A non-invasive quantitative nuclear magnetic resonance detection system for organs

Abstract

The present invention relates to the field of nuclear magnetic resonance technology, and discloses a non-invasive quantitative nuclear magnetic resonance detection system for organs. Through the invention, a new nuclear magnetic resonance measurement system capable of achieving a regional selective excitation effect can be provided, that is, by arranging parallel radio frequency field shielding plates in the peripheral area of ​​the main radio frequency coil of the radio frequency subsystem, part of the radio frequency field of the main radio frequency coil can be shielded, thereby achieving the purpose of not exciting useless signals such as body surface fat, achieving a regional selective excitation effect, and solving the problem of inaccurate fat detection due to the existence of an unsatisfactory excitation area in the current single-sided magnet nuclear magnetic resonance system.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear magnetic resonance, and in particular relates to a non-invasive quantitative nuclear magnetic resonance detection system for organs. Background Art

[0002] Among traditional medical equipment, the technical means that can be used for human organ testing (such as liver testing, etc.) mainly include ultrasound testing, magnetic resonance imaging testing and puncture testing. However, they have their own limitations, such as: (a) Ultrasonic testing: Traditional ultrasonic testing instruments can only perform qualitative measurements and cannot meet the detection needs when the fat content is below 30%; the other type is ultrasound-based fatty liver and liver fibrosis quantitative detection products, the main limitation of which is that they are easily affected by the insufficient penetration of ultrasound, and the success rate is low when testing obese patients; (b) Nuclear magnetic resonance testing, which can use magnetic resonance Dixon technology to quantify fat and magnetic resonance elastography (MRE) technology to measure liver fibrosis. Although the detection accuracy meets the requirements, the price is high. Hospitals can easily spend 5 million or even more to purchase. The cost of a single test is about 3,000 yuan in Jiangsu, for example. The high price makes it impossible to be widely used for early and mid-stage fatty liver monitoring; (c) Puncture testing, such as liver biopsy, this detection method has the absolute highest accuracy in terms of accuracy and is the gold standard for clinical testing, but this detection method is extremely harmful to the human body and is only applicable to absolutely necessary situations. It cannot be widely used, and has extremely high requirements for sample extraction and technician operation level.

[0003] The existing patent CN201911101865.6 "A non-invasive quantitative detection method for organ fat based on magnetic resonance principle" discloses a non-invasive detection technology for organ fat based on a unilateral magnet nuclear magnetic resonance system. Figure 1 As shown in the figure, this technology uses an external computer (i.e., a computer device consisting of a display and a data processor) and a radio frequency RF subsystem and a portable single-sided permanent magnet module to build a low-field nuclear magnetic resonance organ fat non-invasive quantitative detection system. The system has the advantages of portability and low cost, and can achieve non-invasive and safe organ fat quantitative detection. However, due to the use of a single-sided permanent magnet, its magnetic field is extremely uneven, resulting in an irregular excitation area. Figure 2 The excitation region of a single-sided magnet NMR system is shown in a simulated diagram. The excitation region is approximately saddle-shaped, with poor selectivity and limited excitation depth. This excitation region may not completely fall on the organ to be examined. For example, in the saddle-shaped excitation region, the lower region may excite the body surface fat layer, and the top region may excite organs other than the liver, resulting in detection errors.

[0004] Therefore, in view of the non-ideal excitation area of ​​the unilateral magnet NMR system, it is necessary to provide a new NMR measurement system structure to improve the problem of inaccurate fat detection caused by the non-ideal excitation area. Summary of the invention

[0005] In order to solve the problem of inaccurate fat detection due to the existence of an undesirable excitation area in the existing unilateral magnet nuclear magnetic resonance system, the present invention aims to provide a novel organ non-invasive quantitative nuclear magnetic resonance detection system.

[0006] In a first aspect, the present invention provides a non-invasive quantitative nuclear magnetic resonance detection system for an organ, comprising a radio frequency subsystem and a magnet, wherein the magnet is used to generate a static magnetic field in a detection area;

[0007] The radio frequency subsystem includes a nuclear magnetic resonance spectrometer, a radio frequency power amplifier, a preamplifier, a transceiver switch, a radio frequency coil group and a radio frequency field shielding plate, wherein the radio frequency coil group includes a main radio frequency coil, and the radio frequency field shielding plate is arranged in the peripheral area of ​​the main radio frequency coil and is parallel to the main radio frequency coil;

[0008] The measurement sequence pulse signal output end of the nuclear magnetic resonance spectrometer is electrically connected to the signal input end of the radio frequency power amplifier, the measurement sequence pulse signal output end of the radio frequency power amplifier is electrically connected to the first switching end of the transceiver conversion switch, the echo signal input end of the preamplifier is electrically connected to the second switching end of the transceiver conversion switch, the echo signal output end of the preamplifier is electrically connected to the echo signal input end of the nuclear magnetic resonance spectrometer, the controlled end of the transceiver conversion switch is communicatively connected to the control signal output end of the nuclear magnetic resonance spectrometer, and the switching common end of the transceiver conversion switch is electrically connected to the main radio frequency coil;

[0009] The main radio frequency coil is used as a signal transceiver component of the radio frequency subsystem, transmitting a measurement sequence pulse signal from the nuclear magnetic resonance spectrometer so as to generate a pulse vector magnetic field intersecting with the static magnetic field in the detection area, and receiving an echo signal from the detection area;

[0010] The radio frequency field shielding plate is used to shield the main radio frequency coil from generating the pulse vector magnetic field on the non-interested area when the main radio frequency coil transmits the measurement sequence pulse signal.

[0011] Based on the above invention, a new type of nuclear magnetic resonance measurement system can be provided that can achieve regional selective excitation effect, that is, by arranging parallel radio frequency field shielding plates in the peripheral area of ​​the main radio frequency coil of the radio frequency subsystem, part of the radio frequency field of the main radio frequency coil can be shielded, thereby achieving the purpose of not exciting useless signals such as body surface fat, achieving regional selective excitation effect, and solving the problem of inaccurate fat detection due to the existence of an undesirable excitation area in the current single-sided magnet nuclear magnetic resonance system. In addition, because it is based on low-field nuclear magnetic resonance and simplifies the traditional magnetic resonance system for specific needs, the system can be made lighter and more convenient, and can also generate better economic benefits; no imaging is required, the measurement time is short, and the accuracy is high; based on nuclear magnetic resonance technology, the measurement process is highly streamlined, not easily affected by the operator's technique, and has strong repeatability; the measurement process is not easily affected by movement.

[0012] In a possible design, the radio frequency coil group further includes a secondary radio frequency coil, wherein the secondary radio frequency coil is arranged in a peripheral area of ​​the main radio frequency coil and is parallel to the main radio frequency coil;

[0013] The pre-saturation pulse signal output end of the nuclear magnetic resonance spectrometer is also electrically connected to the signal input end of the radio frequency power amplifier, and the pre-saturation pulse signal output end of the radio frequency power amplifier is electrically connected to the auxiliary radio frequency coil;

[0014] The secondary radio frequency coil is used as a signal transmitting component of the radio frequency subsystem, and before or during the transmission of the measurement sequence pulse signal, transmits a pre-saturation pulse signal from the nuclear magnetic resonance spectrometer to generate a radio frequency field covering a non-interest area in the detection area, so that part or all of the magnetization vectors in the non-interest area are parallel to the static magnetic field.

[0015] In a possible design, the radio frequency field shielding plate adopts a flat plate structure, a folding fan structure or any combination thereof made of metal material.

[0016] In a possible design, the nuclear magnetic resonance measurement system further includes a bed, a shielding chamber and a movable probe, wherein the shielding chamber includes a built-in metal shielding layer;

[0017] The shielding chamber covers the manned bed surface of the bed body and has an opening and closing structure so that the person to be examined can enter the space surrounded by the manned bed surface and the shielding chamber;

[0018] The mobile probe is arranged in the space surrounded by the manned bed and the shielding chamber, and can be moved in the left and right directions, head and feet directions and / or front and back directions of the human body to be examined through a mechanical driving mechanism, so as to perform positioning detection of the organs to be examined in the body outside the human body to be examined.

[0019] In a possible design, the bed is grounded, and the metal shielding layer in the shielding compartment is electrically connected to the bed through a detachable connection structure located on the opening and closing edge when the compartment is closed, so that the metal shielding layer is grounded through the bed.

[0020] In a possible design, the shielding compartment includes a torso shielding compartment and a leg shielding compartment, wherein the torso shielding compartment and the leg shielding compartment can be combined to form a closed structure for covering the body below the neck;

[0021] The torso shielding bin comprises a flexible collar and a shielding sleeve portion, wherein the flexible collar is used to allow the head of the person to be examined to extend out of the bin, and the shielding sleeve portion is used to allow the arm of the person to be examined to extend out of the bin so that the arm can hold a grounding handle.

[0022] In a possible design, the grounding handle is made of a conductive material and is grounded through a surge protection circuit.

[0023] In a possible design, the nuclear magnetic resonance measurement system further includes a phase synthesizer and at least one noise measurement coil, wherein the at least one noise measurement coil is arranged in a space surrounded by the manned bed and the shielding chamber and is arranged away from the mobile probe;

[0024] Each noise measuring coil in the at least one noise measuring coil is electrically connected to a noise signal input terminal of the preamplifier, a noise signal output terminal of the preamplifier is electrically connected to a signal input terminal of the phase synthesizer, and a signal output terminal of the phase synthesizer is electrically connected to a noise signal input terminal of the nuclear magnetic resonance spectrometer;

[0025] The nuclear magnetic resonance spectrometer is also used to determine the signal correlation between the first noise signal and the second noise signal according to the first noise signal from the main radio frequency coil and the second noise signal from the at least one noise measurement coil received when the radio frequency power amplifier is turned off before collecting the echo signal;

[0026] The nuclear magnetic resonance spectrometer is also used to determine the noise signal in the echo signal from the main radio frequency coil according to the signal correlation between the first noise signal and the second noise signal and the third noise signal from the at least one noise measurement coil when collecting the echo signal, and then subtract the determined noise signal from the echo signal to obtain a new echo signal with noise reduced.

[0027] In a possible design, the shielding compartment is hinged to the edge of the manned bed surface of the bed body through a hinge structure.

[0028] In a possible design, the magnet adopts a unilateral magnet structure, wherein the unilateral magnet structure has an ergonomic curved surface that fits the body surface adjacent to the target sample organ.

[0029] Beneficial effects of the present invention:

[0030] (1) The present invention provides a novel nuclear magnetic resonance measurement system that can achieve a regional selective excitation effect, that is, by arranging parallel radio frequency field shielding plates in the peripheral area of ​​the main radio frequency coil of the radio frequency subsystem, part of the radio frequency field of the main radio frequency coil can be shielded, thereby achieving the purpose of not exciting useless signals such as body surface fat, achieving a regional selective excitation effect, and solving the problem of inaccurate fat detection due to the existence of an unsatisfactory excitation area in the current single-sided magnet nuclear magnetic resonance system;

[0031] (2) Since it is based on low-field nuclear magnetic resonance and simplifies the traditional magnetic resonance system for specific needs, the system can be made lighter and more convenient, and can also produce better economic benefits; no imaging is required, the measurement time is short, and the accuracy is high; based on nuclear magnetic resonance technology, the measurement process is highly streamlined, not easily affected by the operator's technique, and has strong repeatability; the measurement process is not easily affected by movement;

[0032] (3) A parallel auxiliary RF coil may be arranged in the peripheral area of ​​the main RF coil of the RF subsystem, and a pre-saturation pulse signal may be emitted through the auxiliary RF coil before or during the emission of the measurement sequence pulse signal to generate an RF field covering the non-interested area in the detection area, so that part or all of the magnetization vectors in the non-interested area are parallel to the static magnetic field generated by the magnet, and thus during the measurement, useless signals generated in the non-interested area and interfering with the echo signals generated in the interested area may be weakened or eliminated, thereby further achieving a regional selective excitation effect;

[0033] (4) Through active noise control design, the sensitivity of NMR applications to noise can be reduced, further ensuring the accuracy of measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 It is a structural schematic diagram of a low-field nuclear magnetic resonance organ fat non-invasive quantitative detection system in the prior art.

[0036] Figure 2This is a simulation diagram of the excitation region of a single-sided magnet nuclear magnetic resonance system in the prior art.

[0037] Figure 3 It is a structural schematic diagram of the nuclear magnetic resonance measurement system provided by the present invention.

[0038] Figure 4 It is a schematic diagram of the arrangement of the main radio frequency coil and the radio frequency field shielding plate provided by the present invention.

[0039] Figure 5 It is a schematic diagram of the magnetic field decomposition of the main radio frequency coil and the radio frequency field shielding plate provided by the present invention.

[0040] Figure 6 is a schematic diagram of the specific structure of the radio frequency field shielding plate provided by the present invention, wherein: Figure 6 (a) is a single-layer flat plate structure. Figure 6 (b) is a single-layer folding fan structure. Figure 6 (c) is the combined structure of the lower flat plate and the upper folding fan. Figure 6 (d) is a double-layer flat plate structure. Figure 6 (e) is a double-layer folding fan structure.

[0041] Figure 7 It is a three-dimensional structural schematic diagram of the unilateral magnet structure provided by the present invention.

[0042] Figure 8 It is a schematic diagram of the arrangement of the main radio frequency coil, the secondary radio frequency coil and the radio frequency field shielding plate provided by the present invention.

[0043] Fig. 9 This is a first timing diagram of the measurement sequence pulse signal and the pre-saturation pulse signal provided by the present invention.

[0044] Fig.10 This is a second timing diagram of the measurement sequence pulse signal and the pre-saturation pulse signal provided by the present invention.

[0045] Fig.11 It is a schematic diagram of a cross-sectional view of a human body provided by the present invention.

[0046] Fig.12 This is a schematic diagram of the first usage structure of the bed and the shielding chamber provided by the present invention.

[0047] Fig.13 This is a schematic diagram of the second usage structure of the bed and the shielding chamber provided by the present invention.

[0048] Fig.14 It is a schematic diagram of the open structure of the bed and the shielding chamber provided by the present invention.

[0049] Fig.15 It is a schematic diagram of the three-dimensional structure of the mobile probe provided by the present invention. DETAILED DESCRIPTION

[0050] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that although the description of these embodiments is used to help understand the present invention, it does not constitute a limitation of the present invention. The specific structures and functional details disclosed herein are only used to describe the embodiments of the present invention. However, the present invention can be embodied in many alternative forms, and it should not be understood that the present invention is limited to the embodiments set forth herein.

[0051] It should be understood that although the terms first, second, etc. may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another unit. For example, a first unit can be referred to as a second unit, and similarly, a second unit can be referred to as a first unit without departing from the scope of the exemplary embodiments of the present invention.

[0052] It should be understood that the term "and / or" that may appear in this article is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" that may appear in this article describes another type of association object relationship, indicating that two relationships may exist. For example, A / and B can represent two situations: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0053] It should be understood that when an element is referred to herein as being "connected," "connected," or "coupled" to another element, it can be directly connected or coupled to the other element, or intermediate elements can exist. Conversely, when an element is referred to herein as being "directly connected" or "directly coupled" to another element, no intermediate elements are present. Additionally, other words used to describe the relationship between elements (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.) should be interpreted in a similar manner.

[0054] It should be understood that the terms used herein are only used to describe specific embodiments and are not intended to limit the embodiments of the present invention. If used herein, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates the opposite meaning. It should also be understood that if the terms "include", "comprising", "including", and / or "comprising" are used in this article, the existence of the features, integers, steps, operations, units and / or components stated are specified, and one or more other features, quantities, steps, operations, units, components and / or their combinations are not excluded. Existence or increase.

[0055] It should be understood that it should also be noted that in some alternative possible designs, the functions / actions that appear may be different from the order in which the drawings appear. For example, depending on the functions / actions involved, two figures shown in succession may actually be performed substantially concurrently, or may sometimes be performed in reverse order.

[0056] It should be understood that certain details are provided in the following description to facilitate a complete understanding of the example embodiments. However, one of ordinary skill in the art should understand that the example embodiments can be implemented without these specific details. For example, the system can be shown in a block diagram to avoid obscuring the example with unnecessary details. In other examples, well-known processes, structures, and techniques may not be shown in unnecessary detail to avoid obscuring the example embodiments.

[0057] like Figures 3 to 7 As shown, the organ non-invasive quantitative nuclear magnetic resonance detection system provided in the first aspect of this embodiment includes a radio frequency subsystem and a magnet 2, wherein the magnet 2 is used to generate a static magnetic field in the detection area; the radio frequency subsystem includes a nuclear magnetic resonance spectrometer, a radio frequency power amplifier, a preamplifier, a transceiver conversion switch, a radio frequency coil group and a radio frequency field shielding plate 16, wherein the radio frequency coil group includes a main radio frequency coil 151, and the radio frequency field shielding plate 16 is arranged in the peripheral area of ​​the main radio frequency coil 151 and is parallel to the main radio frequency coil 151; the measurement sequence pulse signal output end of the nuclear magnetic resonance spectrometer is electrically connected to the signal input end of the radio frequency power amplifier, the measurement sequence pulse signal output end of the radio frequency power amplifier is electrically connected to the first switching end of the transceiver conversion switch, and the echo signal input end of the preamplifier is electrically connected to the first switching end of the transceiver conversion switch. The second switching end of the transceiver conversion switch is electrically connected, the echo signal output end of the preamplifier is electrically connected to the echo signal input end of the nuclear magnetic resonance spectrometer, the controlled end of the transceiver conversion switch is communicatively connected to the control signal output end of the nuclear magnetic resonance spectrometer, and the switching common end of the transceiver conversion switch is electrically connected to the main radio frequency coil 151; the main radio frequency coil 151 is used as a signal transceiver component of the radio frequency subsystem, transmitting a measurement sequence pulse signal from the nuclear magnetic resonance spectrometer, so as to generate a pulse vector magnetic field intersecting with the static magnetic field in the detection area, and receive an echo signal from the detection area; the radio frequency field shielding plate 16 is used to shield the main radio frequency coil 151 from generating the pulse vector magnetic field to the non-interested area when the main radio frequency coil 151 transmits the measurement sequence pulse signal.

[0058] like Figures 3 to 7As shown, in the specific structure of the organ non-invasive quantitative nuclear magnetic resonance detection system, the nuclear magnetic resonance spectrometer is used to generate a measurement sequence pulse signal (which is an existing scanning sequence pulse signal, used to excite hydrogen atoms in the target sample and generate a detectable signal, also known as a magnetic resonance signal or an echo signal) in an existing conventional manner, so as to drive one or more of the main radio frequency coils 151, and measure and process the received echo signals to achieve the purpose of non-invasive quantitative detection of organs, which can be achieved using existing instruments and equipment; the radio frequency power amplifier is used to amplify the measurement sequence pulse signal to be transmitted; the preamplifier is used to amplify the received echo signal; the transceiver conversion switch is used to control the switching of the gate signal so that the main radio frequency coil 151 can both transmit the measurement sequence pulse signal and asynchronously receive the echo signal, which can be but not limited to a single-pole double-throw switch.

[0059] When the pulse vector magnetic field generated by the main RF coil 151 in the detection area is orthogonal to the static magnetic field, the efficiency of exciting and generating echo signals is the highest, and the frequency of the pulse vector magnetic field is adjustable to match the Larmor frequency (which is the 1H gyromagnetic ratio multiplied by the field strength of the static magnetic field) at different positions in the region of interest ROI (Region of Interest). Figure 4 and 5As shown, the RF field shielding plate 16 can be made of metal, and its working principle is as follows: when the RF current passes through the main RF coil 151, the RF current generates a magnetic field that changes with time (which can be called the main magnetic field), and induces a current in the RF field shielding plate 16 with the same direction as the RF coil current, and flows in the RF field shielding plate 16 in the form of eddy current. The magnetic field generated by this induced current is superimposed on the magnetic field generated by the RF current. Since the RF field shielding plate 16 is a complete metal body, the induced current on the shielding body flows in a multi-circulation path and changes with the change of the main magnetic field. The magnetic fields generated by the currents in these paths are mostly superimposed in the y direction, while the superposition effect in the x direction is weaker; in the area close to the RF field shielding plate 16, the main magnetic field is almost vertical. The direction perpendicular to the RF field shielding plate 16 enters the area on the RF field shielding plate 16. Therefore, in the area close to the RF field shielding plate 16, the component of the main magnetic field is mainly the y component. Therefore, in the area of ​​the RF field shielding plate 16, the magnetic field generated by the induced current and the main magnetic field are superimposed on each other in the y direction, resulting in the main magnetic field being greatly weakened in a certain area on the RF field shielding plate 16. In the x direction of the area close to the RF field shielding plate 16, some areas are superimposed with the main magnetic field to be enhanced, and some areas are weakened. Since the main magnetic field has a smaller component in the x direction of the area close to the RF field shielding plate 16, and the component of the induced current in the x direction is also weak, the y-direction component of this area is greatly weakened, resulting in the main magnetic field being greatly reduced in a certain area close to the RF field shielding plate 16. Therefore, by adjusting the distance between the RF field shielding plate 16 and the main RF coil 151, the purpose of shielding part of the RF field of the main RF coil 151 can be achieved, thereby achieving the purpose of not exciting useless signals such as body surface fat, and achieving a regional selective excitation effect. Figure 6 As shown, the RF field shielding plate 16 may be, but is not limited to, a flat plate structure made of metal material, a folding fan structure, or any combination thereof, wherein the folding fan structure can increase the path of the induced current circulation, thereby increasing the induced magnetic field in the area close to the RF field shielding plate 16, and improving the ability to weaken the main magnetic field in the area close to the RF field shielding plate 16. In addition, Figure 4 As shown, the number of the RF field shielding plates 16 may be two, and they are arranged bilaterally symmetrically in the outer peripheral area of ​​the main RF coil 151, and are horizontally arranged on the coil base 153 together with the main RF coil 151;

[0060] The magnet 2 is configured as a portable magnet, and the portable magnet is configured in a manner that at least has a unilateral magnet structure, wherein the unilateral magnet structure has an ergonomic curved surface that fits the surface of the body adjacent to the target sample organ, such as Figure 7As shown. The static magnetic field generated by the magnet 2 is used to polarize the hydrogen atoms in the region of interest of the target sample. Figure 7 The unilateral magnet structure shown can make the excitation area of ​​the static magnetic field reach a depth of 12 cm from the magnet surface and 9 cm below the skin, and can also achieve good selectivity for patients with thick subcutaneous fat layer; the field excitation area of ​​the static magnetic field has high selectivity in the depth area of ​​interest, and can avoid signals of internal organs other than the liver. In addition, the magnet 2 can also be a permanent magnet, an electromagnet, or a hybrid of these.

[0061] Thus, through the detailed description of the aforementioned organ non-invasive quantitative nuclear magnetic resonance detection system, a new nuclear magnetic resonance measurement system that can achieve regional selective excitation effect is provided, that is, by arranging parallel radio frequency field shielding plates in the peripheral area of ​​the main radio frequency coil of the radio frequency subsystem, part of the radio frequency field of the main radio frequency coil can be shielded, thereby achieving the purpose of not exciting useless signals such as surface fat, achieving regional selective excitation effect, and solving the problem of inaccurate fat detection due to the existence of an unsatisfactory excitation area in the current single-sided magnet nuclear magnetic resonance system. In addition, because it is based on low-field nuclear magnetic resonance and simplifies the traditional magnetic resonance system for specific needs, the system can be made lighter and more convenient, and can also generate better economic benefits; no imaging is required, the measurement time is short, and the accuracy is high; based on nuclear magnetic resonance technology, the measurement process is highly streamlined, not easily affected by the operator's technique, and has strong repeatability; the measurement process is not easily affected by movement.

[0062] In a possible design, the RF coil group also includes a secondary RF coil 152, wherein the secondary RF coil 152 is arranged in the peripheral area of ​​the main RF coil 151 and is parallel to the main RF coil 151; the pre-saturation pulse signal output end of the nuclear magnetic resonance spectrometer is also electrically connected to the signal input end of the RF power amplifier, and the pre-saturation pulse signal output end of the RF power amplifier is electrically connected to the secondary RF coil 152; the secondary RF coil 152 is used as a signal transmitting component of the RF subsystem, and before or during the transmission of the measurement sequence pulse signal, it transmits the pre-saturation pulse signal from the nuclear magnetic resonance spectrometer to generate a RF field covering the non-interest area in the detection area, so that part or all of the magnetization vectors in the non-interest area are parallel to the static magnetic field. Figure 3 and 8 As shown, the nuclear magnetic resonance spectrometer is also used to generate a pre-saturation pulse signal in an existing conventional manner to drive one or more of the secondary RF coils 152; the RF power amplifier is also used to amplify the pre-saturation pulse signal to be transmitted. The RF field generated by the secondary RF coil 152 is also adjustable. Within the coverage range of its RF field, it can be adjusted as follows: Fig. 9 As shown before transmitting the measurement sequence pulse signal or as Fig.10As shown, during the whole process of transmitting the measurement sequence pulse signal, the pre-saturation pulse signal (which is preferably a pulse signal that can achieve a 90-degree flip angle) is continuously applied to make part or all of the magnetization vectors in the non-interested region parallel to the static magnetic field, so that during measurement, the useless signals generated by the non-interested region (such as subcutaneous fat, etc.) and interfering with the echo signals generated by the interested region (such as liver, etc.) are weakened or eliminated, thereby achieving a regional selective excitation effect. Fig.11 As shown, in the schematic diagram of the cross-sectional view of the human body, the arc 300 is the excitation area (i.e., the detection area) of the main RF coil 151. In the absence of saturation, all signals in this area will be received, that is, the solid line segment 302 in the arc 300 is the area of ​​interest (i.e., the organ to be examined 200), and the dotted line segment 301 in the arc 300 is the area of ​​non-interest (i.e., the area to be saturated). The signal from the area of ​​non-interest will cause a great error in the measurement result. If the area of ​​non-interest is pre-saturated by the secondary RF coil 152, the signal from the area of ​​non-interest can be greatly reduced or eliminated. In addition, the arrangement positions of the RF field shielding plate 16 and the secondary RF coil 152 in the peripheral area of ​​the main RF coil 151 can be, for example, Figure 8 shown.

[0063] In a possible design, the nuclear magnetic resonance measurement system also includes a bed 3, a shielding chamber 4 and a mobile probe 5, wherein the shielding chamber 4 includes a built-in metal shielding layer; the shielding chamber 4 covers the manned bed surface 31 of the bed 3 and has an opening and closing structure so that the person to be examined can enter the space surrounded by the manned bed surface 31 and the shielding chamber 4; the mobile probe 5 is arranged in the space surrounded by the manned bed surface 31 and the shielding chamber 4, and can move in the left and right direction, head and foot direction and / or front and back direction of the person to be examined through a mechanical driving mechanism, so as to perform positioning detection of the organs to be examined in the body outside the person to be examined. Figures 12-14 As shown, the bed 3 is used to carry the human body 100 to be examined. In addition to being used to shield external interference signals, the shielding chamber 4 can also effectively protect the mobile probe 5. It can be made of a hard material and sandwiched with the metal shielding layer, such as a metal mesh, a metal film or a metal sheet; the shielding chamber 4 can be hinged to the edge of the manned bed surface of the bed 3 through a hinge structure so as to open and allow the human body 100 to enter. The mobile probe 5 is used to carry the RF coil group, the RF field shielding plate 16 and the magnet 2, etc., so that during detection, the mechanical drive mechanism can move the human body 100 to the left and right direction, the head and feet direction and / or the front and back direction, so as to realize accurate positioning of the internal organs to be examined on the outside of the human body 100 to be examined, such as Fig.15As shown. Specifically, the bed body 3 is grounded, and the metal shielding layer in the shielding chamber 4 is electrically connected to the bed body 3 through a detachable connection structure 34 located on the opening and closing edge when the chamber body is closed, so that the metal shielding layer is grounded through the bed body 3. The detachable connection structure 34 can be, but is not limited to, a structure in which a spring or a plug is matched with a reserved slot, so as to achieve overall electrical conduction between the shielding chamber 4 and the entire bed, and ensure the shielding effect of the shielding chamber 4.

[0064] In a possible design, the shielding chamber 4 includes a torso shielding chamber 41 and a leg shielding chamber 42, wherein the torso shielding chamber 41 and the leg shielding chamber 42 can be combined to form a closed structure for covering the body below the neck; the torso shielding chamber 41 includes a flexible collar 411 and a shielding sleeve 412, wherein the flexible collar 411 is used to allow the head of the person to be examined to extend out of the chamber, and the shielding sleeve 412 is used to allow the arm of the person to be examined to extend out of the chamber so that the arm can hold the grounding handle 6. Fig.12 As shown, the torso shielding compartment 41 and the leg shielding compartment 42 can be combined to form a closed structure for covering the body below the neck; and as shown Fig.13 As shown, there may also be a semi-enclosed structure (i.e., a semi-open shielding chamber structure) consisting of only the torso shielding chamber 41. The flexible collar 411 is used to cooperate with the neck of the person to be tested 100; the shielding sleeve portion 412 is used to cooperate with the arm portion of the person to be tested 100, which can help the person to be tested 100 to fix the test posture; the grounding handle 16 is used to eliminate the noise that may be introduced by the human body. Specifically, the grounding handle 6 is made of a conductive material and is grounded through a surge protection circuit. In this way, the person to be tested 100 can hold the grounding handle 6 during measurement to ground and eliminate the noise signal conducted through the human body. In detail, the surge protection circuit can be designed as an RC parallel filter circuit to form a high-pass filter with a cut-off frequency of about 60 Hz, that is, this filter circuit has a very high impedance at 60 Hz and a very low impedance at the target frequency. The human body releases the noise induced by the human body by touching the metal pull rod. If the grounded metal rod is directly touched without going through the protection circuit, and this ground is connected to the ground of the outer shielding and power amplifier and other components, instantaneous high voltage or large current (mainly industrial frequency) may be transmitted through the shielding layer to cause danger to people. Since the noise from the human body is usually high-frequency noise, the capacitor has a very low impedance at the target frequency, so it can release the noise to the ground. The high-pass filter has a large impedance at the industrial frequency, which can prevent large current from passing through, thereby protecting the human body.

[0065] In a possible design, the nuclear magnetic resonance measurement system also includes a phase synthesizer and at least one noise measurement coil, wherein the at least one noise measurement coil is arranged in a space surrounded by the manned bed and the shielding chamber and is arranged away from the mobile probe; each noise measurement coil in the at least one noise measurement coil is electrically connected to a noise signal input end of the preamplifier, a noise signal output end of the preamplifier is electrically connected to a signal input end of the phase synthesizer, and a signal output end of the phase synthesizer is electrically connected to a noise signal input end of the nuclear magnetic resonance spectrometer; the nuclear magnetic resonance spectrometer is also used to, before collecting the echo signal, According to the first noise signal received from the main RF coil 151 and the second noise signal from the at least one noise measurement coil when the RF power amplifier is turned off, the signal correlation between the first noise signal and the second noise signal is determined; the nuclear magnetic resonance spectrometer is also used to determine the noise signal in the echo signal from the main RF coil 151 according to the signal correlation between the first noise signal and the second noise signal and the third noise signal from the at least one noise measurement coil when collecting the echo signal, and then subtract the determined noise signal from the echo signal to obtain a new echo signal with reduced noise. Figure 3 As shown, the at least one noise measurement coil includes four noise measurement coils. Since the signal received by the coil is related to the distance from the signal source, the farther the distance, the lower the signal. Therefore, when the noise measurement coil is placed in the shielding chamber 4, it needs to be set away from the mobile probe to ensure that the magnetic resonance signal / echo signal it receives can be ignored; and the noise signal exists in the environment, so it can be considered that the noise measurement coil is only collecting noise signals. The phase synthesizer is used to synthesize noise signals from different noise measurement coils, and then the nuclear magnetic resonance spectrometer receives and processes them; therefore, when the at least one noise measurement coil has only one noise measurement coil, the phase synthesizer can be set by default. The process of determining the signal correlation can adopt existing technologies, such as linear fitting or nonlinear fitting technology; the method of determining the noise signal in the echo signal can still adopt existing technologies. Although the shielding chamber 4 can block most of the noise from the surrounding environment, due to the incompletely closed structure or open structure of the shielding chamber 4, some environmental noise will be introduced through the human body, the shielding chamber or the hospital bed, etc. Therefore, through the aforementioned active noise control design, the sensitivity of the nuclear magnetic resonance application to noise can be reduced, further ensuring the accuracy of the measurement results.

[0066] The embodiments described above are merely illustrative. If a unit described as a separate component is involved, it may or may not be physically separated; if a component shown as a unit is involved, it may or may not be a physical unit, that is, it may be located in one place, or it may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention is described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0068] Finally, it should be noted that the present invention is not limited to the above optional implementations, and anyone can derive other various forms of products under the enlightenment of the present invention. The above specific implementations should not be understood as limiting the scope of protection of the present invention. The scope of protection of the present invention should be based on the definition in the claims, and the description can be used to interpret the claims.

Claims

1. A non-invasive quantitative nuclear magnetic resonance detection system for organs, characterized in that: It comprises a radio frequency subsystem and a magnet (2), wherein the magnet (2) is used to generate a static magnetic field in a detection area; The radio frequency subsystem comprises a nuclear magnetic resonance spectrometer, a radio frequency power amplifier, a preamplifier, a transceiver switch, a radio frequency coil group and a radio frequency field shielding plate (16), wherein the radio frequency coil group comprises a main radio frequency coil (151), and the radio frequency field shielding plate (16) is arranged in the peripheral area of ​​the main radio frequency coil (151) and is parallel to the main radio frequency coil (151); The measurement sequence pulse signal output end of the nuclear magnetic resonance spectrometer is electrically connected to the signal input end of the radio frequency power amplifier, the measurement sequence pulse signal output end of the radio frequency power amplifier is electrically connected to the first switching end of the transceiver conversion switch, the echo signal input end of the preamplifier is electrically connected to the second switching end of the transceiver conversion switch, the echo signal output end of the preamplifier is electrically connected to the echo signal input end of the nuclear magnetic resonance spectrometer, the controlled end of the transceiver conversion switch is communicatively connected to the control signal output end of the nuclear magnetic resonance spectrometer, and the switching common end of the transceiver conversion switch is electrically connected to the main radio frequency coil (151); The main radio frequency coil (151) is used as a signal transceiver component of the radio frequency subsystem, transmitting a measurement sequence pulse signal from the nuclear magnetic resonance spectrometer so as to generate a pulse vector magnetic field intersecting with the static magnetic field in the detection area, and receiving an echo signal from the detection area; The radio frequency field shielding plate (16) is used to shield the main radio frequency coil (151) from generating the pulse vector magnetic field on the non-interested area when the main radio frequency coil (151) transmits the measurement sequence pulse signal; The nuclear magnetic resonance measurement system further comprises a bed (3), a shielding chamber (4) and a movable probe (5), wherein the shielding chamber (4) comprises a built-in metal shielding layer; The shielding chamber (4) covers the manned bed surface (31) of the bed body (3) and has an opening and closing structure so that the person to be examined can enter the space surrounded by the manned bed surface (31) and the shielding chamber (4); The mobile probe (5) is arranged in a space surrounded by the manned bed (31) and the shielding chamber (4), and can be moved in the left-right direction, head-foot direction and / or front-back direction of the human body to be examined through a mechanical driving mechanism, so as to perform positioning detection of the internal organs to be examined outside the human body to be examined; The shielding chamber (4) comprises a torso shielding chamber (41) and a leg shielding chamber (42), wherein the torso shielding chamber (41) and the leg shielding chamber (42) can be combined to form a closed structure for covering the body below the neck; The torso shielding chamber (41) comprises a flexible collar (411) and a shielding sleeve portion (412), wherein the flexible collar (411) is used to allow the head of the person to be examined to extend out of the chamber, and the shielding sleeve portion (412) is used to allow the arm of the person to be examined to extend out of the chamber so that the arm can hold a grounding handle (6).

2. The organ non-invasive quantitative nuclear magnetic resonance detection system according to claim 1, characterized in that: The radio frequency coil group further includes a secondary radio frequency coil (152), wherein the secondary radio frequency coil (152) is arranged in the outer peripheral area of ​​the main radio frequency coil (151) and is parallel to the main radio frequency coil (151); The pre-saturation pulse signal output end of the nuclear magnetic resonance spectrometer is also electrically connected to the signal input end of the radio frequency power amplifier, and the pre-saturation pulse signal output end of the radio frequency power amplifier is electrically connected to the auxiliary radio frequency coil (152); The secondary radio frequency coil (152) is used as a signal transmitting component of the radio frequency subsystem, and transmits a pre-saturation pulse signal from the nuclear magnetic resonance spectrometer before or during the transmission of the measurement sequence pulse signal, so as to generate a radio frequency field covering a non-interest area in the detection area, so that part or all of the magnetization vectors in the non-interest area are parallel to the static magnetic field.

3. The organ non-invasive quantitative nuclear magnetic resonance detection system according to claim 1, characterized in that: The radio frequency field shielding plate (16) is a flat plate structure, a folding fan structure or any combination thereof made of metal material.

4. The organ non-invasive quantitative nuclear magnetic resonance detection system according to claim 1, characterized in that: The bed body (3) is grounded, and the metal shielding layer in the shielding chamber (4) is electrically connected to the bed body (3) via a detachable connection structure (34) located on the opening and closing edge when the chamber body is closed, so that the metal shielding layer is grounded via the bed body (3).

5. The organ non-invasive quantitative nuclear magnetic resonance detection system according to claim 1, characterized in that: The grounding handle (6) is made of a conductive material and is grounded via a surge protection circuit.

6. The organ non-invasive quantitative nuclear magnetic resonance detection system according to claim 1, characterized in that: The nuclear magnetic resonance measurement system further comprises a phase synthesizer and at least one noise measurement coil, wherein the at least one noise measurement coil is arranged in a space surrounded by the manned bed (31) and the shielding chamber (4) and is arranged away from the mobile probe (5); Each noise measuring coil (5) in the at least one noise measuring coil is electrically connected to a noise signal input terminal of the preamplifier, a noise signal output terminal of the preamplifier is electrically connected to a signal input terminal of the phase synthesizer, and a signal output terminal of the phase synthesizer is electrically connected to a noise signal input terminal of the nuclear magnetic resonance spectrometer; The nuclear magnetic resonance spectrometer is also used to determine the signal correlation between the first noise signal and the second noise signal based on the first noise signal received from the main radio frequency coil (151) and the second noise signal from the at least one noise measurement coil when the radio frequency power amplifier is turned off before collecting the echo signal; The nuclear magnetic resonance spectrometer is also used to determine the noise signal in the echo signal from the main radio frequency coil (151) according to the signal correlation between the first noise signal and the second noise signal and the third noise signal from the at least one noise measurement coil when collecting the echo signal, and then subtract the determined noise signal from the echo signal to obtain a new echo signal with reduced noise.

7. The organ non-invasive quantitative nuclear magnetic resonance detection system according to claim 1, characterized in that: The shielding compartment (4) is hingedly connected to the edge of the manned bed surface of the bed body (3) via a hinge structure.

8. The organ non-invasive quantitative nuclear magnetic resonance detection system according to claim 1, characterized in that: The magnet (2) adopts a unilateral magnet structure, wherein the unilateral magnet structure has an ergonomic curved surface that fits the body surface adjacent to the target sample organ.

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