit for Magnetic Resonance Imaging (MRI), comprising:

an outer layer forming an exterior of the RF coil unit;

a pressure reservoir enclosed by the outer layer, wherein the pressure reservoir forms a sealed chamber and a plurality of openings extend through the pressure reservoir; and

an array of RF coil elements enclosed by the outer layer, wherein each RF coil element comprises:

a ring portion disposed on one side of the pressure reservoir; and

a coupling electronics portion disposed at a corresponding opening of the plurality of openings of the pressure reservoir.

12. The RF coil unit of claim 11, wherein each RF coil element further comprises a wire electrically coupled to the coupling electronics portion, the wire and the loop portion disposed on opposite sides of the pressure reservoir.

13. The RF coil unit of claim 11 further comprising a plurality of thermal patches disposed on both sides of the coupling electronics portion.

14. A Radio Frequency (RF) coil unit for Magnetic Resonance Imaging (MRI), comprising:

an outer layer forming an exterior of the RF coil unit;

an opening extending through the outer layer to an interior of the RF coil unit;

a pressure reservoir enclosed within the interior by the outer layer, the pressure reservoir including a plurality of through-holes formed by an inner sidewall of the pressure reservoir, the inner sidewall being offset from an outer sidewall of the pressure reservoir;

a fluid channel extending through the opening of the outer layer to the exterior of the RF coil unit, the fluid channel fluidly coupled to the pressure reservoir;

and

an array of RF coil elements enclosed by the outer layer, wherein each RF coil element comprises:

a ring portion disposed on one side of the pressure reservoir; and

a coupling electronics portion disposed at a corresponding through-hole of the plurality of through-holes of the pressure reservoir.

15. The RF coil unit of claim 14, further comprising a plurality of thermal patches positioned at opposite sides of the pressure reservoir, wherein each of the plurality of vias is closed by a corresponding thermal patch of the plurality of thermal patches.

16. The RF coil unit of claim 14, further comprising a first plurality of thermal patches secured to a first side of the pressure reservoir and a second plurality of thermal patches secured to a second side of the pressure reservoir, wherein each coupling electronics portion is coupled to an exact one of the first plurality of thermal patches and an exact one of the second plurality of thermal patches.

17. The RF coil unit of claim 16, further comprising a first plurality of flexible spacers and a second plurality of flexible spacers disposed between the pressure reservoir and the outer layer, wherein each flexible spacer of the first plurality of flexible spacers is positioned in contact with a respective thermal patch of the first plurality of thermal patches, and wherein each flexible spacer of the second plurality of flexible spacers is positioned in contact with a respective thermal patch of the second plurality of thermal patches.

18. The RF coil unit of claim 14, wherein the fluid channel is configured to be coupled to a vacuum source to flow gas from the pressure reservoir to ambient atmosphere.

19. The RF coil unit of claim 14, wherein the fluid channel comprises a valve configured to fluidly isolate the pressure reservoir from ambient atmosphere in a closed position and to fluidly couple the pressure reservoir to ambient atmosphere or a vacuum source in an open position.

20. The RF coil unit of claim 14, wherein the pressure reservoir is sealed by the inner sidewall and fluidly isolated from ambient atmosphere at each of the plurality of through-holes.

Technical Field

Embodiments of the subject matter disclosed herein relate to Radio Frequency (RF) coils for Magnetic Resonance Imaging (MRI), and more particularly, to surface coils with pressure reservoirs for MRI.

Background

Magnetic Resonance Imaging (MRI) is a medical imaging modality that can create images of the interior of the human body without the use of X-rays or other ionizing radiation. The MRI system includes a superconducting magnet to generate a strong and uniform static magnetic field B₀. When the imaging subject is placed in the magnetic field B₀In (B), the nuclear spins associated with the hydrogen nuclei in the imaging subject become polarized such that the magnetic moments associated with these spins preferentially follow the magnetic field B₀Are aligned resulting in a small net magnetization along that axis. The hydrogen nuclei are excited by a radio frequency signal at or near the resonance frequency of the hydrogen nuclei, which adds energy to the nuclear spin system. When the nuclear spins relax back to their rest energy state, they release the absorbed energy in the form of a Radio Frequency (RF) signal. The RF signals (or MR signals) are detected by one or more RF coil units and transformed into images using a reconstruction algorithm.

In order to detect RF signals emitted by the subject's body, the RF coil unit is typically positioned close to the anatomical feature to be imaged by the MRI system. The quality of the image produced by an MRI system is greatly affected by the degree of conformance of the RF coil unit to the contour of the subject's body during image acquisition.

Disclosure of Invention

In one embodiment, a Radio Frequency (RF) coil unit for Magnetic Resonance Imaging (MRI) includes: an outer layer forming an exterior of the RF coil unit; a pressure reservoir enclosed by the outer layer, wherein the pressure reservoir forms a sealed chamber; and an array of RF coil elements enclosed by the outer layer, wherein the array of RF coil elements is disposed outside of the sealed chamber of the pressure reservoir.

It should be appreciated that the brief description above is provided to introduce in simplified form a selection of 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 defined uniquely 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.

Drawings

The disclosure will be better understood from a reading of the following description of non-limiting embodiments with reference to the attached drawings, in which:

fig. 1 is a block diagram of an MRI system according to an exemplary embodiment.

Fig. 2 shows the RF coil unit in an assembled configuration according to an exemplary embodiment.

Fig. 3 shows an inner part of the RF coil unit of fig. 2 according to an exemplary embodiment.

Fig. 4 shows an exploded view of the RF coil unit of fig. 2-3 according to an exemplary embodiment.

Fig. 5 shows a cross-sectional view of the RF coil unit of fig. 2-4 according to an exemplary embodiment.

Fig. 6-13 each illustrate different configurations of an RF coil unit coupled to a subject anatomy according to an exemplary embodiment.

Fig. 14 schematically shows an exemplary RF coil element of an RF coil unit coupled to a controller unit according to an exemplary embodiment.

The figures illustrate specific aspects of an RF coil unit with a pressure reservoir for MRI. Together with the following description, the drawings illustrate and explain the structural principles, methods, and principles described herein. In the drawings, the size of components may be exaggerated or otherwise modified for clarity. Well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the described components, systems, and methods.

Detailed Description

The following description relates to various embodiments of an RF coil unit. A Magnetic Resonance Imaging (MRI) system, such as the MRI system shown in fig. 1, may include an RF coil unit, such as the RF coil unit shown in fig. 2. The RF coil unit comprises a plurality of flexible RF coil elements (which may be referred to herein as RF coils) and an adjustable pressure reservoir. The pressure reservoir is positioned within the interior formed by the outer layers of the RF coil unit and includes a plurality of openings shaped to receive the coupling electronics of the flexible RF coil element, as shown in fig. 3. Inside the pressure reservoir is a sealed chamber, which is fluidly isolated from the interior of the RF coil unit, as shown in fig. 4, and the pressure inside the pressure reservoir interior can be regulated via a fluid channel, which is arranged to extend through the outer layer of the RF coil unit. The coupling electronics are positioned within the opening of the pressure reservoir as shown in fig. 5. The pressure within the pressure reservoir may be regulated via the fluid channel in order to form the RF coil unit onto the body of the subject to be imaged by the MRI system, as shown in fig. 6 to 13. As shown in fig. 14, the ring portion of each RF coil element may bend or flex with the pressure reservoir when the RF coil unit is formed onto the body of a patient. In this way, when the RF coil unit is formed onto the body of the patient, the loop portion of each RF coil element may be positioned closer to the body, and the imaging signal-to-noise ratio (SNR) of the RF coil unit may be increased.

The RF coil unit can be used to image a variety of different anatomical structures of a subject (e.g., the subject's feet, shoulders, cervical spine, etc.) without the use of straps or other fixation devices. Imaging anatomical structures via conventional RF coil units may be more difficult due to non-uniform shapes and sizes of anatomical structures of different subjects (e.g., patients). However, by constructing the RF coil unit as described herein, the RF coil unit may be adapted to image a variety of anatomical structures of different shapes and/or sizes of patients. The pressure reservoir may maintain its shape when formed on the body by regulating the pressure within the interior of the pressure reservoir. The flexibility of the RF coil element holds the RF coil element in close proximity to the anatomical structure to be imaged. Furthermore, because the RF coil unit may be formed onto the body without using straps or other fasteners, the cost of the RF coil unit may be reduced and the time to set up the RF coil unit for imaging may be reduced relative to conventional RF coil units coupled via straps or other fasteners and a fixation device.

In some embodiments, the RF coil unit can be used as a stabilizer for pediatric scanning by adjusting the pressure within the pressure reservoir to form the RF coil unit onto the body. Movement of the subject during a scan (e.g., during imaging via an MRI system) can lead to imaging artifacts. The improved stiffness of the RF coil unit during scanning may reduce imaging artifacts by reducing the likelihood of subject movement. For example, adjusting the pressure (e.g., gas pressure) within the pressure reservoir by compressing plastic pellets (e.g., polystyrene pellets) disposed within the pressure reservoir may increase the stiffness of the RF coil unit. The increased stiffness of the RF coil unit may substantially reduce movement of the subject to be imaged during a pediatric scan (e.g., imaging of an infant). Because the pressure reservoir is positioned within the RF coil unit, the RF coil unit can maintain the position of the subject to be imaged without additional straps and/or other fasteners. In addition, the outer layer of the RF coil unit may be formed of a soft fabric material in order to enhance patient comfort.

In this configuration, the RF coil unit is positioned against the body of the subject such that the RF coil element is arranged between the body and the pressure reservoir. This arrangement may promote patient comfort and position the RF coil elements close to the body. Therefore, the SNR of the subject image obtained by the MRI system via the RF coil unit can be increased.

In some embodiments, the RF coil unit may include eight (8) RF coil elements. The RF coil elements may be arranged along a layer of flexible cloth, such as fabric, with the pressure reservoir positioned against a ring portion of each RF coil element (e.g., such that the ring portion is positioned between the cloth layer and the pressure reservoir). The RF coil elements each include a loop portion and a coupling electronics portion. The loop portion of each RF coil element may be secured (e.g., sewn) to the cloth. In other embodiments, the cloth may be positioned between the ring portion and the pressure reservoir, wherein the ring portion is secured to the cloth. The coupling electronics of the RF coil element (e.g., feed plate) are placed through an opening extending through the thickness of the pressure reservoir to enable the cable (e.g., wire) coupled to the RF coil element to be positioned at an opposite side of the pressure reservoir (e.g., the side opposite the side where the loop portion is located). Additional layers made of, for example, fabric may be positioned at each side of the pressure reservoir. In some embodiments, the RF coil unit may include additional layers positioned at opposite sides of the coupling electronics and configured to cool the coupling electronics.

The coupling electronics of each RF coil element may be enclosed within a respective plastic housing (e.g., each feed plate of each RF coil element may be enclosed within a separate housing relative to each other feed plate). In some embodiments, the housings of the coupling electronics can be shaped to be positioned within the openings of the pressure reservoir (e.g., each housing can have substantially the same shape as each opening of the pressure reservoir). For each RF coil element, MRI signals may be received (e.g., measured) by the loop portion and processed by corresponding coupling electronics of the RF coil element. The coupling electronics may then transmit the electrical signal to the MRI system via the output cable.

Turning now to FIG. 1, a Magnetic Resonance Imaging (MRI) apparatus 10 is shown. The MRI apparatus 10 includes a static magnetic field magnet unit 12, a gradient coil unit 13, an RF coil unit 14, an RF body or volume coil unit 15, a transmission/reception (T/R) switch 20, an RF driver unit 22, a gradient coil driver unit 23, a data acquisition unit 24, a controller unit 25, a patient table or bed 26, a data processing unit 31, an operation console unit 32, and a display unit 33. In some embodiments, the RF coil unit 14 is a surface coil, which is a local coil that is typically placed near the anatomy of interest of the subject 16. Here, the RF body coil unit 15 is a transmission coil that transmits RF signals, and the local surface RF coil unit 14 receives MR signals. Thus, the transmission body coil (e.g., RF body coil unit 15) and the surface receiving coil (e.g., RF coil unit 14) are separate but electromagnetically coupled components. The MRI apparatus 10 transmits electromagnetic pulse signals to a subject 16 placed in an imaging space 18, in which a static magnetic field is formed to perform scanning to obtain magnetic resonance signals from the subject 16. One or more images of the subject 16 may be reconstructed based on the magnetic resonance signals thus obtained by the scan.

The static field magnet unit 12 includes, for example, an annular superconducting magnet mounted in an annular vacuum vessel. The magnet defines a cylindrical space around the subject 16 and generates a constant main static magnetic field B₀。

The MRI apparatus 10 further comprises a gradient coil unit 13 which forms gradient magnetic fields in the imaging space 18 in order to provide three-dimensional positional information for the magnetic resonance signals received by the RF coil array. The gradient coil unit 13 includes three gradient coil systems each generating a gradient magnetic field along one of three spatial axes perpendicular to each other, and generates a gradient field in each of a frequency encoding direction, a phase encoding direction, and a slice selection direction according to imaging conditions. More specifically, the gradient coil unit 13 applies a gradient field in a slice selection direction (or scanning direction) of the subject 16 to select a slice; and the RF body coil unit 15 or local RF coil array may transmit RF pulses to selected slices of the subject 16. The gradient coil unit 13 also applies a gradient field in a phase encoding direction of the subject 16 to phase encode magnetic resonance signals from slices excited by the RF pulses. The gradient coil unit 13 then applies a gradient field in a frequency encoding direction of the subject 16 to frequency encode the magnetic resonance signals from the slice excited by the RF pulses.

The RF coil unit 14 is provided, for example, to surround a region to be imaged of the subject 16. In some examples, the RF coil unit 14 may be referred to as a surface coil or a receive coil. A static magnetic field B is formed by the static magnetic field magnet unit 12₀The RF coil unit 15 transmits RF pulses as electromagnetic waves to the subject 16 based on control signals from the controller unit 25, and thereby generates high-frequency magnetism in the static magnetic field space or imaging space 18Field B₁. This excites proton spins in the slice of the subject 16 to be imaged. The RF coil unit 14 receives, as a magnetic resonance signal, an electromagnetic wave generated when proton spins thus excited return to being aligned with an initial magnetization vector in a slice to be imaged of the subject 16. In some embodiments, the RF coil unit 14 may transmit RF pulses and receive MR signals. In other embodiments, the RF coil unit 14 may be used only for receiving MR signals, and not for transmitting RF pulses.

The RF body coil unit 15 is provided, for example, so as to surround an imaging space 18, and generates a main magnetic field B in the imaging space 18 in combination with that generated by the static field magnet unit 12₀Orthogonal RF magnetic field pulses to excite the nuclei. In contrast to the RF coil unit 14, which may be disconnected from the MRI apparatus 10 and replaced with another RF coil unit, the RF body coil unit 15 is fixedly attached and connected to the MRI apparatus 10. Furthermore, although local coils such as the RF coil unit 14 may transmit or receive signals only from a local region of the subject 16, the RF body coil unit 15 generally has a larger coverage area. For example, the RF body coil unit 15 may be used to transmit or receive signals to or from the whole body of the subject 16. It will be appreciated that the particular use of the RF coil unit 14 and/or the RF body coil unit 15 depends on the imaging application.

The T/R switch 20 may selectively electrically connect the RF body coil unit 15 to the data acquisition unit 24 when operating in the receive mode, and the T/R switch 20 may selectively electrically connect the RF body coil unit 15 to the RF driver unit 22 when operating in the transmit mode. Similarly, the T/R switch 20 may selectively electrically connect the RF coil unit 14 to the data acquisition unit 24 when the RF coil unit 14 is operating in the receive mode, and the T/R switch 20 may selectively electrically connect the RF coil unit 14 to the RF driver unit 22 when operating in the transmit mode. When both the RF coil unit 14 and the RF body coil unit 15 are used for a single scan, for example, if the RF coil unit 14 is configured to receive MR signals and the RF body coil unit 15 is configured to transmit RF signals, the T/R switch 20 may direct control signals from the RF driver unit 22 to the RF body coil unit 15 while directing the received MR signals from the RF coil unit 14 to the data acquisition unit 24. The coils of the RF body coil unit 15 may be configured to operate in a transmission-only mode or a transmission-reception mode. The coils of the local RF coil unit 14 may be configured to operate in a transmit-receive mode or a receive-only mode.

The RF driver unit 22 includes a gate modulator (not shown), an RF power amplifier (not shown), and an RF oscillator (not shown) for driving an RF coil unit (for example, the RF coil unit 15) and forming a high-frequency magnetic field in the imaging space 18. The RF driver unit 22 modulates an RF signal received from the RF oscillator into a signal having a predetermined timing of a predetermined envelope based on a control signal from the controller unit 25 and using a gate modulator. The RF signal modulated by the gate modulator is amplified by an RF power amplifier and then output to the RF coil unit 15.

The gradient coil driver unit 23 drives the gradient coil unit 13 based on a control signal from the controller unit 25, thereby generating a gradient magnetic field in the imaging space 18. The gradient coil driver unit 23 comprises three driver circuitry (not shown) corresponding to the three gradient coil systems comprised in the gradient coil unit 13.

The data acquisition unit 24 includes a preamplifier (not shown), a phase detector (not shown), and an analog/digital converter (not shown) for acquiring the magnetic resonance signal received by the RF coil unit 14. In the data acquisition unit 24, the phase detector phase detects a magnetic resonance signal received from the RF coil unit 14 and amplified by the preamplifier using the output from the RF oscillator of the RF driver unit 22 as a reference signal, and outputs the phase-detected analog magnetic resonance signal to an analog/digital converter to be converted into a digital signal. The digital signal thus obtained is output to the data processing unit 31.

The MRI apparatus 10 includes a couch 26 for placing the subject 16 thereon. The subject 16 can be moved inside and outside the imaging space 18 by moving the couch 26 based on control signals from the controller unit 25.

The controller unit 25 includes a computer and a recording medium on which a program to be executed by the computer is recorded. The program, when executed by a computer, causes various portions of an apparatus to perform operations corresponding to a predetermined scan. The recording medium may include, for example, a ROM, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, or a nonvolatile memory card. The controller unit 25 is connected to the operation console unit 32 and processes operation signals input to the operation console unit 32, and also controls the examination bed 26, the RF driver unit 22, the gradient coil driver unit 23, and the data acquisition unit 24 by outputting control signals thereto. The controller unit 25 also controls the data processing unit 31 and the display unit 33 based on an operation signal received from the operation console unit 32 to obtain a desired image.

The console unit 32 includes user input devices such as a touch screen, a keyboard, and a mouse. The operator uses the operation console unit 32, for example, to input such data as an imaging protocol, and sets a region where an imaging sequence is to be performed. Data on the imaging protocol and the imaging sequence execution region is output to the controller unit 25.

The data processing unit 31 includes a computer and a recording medium on which a program executed by the computer to execute predetermined data processing is recorded. The data processing unit 31 is connected 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 spectral data by applying various image processing operations to the magnetic resonance signals output from the data acquisition unit 24.

The display unit 33 includes a display device, and displays an image on a display screen of the 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 for an operator to input operation data from the operation console unit 32. The display unit 33 also displays a two-dimensional (2D) slice image or a three-dimensional (3D) image of the subject 16 generated by the data processing unit 31.

Referring now to fig. 2, an RF coil unit 200 is shown in an assembled configuration according to an exemplary embodiment. The RF coil unit 200 may be used as the RF coil unit 14 described above with reference to fig. 1. The RF coil unit 200 includes an outer layer 202 forming an exterior of the RF coil unit 200. In some embodiments, the outer layer 202 may be formed from a relatively soft and flexible material (e.g., fabric). The interior of the RF coil unit 200 includes a plurality of flexible RF coil elements and an adjustable pressure reservoir, as described further below. Each of the RF coil elements may include a loop portion electrically coupled to respective coupling electronics (e.g., a feed plate). The RF coil elements may receive, process and transmit the MR signals to the output connector 210 of the RF coil unit 200 via a coil interface cable 212 electrically coupled to the coupling electronics of each RF coil element. The output connector 210 may interact with an input of an MRI system (e.g., the controller unit 25 of the MRI apparatus 10 shown in fig. 1 and described above) to image a subject (e.g., a patient) via the RF coil unit 200 and the MRI system.

The pressure reservoir disposed within the interior of the RF coil unit 200 comprises a sealed chamber formed of, for example, plastic, leather, or any other suitable material. The sealed chamber is fluidly coupled to the fluid passage 204 extending through the outer layer 202 via the opening 216 of the outer layer 202. The fluid channel 204 may include one or more valves (e.g., check valves) configured to maintain pressure (e.g., gas pressure) within the pressure reservoir. For example, a care provider (e.g., a clinician) may couple the fluid channel 204 to a vacuum pump in order to remove gas from inside the pressure reservoir and reduce the pressure within the pressure reservoir relative to ambient air pressure (e.g., atmospheric pressure). In some embodiments, the fluid channel 204 may include a first valve (e.g., a check valve) that enables gas to flow out of the pressure reservoir but not into the pressure reservoir. The fluid passage 204 may additionally include a second valve (e.g., a pressure relief valve) configured to enable gas flow into the pressure reservoir (e.g., to expand the pressure reservoir from a compressed state to an uncompressed state) during a state in which the second valve is in an open position and to prevent gas flow into the pressure reservoir during a state in which the second valve is in a fully closed position. The first valve and/or the second valve may be normally closed valves that do not allow gas to flow into and/or out of the pressure reservoir during the state in which the valves are in the fully closed position. However, the first valve and/or the second valve may be actuated (e.g., electrically actuated via a processing system of the MRI system, physically actuated by an operator of the MRI system, etc.) from a fully closed position to an open position in order to regulate the pressure within the pressure reservoir (e.g., increase or decrease the gas pressure within the pressure reservoir).

For example, the care provider may couple the fluid channel 204 to a vacuum pump that may open a first valve to flow gas out of the pressure reservoir without flowing gas into the pressure reservoir (e.g., while maintaining a second valve in a fully closed position). Accordingly, the pressure of the pressure reservoir is reduced, the pellets disposed within the pressure reservoir may be compressed together, and the RF coil unit 200 is formed against the body of the subject to be imaged. Then, when the vacuum pump is disengaged from the fluid channel, the first valve may automatically close to maintain a lower pressure of the pressure reservoir. Maintaining the pressure of the pressure reservoir in this way may maintain the shape of the RF coil unit relative to the subject's body. When the scan is complete, the caregiver can actuate the second valve to an open position to allow ambient air to flow into the pressure reservoir. Thus, the pressure within the pressure reservoir may be adjusted to be approximately equal to the ambient air pressure (e.g., the atmospheric air pressure outside of the interior of the pressure reservoir), and the pellets disposed within the interior of the pressure reservoir may no longer be compressed together. Flowing ambient air into the pressure reservoir in this manner (e.g., relieving the pressure within the pressure reservoir) may restore the shape of the RF coil unit 200 to its normal, uncompressed shape (e.g., the shape shown in fig. 2).

In some embodiments, at least one of the valves described above may be integrally formed with the fluid channel 204 (e.g., integrated with the fluid channel as a single unit). In fig. 2, the RF coil unit 200 is substantially rectangular. It should be appreciated that the RF coil unit may be any suitable shape for various applications, such as square, circular, elliptical, etc. The RF coil unit may also be of any suitable size, depending on the application.

Referring now to fig. 3, the internal portion of the RF coil unit 200 of fig. 2 is shown. Fig. 3 shows the RF coil unit 200 in a partial cross-section in order to show the relative arrangement of the RF coil loop portion, the coupling electronics, the pressure reservoir and the other components of the RF coil unit 200. Fig. 2-5 show various views of the RF coil unit 200, and include a reference axis 299 for comparing the different views.

The RF coil unit 200 includes eight (8) RF coil elements arranged to form an RF coil array. Each coil element includes a loop portion and a coupling electronics portion electrically connected to the loop portion. In particular, the RF coil unit 200 includes a first row of RF coil elements including a first loop portion 334 and a first coupling electronics portion 318, a second loop portion 336 and a second coupling electronics portion 320, a third loop portion 338 and a third coupling electronics portion 322, and a fourth loop portion 340 and a fourth coupling electronics portion 324 (e.g., where the first loop portion 334 and the first coupling electronics portion 318 correspond to a first RF coil element, the second loop portion 336 and the second coupling electronics portion 320 correspond to a second RF coil element, etc.). The RF coil unit 200 additionally comprises a second row of RF coil elements comprising a fifth ring portion 342 and a fifth coupling electronics portion 326, a sixth ring portion 344 and a sixth coupling electronics portion 328, a seventh ring portion 346 and a seventh coupling electronics portion 330, and an eighth ring portion 348 and an eighth coupling electronics portion 332. The first row of RF coil elements may partially overlap the second row of RF coil elements. For example, the first ring portion 334 partially overlaps the fifth ring portion 342, the second ring portion 336 partially overlaps the sixth ring portion 344, and so on. Further, within each row, adjacent RF coil elements may partially overlap one another. For example, a first ring portion 334 partially overlaps an adjacent second ring portion 336, a fifth ring portion 342 partially overlaps an adjacent sixth ring portion 344, and so on. Each RF coil element can be electrically isolated from each other RF coil element such that the overlap of the RF coil elements does not interfere with MR signals acquired by the RF coil elements for imaging the subject's body. In some embodiments, the RF coil unit 200 may include a different number of RF coil elements (e.g., 12 RF coil elements, 16 RF coil elements, etc.).

In some embodiments, the loop portion may be disposed along the layer of flexible cloth material such that the loop portion is positioned between the layer of cloth material and the pressure reservoir 300. The loop portion of each RF coil element may be secured (e.g., sewn) to the cloth. In other embodiments, the cloth may be positioned between the ring portion and the pressure reservoir 300, wherein the ring portion is secured to the cloth.

Each RF coil element is coupled (e.g., electrically coupled) to a respective coupling electronics (e.g., a feed plate). In some embodiments, each panel feed is packaged within a respective housing. In some embodiments, the housing may be formed of a plastic material.

In some embodiments, each of the coupling electronics portions is disposed within a respective opening of the pressure reservoir 300. In particular, first coupling electronics portion 318 is disposed within first opening 302, second coupling electronics portion 320 is disposed within second opening 304, third coupling electronics portion 322 is disposed within third opening 306, fourth coupling electronics portion 324 is disposed within fourth opening 308, fifth coupling electronics portion 326 is disposed within fifth opening 310, sixth coupling electronics portion 328 is disposed within sixth opening 312, seventh coupling electronics portion 330 is disposed within seventh opening 314, and eighth coupling electronics portion 332 is disposed within eighth opening 316. Each opening of the pressure reservoir 300 extends through the pressure reservoir 300 (e.g., from a first side 301 of the pressure reservoir 300, as shown in fig. 4, extending completely through the pressure reservoir 300 to an opposing second side 303 of the pressure reservoir 300). Each of the openings is not fluidly coupled to the interior of the pressure reservoir 300 (e.g., gas, such as air, held within the interior of the pressure reservoir 300 does not flow into or out of the pressure reservoir 300 at the first opening 302, the second opening 304, the third opening 306, the fourth opening 308, the fifth opening 310, the sixth opening 312, the seventh opening 314, or the eighth opening 316). The sidewalls of the pressure reservoir 300 (e.g., an inner sidewall such as inner sidewall 337 offset or spaced apart from an outer sidewall such as outer sidewall 339 that forms an outer perimeter of the pressure reservoir 300) are sealed at each of the openings such that each of the openings forms a respective through-hole between the first side 301 and the second side 303 of the pressure reservoir 300, which openings are configured to receive a housing of the coupling electronics. Each of the openings (which may be referred to herein as through-holes) is sealed such that the openings fluidly isolate the interior of the pressure reservoir 300 from ambient atmosphere (e.g., gas does not flow between the interior of the pressure reservoir 300 and ambient atmosphere via the openings).

The coupling electronics may be coupled to the output plate 354 via respective wires, as shown in fig. 3-4, and the output plate 354 may output electrical signals from each of the coupling electronics to the coil interface cable 212. The RF coil unit 200 may additionally include one or more baluns 350 and 352 electrically coupled between the output plate 354 of each RF coil element and the coupling electronics. As described above, the coil interface cable 212 may be coupled to the MRI system in order to transmit signals from the RF coil elements to the MRI system for imaging the subject via the RF coil unit 200.

In some embodiments, each opening of the pressure reservoir 300 (e.g., the first opening 302, the second opening 304, the third opening 306, the fourth opening 308, the fifth opening 310, the sixth opening 312, the seventh opening 314, and the eighth opening 316) may be covered (e.g., closed or capped) with a respective thermal patch 358 and thermal patch 400, as shown in the exploded view of fig. 4. In particular, as described above, when the RF coil unit 200 is fully assembled, the coupling electronics are disposed within the respective openings of the pressure reservoir 300. The opening may be covered by heat patch 358 at a first side 301 of pressure reservoir 300 and the opening may be covered by heat patch 400 at a second side 303 of the pressure reservoir, with the housing positioned within the opening between heat patch 358 and heat patch 400. In this configuration, heat patch 358 and heat patch 400 may help retain the coupled electronic devices within the corresponding openings. Further, in some embodiments, heat patch 358 and/or heat patch 400 may be formed of a material having a high thermal conductivity. Thus, when the RF coil unit 200 is used to image a subject (e.g., a patient), the thermal patch 358 at the first side 301 and the thermal patch 400 at the second side 303 may increase heat transfer away from the housing. The thermal patch may reduce the operating temperature of the coupling electronics, thereby improving patient comfort.

To further promote patient comfort, in some embodiments, the RF coil unit 200 may include a first plurality of flexible spacers 356 positioned between the first side 301 of the pressure reservoir 300 and the first outer layer 360 of the RF coil unit 200 and/or a second plurality of flexible spacers 402 positioned between the second side 303 of the pressure reservoir 300 and the opposing second outer layer 364 of the RF coil unit 200. The first outer layer 360 and the second outer layer 364 may correspond to the outer layer 202 in fig. 2. In some embodiments, first outer layer 360 and second outer layer 364 are made from a single sheet of material that is folded. In some embodiments, the first and second outer layers 360 and 364 are made of two pieces of material that are sewn together to form the exterior of the RF coil unit 200. In some embodiments, the flexible spacer 356 and the flexible spacer 402 may be formed of a foam material. In other embodiments, the flexible spacer 356 and the flexible spacer 402 may be formed from a flame retardant material. In some embodiments, each of the flexible spacers 356 at the first side 301 may be positioned in contact with a respective one of the heat patches 358 (e.g., positioned directly against the respective heat patch without other components therebetween), and each of the flexible spacers 402 at the second side 303 may be positioned in contact with a respective one of the heat patches 400. The flexible spacer 356 and the flexible spacer 402 may increase the amount of air within the RF coil unit 200 surrounding the opening of the pressure reservoir 300, which may reduce the temperature of the coupling electronics during operation.

After the RF coil unit 200 is fully assembled along the assembly axis 499, the coupling electronics within each housing are coupled to both the RF coil elements at the second side 303 and the wires at the first side 301. In this configuration, each RF coil element positioned at second side 303 is electrically coupled to a corresponding electrical line positioned at first side 301 through coupling electronics within a corresponding housing, where each electrical line is joined to output board 354 at first side 301.

The relative arrangement of the RF coil elements, the pressure reservoir 300 and the housing is further illustrated by the cross-sectional view (taken along the axis 214 shown in fig. 2-3) of the RF coil unit 200 shown in fig. 5. As shown in fig. 5, the pressure reservoir 300 may include a loose fill in the interior volume of the pressure reservoir that includes a plurality of particles, such as pellets 510, within the pressure reservoir. The pellets may be composed of polystyrene or other suitable material.

In some embodiments, the outer layers (e.g., the first outer layer 360 and the second outer layer 364) of the RF coil unit 200 may include multiple sub-layers and/or different types of materials. In the embodiment shown in fig. 5, the second outer layer 364 comprises three sub-layers, each of which is formed of a different material. In particular, the second outer layer 364 includes an outermost sub-layer 502, an innermost sub-layer 506, and an intermediate sub-layer 504. In some embodiments, innermost sub-layer 506 may be formed of a flame retardant textile material, intermediate sub-layer 504 may be formed of a flame retardant material, and outermost sub-layer 502 may be formed of a polyurethane coated textile material. However, in other embodiments, the outer layer may include a different number of sub-layers and/or different types of materials.

Referring now to fig. 6-13, various coupling configurations of the RF coil units are shown. In particular, fig. 6 shows an RF coil unit 600 formed onto a subject 602, fig. 7 shows an RF coil 700 formed onto a subject 702, fig. 8 shows an RF coil 800 formed onto a subject 802, fig. 9 shows an RF coil 900 formed onto a subject 902, fig. 10 shows an RF coil 1000 formed onto a subject 1002, fig. 11 shows an RF coil 1100 formed onto a subject 1102, fig. 12 shows an RF coil 1200 formed onto a subject 1202, and fig. 13 shows an RF coil 1300 formed onto a subject 1302. In some embodiments, each of the RF coil units 600, 700, 800, 900, 1000, 1100, 1200 and 1300 may be the same as the RF coil unit 200 described above with reference to fig. 2-5. Each of the RF coil units includes a pressure reservoir, which may be the same as the pressure reservoir 300 described above. In each of fig. 6-13, similar to the above example, the pressure (e.g., gas pressure) within the interior of the pressure reservoir is reduced to below atmospheric pressure in order to form the RF coil unit onto the subject's body (e.g., such that pellets disposed within the interior of the pressure reservoir are compressed to increase the stiffness of the pressure reservoir and the RF coil unit).

Fig. 6 shows an RF coil unit 600 formed to the neck and chest of a subject 602, fig. 7 shows an RF coil unit 700 formed to the shoulder of a subject 702, fig. 8 shows an RF coil unit 800 formed to the head and neck of a subject 802, fig. 9 shows an RF coil unit 900 formed to the head of a subject 902, fig. 10 shows an RF coil unit 1002 formed to the torso of a subject 1002 (e.g., an infant), fig. 11 shows an RF coil unit 1100 formed to the lower back of a subject 1102, fig. 12 shows an RF coil unit 1200 formed to the feet of a subject 1202, and fig. 13 shows an RF coil unit 1300 formed to the knee of a subject 1302. As described above, in some embodiments, each of the RF coil units shown in fig. 6-13 may be the same as the RF coil unit 200 shown in fig. 2-5 and described above. Accordingly, the RF coil unit 200 can be formed to a plurality of different anatomical structures of the subject to be imaged shown in fig. 6 to 13. The examples shown in fig. 6-13 are non-limiting, and in some embodiments, the RF coil unit 200 can be formed onto other anatomical features of the subject (e.g., the subject's thighs, arms, upper back, etc.).

Turning now to fig. 14, there is shown a schematic diagram of an RF coil element 1402 comprising a loop portion 1401 coupled to a controller unit 1410 via coupling electronics portion 1403 and coil interface cable 1412. The RF coil element 1402 is one non-limiting example of an RF coil element of the RF coil unit 200.

In some embodiments, ring portion 1401 may be a distributed capacitance ring portion (also referred to as an "air coil"), as disclosed in patent application PCT/US2017/062971, which is incorporated by reference herein for all purposes. In other embodiments, loop portion 1401 may be any suitable flexible coil (e.g., a coil comprising copper wires and discrete capacitors).

The coupling electronics portion 1403 may be coupled to the loop portion of the RF coil element 1402. In some embodiments, coupling electronics portion 1403 may include decoupling circuit 1404, impedance inverter circuit 1406, and preamplifier 1408. The decoupling circuit 1404 may effectively decouple the RF coil element 1402 during transmit operations. Generally, the RF coil element 1402 in its receive mode may be coupled to a body of a subject being imaged by the MR device in order to receive electromagnetic radiation from the body. The RF coil element 1402 may be decoupled from the RF body coil when the RF body coil is transmitting RF signals. Decoupling of the receive coil and the transmit coil may be accomplished using a resonant circuit and a PIN diode, a micro-electro-mechanical system (MEMS) switch, or another type of switching circuit. In this context, the switching circuit may activate a demodulation circuit operatively connected to the RF coil element 1402.

Impedance inverter circuitry 1406 may form an impedance matching network between RF coil elements 1402 and preamplifier 1408. Impedance inverter circuitry 1406 is configured to convert the coil impedance of RF coil element 1402 to the optimal source impedance of preamplifier 1408. The impedance inverter circuit 1406 may include an impedance matching network and an input balun. The preamplifiers 1408 receive MR signals from the corresponding RF coil elements 1402 and amplify the received MR signals. In one example, the preamplifier may have a low input impedance configured to produce a relatively high impedance in the coil to reduce coupling between the coil elements in the receive mode.

Coil interface cables 1412, such as RF coil array interface cables, may be used to transmit signals between the RF coil elements of the RF coil unit and other aspects of the processing system, for example to control the RF coil elements and/or to receive information from the RF coil elements.

A technical effect of configuring the RF coil unit to be formed onto the body of the patient by adjusting the gas pressure within the pressure reservoir is to position the RF coil elements closer to the body of the patient to increase the SNR, wherein the coupling electronics of the RF coil elements are positioned within the openings of the pressure reservoir to increase the thermal performance of the RF coil unit and to promote patient comfort.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural said elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments "comprising," "including," or "having" an element or a plurality of elements having a particular property may include additional such elements not having that property. The terms "including" and "in … are used as shorthand, language equivalents of the respective terms" comprising "and" wherein ". Furthermore, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements or a particular positional order on their objects.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the relevant art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those of ordinary skill in the art. Such 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 with insubstantial differences from the literal languages of the claims.