Birdcage coil assembly for magnetic resonance imaging of a subject's head

Abstract

The application relates to the technical field of magnetic resonance, in particular to a birdcage coil assembly for performing magnetic resonance imaging on the head of a subject, comprising: a chamber configured to accommodate the head of the subject and having an open end and a crown end oppositely arranged in the length direction of the subject, wherein the cross-sectional dimension of the crown end is smaller than that of the open end; and a birdcage coil arranged around the chamber and comprising a first end ring at the open end, a second end ring at the crown end, and a plurality of legs connecting the first end ring and the second end ring, the dimension of the second end ring being smaller than that of the first end ring.

Description

Technical Field

[0001] This application relates to the field of magnetic resonance imaging technology, and more particularly to a birdcage coil assembly for performing magnetic resonance imaging on the head of a subject. Background Technology

[0002] In existing technologies, birdcage coil assemblies used for head magnetic resonance imaging are typically constructed as cylindrical structures with open ends. However, this design leads to significant signal attenuation at both ends of the coil assembly (head-side and foot-side). Therefore, the length of the birdcage coil's legs is generally designed to be significantly longer than the target field of view along the body length required for imaging. However, the longer the birdcage coil's legs, the lower its transmission efficiency or signal-to-noise ratio. Summary of the Invention

[0003] In view of this, this application provides a birdcage coil assembly for performing magnetic resonance imaging on the head of a subject.

[0004] The birdcage coil assembly for magnetic resonance imaging of a subject's head proposed in this application includes:

[0005] A chamber configured to accommodate the head of the subject, and having an open end and a top end of the head disposed opposite each other in the length direction of the subject, wherein the cross-sectional dimension of the top end of the head is smaller than the cross-sectional dimension of the open end of the head.

[0006] A birdcage coil, which is arranged around the chamber, includes a first end ring at the open end, a second end ring at the top of the head, and a plurality of legs connecting the first end ring and the second end ring, wherein the second end ring is smaller than the first end ring.

[0007] In some possible implementations, the cross-sectional dimensions of the chamber gradually decrease in the direction from the opening end to the tip of the head.

[0008] In some possible implementations, the legs extend along the shape of the boundary of the chamber in the length direction.

[0009] In some possible implementations, the first end ring has a first capacitor at a position between any two adjacent legs, and the second end ring has a second capacitor at a position between any two adjacent legs, the capacitance values ​​of the first capacitors are the same as each other, the capacitance values ​​of the second capacitors are the same as each other, and the capacitance value of the first capacitor is less than the capacitance value of the second capacitor.

[0010] In some possible implementations, including:

[0011] A nasal receiving cavity, which communicates with the chamber and protrudes toward the outer periphery of the chamber, is configured to receive the subject's nose;

[0012] The first of the plurality of legs extends across the nasal receiving cavity and has a protruding extension at the nasal receiving cavity that protrudes toward the outer periphery of the cavity relative to each of the other legs.

[0013] The first leg has a third capacitor configured such that the reactance of the first leg is the same as the reactance of each of the other legs.

[0014] In some possible implementations, including:

[0015] The housing defines the chamber and the nose receiving cavity, and supports the birdcage coil.

[0016] In some possible implementations, the housing includes:

[0017] The inner shell portion has a first inner surface and a first outer surface, the first inner surface defining the chamber and the nasal receiving cavity;

[0018] The housing portion has a second inner surface facing the first outer surface and a second outer surface opposite to the second inner surface;

[0019] The first end ring, the second end ring, and the plurality of legs are all disposed against the first outer peripheral surface.

[0020] In some possible implementations, the component includes:

[0021] The lower body has a downwardly recessed first recess and is configured to support the subject's head in the first recess;

[0022] The upper body is detachably mounted to the upper side of the lower body and has an upwardly recessed second recess, the first recess and the second recess together defining the chamber.

[0023] In some possible implementations, the upper body includes the upper half of the birdcage coil, and the lower body includes the lower half of the birdcage coil. When the upper body is mounted on the lower body, the upper half and the lower half are electrically connected, thereby forming the birdcage coil.

[0024] In some possible implementations, the birdcage coil is a dual-frequency coil, and the dimension of the chamber along the left-right direction of the subject is smaller than the dimension of the chamber along the front-back direction of the subject.

[0025] According to the embodiments of this application, the birdcage coil assembly for magnetic resonance imaging of a subject's head has an irregularly shaped structure. Without increasing the number of legs, it improves the efficiency of the coil, especially the efficiency and signal-to-noise ratio at the top of the head. Moreover, it is adapted to the shape of the human head and will not cause a significant decrease in the user experience for the subject. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of this application, and are not intended to limit this application.

[0027] Figure 1 This is a schematic diagram of a birdcage coil assembly provided in one embodiment of this application.

[0028] Figure 2 yes Figure 1 A schematic diagram of the birdcage coil assembly after the housing of the upper body has been opened.

[0029] Figure 3 yes Figure 2 The front view.

[0030] Explanation of reference numerals in the attached figures:

[0031] DR1 - length direction, DR2 - circumferential direction;

[0032] 100-Birdcage coil assembly;

[0033] 1- Upper body,

[0034] 2-Lower body;

[0035] 3-Cavity, 3a-Opening end, 3b-Top of head;

[0036] 4-Birdcage coil;

[0037] 5-First end ring;

[0038] 6-Second end ring;

[0039] 7-outrigger;

[0040] 8-Inner shell portion;

[0041] 9-Outer shell portion;

[0042] 10 - Shell;

[0043] 11-Nasal cavity. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the described embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It is understood that, without conflict, some technical means of the various embodiments described herein can be substituted for or combined with each other.

[0045] In the description of this application, the terms "first," "second," etc., are used only to distinguish the described objects and have no sequential or technical meaning. Therefore, objects specified with "first," "second," etc., may explicitly or implicitly include one or more of those objects, and, for example, the term "first element" itself does not imply the existence of a "second element," nor does the term "second element" itself imply the existence of a "first element." Furthermore, words such as "a" or "one" do not indicate a quantity limitation, but rather indicate the presence of at least one, while "multiple" indicates not less than two.

[0046] Figures 1 to 3 A birdcage coil assembly 100 (hereinafter, sometimes simply referred to as assembly 100) according to an embodiment of the present application is shown, which is suitable for magnetic resonance imaging of the head of a subject, including a housing 10 defining a chamber 3 and a birdcage coil 4 installed in the housing 10.

[0047] The chamber 3 is configured to accommodate the head of the examinee and has an open end 3a and a top end 3b disposed opposite each other in the longitudinal direction DR1 of the examinee, and the cross-sectional dimension of the top end 3b is smaller than that of the open end 3a. It should be understood that the top end 3b of the chamber 3 is the end side corresponding to the top of the examinee's head, and therefore, the open end 3a is the other end side corresponding to a body part (e.g., neck or chin) opposite to the top of the examinee's head in the longitudinal direction DR1.

[0048] The birdcage coil 4 is arranged around the chamber 3 and includes a first end ring 5 located at the open end 3a, a second end ring 6 located at the top end 3b, and a plurality of legs 7 connecting the first end ring 5 and the second end ring 6. In accordance with the formation of the chamber 3, the size of the second end ring 6 is smaller than the size of the first end ring 5.

[0049] Understandably, reducing the size of the top-side of the chamber 3 accommodating the subject's head, and consequently reducing the size of the second end ring 6 of the birdcage coil 4, results in a smaller overall size of the birdcage coil 4. This allows it to be placed closer to the subject's head, thus helping to suppress signal attenuation and improve coil efficiency, particularly the efficiency and signal-to-noise ratio at the top of the head. Furthermore, since the human head itself is characterized by a smaller top-side dimension than the non-top-side dimension, this design does not significantly reduce adaptability to different head shapes.

[0050] In this embodiment, the birdcage coil 4 is a transmitting coil used to transmit radio frequency signals to the subject's head to excite the hydrogen nuclei within the subject's head to generate magnetic resonance signals. In other embodiments, the birdcage coil 4 can also be a receiving coil used to receive magnetic resonance signals from the subject's head. In still other embodiments, the birdcage coil 4 is both a transmitting and receiving coil, i.e., a combined transmitting and receiving coil.

[0051] Furthermore, each leg of the birdcage coil 4 extends along the shape of the boundary of the chamber 3 in the longitudinal direction DR1. Therefore, it helps to reduce the overall size of the birdcage coil 4 and helps to bring the legs 7 closer to the chamber 3 and the subject's head.

[0052] The total number of legs 7 is preferably an integer multiple of 4. Specifically, in this embodiment, the birdcage coil 4 has a total of 16 legs 7. Furthermore, the first end ring 5 has a first capacitor (not shown) between any two adjacent legs 7, and the second end ring 6 has a second capacitor (not shown) between any two adjacent legs 7. Therefore, the number of first capacitors and second capacitors is also 16 each. The capacitance values ​​of all first capacitors are the same, the capacitance values ​​of all second capacitors are the same, and the capacitance value of the first capacitor is less than the capacitance value of the second capacitor. This design can address the degradation of signal uniformity caused by the size difference between the first end ring 5 and the second end ring 6, thus ensuring the signal uniformity of the birdcage coil 4.

[0053] In this embodiment, chamber 3 is closed at the top tip 3b. In other embodiments, chamber 3 is open at the top tip 3b.

[0054] The component also includes a nasal receiving cavity 11 that communicates with chamber 3 and protrudes toward the outer periphery of chamber 3. In use, the nasal receiving cavity 11 is used to receive the subject's nose. In this way, it is not necessary to increase the size of the part of chamber 3 corresponding to the position of the subject's nose, thus helping to reduce the size of chamber 3 and birdcage coil 4.

[0055] In some embodiments, one of the plurality of legs 7, namely the first leg 7, extends across the nose receiving cavity 11 and has a protruding extension (raised curved section) at the nose receiving cavity 11 that protrudes towards the outer periphery of the cavity 3 relative to each of the other legs 7. That is, the first leg 7 extends and protrudes along the contour of the nose receiving cavity 11. Moreover, the first leg 7 has a third capacitor connected in series with the first leg 7, which is configured to make the reactance value of the first leg 7 the same as the reactance value of each of the other legs 7. In other words, in order to accommodate the protruding shape of the nose receiving cavity 11, the shape of the first leg 7 is different from that of each of the other legs 7. If the first leg 7 is not further modified, the signal uniformity of the birdcage coil 4 will deteriorate due to the change in the shape of the first leg 7. However, the third capacitor connected in series with the first leg 7 makes the reactance value of the first leg 7 the same as that of each of the other legs 7, thus ensuring the signal uniformity of the birdcage coil 4.

[0056] The component 100 includes a housing 10 formed substantially entirely of plastic, which defines the aforementioned chamber 3 and the nose receiving cavity, and the aforementioned birdcage coil 4 is mounted inside the housing 10 and supported by the housing 10.

[0057] Specifically, the housing 10 includes an inner shell portion 8 and an outer shell portion 9. The inner shell portion 8 has a first inner surface and a first outer surface opposite to the first inner surface, wherein the first inner surface defines at least a majority of the chamber 3 and at least a majority of the nose receiving cavity 11, and a first end ring 5, a second end ring 6, and a plurality of legs 7 are disposed abutting the first outer peripheral surface. The outer shell portion 9 has a second inner surface facing the first outer surface and a second outer surface opposite to the second inner surface, wherein the second outer surface defines at least a majority of the outer surface of the assembly 100. When manufacturing the assembly 100, the outer shell portion 9 can be installed onto the inner shell portion 8 after the birdcage coil 4 is installed onto the first outer surface of the inner shell portion 8.

[0058] Alternatively, the component 100 can be described as including an upper body 1 and a lower body 2. The lower body 2 has a downwardly recessed first recess in which the lower body 2 supports the subject's head. The upper body 1 is detachably mounted to the upper side of the lower body 2 and has an upwardly recessed second recess. When the upper body 1 and the lower body 2 are assembled together, the first and second recesses together define the aforementioned chamber 3.

[0059] Furthermore, the upper body 1 includes a portion of the housing 10 (i.e., a portion of the inner shell portion 8 and the outer shell portion 9) and the upper half of the birdcage coil 4, which is supported by this portion of the housing 10. The lower body 2 includes another portion of the housing 10 (i.e., another portion of the inner shell portion 8 and the outer shell portion 9) and the lower half of the birdcage coil 4, which is also supported by this other portion of the housing 10. When the upper body 1 is installed onto the lower body 2, the upper and lower halves of the birdcage coil 4 are electrically connected, thereby forming a complete birdcage coil 4.

[0060] The upper half of the birdcage coil 4 may include the upper half of the first end ring 5, the upper half of the second end ring 6, and seven legs 7 connecting the upper half of the first end ring 5 and the upper half of the second end ring 6. Each of the upper half of the first end ring 5 and the upper half of the second end ring 6 has an electrical connector on both sides of the opening in the second recess. The lower half of the birdcage coil 4 may include the lower half of the first end ring 5, the lower half of the second end ring 6, and nine additional legs 7 connecting the lower half of the first end ring 5 and the lower half of the second end ring 6. Each of the lower half of the first end ring 5 and the lower half of the second end ring 6 has an electrical connector on both sides of the opening in the first recess. When the upper body 1 is installed onto the lower body 2, the aforementioned electrical connectors precisely engage with the aforementioned electrical connectors to achieve electrical connection between the upper and lower half rings, thereby forming a complete first end ring 5 and a complete second end ring 6, and thus forming a complete birdcage coil 4.

[0061] Based on the fact that the left-right dimension of the human head is smaller than the front-back dimension, in order to further reduce the size of the chamber 3 and the component 100, this embodiment also sets the left-right dimension of the chamber 3 along the subject to be smaller than the front-back dimension of the chamber 3 along the subject.

[0062] In some embodiments, the birdcage coil 4 can be configured as a dual-frequency coil.

Claims

1. A birdcage coil assembly for magnetic resonance imaging of a subject's head, characterized in that, include: A chamber configured to accommodate the head of the subject, and having an open end and a top end of the head disposed opposite each other in the length direction of the subject, wherein the cross-sectional dimension of the top end of the head is smaller than the cross-sectional dimension of the open end of the head. A birdcage coil, which is arranged around the chamber, includes a first end ring at the open end, a second end ring at the top of the head, and a plurality of legs connecting the first end ring and the second end ring, wherein the second end ring is smaller than the first end ring.

2. The assembly of claim 1, wherein, The cross-sectional dimensions of the chamber gradually decrease in the direction from the opening end to the top of the head.

3. The assembly of claim 1, wherein, The legs extend along the shape of the boundary of the chamber in the length direction.

4. The assembly of claim 1, wherein, The first end ring has a first capacitor at a position between any two adjacent legs, and the second end ring has a second capacitor at a position between any two adjacent legs. The capacitance values ​​of each of the first capacitors are the same, the capacitance values ​​of each of the second capacitors are the same, and the capacitance value of the first capacitor is less than the capacitance value of the second capacitor.

5. The assembly of claim 1, wherein, include: A nasal receiving cavity, which communicates with the chamber and protrudes toward the outer periphery of the chamber, is configured to receive the subject's nose; The first of the plurality of legs extends across the nasal receiving cavity and has a protruding extension at the nasal receiving cavity that protrudes toward the outer periphery of the cavity relative to each of the other legs. The first leg has a third capacitor configured such that the reactance of the first leg is the same as the reactance of each of the other legs.

6. The assembly of claim 5, wherein, include: The housing defines the chamber and the nose receiving cavity, and supports the birdcage coil.

7. The assembly of claim 6, wherein, The housing includes: The inner shell portion has a first inner surface and a first outer surface, the first inner surface defining the chamber and the nasal receiving cavity; The housing portion has a second inner surface facing the first outer surface and a second outer surface opposite to the second inner surface; The first end ring, the second end ring, and the plurality of legs are all disposed against the first outer peripheral surface.

8. The assembly of claim 1, wherein, The components include: The lower body has a downwardly recessed first recess and is configured to support the subject's head in the first recess; The upper body is detachably mounted to the upper side of the lower body and has an upwardly recessed second recess, the first recess and the second recess together defining the chamber.

9. The assembly of claim 8, wherein, The upper body includes the upper half of the birdcage coil, and the lower body includes the lower half of the birdcage coil. When the upper body is installed on the lower body, the upper half and the lower half are electrically connected, thereby forming the birdcage coil.

10. The assembly of claim 1, wherein, The birdcage coil is a dual-frequency coil, and the dimension of the chamber along the left-right direction of the subject is smaller than the dimension of the chamber along the front-back direction of the subject.

Images