Radio frequency transceiver circuit, magnetic resonance coil array and magnetic resonance coil equipment

Abstract

The invention relates to the technical field of nuclear magnetic resonance, in particular to a radio frequency transceiver circuit, a magnetic resonance coil array and magnetic resonance coil equipment. The radio frequency transceiver circuit includes: a first node connected to a coil unit having a first resonant frequency; the second node is connected to the first node through a radio frequency transmitting branch and is connected to the radio frequency power divider; the third node is connected to the pre-amplifier; the radio frequency transmitting branch comprises a first diode connected between the second node and the first node; a bias voltage input node connected to the anode of the first diode via a second inductor and a first node, the self-resonance of the second inductor being at a first resonant frequency; the first capacitor is connected with the first diode in parallel; the second capacitor and the third inductor are connected in series and connected to the two ends of the first capacitor in parallel; and the first diode, the first capacitor, the second capacitor and the third inductor in the cut-off state form a resonance blocking circuit which resonates at a first resonance frequency.

Description

Technical Field

[0001] The present application relates to the field of nuclear magnetic resonance technology, and in particular to a radio frequency transceiver circuit, a magnetic resonance coil array, and a magnetic resonance coil device. Background Art

[0002] In magnetic resonance imaging (MRI) systems, radio frequency coils with both transmitting and receiving functions, i.e., integrated transceiver coils, are common. They can both transmit radio frequency signals to the subject to excite relevant atomic nuclei (e.g., hydrogen nuclei or phosphorus nuclei) in the subject's body to generate magnetic resonance signals, and receive magnetic resonance signals from the subject.

[0003] Whether the transceiver coil operates in transmit mode or receive mode, reliable isolation is required between the transmitting and receiving ends of the coil to ensure high transmission efficiency and high receiving sensitivity, especially when the coil is positioned relatively far away from the object being inspected. Summary of the Invention

[0004] In order to solve at least one of the above technical problems, the present application proposes a radio frequency transceiver circuit, a magnetic resonance coil array, and a magnetic resonance coil device.

[0005] In a first aspect, a radio frequency transceiver circuit is proposed, comprising:

[0006] a first node for connecting to a first coil unit having a first resonant frequency and connected to a ground potential via a first inductor, wherein a self-resonant frequency of the first inductor is the same as the first resonant frequency;

[0007] a second node connected to the first node via a radio frequency transmission branch, configured to receive a first radio frequency signal from a power output terminal of the first radio frequency power splitter, and provide the first radio frequency signal to the first coil unit via the radio frequency transmission branch and the first node, wherein a frequency of the first radio frequency signal is the same as the first resonant frequency;

[0008] a third node connected to the first node via a radio frequency receiving branch, configured to receive a first magnetic resonance signal of the first resonant frequency from the first coil unit via the first node and the radio frequency receiving branch, and supply the first magnetic resonance signal to a first preamplifier;

[0009] The radio frequency transmission branch includes:

[0010] a first diode having an anode connected to the second node and a cathode connected to the first node;

[0011] a bias voltage input node configured to selectively receive a bias voltage and connected to the anode of the first diode via a second inductor and the first node in sequence, the self-resonant frequency of the second inductor being the same as the first resonant frequency;

[0012] a first capacitor connected in parallel with the first diode;

[0013] a second capacitor and a third inductor connected in series with each other and connected in parallel across the first capacitor;

[0014] The first diode, the first capacitor, the second capacitor and the third inductor in the cut-off state form a resonance blocking circuit that resonates at the first resonance frequency.

[0015] In some possible implementations, the radio frequency transmission branch includes:

[0016] a second diode connected between the second inductor and the second node, with an anode facing the second inductor;

[0017] a third capacitor connected between the second inductor and the anode of the first diode;

[0018] A fourth inductor is connected between the second node and the anode of the first diode, and a self-resonant frequency of the fourth inductor is the same as the first resonant frequency.

[0019] In some possible implementations, the radio frequency receiving branch includes:

[0020] a third diode connected between the first node and the first inductor, with an anode facing the first node;

[0021] a fourth capacitor connected between a connection point between the third diode and the first inductor and the third node;

[0022] A fifth inductor is connected in parallel between the first node and the third node, and together with the fourth capacitor and the third diode in the on state, forms a resonant blocking circuit with a resonant frequency the same as the first resonant frequency. The self-resonant frequency of the fifth inductor is different from the first resonant frequency.

[0023] In a second aspect, a magnetic resonance coil array is proposed, comprising:

[0024] N radio frequency transceiver circuits as described in the first aspect, where N is an integer not less than 4;

[0025] N first coil units are respectively connected to the first nodes of the N radio frequency transceiver circuits;

[0026] The first radio frequency power splitter has N power output ends respectively connected to the second nodes of the N radio frequency transceiver circuits;

[0027] The N first preamplifiers are respectively connected to the third nodes of the N radio frequency transceiver circuits.

[0028] In some possible implementations, the power output end is connected to the second node via a fifth capacitor, the third node is connected to the input end of the first preamplifier via a sixth capacitor, and the sixth capacitor is an adjustable capacitor with an adjustable capacitance value.

[0029] In some possible implementations, the first node is connected to the first coil unit via a seventh capacitor.

[0030] In some possible implementations, the N bias voltage input nodes of the N radio frequency transceiver circuits are connected to the same bias voltage generator.

[0031] In a third aspect, a magnetic resonance coil device is provided, comprising:

[0032] a housing defining an inspection cavity for receiving an object under inspection;

[0033] The magnetic resonance coil array according to the second aspect is a first magnetic resonance coil array, which is installed in the housing, and N first coil units are arranged around the inspection cavity;

[0034] a second magnetic resonance coil array, comprising N second coil units installed in the housing, wherein the N second coil units are arranged around the examination cavity;

[0035] The first resonant frequency of the first coil unit corresponds to hydrogen nuclei, and the second resonant frequency of the second coil unit corresponds to non-hydrogen nuclei.

[0036] The second resonance frequency of the second coil unit corresponds to sodium nuclei.

[0037] In some possible implementations, the RF transceiver circuit is a first RF transceiver circuit, the second magnetic resonance coil array includes a second RF transceiver circuit, and the second RF transceiver circuit includes all remaining parts of the first RF transceiver circuit except the first capacitor, the second capacitor, and the third inductor.

[0038] The RF transceiver circuit provided by the present application includes: a first node, which is used to be connected to a first coil unit having a first resonant frequency and is connected to the ground potential via a first inductor, and the self-resonant frequency of the first inductor is the same as the first resonant frequency; a second node, which is connected to the first node via a RF transmitting branch, is used to receive a first RF signal from the power output end of the first RF power divider, and provide the first RF signal to the first coil unit via the RF transmitting branch and the first node, and the frequency of the first RF signal is the same as the first resonant frequency; a third node, which is connected to the first node via a RF receiving branch, is used to receive a first magnetic field of the first resonant frequency from the first coil unit via the first node and the RF receiving branch. The invention relates to a first preamplifier for transmitting a first magnetic resonance signal and supplying a first magnetic resonance signal to the first preamplifier. The radio frequency transmission branch includes: a first diode having an anode connected to the second node and a cathode connected to the first node; a bias voltage input node configured to selectively receive a bias voltage and connected to the anode of the first diode via a second inductor and the first node, wherein the self-resonant frequency of the second inductor is the same as the first resonant frequency; a first capacitor connected in parallel with the first diode; a second capacitor and a third inductor connected in series and connected in parallel across the first capacitor; wherein the first diode, the first capacitor, the second capacitor, and the third inductor in a cut-off state form a resonant blocking circuit that resonates at the first resonant frequency. Therefore, when the first coil unit configured with this radio frequency transceiver circuit operates in a receiving mode, even if the first radio frequency power divider still provides the first radio frequency signal to the second node, the first radio frequency signal cannot be transmitted to the first node or into the first coil unit, thereby affecting the first coil unit's reception of the first magnetic resonance signal. More importantly, the first magnetic resonance signal from the first coil unit cannot be transmitted to the second node through the aforementioned resonant blocking circuit, and excellent isolation is achieved between the receiving and transmitting ends of the first coil unit. Moreover, compared with the case where the first capacitor, the second capacitor and the third inductor are not configured, the isolation is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present application, and are not limitations to the present application.

[0040] Figure 1 Schematic diagram of the structure of the magnetic resonance coil device provided in an embodiment of the present application.

[0041] Figure 2 yes Figure 1 Schematic diagram from another perspective.

[0042] Figure 3 yes Figure 1 Schematic diagram from another perspective.

[0043] Figure 4 yes Figure 1 Schematic diagram of the radio frequency coil of the magnetic resonance coil device shown.

[0044] Figure 5 yes Figure 4 Schematic diagram from another perspective.

[0045] Figure 6 3 is a schematic diagram of the circuit structure corresponding to a coil unit in the first coil array.

[0046] Figure 7 Schematic diagram of the circuit structure corresponding to a coil unit in the second coil array.

[0047] Figure 8 This is an isolation curve between the second node and the third node obtained by testing when the first coil unit in the magnetic resonance coil device provided in an embodiment of the present application operates in the receiving mode, wherein the main magnetic field, i.e., the B0 field, is a 7.0T ultra-high magnetic field. Under the 7.0T ultra-high magnetic field, the Larmor frequency of the hydrogen nucleus is 297.2MHZ.

[0048] Figure 9 This is an isolation curve between the second node and the third node obtained by testing when the first coil unit operates in a receiving mode under a 7.0T ultra-high magnetic field after removing the first capacitor, the second capacitor, and the third inductor of the first RF transceiver circuit in the magnetic resonance coil device provided in an embodiment of the present application.

[0049] Figure 10 A magnetic resonance image of a subject's head obtained using a first coil array in a magnetic resonance coil apparatus provided in an embodiment of the present application based on a turbo spin echo sequence (TSE) and hydrogen nuclear magnetic resonance, wherein the repetition time is 7000 ms, the echo time is 66 ms, the flip angle is 120°, and the resolution is 1×1×2 mm. 3 .

[0050] Figure 11 A magnetic resonance image of a subject's head obtained using a first coil array in a magnetic resonance coil apparatus provided in an embodiment of the present application based on a magnetization-prepared rapid acquisition gradient echo sequence (MPRAGE) and hydrogen nuclear magnetic resonance, wherein repetition time = 2270 ms, echo time = 1.87 ms, inversion time = 900 ms, flip angle = 6°, and resolution = 1×1×1 mm 3 .

[0051] Figure 12 A magnetic resonance image of a subject's head obtained using a first coil array in a magnetic resonance coil apparatus provided by an embodiment of the present application based on a fluid-attenuated inversion recovery sequence (FLAIR) and hydrogen nuclear magnetic resonance, wherein the repetition time is 9000 ms, the echo time is 76 ms, the inversion time is 2600 ms, the flip angle is 120°, and the resolution is 1×1×2 mm. 3 .

[0052] Figure 13 A magnetic resonance image of a subject's head obtained using a density-adapted 3D radial acquisition sequence (DA-3D-RAD) and sodium nuclear magnetic resonance using the second coil array in the magnetic resonance coil apparatus provided in an embodiment of the present application, wherein the repetition time is 120 ms, the echo time is 0.35 ms, the flip angle is 90°, 5000 projections are obtained, and the resolution is 3×3×3 mm. 3 .

[0053] Figure 14 Schematic diagram of the structure of the magnetic resonance coil device provided in an embodiment of the present application.

[0054] Figure 15 This is a structural block diagram of the magnetic resonance system provided in an embodiment of the present application.

[0055] Description of reference numerals:

[0056] 1000-Magnetic Resonance System;

[0057] 100-magnetic resonance coil equipment, 200-transmitter, 300-receiver;

[0058] DR1-horizontal direction, DR2-vertical direction, DR3-separation direction;

[0059] 1- base;

[0060] 2-shell;

[0061] 3- RF coil;

[0062] 4- lower seat body, 4a- lower sliding groove;

[0063] 5-upper seat, 5a-upper slide, 5b-through threaded hole, 5c-linear guide;

[0064] 6- lifting mechanism;

[0065] 7- first connecting rod;

[0066] 8-second connecting rod;

[0067] 9-third connecting rod;

[0068] 10- fourth connecting rod;

[0069] 11-adjusting screw, 11a-handwheel;

[0070] 12-connection seat;

[0071] 13-head support seat, 13a-arc plate;

[0072] 14- small animal support seat;

[0073] 15-first part, 15a-insert;

[0074] 16-second part, 16a-slot;

[0075] 17-locking bolt;

[0076] 18-inspection cavity, 18a-opening;

[0077] 19- outer surface of the shell;

[0078] 20-inner surface of the shell;

[0079] 21- first coil array;

[0080] 22- second coil array;

[0081] 23-first coil unit;

[0082] 24-second coil unit;

[0083] 25-first radio frequency power splitter;

[0084] 26-first preamplifier;

[0085] 27-second radio frequency power splitter;

[0086] 28-second preamplifier;

[0087] 29-Barron;

[0088] 30-slider;

[0089] 31-first radio frequency transceiver circuit;

[0090] 32-second radio frequency transceiver circuit;

[0091] C0, C t -Tuning capacitor of the coil unit, C m - Matching capacitors for coil units;

[0092] n1-first node, n2-second node, n3-third node, n4-bias voltage input node;

[0093] C1-first capacitor, C2-second capacitor, C3-third capacitor, C4-fourth capacitor, C5-fifth capacitor, C6-sixth capacitor, C7-seventh capacitor;

[0094] D1-first diode, D2-second diode, D3-third diode;

[0095] L1-first inductor, L2-second inductor, L3-third inductor, L4-fourth inductor, L5-fifth inductor;

[0096] GND-ground potential. DETAILED DESCRIPTION

[0097] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application. It is understood that, in the absence of conflict, some technical means of the various embodiments described herein can be replaced or combined with each other.

[0098] In the description of this application, the terms "first," "second," etc., if used, are used solely to distinguish the objects being described and do not convey any order or technical meaning. Thus, an object defined as "first," "second," etc. may explicitly or implicitly include one or more of such objects. Furthermore, for example, the term "first element" alone does not imply the presence of a "second element," nor does the term "second element" alone imply the presence of a "first element." Furthermore, the terms "a" or "an," and the like, do not denote a limitation on quantity, but rather indicate the presence of at least one, and "plurality" means at least two.

[0099] In the description of this application, the terms "including" and "having" indicate the existence of the stated features, numbers, operations, elements and / or their combinations, but do not exclude the existence or addition of one or more other features, numbers, operations, elements and / or their combinations.

[0100] In the description of this application, if there are similar terms such as "configured to" or "constructed to", they can generally be interchanged with "having the ability to...", "designed to", "for" or "capable of", depending on the context.

[0101] In the description of this application, reference to "one embodiment" or "some embodiments" means that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in one or more embodiments of the application. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in other embodiments," etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized.

[0102] Figures 1 to 3 A magnetic resonance coil device 100 provided in an embodiment of the present application is shown. The device 100 includes a base 1 , a housing 2 supported by the base 1 , and a radio frequency coil 3 installed in the housing 2 .

[0103] The base 1 is constructed as a height-adjustable lift structure, comprising a lower base 4 removably secured to the MRI bed, and an upper base 5 connected to the upper side of the lower base 4 via a lift mechanism 6. The lift mechanism 6 can be operated to elevate the upper base 5 relative to the lower base 4, and therefore, the MRI bed. Furthermore, two opposing sides of the upper base 5 have linear guide rails 5c extending in the horizontal direction DR1.

[0104] The housing 2 is formed into a roughly cylindrical shape, open at one end and closed at the other. This defines an inspection cavity 18 within the housing, capable of receiving an examination subject. The inspection cavity 18 has an opening 18a oriented in the horizontal direction DR1. In this embodiment, the examination subject is a human head. The housing 2 is connected to the linear guide 5c of the upper base 5 via a slider 30 disposed at its bottom, allowing for movement in the horizontal direction DR1. A portion of the housing 2 extends into the gap between the curved plate 13a and the upper base 5, thereby receiving the curved plate 13a within the inspection cavity 18 defined by the housing 2. As a result, the sliding engagement between the slider 30 and the linear guide 5c allows adjustment of the relative position of the housing 2 relative to the curved plate 13a and, by extension, the subject's head. Furthermore, the slider 30 can be secured to the linear guide 5c at various locations using fastening bolts (not shown), thereby stably maintaining the relative position of the RF coil 3 within the housing 2 and the examination subject during imaging examinations.

[0105] See Figure 4 and Figure 5The RF coil 3 includes a first coil array 21 and a second coil array 22, and both the first coil array 21 and the second coil array 22 are mounted inside the housing 2, that is, within the thickness space between the inner surface 2020 and the outer surface 19 of the housing, wherein the inner surface 20 defines the boundary of the inspection cavity 18. Furthermore, the housing 2 can be opened to expose the first coil array 21 and the second coil array 22, thereby facilitating maintenance of the first coil array 21 and the second coil array 22. In practice, the first coil array 21 and the second coil array 22 can be mounted to the inner shell while the housing 2 is open, and then the housing 2 can be closed to conceal and protect the first coil array 21 and the second coil array 22. The first coil array 21 and the second coil array 22 may also be referred to as a first magnetic resonance coil array and a second magnetic resonance coil array.

[0106] The first coil array 21 includes eight first coil units 23 arranged around the inspection cavity 18 and around the aforementioned horizontal direction DR1. The second coil array 22 includes eight second coil units 24 arranged around the inspection cavity 18 and around the aforementioned horizontal direction DR1. The first coil units 23 have a first resonant frequency corresponding to hydrogen nuclei, and the second coil units 24 have a second resonant frequency corresponding to sodium nuclei. That is, the resonant frequency of the first coil unit 23 is the Larmor frequency of hydrogen nuclei, and the resonant frequency of the second coil unit 24 is the Larmor frequency of sodium nuclei. Under an ultra-high field strength of 7.0T, the Larmor frequency of hydrogen nuclei is 297.2 MHz. Therefore, the Larmor frequency of sodium nuclei can be detected by Figure 6 The tuning capacitor C of the first coil unit 23 t The capacitor is adjusted so that the resonance of the first coil unit 23 is at 297.2 MHz, so that the device 100 can be applied to a 7.0 T ultra-high field strength MRI system.

[0107] In this embodiment, the eight first coil units 23 are arranged into a closed loop structure that surrounds the inspection cavity 18 on the entire circumference, and the eight second coil units 24 are also arranged into a closed loop structure that surrounds the inspection cavity 18 on the entire circumference, and the eight first coil units 23 are located on the outer side of the eight second coil units 24, and any two adjacent first coil units 23 partially overlap for decoupling, and any two adjacent second coil units 24 partially overlap for decoupling.

[0108] In this embodiment, both the first coil unit 23 and the second coil unit 24 are integrated transceiver coils. Therefore, in use, on the one hand, the first coil array 21 can be used to transmit a radio frequency signal of a first resonant frequency to the subject's head to generate a B1 field, thereby exciting the hydrogen nuclei in the subject's head to generate a magnetic resonance signal (or magnetic resonance radio frequency signal) of the first resonant frequency. The first coil unit 23 can then be used to receive the magnetic resonance signal of the hydrogen nuclei, thereby obtaining a magnetic resonance image of the subject's head based on the magnetic resonance effect of the hydrogen nuclei. On the other hand, the second coil array 22 can be used to transmit a radio frequency signal of a second resonant frequency to the subject's head to generate a B1 field, thereby exciting the sodium nuclei in the subject's head to generate a magnetic resonance signal of the second resonant frequency. The second coil unit 24 can then be used to receive the magnetic resonance signal of the sodium nuclei, thereby obtaining a magnetic resonance image of the subject's head based on the magnetic resonance effect of the sodium nuclei. Furthermore, in some embodiments, the magnetic resonance image based on the hydrogen nuclei can be fused with the magnetic resonance image based on the sodium nuclei to obtain a fused magnetic resonance image based on the hydrogen and sodium nuclei.

[0109] The lifting mechanism 6 of the base 1 includes a pair of lower sliding grooves 4 a, a pair of upper sliding grooves 5 a, a pair of first connecting rods 7 , a pair of second connecting rods 8 , a third connecting rod 9 , a fourth connecting rod 10 and an adjusting screw 11 .

[0110] A pair of lower grooves 4 a are formed on the lower seat 4 and extend in the horizontal direction DR1 , and the pair of lower grooves 4 a are spaced apart from each other in a horizontal spacing direction DR3 that is perpendicular to the horizontal direction DR1 .

[0111] A pair of upper slide grooves 5 a are formed on the upper base 5 and extend in parallel with each other along the horizontal direction DR1 , and the pair of upper slide grooves 5 a are also spaced apart from each other in the spacing direction DR3 .

[0112] The pair of first connecting rods 7 are cross-connected at their midpoint, rotatably about a separation direction DR3. The first end of the first connecting rod is rotatably connected to the lower base 4, and the second end is slidably and rotatably connected to the first upper groove 5a of the pair of upper grooves 5a. The second first connecting rod 7 has a first end slidably and rotatably connected to the first lower groove 4a of the pair of lower grooves 4a, and a second end is rotatably connected to the upper base 5.

[0113] The pair of second connecting rods 8 are cross-connected at their midpoint, rotatably about the separation direction DR3. The first end of the first second connecting rod is rotatably connected to the lower base 4, and the second end is slidably and rotatably connected to the second upper groove 5a of the pair of upper grooves 5a. The first end of the second second connecting rod 8 is slidably and rotatably connected to the second lower groove 4a of the pair of lower grooves 4a, and the second end is rotatably connected to the upper base 5. In this embodiment, the first connecting rods 7 and the second connecting rods 8 have the same length, and the lower grooves 4a and the upper grooves 5a have the same length.

[0114] The third link 9 extends along the spacing direction DR3 and connects the second end of the first first link 7 and the second end of the first second connecting rod. Specifically, the opposite ends of the third link 9 are slidably inserted into the pair of upper slide grooves 5a, and the second end of the first first link 7 and the second end of the first second connecting rod are respectively connected to the opposite ends of the third link 9 so as to be rotatable but not movable along the spacing direction DR3. In other words, the second end of the first first link 7 and the second end of the first second connecting rod are slidably and rotatably connected to the pair of upper slide grooves 5a via the third link 9.

[0115] The fourth link 10 extends along the spacing direction DR3 and connects the first end of the second first link 7 and the first end of the second second connecting link. Specifically, the opposite ends of the fourth link 10 are slidably inserted into the pair of lower slide grooves 4a, and the first end of the second first link 7 and the first end of the second second connecting link are respectively connected to the opposite ends of the fourth link 10 so as to be rotatable but not movable along the spacing direction DR3. In other words, the first end of the second first link 7 and the first end of the second second connecting link are slidably and rotatably connected to the pair of lower slide grooves 4a via the fourth link 10.

[0116] An adjustment screw 11 extends in the horizontal direction DR1 and is threadedly engaged with the through-threaded hole 5b of the upper base 5. A handwheel 11a is provided at one end of the adjustment screw 11, and the other end is connected to the third connecting rod 9 so that it can rotate but cannot move in the horizontal direction DR1. The adjustment screw 11 is configured so that manual rotation of the handwheel 11a drives the third connecting rod 9 in the horizontal direction DR1, thereby causing the upper base 5 to rise or fall relative to the lower base 4.

[0117] The hand wheel 11 a is disposed on the side of the inspection cavity 18 opposite to the opening 18 a in the horizontal direction DR1 , which helps to spatially keep the adjustment screw 11 and the hand wheel 11 a of the adjustment screw 11 away from the body of the subject.

[0118] In this embodiment, the aforementioned other end of the adjusting screw 11 is connected to the third connecting rod 9 via a connecting seat 12. The connecting seat 12 has a first hole penetrated by the third connecting rod 9 and a second hole for receiving the aforementioned other end of the adjusting screw 11. The aforementioned other end of the adjusting screw 11 is coupled to the second hole so as to be rotatable but not movable in the horizontal direction DR1. Specifically, the second hole has an annular groove recessed from the hole wall surface thereof, and the aforementioned other end of the adjusting screw 11 has a circle of flanges protruding toward the outer peripheral side, which are rotatably embedded in the annular groove of the second hole. As a result, the second hole allows the adjusting screw 11 to rotate but prevents the adjusting screw 11 from moving in the horizontal direction DR1.

[0119] In some embodiments, in order to facilitate the assembly of the adjusting screw 11 and the connecting seat 12, the connecting seat 12 is configured to be formed by connecting two separate sub-parts, and the two parts of the second hole in the radial direction are respectively defined by the two sub-parts.

[0120] A head support 13 for supporting the subject's head is detachably connected to the upper base 5 of the base 1. A portion of the head support 13 is formed as a curved plate 13a that conforms to the contour of the human head (more specifically, the posterior contour of the head). The curved plate 13a and the upper base 5 are spaced apart in the vertical direction DR2. When in use, the curved plate 13a extends into the inspection cavity 18 through the opening 18a.

[0121] Please also see Figures 4 to 7 To provide RF excitation signals to the first coil units 23 and acquire magnetic resonance signals from the first coil units 23, the first coil array 21 further includes eight first RF transceiver circuits 31, respectively connected to the eight first coil units 23; a first RF power splitter 25, respectively connected to the RF input terminals (corresponding to the second node n2 described later) of the eight first RF transceiver circuits 31 and capable of providing a first RF signal at a first resonant frequency; and eight first preamplifiers 26, respectively connected to the magnetic resonance signal output terminals (corresponding to the third node n3 described later) of the eight first RF transceiver circuits 31 and capable of amplifying the magnetic resonance signals. Similarly, to provide RF excitation signals to the second coil units 24 and acquire magnetic resonance signals from the second coil units 24, the second coil array 22 further includes eight second RF transceiver circuits 32, respectively connected to the RF input terminals of the eight second RF transceiver circuits 32 and capable of providing a second RF signal at a second resonant frequency; and eight second preamplifiers 28, respectively connected to the magnetic resonance signal output terminals of the eight second RF transceiver circuits 32 and capable of amplifying the magnetic resonance signals. To keep it simple, Figure 6 Only one of the eight first RF transceiver circuits 31 is shown. Figure 7 Only one of the eight second RF transceiver circuits 32 is shown.

[0122] like Figure 6 As shown, the first RF transceiver circuit 31 includes a first node n1, a second node n2, a third node n3, a RF transmission branch connected between the second node n2 and the first node n1, and a RF reception branch connected between the third node n3 and the first node n1. The first node n1 is the RF signal output terminal and magnetic resonance signal receiving terminal of the first RF transceiver circuit 31, and is connected to the first coil unit 23 having a first resonant frequency (e.g., 297.2 MHz) via a seventh capacitor C7 and a balun 29. The second node n2 is the RF signal receiving terminal of the first RF transceiver circuit 31, and is connected to a power output terminal of the first RF power divider 25 via a fifth capacitor C5. The third node n3 is the magnetic resonance signal output terminal of the first RF transceiver circuit 31, and is connected to the input terminal of a preamplifier via a sixth capacitor C6.

[0123] The first RF power splitter 25 has one power input and eight power outputs. By supplying an RF power signal to its power input, its eight power outputs can output the same first RF signal at the first resonant frequency. In practice, the MRI system's transmitter can be used to provide the aforementioned RF power signal to the power input of the first RF power splitter 25. When the first coil array 21 is operating in a transmitting state, each power output of the first RF power splitter 25 provides a first RF signal at the first resonant frequency to the second node n2 of each first RF transceiver circuit 31. This first RF signal is then provided to the first coil unit 23 via the RF transmission branch and the first node n1. The first coil unit 23, resonating at the first resonant frequency, transmits the first RF signal toward the examination cavity 18, particularly the subject (e.g., the subject's head) within the examination cavity 18, thereby generating a B1 field within the examination cavity 18.

[0124] The first preamplifier 26 can obtain the first magnetic resonance signal at the first resonant frequency from the first coil unit 23 from the third node n3 of the first RF transceiver circuit 31, amplify the first magnetic resonance signal, and then provide it to the receiver 300 of the magnetic resonance system 1000. When the first coil array 21 is operating in a receiving state, the first magnetic resonance signal at the first resonant frequency received by the first coil unit 23 is provided to the third node n3 via the first node n1 and the RF receiving branch, and then provided to the input end of the first preamplifier 26 via the third node n3.

[0125] The first node n1 is connected to the ground potential GND via the first inductor L1 , wherein the self-resonant frequency of the first inductor L1 is the same as the first resonant frequency. Therefore, the first RF signal / first magnetic resonance signal transmitted to the first node n1 does not flow to the ground.

[0126] The RF transmission branch includes a first diode D1, a bias voltage input node n4, a first capacitor C1, a second capacitor C2, and a third inductor L3. The anode of the first diode D1 is connected to the second node n2, and the cathode is connected to the first node n1. The bias voltage input node n4 is configured to selectively receive a bias voltage supplied by an external circuit (a bias voltage generator) and is connected to the anode of the first diode D1 via the second inductor L2 and the second node n2, in sequence. The self-resonant frequency of the second inductor L2 is the same as the first resonant frequency. The first capacitor C1 is connected in parallel with the first diode D1. The second capacitor C2 and the third inductor L3 are connected in series and then in parallel across the first capacitor C1, and therefore also across the first diode D1. The first diode D1 (having a junction capacitance) in the off state, the first capacitor C1, the second capacitor C2, and the third inductor L3 constitute a resonant blocking circuit that resonates at the first resonant frequency.

[0127] With this design, when the bias voltage input node n4 receives a bias voltage higher than ground GND, the first diode D1 is conductive. The first RF signal introduced from the second node n2 can be supplied to the first coil unit 23 via the conductive first diode D1 and the first node n1, causing the first coil unit 23 to operate in transmit mode. Because the first inductor L1, connected between the first node n1 and ground GND, resonates at the first resonant frequency, the first RF signal is prevented from being transmitted to ground via the first inductor L1, causing power loss. This ensures the transmission efficiency of the first coil array 21. Furthermore, when the bias voltage input node n4 receives a bias voltage, the second capacitor C2, which provides a DC blocking function, prevents DC current from flowing through the third inductor L3.

[0128] When the first coil unit 23 operates in the receiving mode, the bias voltage input node n4 does not receive the bias voltage. Thus, the first diode D1 is in the off state due to the absence of the bias voltage. Since the resonant frequency of the resonant blocking circuit formed by the off-state first diode D1, the first capacitor C1, the second capacitor C2, and the third inductor L3 is the first resonant frequency, even though the first RF power divider 25 still provides the first RF signal to the second node n2, the first RF signal cannot be transmitted to the first node n1 and the first coil unit 23, thereby affecting the first coil unit 23's reception of the first magnetic resonance signal. More importantly, the first magnetic resonance signal from the first coil unit 23 cannot be transmitted to the second node n2 through the aforementioned resonant blocking circuit. Therefore, in the receiving mode, the receiving end and the transmitting end of the first coil unit 23 have very good isolation.

[0129] Figure 8The isolation between the second node n2 and the third node n3 obtained by testing when the first coil unit 23 works in the receiving mode (7.0T ultra-high field) is shown. Figure 9 The first RF transceiver circuit 31 is shown after the first capacitor C1, the second capacitor C2 and the third inductor L3 are removed (thus Figure 7 The structure of the second RF transceiver circuit 32 shown in FIG is basically the same. When the first coil unit 23 operates in receive mode (7.0T ultra-high field), the isolation between the second node n2 and the third node n3 is measured. It can be seen that without the first capacitor C1, the second capacitor C2, and the third inductor L3, the isolation between the transmitting end (second node n2) and the receiving end (third node n3) of the first coil unit 23 is -16dB. After the first capacitor C1, the second capacitor C2, and the third inductor L3 are configured, the isolation between the transmitting end (second node n2) and the receiving end (third node n3) of the first coil unit 23 is improved to -32dB. The inventors believe that this phenomenon occurs because, without the first capacitor C1, the second capacitor C2, and the third inductor L3, although the first diode D1 is in an off-state due to the lack of applied bias voltage, the off-state first diode D1 has a junction capacitance. Therefore, a portion of the first magnetic resonance signal transmitted to the first node n1 is transmitted to the second node n2 via the first diode D1. However, after the first capacitor C1, the second capacitor C2, and the third inductor L3 are configured, the off-state first diode D1, the first capacitor C1, the second capacitor C2, and the third inductor L3 form a resonant blocking circuit with the first resonant frequency. Therefore, essentially no magnetic resonance signal can be transmitted to the transmitting end of the coil, significantly improving isolation. Therefore, when designing the first RF transceiver circuit 31, after determining the junction capacitance of the first diode D1, the first capacitor C1 and the second capacitor C2, as well as the third inductor L3, can be selected based on calculations and experimental testing to have appropriate capacitance values ​​for the first capacitor C1 and the second capacitor C2, and an appropriate inductance value for the third inductor L3, thereby constructing a resonant blocking circuit that resonates at the first resonant frequency.

[0130] Please continue to see Figure 6 The RF transmission branch further includes a second diode D2, a third capacitor C3, and a fourth inductor L4. The second diode D2 is connected between the second inductor L2 and the second node n2, with the anode of the second diode D2 facing the second inductor L2. The third capacitor C3 is connected between the second inductor L2 and the anode of the first diode D1. The fourth inductor L4 is connected between the second node n2 and the anode of the first diode D1, and the self-resonant frequency of the fourth inductor L4 is the same as the first resonant frequency.

[0131] The third capacitor C3 and the second diode D2 can provide a transmission path for the first RF signal from the second node n2 to the anode of the first diode D1. Furthermore, when a bias voltage is not supplied to the bias voltage input node n4, the second diode D2 can reduce both the risk of the first RF signal being transmitted to the first node n1 and the risk of the magnetic resonance signal being transmitted to the second node n2. Specifically, when a bias voltage is supplied to the bias voltage input node n4, compared to a case where the third capacitor C3 is replaced with a wire, the third capacitor C3 can prevent the second diode D2 from being short-circuited and turned off. Obviously, the turned-off second diode D2 cannot provide a transmission path for the first RF signal from the second node n2 to the anode of the first diode D1. In addition, the fourth inductor L4 can provide a transmission path for the bias voltage from the second node n2 to the anode of the first diode D1, and based on the fact that the fourth inductor L4 resonates at the first resonant frequency and thus cuts off the signal of the first resonant frequency, compared with the case where the fourth inductor L4 is replaced by a wire, when the bias voltage is not supplied to the bias voltage input node n4, the risk of the first radio frequency signal being transmitted to the first node n1 and the risk of the magnetic resonance signal being transmitted to the second node n2 can be reduced.

[0132] The RF receive branch includes a third diode D3, a fourth capacitor C4, and a fifth inductor L5. The third diode D3 is connected between the first node n1 and the first inductor L1, with the anode of the third diode D3 facing the first node n1. The fourth capacitor C4 is connected between the connection point (reference numeral omitted) between the third diode D3 and the first inductor L1 and the third node n3. The fifth inductor L5 is connected between the first node n1 and the third node n3 in parallel with the third diode D3 and the fourth capacitor C4. Together with the fourth capacitor C4 and the conductive third diode D3, the fifth inductor L5 forms another resonant blocking circuit having a resonant frequency identical to the first resonant frequency. The self-resonant frequency of the fifth inductor L5 is different from the first resonant frequency.

[0133] Because the resonant blocking circuit formed by the fifth inductor L5, the conductive third diode D3, and the fourth capacitor C4 resonates at the first resonant frequency and blocks signals at the first resonant frequency, the first RF signal used to generate the B1 field is not transmitted to the third node n3, i.e., the receiving end of the coil, in transmit mode. Furthermore, because the self-resonant frequency of the fifth inductor L5 differs from the first resonant frequency, in receive mode (when the third diode D3 is off), the first magnetic resonance signal from the first coil unit 23 can be transmitted via the fifth inductor L5 to the third node n3 and supplied to the first preamplifier 26.

[0134] In addition, the fifth capacitor C5 is connected between the power output terminal of the first RF power splitter 25 and the second node n2, thereby preventing the aforementioned bias voltage from being transmitted to the first RF power splitter 25. Furthermore, the sixth capacitor C6 is connected between the input terminal of the first preamplifier 26 and the third node n3, thereby preventing the aforementioned bias voltage from being transmitted to the first preamplifier 26 via the fifth inductor L5.

[0135] The sixth capacitor C6 is a matching capacitor of the preamplifier and is an adjustable capacitor with an adjustable capacitance value.

[0136] exist Figure 6 In the embodiment, the first node n1 is connected to the first coil unit 23 via the seventh capacitor C7 and the balun 29 (balun), wherein the balun 29 is used to suppress the common-mode current on the coaxial cable shielding layer, which can reduce the heat generation and common-mode interference on the coaxial cable, and the seventh capacitor C7 can prevent the bias voltage from being transmitted to the first coil unit 23.

[0137] Although the resonant blocking circuit composed of the first diode D1 in the cut-off state, the first capacitor C1, the second capacitor C2 and the third inductor L3 has excellent signal blocking properties for the signal of the first resonant frequency, a lot of debugging work is required when constructing the resonant blocking circuit, and it is not conducive to reducing the cost of circuit hardware. The Larmor frequency of the sodium nucleus (the second resonant frequency) is significantly lower than the Larmor frequency of the hydrogen atom (the first resonant frequency). We found that when the first capacitor C1, the second capacitor C2 and the third inductor L3 are omitted, at the lower Larmor frequency of the sodium nucleus, the first diode D1 alone can achieve a sufficiently good isolation effect between the transmitter and the receiver. Therefore, based on the simplicity of debugging and cost-effectiveness, Figure 6 As shown in the figure, for the first RF transceiver circuit 31 of the first coil unit 23, Figure 7 The second RF transceiver circuit 32 for the second coil unit 24 omits the first capacitor C1, the second capacitor C2 and the third inductor L3, but retains all other electrical components of the first RF transceiver circuit 31. Based on the above introduction to the first RF transceiver circuit 31, those skilled in the art will understand that Figure 7 The working principle of the second RF transceiver circuit 32 is well known, so it will not be described in detail.

[0138] In the first coil array 21 , a total of eight bias voltage input nodes n4 of eight RF transceiver circuits may be connected to the same bias voltage generator.

[0139] The number of first coil units 23 and the number of second coil units 24 may not be eight, and may be the same or different. However, to ensure the quality of magnetic resonance imaging, the number of first coil units 23 and second coil units 24 should generally not be less than four.

[0140] Please review Figure 4 and Figure 5 The eight first coil units 23 forming the first coil array 21 are arranged on the outer periphery of the eight second coil units 24 forming the second coil array 22, and are radially spaced a certain distance apart. In this embodiment, the second coil units 24 located on the inner periphery are designed as square coil units, while the first coil units 23 located on the outer periphery are designed as circular coil units.

[0141] It is understood that, compared to the circular first coil unit 23, configuring the second coil unit 24 in a square shape helps increase the signal coverage of the second coil array 22, thereby obtaining a wide-range magnetic resonance image of the subject. Although configuring the first coil unit 23 in a square shape can increase the signal coverage of the first coil array 21, the area of ​​a single square coil unit is larger than that of a single circular coil unit with the same length and width, and exhibits relatively poor transmission efficiency and receiving sensitivity. Moreover, the first coil unit 23 is relatively far away from the examination cavity 18 and the subject, and performs magnetic resonance imaging based on hydrogen nuclei with a high Larmor frequency. Therefore, when the first coil unit 23 is configured in a square shape, the image quality of hydrogen nuclear magnetic resonance imaging is significantly reduced. Unlike the above situation, the second coil unit 24 on the inner circumference is constructed in a square shape. Although the transmission efficiency and receiving sensitivity of the second coil unit 24 itself are reduced, since the second coil unit 24 is very close to the inspection cavity 18 and the object under examination, and the second coil unit 24 performs magnetic resonance imaging based on sodium nuclei with a low Larmor frequency, high-quality magnetic resonance images that meet application requirements can still be obtained.

[0142] Figure 10 FIG. 1 shows a magnetic resonance image of a subject's head obtained using the first coil array 21 based on a turbo spin echo sequence (TSE) and hydrogen nuclear magnetic resonance, wherein repetition time = 7000 ms, echo time = 66 ms, flip angle = 120°, and resolution = 1×1×2 mm. 3 .

[0143] Figure 11Magnetic resonance images of the subject's head obtained using the first coil array 21 based on a magnetization-prepared rapid acquisition gradient echo (MPRAGE) sequence and hydrogen nuclear magnetic resonance are shown, wherein repetition time = 2270 ms, echo time = 1.87 ms, inversion time = 900 ms, flip angle = 6°, and resolution = 1×1×1 mm 3 .

[0144] Figure 12 FIG2 shows a magnetic resonance image of the subject's head obtained using the first coil array 21 based on a fluid-attenuated inversion recovery (FLAIR) sequence and hydrogen nuclear magnetic resonance, wherein the repetition time is 9000 ms, the echo time is 76 ms, the inversion time is 2600 ms, the flip angle is 120°, and the resolution is 1×1×2 mm. 3 .

[0145] Figure 13 FIG. 1 shows a magnetic resonance image of a subject's head obtained using the second coil array 22 based on a density-adapted 3D radial acquisition sequence (DA-3D-RAD) and sodium nuclear magnetic resonance, wherein repetition time = 120 ms, echo time = 0.35 ms, flip angle = 90°, 5000 projections, and a resolution of 3×3×3 mm. ... 3 .

[0146] from Figures 10 to 13 It can be seen that the device 100 is capable of performing 1 mm isotropic hydrogen structural imaging and 3 mm isotropic resolution sodium imaging within a clinically acceptable scanning time (20 to 30 minutes), and the hydrogen and sodium images can be well aligned, which facilitates image post-processing.

[0147] As previously mentioned, the base 1 is constructed as a height-adjustable lift structure. Therefore, when the device 100 is mounted on an MRI couch of varying configurations, the height of the housing 2 can be adjusted by raising or lowering the upper base 5 of the base 1, thereby positioning the examination cavity 18 and the RF coil 3 at the center of the main magnet associated with the MRI couch.

[0148] As mentioned above, the head support seat 13 is detachably supported on the base 1. Therefore, the head support seat 13 can be replaced with a support seat suitable for supporting other objects to be examined. Figure 14In the illustrated embodiment, the head support 13 is detached and replaced with an animal support capable of supporting small animals such as mice and rats. The animal support is detachably supported on the upper body 5 of the base 1. By replacing the head support 13 with the animal support, the apparatus 100 is capable of performing magnetic resonance imaging on small animals, thereby enabling scientific research.

[0149] To obtain high-quality MRI images, the small animal being examined can be positioned in the center of the examination cavity 18. However, different animals have different body sizes, and even the same animal may have significantly different positioning on the support during two MRI examinations. To address this issue, the present embodiment of the present invention configures the animal support as a liftable structure that can be raised and lowered relative to the examination cavity 18. This allows the small animal being examined to be positioned in the center of the examination cavity 18 by adjusting the animal support.

[0150] Specifically, the animal support seat includes a first portion 15, a second portion 16, and a locking bolt 17. The first portion 15 is removably connected to the upper body 5 of the base 1 outside the inspection chamber 18 via screws (not shown). The first portion 15 includes an upwardly projecting insert 15a having a threaded hole (not shown) extending in the horizontal direction DR1. The second portion 16 is used to support the small animal being examined and includes a downwardly opening slot 16a that receives the insert 15a for movement in the vertical direction DR2. The locking bolt 17 screws into the threaded hole of the insert 15a and, when rotated, has a locked state and a released state. In the released state, the locking bolt 17 allows the second portion 16 to move relative to the first portion 15 in the vertical direction DR2. In the locked state, the cap of the locking bolt 17 presses against the second portion 16, thereby securing the second portion 16 to the first portion 15 in the vertical direction DR2.

[0151] like Figure 15 As shown, the embodiment of the present application further provides a magnetic resonance system 1000, which includes the aforementioned magnetic resonance coil device 100, a transmitter 200, and a receiver 300. The transmitter 200 is connected to the input terminals of the RF power splitters 25 and 27 and is configured to generate a radio frequency signal supplied to the input terminals of the RF power splitters. The receiver 300 is connected to the output terminals of the preamplifiers 26 and 28 and is configured to receive a magnetic resonance signal from the subject at the output terminals of the preamplifiers.

Claims

1. A radio frequency transceiver circuit, characterized in that: include: a first node for connecting to a first coil unit having a first resonant frequency and connected to a ground potential via a first inductor, wherein a self-resonant frequency of the first inductor is the same as the first resonant frequency; a second node, connected to the first node via a radio frequency transmission branch, configured to receive a first radio frequency signal from a power output terminal of the first radio frequency power splitter, and provide the first radio frequency signal to the first coil unit via the radio frequency transmission branch and the first node, wherein a frequency of the first radio frequency signal is the same as the first resonant frequency; a third node connected to the first node via a radio frequency receiving branch, configured to receive a first magnetic resonance signal of the first resonant frequency from the first coil unit via the first node and the radio frequency receiving branch, and supply the first magnetic resonance signal to a first preamplifier; The radio frequency transmission branch includes: a first diode having an anode connected to the second node and a cathode connected to the first node; a bias voltage input node configured to selectively receive a bias voltage and connected to the anode of the first diode via a second inductor and the first node in sequence, the self-resonant frequency of the second inductor being the same as the first resonant frequency; a first capacitor connected in parallel with the first diode; a second capacitor and a third inductor connected in series with each other and connected in parallel across the first capacitor; The first diode, the first capacitor, the second capacitor and the third inductor in the cut-off state form a resonance blocking circuit that resonates at the first resonance frequency.

2. The radio frequency transceiver circuit according to claim 1, wherein: The radio frequency transmission branch includes: a second diode connected between the second inductor and the second node, with an anode facing the second inductor; a third capacitor connected between the second inductor and the anode of the first diode; A fourth inductor is connected between the second node and the anode of the first diode, and a self-resonant frequency of the fourth inductor is the same as the first resonant frequency.

3. The radio frequency transceiver circuit according to claim 2, wherein: The radio frequency receiving branch includes: a third diode connected between the first node and the first inductor, with an anode facing the first node; a fourth capacitor connected between a connection point between the third diode and the first inductor and the third node; A fifth inductor is connected in parallel between the first node and the third node, and together with the fourth capacitor and the third diode in the on state, forms a resonant blocking circuit with a resonant frequency the same as the first resonant frequency. The self-resonant frequency of the fifth inductor is different from the first resonant frequency.

4. A magnetic resonance coil array, characterized in that: include: N radio frequency transceiver circuits according to any one of claims 1 to 3, wherein N is an integer not less than 4; N first coil units are respectively connected to the first nodes of the N radio frequency transceiver circuits; The first radio frequency power splitter has N power output ends respectively connected to the second nodes of the N radio frequency transceiver circuits; The N first preamplifiers are respectively connected to the third nodes of the N radio frequency transceiver circuits.

5. The magnetic resonance coil array according to claim 4, wherein: The power output terminal is connected to the second node via a fifth capacitor, the third node is connected to the input terminal of the first preamplifier via a sixth capacitor, and the sixth capacitor is an adjustable capacitor with an adjustable capacitance value.

6. The magnetic resonance coil array according to claim 4, wherein: The first node is connected to the first coil unit via a seventh capacitor.

7. The magnetic resonance coil array according to any one of claims 4 to 6, characterized in that: The N bias voltage input nodes of the N radio frequency transceiver circuits are connected to the same bias voltage generator.

8. A magnetic resonance coil device, characterized in that: include: a housing defining an inspection cavity for receiving an object under inspection; The magnetic resonance coil array according to any one of claims 4 to 7, which is a first magnetic resonance coil array, is installed in the housing, and N first coil units are arranged around the examination cavity; a second magnetic resonance coil array, comprising N second coil units installed in the housing, wherein the N second coil units are arranged around the examination cavity; The first resonant frequency of the first coil unit corresponds to hydrogen nuclei, and the second resonant frequency of the second coil unit corresponds to non-hydrogen nuclei.

9. The magnetic resonance coil apparatus according to claim 8, wherein The second resonance frequency of the second coil unit corresponds to sodium nuclei.

10. The magnetic resonance coil apparatus according to claim 8, wherein The RF transceiver circuit is a first RF transceiver circuit, the second magnetic resonance coil array includes a second RF transceiver circuit, and the second RF transceiver circuit includes all remaining parts of the first RF transceiver circuit except the first capacitor, the second capacitor and the third inductor.

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