CN117741531A - Body coil for nuclear magnetic resonance, nuclear magnetic resonance detection device and control method - Google Patents

Abstract

The present disclosure provides a body coil for nuclear magnetic resonance, a nuclear magnetic resonance detection apparatus, and a control method. Wherein, the body coil includes: the first end ring and the second end ring are opposite and are arranged at intervals; and a plurality of antenna legs disposed in an array about the first end ring and the second end ring, a first end of each of the plurality of antenna legs being connected to the first end ring and a second end being connected to the second end ring. The antenna legs comprise a plurality of resonant antenna legs and a plurality of detuned antenna legs, each detuned antenna leg of the plurality of detuned antenna legs is provided with a switching diode, the switching diodes are disconnected in the transmitting state of the body coil, the resonant frequency of the body coil is the same as the frequency of the radio frequency signals transmitted by the body coil and used for nuclear magnetic resonance detection, and the switching diodes are conducted in the detuned state of the body coil.

Description

Body coil for nuclear magnetic resonance, nuclear magnetic resonance detection device and control method

Technical Field

The disclosure relates to the technical field of medical instruments, in particular to a body coil for nuclear magnetic resonance, nuclear magnetic resonance detection equipment and a control method.

Background

Currently, magnetic Resonance Imaging (MRI) examination has become a common imaging examination modality. In a magnetic resonance system, a magnetic resonance coil is generally divided into a transmitting coil for transmitting a transmitting RF signal (radio frequency signal) to an object to be detected and a receiving coil. The magnetic dipole of the object to be detected generates nuclear magnetic resonance under the action of the magnetic field and generates MR signals (magnetic resonance signals), and the receiving coil is used for receiving the MR signals. The transmit coil (also referred to as a main coil) typically employs a birdcage configuration, and the receive coil is typically disposed within the transmit coil.

Since the transmitting coil and the receiving coil operate in the same frequency environment, the two have the same resonant frequency, and the coupling between the two is strong when the receiving coil operates. This strong coupling affects the signal reception of the receiving coil, where it is necessary to add a detuning circuit to the transmitting coil and the receiving coil, i.e. the transmitting coil detunes the transmitting coil frequency by the action of the detuning circuit when the receiving coil is in operation.

Disclosure of Invention

In view of this, the present disclosure proposes, in one aspect, a body coil for nuclear magnetic resonance, comprising: the first end ring and the second end ring are opposite and are arranged at intervals; and a plurality of antenna legs arranged around the first end ring and the second end ring, wherein a first end of each antenna leg of the plurality of antenna legs is connected to the first end ring, a second end is connected to the second end ring, the plurality of antenna legs comprises a plurality of resonant antenna legs and a plurality of detuned antenna legs, each detuned antenna leg of the plurality of detuned antenna legs is provided with a switching diode, the switching diode is turned off in an emission state of the body coil, a resonant frequency of the body coil is the same as a frequency of a radio frequency signal emitted by the body coil for nuclear magnetic resonance detection, and the switching diode is turned on in a detuned state of the body coil.

Another aspect of the present disclosure proposes a nuclear magnetic resonance detection apparatus, comprising: a power supply for providing a radio frequency current; the body coil is controllably connected to a power supply and configured to transmit a radio frequency signal to a detection object when receiving a radio frequency current; and a receiving coil configured to receive the magnetic resonance signal from the detection subject.

Another aspect of the present disclosure proposes a control method for the above-mentioned nuclear magnetic resonance detection apparatus, including: an electrical connection between the conductive body coil and the power source; switching off switching diodes on a plurality of antenna legs of the body coil to allow the body coil to emit radio frequency signals to the detection object; after waiting for a preset time, disconnecting the electrical connection between the body coil and the power supply; and switching diodes on the plurality of antenna legs of the body coil to wait for the receiving coil to receive the magnetic resonance signal from the subject.

According to some embodiments of the present disclosure, the switching diode is turned off in the body coil emission mode; the switching diode is turned on in a receiving mode of the receiving coil and the body coil is put in a detuned state by increasing the number of antenna legs in the on state. In the transmit mode of the body coil, the switching diode is turned off, so no radio frequency current passes through the switching diode; in the receiving mode of the receiving coil, the switching diode is turned on, but the body coil is already disconnected from the external power supply, so that no radio frequency current is yet passed through the switching diode. Thus, in embodiments of the present disclosure, the switching diode does not need to withstand a large radio frequency current, and thus the switching diode is not fragile, thereby increasing the overall lifetime of the body coil.

Drawings

The above and other features and advantages of the present disclosure will become more apparent to those of ordinary skill in the art by describing in detail embodiments thereof with reference to the attached drawings, in which:

FIG. 1a is a schematic diagram of a related art body coil;

FIG. 1b is a schematic diagram of an equivalent coil of the body coil shown in FIG. 1a when the switching diode is turned on;

FIG. 1c is a schematic diagram of an equivalent coil of the body coil shown in FIG. 1a when the switching diode is turned off;

fig. 2a is a schematic diagram of a body coil according to one embodiment of the present disclosure;

FIG. 2b is a schematic diagram of the equivalent coil of the body coil shown in FIG. 2a when the switching diode is turned off;

FIG. 2c is a schematic diagram of the equivalent coil of the body coil shown in FIG. 2a when the switching diode is turned on;

fig. 3a is a schematic diagram of a body coil according to another embodiment of the present disclosure;

FIG. 3b is a schematic diagram of the equivalent coil of the body coil shown in FIG. 3a when the switching diode is turned off;

FIG. 3c is a schematic diagram of the equivalent coil of the body coil shown in FIG. 3a when the switching diode is turned on;

fig. 4a is a schematic diagram of a body coil according to another embodiment of the present disclosure;

FIG. 4b is a schematic diagram of the equivalent coil of the body coil shown in FIG. 4a when the switching diode is turned off;

FIG. 4c is a schematic diagram of the equivalent coil of the body coil shown in FIG. 4a when the switching diode is turned on;

fig. 5a is a schematic diagram of a body coil according to another embodiment of the present disclosure;

FIG. 5b is a schematic diagram of the equivalent coil of the body coil shown in FIG. 5a with the switching diode turned off;

FIG. 5c is a schematic diagram of the equivalent coil of the body coil shown in FIG. 5a when the switching diode is turned on;

FIG. 6 is a block diagram of a nuclear magnetic resonance detection apparatus according to one embodiment of the present disclosure; and

fig. 7 is a flowchart of a control method for a nuclear magnetic resonance detection apparatus according to one embodiment of the present disclosure.

Wherein, the reference numerals are as follows:

a body coil 10; a first end ring 110, a second end ring 120, an antenna leg 200, a resonant antenna leg 210, a detuned antenna leg 220, a first antenna leg 201, a second antenna leg 202, and a third antenna leg 203; a switching diode 300, a first end-ring capacitor 410, a second end-ring capacitor 420, and an antenna leg capacitor 430;

a nuclear magnetic resonance detection apparatus 1; a power supply 20; and a receiving coil 30.

Detailed Description

For a clearer understanding of the technical features, objects, and effects of the present disclosure, specific embodiments of the disclosure will now be described with reference to the drawings in which like reference numerals represent like parts throughout the several views.

In this document, "schematic" means "serving as an example, instance, or illustration," and any illustrations, embodiments described herein as "schematic" should not be construed as a more preferred or advantageous solution.

For simplicity of the drawing, only the portions relevant to the present disclosure are schematically shown in each drawing, which do not represent the actual structure thereof as a product. Additionally, in order to simplify the drawing for ease of understanding, components having the same structure or function in some of the drawings are shown schematically with only one of them, or only one of them is labeled.

Herein, "a" means not only "only this one" but also "more than one" case. Herein, "first", "second", etc. are used merely to distinguish one from another, and do not indicate their importance and order, and preconditions for existence of one another, etc.

FIG. 1a is a schematic diagram of a related art body coil; FIG. 1b is a schematic diagram of an equivalent coil of the body coil shown in FIG. 1a when the switching diode is turned on; fig. 1c is a schematic diagram of an equivalent coil of the body coil shown in fig. 1a when the switching diode is turned off. As shown in fig. 1, the body coil 10 includes: the first and second end rings 110 and 120 and a plurality of antenna legs 200 having both ends connected to the first and second end rings 110 and 120, respectively. Each antenna leg 200 of the plurality of antenna legs 200 is provided with a switching diode 300 for switching on or off the antenna leg 200.

The principle of operation of the body coil 10 of the related art is: when the body coil 10 for nuclear magnetic resonance is connected to an external power source, the body coil 10 is in an emission state as shown in fig. 1 b. At this time, the switching diode 300 is controlled to be in a conductive state by an electric signal, and a radio frequency current will flow through the antenna leg 200, so that the body coil 10 emits a radio frequency signal having a frequency equal to the resonance frequency of the body coil 10. In general, the resonant frequency of the body coil 10 is related to the number of antenna legs 200, and thus, body coils 10 having different numbers of antenna legs 200 will emit radio frequency signals of different frequencies. After the transmission of the radio frequency signal, the body coil 10 will be disconnected from the external power source and the associated receiving coil is in the receiving mode, at which time the switching diode 300 is controlled by the electrical signal to be in an off state, as shown in fig. 1 c. When the number of the antenna legs 200 in the on state is reduced by controlling the switching diode 300, the resonance frequency of the body coil 10 is changed with respect to the resonance frequency of the body coil 10 in the transmitting state, i.e., the body coil 10 is in the detuned state at this time, so that coupling with the receiving coil is impossible or weak. This prevents the body coil 10 from affecting the signal reception of the receiving coil when the receiving coil receives a signal.

However, in the related art, when the body coil 10 is in the transmitting state, the current value of the radio frequency current flowing through the plurality of antenna legs 200 is large, and thus, the switching diode 300 provided on the antenna legs 200 will also receive a large magnitude current. This will result in the switching diode 300 being more susceptible to damage, thereby reducing the overall lifetime of the body coil 10.

The body coil 10 for nuclear magnetic resonance according to the embodiment of the present disclosure will be described in detail with reference to fig. 2a to 5 c.

According to an embodiment of the present disclosure, there is provided a body coil 10 for nuclear magnetic resonance, the body coil 10 including: the first and second end rings 110, 120 are disposed opposite and spaced apart from each other, and a plurality of antenna legs 200. The plurality of antenna legs 200 are arranged around the first end ring 110 and the second end ring 120, a first end of each antenna leg 200 of the plurality of antenna legs 200 being connected to the first end ring 110 and a second end being connected to the second end ring 120. The plurality of antenna legs 200 includes a plurality of resonant antenna legs 210 and a plurality of detuned antenna legs 220, with a switching diode 300 disposed on each of the plurality of detuned antenna legs 220, the switching diode 300 configured to conduct to detune the body coil 10. In the transmitting state of the body coil, the switching diode 300 is turned off, and the body coil transmits a radio frequency signal for nuclear magnetic resonance detection. The resonance frequency of the body coil is the same as the frequency of the radio frequency signal for nuclear magnetic resonance detection. While in the detuned state of the body coil, the switching diode 300 is turned on, and thus the number of antenna legs turned on in the detuned state is greater than the number of antenna legs in the radiating (tuned) state.

Fig. 2a is a schematic diagram of a body coil 10 according to one embodiment of the present disclosure; fig. 2b is an equivalent coil schematic diagram of the body coil 10 shown in fig. 2a when the switching diode 300 is turned off; fig. 2c is an equivalent coil schematic diagram of the body coil 10 shown in fig. 2a when the switching diode 300 is turned on. As shown in fig. 2a, the first end ring 110 and the second end ring 120 are identical in size and model, and the plane in which the first end ring 110 and the plane in which the second end ring 120 are located are parallel to each other, and the plurality of antenna legs 200 are disposed parallel to each other, and both ends of each antenna leg 200 are connected to the first end ring 110 and the second end ring 120, respectively, thereby forming a "birdcage" like shape, and thus, the body coil 10 is also referred to as a birdcage coil.

The plurality of antenna legs 200 includes a plurality of resonant antenna legs 210 and a plurality of detuned antenna legs 220. In the embodiment shown in fig. 2a, the number of the plurality of resonant antenna legs 210 and the plurality of detuned antenna legs 220 is the same, for example, all 8, and the plurality of resonant antenna legs 210 and the plurality of detuned antenna legs 220 are alternately arranged at intervals in the circumferential direction of the first end ring 110 and the second end ring 120. In other embodiments, the number of the plurality of resonant antenna legs 210 and the plurality of detuned antenna legs 220 may be different. The plurality of antenna legs are further arranged to: a second preset number of detuned antenna legs 220 are arranged consecutively per a first preset number of resonant antenna legs 210 in the circumferential direction of the first end ring and the second end ring.

The body coil 10 of the present embodiment operates on the principle that: when the body coil 10 for nuclear magnetic resonance is connected to the external power source 20, the body coil 10 is in an emission state as shown in fig. 2 b. At this time, the switching diode 300 is controlled to be in an off state by an electric signal, and only the antenna leg 200 where the switching diode 300 is not provided has a radio frequency current, the body coil 10 will emit a radio frequency signal, and the frequency of the radio frequency signal and the number of the resonant antenna legs 210 are related to the circuit arrangement inside the body coil 10. After the transmission of the rf signal, the body coil 10 is disconnected from the external power source 20, and the associated receiving coil 30 is in the receiving mode, at which time the switching diode 300 is controlled by the electrical signal to be in a conducting state, as shown in fig. 2 c. Since the number of the antenna legs 200 in the on state is increased by controlling the switching diode 300, the resonance frequency of the body coil 10 is changed with respect to the resonance frequency of the body coil 10 in the transmitting state, i.e., the body coil 10 is in the detuned state at this time, so that coupling with the receiving coil 30 is impossible or coupling strength is small. This prevents the body coil 10 from affecting the signal reception of the receiving coil 30 when the receiving coil 30 receives a signal.

The diode of the body coil 10 of the present embodiment operates in the opposite manner to the diode of the body coil 10 of the related art, that is, the switching diode 300 is turned off in the body coil 10 emission mode; the switching diode 300 is turned on in the reception mode of the reception coil 30 and the body coil 10 is put in a detuned state by increasing the number of the antenna legs 200 in the on state. The above-mentioned body coil 10 can be understood as adding the detuned antenna leg 220 with the switching diode 300 in addition to the original body coil 10, so that compared with the prior art in which the detuning of the body coil 10 is achieved by reducing the number of the antenna legs in the on state, the body coil 10 of the present embodiment actually achieves the detuning of the body coil 10 by increasing the number of the antenna legs, thereby achieving a completely new detuning mode of the body coil 10.

The above arrangement is such that in the transmit mode of the body coil 10, the switching diode 300 is turned off, so that no radio frequency current passes through the switching diode 300; while in the receive mode of the receive coil 30, the switching diode 300 is on, but the body coil 10 is already off from the external power source 20, and therefore no radio frequency current is still passing through the switching diode 300. Thus, in embodiments of the present disclosure, the switching diode 300 does not need to withstand a large radio frequency current, and thus the switching diode 300 is less prone to damage, thereby increasing the overall useful life of the body coil 10.

As described above, the plurality of antenna legs 200 are disposed around the first end ring 110 and the second end ring 120, and thus the antenna legs 200 are disposed along the circumferential direction of the first end ring 110 or the second end ring 120. The plurality of antenna legs are further arranged to: a second preset number of detuned antenna legs 220 are arranged consecutively per a first preset number of resonant antenna legs 210 in the circumferential direction of the first end ring and the second end ring. As shown in fig. 2a, the resonant antenna legs 210 and the detuned antenna legs 220 are spaced apart, and as shown in fig. 3a, one detuned antenna leg 220 may be arranged every two resonant antenna legs 210. In other embodiments, other arrangements may be included, such as: two detuned antenna legs 220, etc., are arranged consecutively every three resonant antenna legs 210, which are not described in detail here. The intervals between the plurality of antenna legs 200 may be the same so that the plurality of antenna legs 200 are uniformly arranged in the circumferential direction of the first end ring 110 and the second end ring 120.

In some embodiments, as shown in fig. 2a, the resonant antenna legs 210 and the detuned antenna legs 220 are arranged at intervals, and the switching diode 300 is disposed only on the detuned antenna legs 220, so that a body coil 10 in which the antenna legs 200 provided with the switching diode 300 and the antenna legs 200 not provided with the switching diode 300 are alternately arranged can be obtained, and if the number of the plurality of antenna legs 200 is 16, the total number of the antenna legs 200 provided with the switching diode 300 is 8. In other examples, a second preset number of detuned antenna legs 220 may be arranged consecutively per a first preset number of resonant antenna legs 210, and said second preset number is smaller than or equal to said first preset number, as shown in fig. 3a, one detuned antenna leg 220 being arranged per two resonant antenna legs 210 per interval, such that a body coil configuration of one antenna leg 200 provided with a switching diode 300 per two antenna legs 200 without a switching diode 300 per interval may result, and if the number of the plurality of antenna legs 200 is 12, the total number of detuned antenna legs 220 provided with switching diodes 300 is 4.

The above arrangement can make the arrangement of the antenna leg 200 and the switching diode 300 of the body coil 10 more uniform, so that the structure of the main coil can be simplified, and the manufacturing of the body coil 10 is facilitated.

It will be appreciated that for a primary coil that emits RF signals at a predetermined frequency, the number of antenna legs 200 that are on in the transmit mode, i.e., resonant antenna legs 210, is predetermined, and that the greater the number of detuned antenna legs 220, the greater the number of switching diodes 300 that are provided. If the number of diodes is large, the overall cost of the body coil 10 is high; if the number of diodes is smaller, the difference between the number of the antenna legs 200 in the conductive state and the non-conductive state of the body coil 10 is smaller, so that the detuning effect of the body coil 10 is not significant. Accordingly, in some embodiments, the ratio of the number of the plurality of resonant antenna legs 210 and the plurality of detuned antenna legs 220 may be appropriately selected to increase the detuning effect of the body coil 10 as much as possible while ensuring low cost. The above quantitative ratio may be between 1 and 4 in consideration of the above factors.

In some embodiments, the body coil 10 is a high-pass body coil 10, the high-pass body coil 10 further comprising: a plurality of first end ring capacitors 410 and a plurality of second end ring capacitors 420. A plurality of first end ring capacitors 410 are disposed on the first end ring 110 and a plurality of second end ring capacitors 420 are disposed on the second end ring 120. The plurality of first end ring capacitors 410 and the plurality of second end ring capacitors 420 are symmetrically arranged on the first end ring 110 and the second end ring 120, respectively. It will be appreciated that the body coil 10 is in fact constituted by an oscillating circuit, and therefore it comprises a plurality of capacitors for setting the frequency of the RF signal generated by the body coil 10. For a high-pass body coil 10, the capacitors are disposed on the first end ring and the second end ring, and the number of disposed capacitors and the parameters of the capacitors will affect the resonant frequency of the body coil 10.

In some embodiments, the plurality of first end ring capacitors 410 and the plurality of second end ring capacitors 420 may be arranged as follows. Fig. 4a is a schematic view of a body coil 10 according to another embodiment of the present disclosure; fig. 4b is an equivalent coil schematic diagram of the body coil 10 shown in fig. 4a when the switching diode 300 is turned off; fig. 4c is an equivalent coil schematic diagram of the body coil 10 shown in fig. 4a when the switching diode 300 is turned on. As shown in fig. 4a, the plurality of antenna legs 200 includes a first antenna leg 201 as a detuned antenna leg 220 and a second antenna leg 202 and a third antenna leg 203 adjacent to the first antenna leg 201, the second antenna leg 202 and the third antenna leg 203 may be resonant antenna legs 210. The plurality of first end loop capacitors 410 includes a first capacitor C1 and a second capacitor C2, and the plurality of second end loop capacitors 420 includes a third capacitor C3 and a fourth capacitor C4, wherein the first capacitor C1 is disposed between the connection point of the first antenna leg 201 and the first end loop to the connection point of the second antenna leg 202 and the first end loop; the second capacitor C2 is disposed between the connection point of the first antenna leg 201 and the first end ring to the connection point of the third antenna leg 203 and the first end ring. A third capacitor C3 is disposed between the connection point of the first antenna leg 201 and the second end ring and the connection point of the second antenna leg 202 and the second end ring; and a fourth capacitor C4 is disposed between the connection point of the first antenna leg 201 and the second end ring to the connection point of the third antenna leg 203 and the second end ring. That is, capacitors are provided on both sides of the connection point where the first antenna leg 201 is connected to the first end ring, and capacitors are also provided on both sides of the connection point where the first antenna leg 200 is connected to the second end ring. The parameters and the model of the first to fourth capacitors C1 to C4 may be the same.

When the high-pass body coil 10 of the present embodiment is in the transmitting state, all the switching diodes 300 are turned off, the equivalent body coil 10 will be shown in fig. 4b, the first capacitor C1 and the second capacitor C2 are connected in series to form a new capacitor, and similarly, the third capacitor C3 and the fourth capacitor C4 are connected in series to form a new capacitor, and at this time, the resonant frequency of the body coil 10 will be determined by the two newly generated capacitors. When the capacitors of the present embodiment are in the non-transmitting state (i.e. when the receiving coil 30 receives the RM signal), all the switching diodes 300 are turned on, the equivalent coil 10 is shown in fig. 4C, the first capacitor C1 and the second capacitor C2 are two independent capacitors, and similarly, the third capacitor C3 and the fourth capacitor C4 are two independent capacitors, and at this time, the resonant frequency of the body coil 10 is determined by the first capacitor C1 to the fourth capacitor C4.

Thus, it can be seen that by arranging the capacitor in the form shown in fig. 4a, not only does the number of antenna legs 200 in the on-state change during switching of the body coil 10 between the transmitting mode and the non-transmitting mode, but the configuration of the capacitor also changes. The change in the capacitive configuration will further increase the amplitude of the change in the resonant frequency of the body coil 10 relative to the number of antenna legs 200 that only change the on state, thereby making the detuning of the body coil 10 in the non-transmitting mode more pronounced, which will increase the effect of the subsequent acquisition of RM signals by the receiving coil 30. In addition, by introducing capacitors with different parameters, the tuning-off frequency of the body coil 10 can be regulated, so that the tuning-off frequency of the body coil 10 can reach a desired frequency range.

In some embodiments, the body coil 10 is a low-pass body coil 10, the low-pass body coil 10 further comprising: a plurality of antenna-leg capacitors 430, each antenna-leg capacitor 430 of the plurality of antenna-leg capacitors 430 being disposed on a corresponding antenna leg 200. Fig. 5a is a schematic view of a body coil 10 according to another embodiment of the present disclosure; fig. 5b is an equivalent coil schematic diagram of the body coil 10 shown in fig. 5a when the switching diode 300 is turned off; fig. 5c is an equivalent coil schematic diagram of the body coil 10 shown in fig. 5a when the switching diode 300 is turned on. As shown in fig. 5a, for the low-pass body coil 10, the capacitors are provided on the antenna legs 200, one for each antenna leg 200. For the antenna leg 200 provided with the switching diode 300, the switching diode 300 and the antenna leg capacitor 430 are provided in series. Fig. 5a shows three antenna legs 200, with one antenna leg capacitor 430 (i.e., a fifth capacitor C1', a sixth capacitor C2', and a seventh capacitor C3 ') disposed on each antenna leg 200.

When the low-pass body coil 10 of the present embodiment is in the transmitting state, all the switching diodes 300 are turned off, the equivalent coil 10 will be shown in fig. 5b with the fifth capacitor C1' and the seventh capacitor C3' on the conductive antenna leg 200, and thus still active, but the sixth capacitor C2' is turned off and in the disabled state. At this time, the resonance frequency of the body coil 10 will be determined only by the fifth capacitor C1 'and the seventh capacitor C3'. When the capacitors of the present embodiment are in a non-transmitting state (i.e., when the receiving coil 30 receives RM signals), all the switching diodes 300 are turned on, the equivalent coil 10 will be effective as shown in fig. 4C, and the fifth capacitor C1', the sixth capacitor C2' and the seventh capacitor C3', and at this time, the resonant frequency of the body coil 10 is commonly determined by the fifth capacitor C1' to the seventh capacitor C3 '.

Thus, it can be seen that by arranging the capacitor in the form shown in fig. 5a, not only does the number of antenna legs 200 in the on-state change during switching of the body coil 10 between the transmitting mode and the non-transmitting mode, but the configuration of the capacitor also changes. The change in the capacitive configuration will further increase the amplitude of the change in the resonant frequency of the body coil 10 relative to the number of antenna legs 200 that only change the on state, thereby making the detuning of the body coil 10 in the non-transmitting mode more pronounced, which will increase the effect of the subsequent acquisition of RM signals by the receiving coil 30. In addition, by introducing capacitors with different parameters, the tuning-off frequency of the body coil 10 can be regulated, so that the tuning-off frequency of the body coil 10 can reach a desired frequency range.

According to another aspect of the present disclosure, the present disclosure further provides a nuclear magnetic resonance detection apparatus 1, and fig. 6 is a block diagram of the structure of the nuclear magnetic resonance detection apparatus 1 according to an embodiment of the present disclosure. As shown in fig. 6, the nuclear magnetic resonance detection apparatus 1 includes: a power supply 20, the body coil 10 described above, and a receiving coil 30. A power supply 20 may be provided outside the body coil 10 for providing radio frequency current. The body coil 10 is controllably connected to a power supply 20 configured to transmit a radio frequency signal to a test subject upon receiving a radio frequency current. The receive coil 30 is configured to receive magnetic resonance signals from a subject. In some embodiments, the receiving coil 30 may be disposed inside the body coil 10, and its specific position inside the body coil 10 may be flexibly set according to the detection site.

The nuclear magnetic resonance detection apparatus 1 of the present embodiment operates on the principle that: after the nuclear magnetic resonance detection apparatus 1 is started, the electrical connection between the body coil 10 and the power supply 20 is turned on, at which time the power supply 20 supplies a radio frequency current to the body coil 10, and the body coil 10 enters a transmission mode and transmits an RF signal. The magnetic dipoles of the object to be detected undergo nuclear magnetic resonance under the magnetic field of the RF signal and generate MR signals (magnetic resonance signals). After a preset time, the electrical connection between the body coil 10 and the power supply 20 is disconnected, the power supply 20 stops supplying the radio frequency current to the antenna leg 200 in the body coil 10, and the body coil 10 exits the transmission mode and stops transmitting the radio frequency signal. At this time, the magnetic resonance signal from the detection subject is received by the receiving coil 30. The receive coil 30 may also be connected to an image display device such that the magnetic resonance signals are displayed as images for viewing by a human subject.

According to another aspect of the present disclosure, the present disclosure also provides a control method of the nuclear magnetic resonance detection apparatus 1. Fig. 7 is a flowchart of a control method 700 for the nuclear magnetic resonance detection apparatus 1 according to an embodiment of the present disclosure, as shown in fig. 7, the method 700 includes:

step 710, conducting an electrical connection between the body coil 10 and the power source 20;

step 720, switching off the switching diodes 300 on the plurality of antenna legs 200 of the body coil 10 to allow the body coil 10 to transmit a radio frequency signal to the detection object;

step 730, after waiting for a preset time, disconnecting the electrical connection between the body coil 10 and the power source 20; and

step 740 turns on the switching diodes 300 on the plurality of antenna legs 200 of the body coil 10 to wait for the receiving coil 30 to receive the magnetic resonance signal from the subject.

For step 710, after the nuclear magnetic resonance detection apparatus 1 is started, the apparatus will conduct the electrical connection between the body coil 10 and the power supply 20, at which point the power supply 20 supplies the radio frequency current to the body coil 10. In step 720, the switching diodes 300 on the plurality of antenna legs 200 of the body coil 10 may be turned off while the electrical connection between the body coil 10 and the power source 20 is turned on, and at this time, the antenna legs 200 of the body coil 10 where the switching diodes 300 are not disposed will pass radio frequency current, and the body coil 10 enters the transmitting mode. The frequency of the radio frequency signal emitted by the body coil 10 is equal to the resonance frequency of the body coil 10, and in general, the resonance frequency of the body coil 10 is related to the number of antenna legs 200, that is, the frequency of the radio frequency signal is directly related to the number of antenna legs 200. Taking the body coil 10 shown in fig. 2b as an example, only 8 antenna legs 200 are turned on after the body coil 10 enters the transmitting mode, and the frequency of the radio frequency signal is the resonance frequency of the body coil 10 with 8 antenna legs 200.

In step 730, the preset time allows the magnetic field generated by the rf signal to interact with the object to be detected, so that the object to be detected generates the RM signal, and the preset time may be set according to the parameters of the nmr detection apparatus 1 and the specific requirements of the detection process. After a preset time, the electrical connection between the body coil 10 and the power supply 20 is disconnected, the power supply 20 stops supplying the radio frequency current to the antenna leg 200 in the body coil 10, and the body coil 10 exits the transmission mode and stops transmitting the radio frequency signal. In step 740, magnetic resonance signals from the object to be detected are received by the receiving coil 30, and the received magnetic resonance signals can be subsequently converted into digital signals by an analog-to-digital converter for representing the detection result of the object to be detected. The digital signal may be displayed as an image, for example, for viewing by a human detector. When the receiving coil 30 receives a magnetic resonance signal from a detection subject, the switching diodes 300 on the plurality of antenna legs 200 of the body coil 10 are turned on, and at this time, the number of antenna legs 200 in the on state increases. Still taking the body coil 10 shown in fig. 2c as an example, the number of the antenna legs 200 in the on-state increases from 8 to 16, and at this time the resonance frequency of the body coil 10 will change and be in the detuned state. The coupling between the body coil 10 and the receiving coil 30 in the detuned state will be greatly reduced, thereby avoiding the influence on the signal received by the receiving coil 30 and improving the final detection effect.

It should be noted that, in other embodiments, the steps in the control method for the nuclear magnetic resonance detection apparatus 1 may also be performed in a different order than the steps in the method 700. For example, step 720 may be performed first, followed by step 710 of first disconnecting the switching diodes 300 on the plurality of antenna legs 200 of the body coil 10 and then turning on the electrical connection between the body coil 10 and the power supply 20. In summary, the implementation of the control method of the present disclosure is not dependent on the order of execution of the steps.

The foregoing is illustrative only and is not intended to limit the present disclosure, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the present disclosure are intended to be included within the scope of the present disclosure.

Claims (9)

1. A body coil for nuclear magnetic resonance, comprising:

the first end ring and the second end ring are opposite and are arranged at intervals; and

a plurality of antenna legs disposed in an array about the first end ring and the second end ring, a first end of each of the plurality of antenna legs connected to the first end ring and a second end connected to the second end ring, wherein

The antenna legs comprise a plurality of resonant antenna legs and a plurality of detuned antenna legs, each detuned antenna leg of the plurality of detuned antenna legs is provided with a switching diode, the switching diodes are disconnected in the transmitting state of the body coil, the resonant frequency of the body coil is the same as the frequency of the radio frequency signals transmitted by the body coil and used for nuclear magnetic resonance detection, and the switching diodes are conducted in the detuned state of the body coil.

2. The body coil of claim 1 wherein,

the plurality of antenna legs are further arranged to: a second predetermined number of detuned antenna legs is arranged consecutively at intervals of a first predetermined number of resonant antenna legs in the circumferential direction of the first end ring and the second end ring.

3. The body coil of claim 2 wherein,

the plurality of resonant antenna legs and the plurality of detuned antenna legs are alternately spaced apart in a circumferential direction of the first end ring and the second end ring.

4. The body coil of claim 2 wherein,

the second preset number is less than or equal to the first preset number.

5. The body coil of any one of claims 1-4, wherein the body coil is a high-pass body coil, the high-pass body coil further comprising:

a plurality of first end ring capacitors disposed on the first end ring; and

a plurality of second end ring capacitors disposed on the second end ring, wherein

The plurality of first end ring capacitors and the plurality of second end ring capacitors are symmetrically arranged on the first end ring and the second end ring, respectively.

6. The body coil of claim 5 wherein the plurality of antenna legs includes a first antenna leg disposed as the detuned antenna leg and second and third antenna legs adjacent to the first antenna leg as the resonant antenna leg, the plurality of first end loop capacitors including a first capacitor and a second capacitor, the plurality of second end loop capacitors including a third capacitor and a fourth capacitor, wherein,

the first capacitor is arranged between a connection point of the first antenna leg and the first end ring and a connection point of the second antenna leg and the first end ring;

the second capacitor is arranged between a connection point of the first antenna leg and the first end ring and a connection point of the third antenna leg and the first end ring;

the third capacitor is arranged between the connection point of the first antenna leg and the second end ring and the connection point of the second antenna leg and the second end ring; and is also provided with

The fourth capacitor is disposed between a connection point of the first antenna leg and the second end ring to a connection point of the third antenna leg and the second end ring.

7. The body coil of any one of claims 1-4, wherein the body coil is a low-pass body coil, the low-pass body coil further comprising:

a plurality of antenna leg capacitors, each of the plurality of antenna leg capacitors disposed on a corresponding antenna leg.

8. A nuclear magnetic resonance detection apparatus comprising:

a power supply for providing a radio frequency current;

the body coil of any one of claims 1-7, controllably connected to the power supply, configured to transmit a radio frequency signal to a test object upon receiving a radio frequency current; and

a receiving coil configured to receive magnetic resonance signals from the detection subject.

9. A control method for the nuclear magnetic resonance detection apparatus according to claim 8, comprising:

conducting an electrical connection between the body coil and the power source;

switching off switching diodes on a plurality of antenna legs of the body coil to allow the body coil to transmit radio frequency signals to a detection object;

after waiting for a preset time, disconnecting the electrical connection between the body coil and the power supply; and

switching diodes on a plurality of antenna legs of the body coil are turned on to wait for the receiving coil to receive magnetic resonance signals from the detection subject.