RF receiver coil with equal perimeter loops

Abstract

An RF receive coil assembly (180) for a magnetic resonance imaging system (100) includes a flexible housing (191). The RF coil assembly (180) also includes an RF coil (182) enclosed within the flexible housing (191). The RF coil (182) includes a plurality of loops (184), each loop (184) of the plurality of loops (184) having a same circumference (186).

Description

BACKGROUND

[0001] The subject matter disclosed herein relates to medical imaging, and more particularly, to radio frequency (RF) receive coils for magnetic resonance imaging (MRI) systems having rings of equal circumference.

[0002] Non-invasive imaging techniques allow for obtaining images of internal structures or features of a patient / subject without performing an invasive procedure on the patient / subject. In particular, such non-invasive imaging techniques rely on various physical principles (such as differential transmission of X-rays through a target volume, reflection of sound waves within a volume, paramagnetism of different tissues and materials within a volume, decomposition of a target radioactive isotope within a body, etc.) to collect data and construct images or otherwise represent the observed internal features of the patient / subject.

[0003] During MRI, when a material such as human tissue is subjected to a uniform magnetic field (polarizing field Bo), the individual magnetic moments of the spins in the tissue attempt to align with this polarizing field, but precess about it in random order at their characteristic Larmor frequency. If the material or tissue is subjected to a magnetic field (excitation field Bi) which is in the x-y plane and which is near the Larmor frequency, the net aligned moment or "longitudinal magnetization" M z can be rotated or "tilted" into the x-y plane, creating a net transverse magnetic moment M t After the excitation signal Bi is terminated, the excited spins emit a signal which can be received and processed to form an image.

[0004] When producing images with these signals, magnetic field gradients (G x , G y , and G z ) are employed. Typically, the region to be imaged is scanned with a series of measurement cycles in which the gradients are varied according to the particular localization method used. The resulting set of received nuclear magnetic resonance (NMR) signals is digitized and processed to reconstruct an image using one of the well-known reconstruction techniques.

[0005] Traditionally, older low-field (less than 1 Tesla) MRI systems have been considered to be poor performers due to a variety of factors (e.g., limited spatial resolution associated with poor image quality, limited variety of image sequences and parameters, inefficient temporal resolution associated with low signal-to-noise ratio (SNR), etc.). However, certain technological advances (e.g., artificial intelligence assisted reconstruction and noise reduction) have attracted new attention to older low-field MRI systems. However, one limiting factor that remains is the limited availability of receiver coils to be used with low-field MRI systems. For low-field MRI systems, the receiver array needs to have large elements because the noise produced by the human body is less than the inherent noise produced by the antenna conductors. This forces the number of elements (e.g., channels) in the field of view (FOV) to be limited. SUMMARY

[0006] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are only presented by way of example and are not intended to limit the scope of the disclosure. Indeed, the disclosure can encompass a variety of aspects that can not be set forth below.

[0007] In one embodiment, an RF receive coil assembly for a magnetic resonance imaging system is provided. The RF receive coil assembly includes an RF coil enclosed within a flexible housing. The RF coil includes a plurality of loops, each loop of the plurality of loops having a same circumference.

[0008] In another embodiment, an RF coil array assembly for an MRI system is provided. The RF coil array assembly includes a first RF coil including a first plurality of loops, each loop of the first plurality of loops having a first same circumference. The RF coil array assembly further includes a second RF coil including a second plurality of loops, each loop of the second plurality of loops having a second same circumference.

[0009] In another embodiment, an MRI system is provided. The MRI system includes an imaging portion having an RF receive coil, wherein the RF receive coil includes a plurality of loops, each loop of the plurality of loops having a same circumference. BRIEF DESCRIPTION OF DRAWINGS

[0010] These and other features, aspects, and advantages of the present application will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0011] Figure 1 An embodiment of a magnetic resonance imaging (MRI) system suitable for use with the technology disclosed is shown;

[0012] Figure 2 is a schematic of an RF coil array and its topology in accordance with aspects of the present disclosure;

[0013] Figure 3 is a cross-section of an RF coil in accordance with aspects of the present disclosure;

[0014] Figure 4 is a schematic of a topology of RF coils within an RF coil array in accordance with aspects of the present disclosure;

[0015] Figure 5 is a schematic of another topology of RF coils within an RF coil array in accordance with aspects of the present disclosure;

[0016] Figure 6 is a schematic diagram of yet another topology of RF coils within an RF coil array in accordance with aspects of the present disclosure;

[0017] Figure 7 is a schematic diagram of a topology of RF coils within an RF coil array (e.g., with equal circumference rings) in accordance with aspects of the present disclosure;

[0018] Figure 8 is a schematic diagram of another topology of RF coils within an RF coil array (e.g., with equal circumference rings) in accordance with aspects of the present disclosure;

[0019] Figure 9 is a perspective view of an RF coil array assembly with a front array and a back array in accordance with aspects of the present disclosure;

[0020] Figure 10 shows an arrangement of an RF coil array assembly on a subject and associated planes utilized during analysis in accordance with aspects of the present disclosure;

[0021] Figure 11 shows various sensitivity maps utilizing the coil array assembly in Figure 10 in accordance with aspects of the present disclosure;

[0022] Figure 12 shows signal-to-noise ratio (SNR) of reconstructed images utilizing the coil array assembly in Figure 10 in accordance with aspects of the present disclosure (e.g., for a first axial plane);

[0023] Figure 13 shows signal-to-noise ratio (SNR) of reconstructed images utilizing the coil array assembly in Figure 10 in accordance with aspects of the present disclosure (e.g., for a longitudinal partition plane);

[0024] Figure 14 shows geometric factors of reconstructed images utilizing the coil array assembly in Figure 10 in accordance with aspects of the present disclosure (e.g., for a first axial plane in a left-to-right direction) at multiple acceleration factors;

[0025] Figure 15 shows geometric factors of reconstructed images utilizing the coil array assembly in Figure 10 in accordance with aspects of the present disclosure (e.g., for a first axial plane in an anterior-to-posterior direction) at multiple acceleration factors;

[0026] Figure 16 shows geometric factors of reconstructed images utilizing the coil array assembly in Figure 10a geometric factor of a reconstructed image of the coil array assembly in the

[0027] Figure 17 a perspective view of an RF coil array having a stretchable loop (e.g., in a relaxed state) is shown in accordance with aspects of the present disclosure; Figure 10 a geometric factor of a reconstructed image of the coil array assembly in the

[0028] Figure 18 a perspective view of an RF coil array having a stretchable loop (e.g., in a relaxed state) is shown in accordance with aspects of the present disclosure;

[0029] Figure 19 a perspective view of an RF coil array (e.g., in a stretched state) is shown in Figure 18

[0030] a perspective view of an RF coil array (e.g., in a partially stretched state) is shown in Figure 20 Figure 18 a perspective view of an RF coil array (e.g., in a partially stretched state) is shown inDETAILED DESCRIPTION

[0031] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation can be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which can vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0032] When introducing elements of various embodiments of the present inventive subject matter, the articles "a," "an," "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there can be additional elements other than the listed elements. Additionally, any numerical examples in the following discussion are intended to be non-limiting and, therefore, additional numerical values, ranges, and percentages are within the scope of the disclosed embodiments.

[0033] ​While various aspects of the discussion below are presented in the context of medical imaging, it will be appreciated that the disclosed technology is not limited to such medical contexts. Rather, the examples and explanations provided in such medical contexts are merely for ease of explanation by providing examples of real-world implementations and applications. However, the disclosed technology can also be used in other contexts, such as image reconstruction for non-destructive inspection of manufactured parts or goods (i.e., quality control or quality review application scenarios) and / or non-invasive inspection of packages, boxes, luggage, etc. (i.e., security or screening application scenarios). Generally, the disclosed technology can be used in any imaging or screening context or image processing or photography field in which a set or class of acquired data undergoes a reconstruction process to generate an image or volume.

[0034] Older MRI systems are typically limited to a smaller number of channels because at low fields (less than 1 T), the coil elements need to have a larger size. When retrofitting such systems within an RF receive array, it is desirable to maximize the acceleration (e.g., of the array during parallel imaging) in all directions. The disclosed embodiments provide an RF receive array or array assembly that includes a topology that maximizes the acceleration in all directions (e.g., up to R=3). The RF receive array includes an RF coil having 8 elliptical loops with 3 different eccentricities, where each loop has the same circumference. Having each loop with the same circumference simplifies loop management (e.g., manufacturing, tuning, maintenance, etc.). Additionally, the loops have a distributed capacitance configuration. In particular, the RF coil is made from a coaxial conductor having a cross-section that is configured to generate an exact capacitance for loop tuning at a particular frequency (e.g., 21.29 megahertz (MHz)). The loops include increased transparency and reliability and are lightweight compared to typical RF coils. The RF receive array assembly can include a 16-channel topology to provide the highest combined acceleration. For example, a front RF receive array can include an RF coil having 8 loops with the same circumference, and a back RF receive array can include an RF coil having 8 loops with the same circumference. In certain embodiments, the topology of the front RF receive array and the topology of the back RF receive array can be the same. The RF receive array assembly can be used with a low-field MRI scanner (less than 1 T). In certain embodiments, the RF receive array assembly can be used with a 0.5 T MRI scanner.

[0035] In view of the above, Figure 1 A magnetic resonance imaging (MRI) system 100 is shown schematically as including a scanner 102, scanner control circuitry 104, and system control circuitry 106. The MRI system 100 is generally configured to perform MR imaging in accordance with the embodiments described herein.

[0036] The system 100 additionally includes a remote access and storage system or device, such as a picture archiving and communication system (PACS) 108, or other device, such as a remote radiology facility, enabling on-site or off-site access to data acquired by the system 100. In this way, MR data can be acquired and then processed and evaluated on-site or off-site. While the MRI system 100 can include any suitable scanner or detector, in the illustrated embodiment, the system 100 includes a whole-body scanner 102 having a housing 120 through which a bore 122 will be formed. A diagnostic table 124 is movable into the bore 122 so that a patient 126 can be positioned therein for imaging of selected anatomical structures within the patient.

[0037] The scanner 102 includes a series of associated coils for producing controlled magnetic fields for exciting spin magnetic material within the anatomy of a subject being imaged. In particular, a primary magnet coil 128 is provided for generating a primary magnetic field Bo that is generally aligned with the bore 122. A series of gradient coils 130, 132, and 134 allow controlled gradient magnetic fields to be generated during an examination sequence for positionally encoding certain spin magnetic nuclei within the patient 126. A radio frequency (RF) coil 136 (e.g., an RF transmit coil) is configured to generate RF pulses for exciting certain spin magnetic nuclei within the patient. In addition to coils that can be local to the scanner 102, the system 100 includes a set of receive coils or RF receive coils 138 (e.g., an array of coils) configured for placement proximal to the patient 126 (e.g., against the patient). For example, the receive coils 138 can include a cervical / thoracic / lumbar (CTL) coil, a head coil, a single-sided spine coil, etc. Generally, the receive coils 138 are placed proximal to or over the head of the patient 126 in order to receive weak RF signals (weak relative to the transmitted pulses generated by the scanner coils) generated by certain spin magnetic nuclei within the patient 126 as the patient 126 returns to its relaxed state.

[0038] The various coils of the system 100 are controlled by external circuitry to generate the required fields and pulses in a controlled manner and to read the emissions from spin magnetic material. In the illustrated embodiment, a main power supply 140 provides power to the primary field coil 128 to generate the primary magnetic field Bo. A power input 44 (e.g., power from a utility or power grid), a power distribution unit (PDU), a power supply (PS), and a driver circuit 150 together provide power to cause the gradient field coils 130, 132, and 134 to pulse. The driver circuit 150 can include amplification and control circuitry for supplying current to the coils in accordance with a defined pulse sequence output by the scanner control circuitry 104.

[0039] Another control circuit 152 is provided for regulating the operation of the RF coil 136. Circuit 152 includes a switching device for alternating between an active operating mode and a passive operating mode, wherein the RF coil 136 transmits a signal and does not transmit a signal, respectively. Circuit 152 also includes an amplifier circuit configured to generate RF pulses. Similarly, a receiving coil 138 is connected to a switch 154 capable of switching the receiving coil 138 between a receiving mode and a non-receiving mode. Thus, in receiving mode, the receiving coils 138 resonate with the RF signal generated by the release of the vortex nucleus within the patient 126, while in non-receiving mode, they do not resonate with the RF energy from the transmitting coil (i.e., coil 136) to prevent unintended operation. Additionally, the receiving circuit 156 is configured to receive data detected by the receiving coil 138 and may include one or more multiplexing and / or amplification circuits.

[0040] It should be noted that although the scanner 102 and the control / amplification circuit described above are shown connected by a single wire, in practical instances, many such wires may exist. For example, separate wires may be used for control, data communication, power transmission, etc. Furthermore, appropriate hardware may be provided along each type of wire for proper processing of data and current / voltage. In practice, various filters, digitizers, and processors may be provided between the scanner and either or both of the scanner control circuit 104 and system control circuit 106.

[0041] As shown in the figure, the scanner control circuit 104 includes an interface circuit 158 ​​that outputs signals for driving the gradient field coil and the RF coil, and for receiving data representing the magnetic resonance signals generated in the examination sequence. The interface circuit 158 ​​is connected to a control and analysis circuit 160. Based on a defined scheme selected via the system control circuit 106, the control and analysis circuit 160 executes commands for driving circuits 150 and 152.

[0042] The control and analysis circuit 160 is also used to receive magnetic resonance signals and perform subsequent processing before transmitting the data to the system control circuit 106. The scanner control circuit 104 also includes one or more memory circuits 162 that store configuration parameters, pulse sequence descriptions, inspection results, etc. during operation.

[0043] Interface circuitry 164 is coupled to control and analysis circuitry 160 for exchanging data between scanner control circuitry 104 and system control circuitry 106. In some embodiments, control and analysis circuitry 160, while shown as a single unit, may include one or more hardware devices. System control circuitry 106 includes interface circuitry 166 that receives data from scanner control circuitry 104 and transmits data and commands back to scanner control circuitry 104. Control and analysis circuitry 168 may include a CPU on a general-purpose or application-specific computer or workstation. Control and analysis circuitry 168 is coupled to memory circuitry 170 to store programming code for operating the MRI system 100 and to store processed image data for subsequent reconstruction, display, and transmission. The programming code may execute one or more algorithms configured to perform reconstruction of the acquired data as described below when executed by a processor. In some embodiments, memory circuitry 170 may store one or more neural networks for reconstruction of the acquired data as described below. In some embodiments, image reconstruction may occur on a separate computing device having processing circuitry and memory circuitry.

[0044] Additional interface circuitry 172 may be provided for exchanging image data, configuration parameters, etc., with external system components such as remote access and storage devices 108. Finally, system control and analysis circuitry 168 may be communicatively coupled to various peripheral devices to facilitate the operator interface and generate hard copies of the reconstructed images. In the illustrated embodiment, these peripheral devices include a printer 174, a display 176, and a user interface 178, which includes devices such as a keyboard, mouse, and touchscreen (e.g., integrated with display 176).

[0045] Figure 2 This is a schematic diagram of an RF coil array 180 (e.g., an RF receiving coil array) and its topology. The RF coil array 180 can be used in MRI systems (e.g., Figure 1 In an MRI system 100, an RF coil array 180 includes an RF coil 182 having a plurality of loops 184 (e.g., elements or channels), each loop 184 having a circumference 186. Figure 1 In the illustrated topology, each ring 184 has a different perimeter 186. In some embodiments, as discussed below, each ring 184 may have the same perimeter 186 (e.g., to simplify ring management). The RF coil array 180 may be used as a front or rear array during MRI imaging. In some embodiments, the RF coil array assembly may include both a front and rear array (e.g., for whole-body imaging) to provide 16 channels.

[0046] like Figure 2The depicted rings 184 comprise eight rings (e.g., labeled 1-8). Each ring 184 is coupled to an electronics unit 185, which in turn is coupled to a coil interface cable 186. The coil interface cable 186 of each ring 184 is coupled to a balun 187 (e.g., an integrated balun cable bundle). Each electronics unit 185 may include various components (e.g., decoupling circuitry, impedance inverter circuitry, and preamplifiers). The balun 187 may function as an RF notch filter. The balun 187 (via cable 188) is coupled to a P-connector 190 (e.g., a port connector) that enables the RF coil array 180 to be coupled to an interface of an MRI system that couples imaging components to processing components.

[0047] Ring 184 is disposed within a flexible housing 191 (e.g., a blanket). The flexible housing 191 has a rectangular shape. In some embodiments, the flexible housing 191 has a square shape. The RF coil array 180 provides a target coverage area with a field of view of approximately 50 cm. In the left-right direction, the length 192 of the housing 188 and the coverage area are approximately 55 cm. In some embodiments, the length 192 and the coverage area in the left-right direction are approximately 50 cm. In the up-down direction, the length 194 and the coverage area are approximately 50 cm. In some embodiments, the ring 184 is not stretchable, but the housing 191 includes corresponding holes radially located within each ring 184, allowing the housing 191 to stretch around the subject to be imaged. In some embodiments, the ring 184 is not stretchable. In some embodiments, the ring 184 is stretchable (e.g., due to a liquid metal conductor or a zigzag trace), such as... Figures 18 to 20 As shown in the image.

[0048] Ring 184 has three different eccentricities. For example, rings 1, 3, 4, and 6 (e.g., having a more rounded shape) have the same eccentricity and associated dimensions. Rings 2 and 5 have the same eccentricity (e.g., slightly more slender than rings 1, 3, 4, and 6) and associated dimensions. Rings 7 and 8 have the same eccentricity (e.g., having a more slender elliptical shape) and associated dimensions. Rings 1, 3, 4, and 6 are more slender along length 192. Rings 2 and 5 are more slender along length 194. Rings 7 and 8 are more slender along length 192. Figure 2 As depicted, rings 2 and 5 are positioned between rings 1, 3, 4 and 6, while rings 7 and 8 are located on the bottom portion of the RF coil array 180 (i.e., the portion closer to the feet of the subject being imaged).

[0049] like Figure 2As depicted, each ring 184 overlaps with at least two adjacent rings 184. For example, ring 1 and ring 3 each overlap with two adjacent rings 184. Rings 4, 6, 7, and 8 each overlap with three adjacent rings 184. Ring 5 overlaps with five adjacent rings 184.

[0050] Each ring 184 includes a distributed capacitance configuration. Specifically, each ring 184 includes a coaxial conductor having a cross-section configured to generate precise capacitance for ring tuning at a specific frequency (e.g., 21.29 MHz). Figure 3 The depicted coaxial coil loop portion 198 (of loop 184) includes a circular center conductor 200, an outer concentric shield 202, and a dielectric material 204 therebetween. The center conductor 200 may be made of copper (e.g., silver-plated copper), and the dielectric material 204 may be rubber, plastic, or another dielectric material (e.g., fluoropropylene (FEP) or polytetrafluoroethylene (pTFE)). The outer concentric shield 202 may encapsulate or otherwise surround the dielectric material 204 and the center conductor 200, and may be made of braided copper or other suitable conductive material. The center conductor 200, the dielectric material 204, and the outer shield 202 all have a common central axis 206. Additionally, although in Figure 3 Not shown in the diagram, but in some examples, an outer sheath (e.g., made of a dielectric material) may surround the outer shield 202. Although in Figure 3 The image shows two coaxial conductors (center conductor 200 and outer shield 204), but the RF coil loop portion may include three or more coaxial conductors encapsulated in a dielectric material and spaced apart from each other. In some embodiments, the center conductor 200 may be made of a liquid metal conductor so that the loop 184 can be stretched. Alternatively, each loop 184 may include braided wire, regularly stranded wire, or a spiral woven into an extendable non-conductive support or zigzag trace (e.g., such as...). Figures 18 to 20 (as shown in the image).

[0051] Back Figure 2 The RF coil 182 can utilize AIR from General Electric Healthcare. TM The RF coil 182 is designed using coil technology. This allows the RF coil 182 to be lightweight and flexible. For example, each RF coil 182 (e.g., for a front or rear array) can weigh 800 grams or less. The weight of each RF coil 182 with all the attachment cables in the attachment cable can be 2.5 kilograms or less. In addition, the loop 184 of the RF coil 182 is transparent, thus contributing to the signal-to-noise ratio.

[0052] Figure 4An alternative topology for RF coil 182 of RF coil array 180 is depicted. As depicted, rings 1, 3, 4, and 6 (e.g., having a more rounded shape) have the same eccentricity and associated dimensions. Rings 2 and 5 have the same eccentricity (e.g., slightly more elongated than rings 1, 3, 4, and 6) and associated dimensions. Rings 7 and 8 have the same eccentricity (e.g., having a more elongated elliptical shape) and associated dimensions. Rings 1, 3, 4, and 6 are more elongated along length 192. Rings 2 and 5 are more elongated along length 194. Rings 7 and 8 are more elongated along length 192. Figure 4 As depicted, rings 2 and 5 are positioned between rings 1, 3, 4 and 6, while rings 7 and 8 are located on the bottom portion of the RF coil array 180 (i.e., the portion closer to the feet of the subject being imaged). Figure 4 The topology of RF coil 182 in the middle is similar to Figure 2 The topology in the text, except that rings 2 and 5 are more circular and along Figure 4 The length 194 is not very slender. Lengths 192 and 194 are approximately 55cm and 50cm respectively.

[0053] like Figure 4 As depicted, each ring 184 overlaps with at least two adjacent rings 184. For example, ring 1 and ring 3 each overlap with two adjacent rings 184. Rings 4, 6, 7, and 8 each overlap with three adjacent rings 184. Ring 5 overlaps with five adjacent rings 184.

[0054] Figure 5 Another topology of RF coil 182 of RF coil array 180 is depicted. As depicted, rings 1, 3, 6, and 8 (e.g., having a more rounded shape) have the same eccentricity and associated dimensions. Rings 2 and 7 have the same eccentricity (e.g., slightly more elongated than rings 1, 3, 6, and 8) and associated dimensions. Rings 4 and 5 have the same eccentricity (e.g., having a more elongated elliptical shape) and associated dimensions. Rings 2 and 7 are more elongated along length 194 than rings 1, 3, 6, and 8. Rings 4 and 5 are more elongated along length 192 than rings 1, 2, 3, 6, 7, and 8. Figure 5 As depicted, rings 1, 3, 6, and 8 are positioned at the corners of the RF coil array 180. Rings 4 and 5 are located at the center between rings 1, 2, and 3 (these rings are near the upper portion of the RF coil array 180) and rings 6, 7, and 8 (these rings are near the bottom portion of the RF coil array 180). Ring 2 is located between rings 1 and 3, while ring 7 is located between rings 6 and 8. Lengths 192 and 194 are approximately 55 cm and 50 cm, respectively.

[0055] like Figure 5As depicted, each ring 184 overlaps with at least two adjacent rings 184. For example, rings 1, 3, 6, and 8 each overlap with two adjacent rings 184. Rings 2 and 7 each overlap with four adjacent rings 184. Rings 4 and 5 each overlap with five adjacent rings 184.

[0056] Figure 6 Another topology of RF coil 182 of RF coil array 180 is depicted. As depicted, rings 1, 3, 6, and 8 (e.g., having a more rounded shape) have the same eccentricity and associated dimensions. Rings 2 and 7 have the same eccentricity (e.g., having a more elongated elliptical shape) and associated dimensions. Rings 4 and 5 have the same eccentricity (e.g., also having a more elongated elliptical shape) and associated dimensions. Rings 2 and 7 are more elongated along length 194 than rings 1, 3, 4, 5, 6, and 8. Rings 4 and 5 are more elongated along length 192 than rings 1, 2, 3, 6, 7, and 8. Figure 6 As depicted, rings 1, 3, 6, and 8 are positioned at the corners of the RF coil array 180. Rings 4 and 5 are located at the center between rings 1, 2, and 3 (these rings are near the upper portion of the RF coil array 180) and rings 6, 7, and 8 (these rings are near the bottom portion of the RF coil array 180). Ring 2 is located between rings 1 and 3, while ring 7 is located between rings 6 and 8. Lengths 192 and 194 are approximately 55 cm and 50 cm, respectively.

[0057] like Figure 6 As depicted, each ring 184 overlaps with at least two adjacent rings 184. For example, rings 1, 3, 6, and 8 each overlap with two adjacent rings 184. Rings 2, 4, 5, and 7 each overlap with five adjacent rings 184.

[0058] Figures 7 to 10 An RF coil 182 is depicted with rings 184 having equal circumferences of 186. Each ring 184 having the same circumference of 186 simplifies ring management (e.g., manufacturing, tuning, maintenance, etc.). Figure 7 The topology of RF coils 182 in an RF coil array 180 is depicted, wherein the rings have equal circumferences 186. As depicted, rings 1, 3, 4, and 6 (e.g., having more rounded shapes) have the same eccentricity and associated dimensions. Rings 2 and 7 have the same eccentricity (e.g., having more elongated elliptical shapes than rings 1, 3, 4, and 6) and associated dimensions. Rings 7 and 8 have the same eccentricity (e.g., also having more elongated elliptical shapes) and associated dimensions. Rings 2 and 5 are more elongated along length 194 than rings 1, 3, 4, 6, 7, and 8. Rings 7 and 8 are more elongated along length 192 than rings 1 to 6. Figure 7As depicted, rings 1 and 3 are positioned in the upper corner of the RF coil array 180, with rings 4 and 6 located directly below. Ring 2 is centered between rings 1 and 3, while ring 6 is centered between rings 4 and 6. Rings 7 and 8 are positioned in the lower corner of the RF coil array 180. Lengths 192 and 194 are approximately 55 cm and 50 cm, respectively.

[0059] like Figure 7 As depicted, each ring 184 overlaps with at least two adjacent rings 184. For example, ring 1 and ring 3 each overlap with two adjacent rings 184. Rings 2, 4, 6, 7, and 8 each overlap with three adjacent rings 184. Ring 5 overlaps with five adjacent rings 184.

[0060] Figure 8 Another topology of RF coil 182 in RF coil array 180 is depicted, wherein the rings have equal circumference 186. As depicted, rings 1, 3, 4, and 6 (e.g., having a more rounded shape) have the same eccentricity and associated dimensions. Rings 2 and 7 have the same eccentricity (e.g., having a more elongated elliptical shape than rings 1, 3, 4, and 6) and associated dimensions. Rings 7 and 8 have the same eccentricity (e.g., also having a more elongated elliptical shape) and associated dimensions. Rings 2 and 5 are more elongated along length 194 than rings 1, 3, 4, 6, 7, and 8. Rings 7 and 8 are more elongated along length 192 than rings 1 to 6. Figure 8 As depicted, rings 1 and 3 are positioned in the upper corner of the RF coil array 180, with rings 4 and 6 located directly below. Ring 2 is centered between rings 1 and 3, while ring 6 is centered between rings 4 and 6. Rings 7 and 8 are positioned in the lower corner of the RF coil array 180. Lengths 192 and 194 are approximately 50 cm and 50 cm respectively (i.e., identical). Figure 7 The length of the RF coil array 180 in the middle is 192, which is greater than Figure 8 The length in.

[0061] like Figure 8 As depicted, each ring 184 overlaps with at least two adjacent rings 184. For example, ring 1 and ring 3 each overlap with two adjacent rings 184. Rings 2, 4, 6, 7, and 8 each overlap with three adjacent rings 184. Ring 5 overlaps with five adjacent rings 184.

[0062] Figure 9This is a perspective view of an RF coil array assembly 218 having a front array 220 and a rear array 222 configured to be positioned around a subject for MRI. Each array 220, array 222 includes an RF coil with eight loops having three different eccentricities as discussed above. Therefore, the RF coil array assembly 218 has 16 channels (e.g., eight channels for each array 220, array 222). Furthermore, in some embodiments, each of the eight loops has the same circumference. In some embodiments, the corresponding RF coils within arrays 220, array 222 have a... Figure 9 The same topology is used in both arrays. In some implementations, the corresponding RF coils within arrays 220 and 222 have different topologies.

[0063] like Figure 9 As depicted, the RF coils for each array 220, array 222 are enclosed within a corresponding flexible housing 191. Each flexible housing 191 includes a hole or opening 224. Each hole or opening 224 may be radially located within the ring. The opening 224 increases the flexibility of the arrays 220, array 222. In some embodiments, the flexible housing 191 may contain a deformable material therein. The deformable material may include foam, memory foam, expandable foam, polyurethane foam, gels such as hydrogels, water balloons, or other suitable deformable materials. When a subject lies on the array (e.g., array 222), the subject will sink into the deformable material, and the RF coils can conform to the unique shape of the subject and thus rest precisely against the patient's body.

[0064] like Figure 9 As depicted, each array 220, array 222 has a balun 187 coupled to a corresponding loop of an RF coil. The balun 187 of arrays 220, array 222 is coupled to a common P connector 190, which enables arrays 220, array 222 to be coupled to an interface of an MRI system that couples imaging components to processing components.

[0065] Figure 10 The arrangement of a 16-channel RF coil array 226 (e.g., with an 8-channel front array 228 and an 8-channel rear array 230) on a subject 232 and the plane utilized during simulation using three-dimensional (3D) electromagnetic software are depicted. Figure 10 As depicted, the front array 228 is positioned on top of the subject 232, and the rear array 230 is positioned below the subject 232. These planes include an axial plane 234, an axial plane 236, and a longitudinally bisecting plane 238.

[0066] Figure 11The simulation using 3D electromagnetic software is described. Figure 10 Sensitivity mapping diagrams of RF coil array 226. Sensitivity mapping diagram 240 along axial plane 234. Sensitivity mapping diagram 242 along axial plane 236. Sensitivity mapping diagram 244 along longitudinal plane 238.

[0067] Figure 12 It shows the use of Figure 10 The signal-to-noise ratio (SNR) of the reconstructed image using the coil array assembly 226 (e.g., along the axial plane 234) is shown. SNR mapping chart 246 is used for images reconstructed using a proprietary reconstruction algorithm. SNR mapping chart 248 is used for images reconstructed using an optimal reconstruction algorithm (e.g., weighted sum of squares). Uniformity mapping chart 250 illustrates the difference in SNR between the two different reconstruction techniques. In either case, the SNR using the coil array assembly is relatively high (i.e., compared to a typical coil array assembly used in a low-field MRI scanner).

[0068] Figure 14 It shows the use of Figure 10 The signal-to-noise ratio (SNR) of the reconstructed image using the coil array assembly 226 (e.g., along the longitudinal bisecting plane 238) is shown. SNR mapping chart 258 is used for images reconstructed using a proprietary reconstruction algorithm. SNR mapping chart 260 is used for images reconstructed using an optimal reconstruction algorithm (e.g., weighted sum of squares). Uniformity mapping chart 262 illustrates the difference in SNR between the two different reconstruction techniques. In either case, the SNR using the coil array assembly is relatively high (i.e., compared to a typical coil array assembly used in a low-field MRI scanner).

[0069] As described above, the topology of the RF coil loops maximizes acceleration in all directions (e.g., during parallel imaging of the array). Figures 14 to 17 It shows the use of Figure 10 The coil array assembly 226 in the middle is for use along the Figure 10 The different phase encoding directions of the plane marked in the figure represent the geometric factors (g or G factors) of the reconstructed images, ranging from acceleration factors R=2 to R=4. A G factor less than 2 is considered good. Figure 14 The G factor is shown along the axial plane 234 in the direction from left to right. Figure 15 The G factor is shown for the axial layer along the axial plane 234 in the direction from front to back. Figure 16 The G-factor is shown along the sagittal plane of the longitudinal bifurcation plane 238 in the direction from front to back. Figure 17 The G-factor is shown along the sagittal plane of the longitudinal bifurcation plane 238 in a top-to-bottom direction. Figures 14 to 17In this context, for each plane and each direction of the layer, the G factor is less than 2 and can reach at least R = 3. In some cases, the G factor is less than 2 and can reach at least R = 4. Figures 14 to 17 The topology of the RF receiver array assembly 236 is shown to maximize acceleration in all directions (e.g., up to R=3).

[0070] Figures 18 to 20 A perspective view of an RF coil array 180 with a stretchable ring 184 is shown. Generally, the RF coil 182 and its ring 184 are as described above. Figures 18 to 20 The RF coil 180 is configured to be stretched (e.g., due to having a liquid metal conductor or a tortuous trace). This allows the RF coil array to better conform to the subject being imaged. Figure 18 The loop 184 is shown in a relaxed state. Figure 19 The ring 184 is shown in a stretched state. Figure 20 A ring 184 in a partially stretched state is shown. Each ring 184 of the RF coil 182 is arranged in a zigzag pattern along the elliptical outline of the ring 184. The angles along the zigzag pattern are circular. The design of the coil configured for stretching can be used in any topology of the RF coil 182 where it is desired that a portion of the coil 182 is stretched.

[0071] The technical advantages of the disclosed embodiments include providing an RF receiver array or array assembly comprising a topology that maximizes acceleration in all directions (e.g., up to R=3). The RF receiver array includes an RF coil with eight elliptical loops having three different eccentricities, each loop having the same circumference. Having each loop with the same circumference simplifies loop management (e.g., manufacturing, tuning, maintenance, etc.). Additionally, the loops have a distributed capacitance configuration. Specifically, the RF coils are made of a coaxial conductor having a cross-section configured to generate precise capacitance for loop tuning at a specific frequency (e.g., 21.29 MHz). Compared to typical RF coils, the loops include increased transparency and reliability and are lightweight. The RF receiver array assembly may include a 16-channel topology to provide the highest combined acceleration. The RF receiver array assembly can be used with low-field MRI scanners (less than 1T) to improve MRI imaging quality.

[0072] Referring to the technology presented herein and protected by the claims, and applying it to physical objects and concrete examples of practical nature, which explicitly improves the present art, it is therefore not abstract, intangible, or purely theoretical. Furthermore, if any claim appended to the end of this specification contains one or more elements designated as “means for [performing]…[function]” or “steps for [performing]…[function]”, such elements are intended to be interpreted pursuant to Section 35, Subsection 112(f) of the USC. However, for any claim containing elements designated in any other manner, such elements are not intended to be interpreted pursuant to Section 35, Subsection 112(f) of the USC.

[0073] This written description uses examples to disclose the invention, including the best mode, and also enables those skilled in the art to practice the invention, including making and using any device or system and performing any included methods. The scope of the invention is defined by the claims and may include other examples that would occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that have minor differences from the literal language of the claims.

Claims

1. A radio frequency receiving coil assembly for a magnetic resonance imaging system, the radio frequency receiving coil assembly comprising: Flexible shell; and An RF coil, the RF coil being enclosed within the flexible housing, wherein the RF coil comprises a plurality of rings, each of the plurality of rings having the same circumference, the plurality of rings comprising three different eccentricities.

2. The radio frequency receiving coil assembly according to claim 1, wherein the plurality of rings has eight rings.

3. The radio frequency receiving coil assembly of claim 1, wherein each of the plurality of rings has distributed capacitance.

4. The radio frequency receiving coil assembly of claim 1, wherein the flexible housing comprises a rectangular shape.

5. The radio frequency receiving coil assembly of claim 4, wherein the flexible housing comprises a square shape.

6. The radio frequency receiving coil assembly of claim 1, wherein the flexible housing includes a hole located within a respective circumference of one or more of the plurality of rings, wherein the hole is configured to allow the flexible housing to stretch.

7. The radio frequency receiving coil assembly of claim 1, wherein each ring partially overlaps with at least two other rings of the plurality of rings.

8. The radio frequency receiving coil assembly of claim 1, wherein the radio frequency receiving coil assembly is configured to be utilized during an accelerated scan having an acceleration factor of up to 3.

9. The radio frequency receiving coil assembly of claim 1, wherein the magnetic resonance imaging system is configured to operate with a magnetic field strength of less than 1 Tesla.

10. A radio frequency coil array assembly for a magnetic resonance imaging system, the radio frequency coil array assembly comprising: A first RF coil, the first RF coil comprising a first plurality of rings, each of the first plurality of rings having a first identical circumference, the first plurality of rings comprising three different eccentricities; and The second RF coil includes a second plurality of rings, each of the second plurality of rings having a second identical circumference, and the second plurality of rings including three different eccentricities.

11. The radio frequency coil array assembly of claim 10, the radio frequency coil array assembly comprising a first flexible housing and a second flexible housing spaced apart from the first flexible housing, wherein the first RF coil is surrounded within the first flexible housing to form a first RF coil array, and the second RF coil is surrounded within the second flexible housing to form a second RF coil array.

12. The radio frequency coil array assembly of claim 11, wherein the first RF coil array and the second RF coil array are configured to operate as a rear array and a front array, respectively, when arranged on an object and utilized during imaging scanning with the magnetic resonance imaging system.

13. The radio frequency coil array assembly of claim 10, wherein the first plurality of rings and the second plurality of rings each have the same number of rings.

14. The radio frequency coil array assembly of claim 13, wherein the first plurality of rings and the second plurality of rings each have eight rings.

Images