WO2022205575A1 - 一种适用于器官无创定量检测的核磁共振测量*** - Google Patents

一种适用于器官无创定量检测的核磁共振测量*** Download PDF

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WO2022205575A1
WO2022205575A1 PCT/CN2021/093488 CN2021093488W WO2022205575A1 WO 2022205575 A1 WO2022205575 A1 WO 2022205575A1 CN 2021093488 W CN2021093488 W CN 2021093488W WO 2022205575 A1 WO2022205575 A1 WO 2022205575A1
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radio frequency
magnetic resonance
nuclear magnetic
shielding
signal
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PCT/CN2021/093488
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English (en)
French (fr)
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罗海
王伟谦
陈潇
赵越
解运浩
吴子岳
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无锡鸣石峻致医疗科技有限公司
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Priority to US17/792,408 priority Critical patent/US20230341491A1/en
Publication of WO2022205575A1 publication Critical patent/WO2022205575A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/483—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy
    • G01R33/4838—NMR imaging systems with selection of signals or spectra from particular regions of the volume, e.g. in vivo spectroscopy using spatially selective suppression or saturation of MR signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/4828—Resolving the MR signals of different chemical species, e.g. water-fat imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/48—Other medical applications
    • A61B5/4869—Determining body composition
    • A61B5/4872—Body fat
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
    • G01R33/34007—Manufacture of RF coils, e.g. using printed circuit board technology; additional hardware for providing mechanical support to the RF coil assembly or to part thereof, e.g. a support for moving the coil assembly relative to the remainder of the MR system
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
    • G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
    • G01R33/34092—RF coils specially adapted for NMR spectrometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/42—Screening
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/42—Screening
    • G01R33/422—Screening of the radio frequency field
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/565—Correction of image distortions, e.g. due to magnetic field inhomogeneities
    • G01R33/56563—Correction of image distortions, e.g. due to magnetic field inhomogeneities caused by a distortion of the main magnetic field B0, e.g. temporal variation of the magnitude or spatial inhomogeneity of B0
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/70—Means for positioning the patient in relation to the detecting, measuring or recording means
    • A61B5/704—Tables

Definitions

  • the invention belongs to the technical field of nuclear magnetic resonance, and in particular relates to a nuclear magnetic resonance measurement system suitable for non-invasive quantitative detection of organs.
  • the technical means that can be used for human organ testing mainly include ultrasonic testing, nuclear magnetic resonance testing and puncture testing.
  • ultrasonic testing mainly include ultrasonic testing, nuclear magnetic resonance testing and puncture testing.
  • MRE Magnetic Resonance Elastography
  • the existing patent CN201911101865.6 "A Non-invasive Quantitative Detection Method of Organ Fat Based on Magnetic Resonance Principle" discloses a non-invasive detection technology of organ fat based on a unilateral magnet nuclear magnetic resonance system.
  • this technique 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 unilateral permanent magnet module to construct a low-field MRI organ fat noninvasive
  • the quantitative detection system which has the advantages of portability and low cost, can realize non-invasive and safe quantitative detection of organ fat.
  • the magnetic field is extremely non-uniform, resulting in an irregular surface in the excitation region.
  • the excitation region of a single-sided magnet NMR system is a simulated diagram, and the excitation region is approximately saddle-shaped, with poor selectivity and limited excitation depth. This excitation area may not fall completely on the organ to be examined.
  • the lower region may excite the body surface fat layer, and its top may excite organs other than the liver, resulting in detection errors.
  • the present invention aims to provide a novel nuclear magnetic resonance measurement system suitable for non-invasive quantitative detection of organs.
  • the present invention provides a nuclear magnetic resonance measurement system suitable for non-invasive quantitative detection of organs, comprising a radio frequency subsystem and a magnet, wherein the magnet 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 switch, and a radio frequency coil set, wherein the radio frequency coil set includes a main radio frequency coil and a secondary radio frequency coil, and the secondary radio frequency coil arranged in a peripheral region of the main radio frequency coil and parallel to the main radio frequency coil;
  • the measurement sequence pulse signal output end and the pre-saturation pulse signal output end of the nuclear magnetic resonance spectrometer are respectively electrically connected to the signal input end of the radio frequency power amplifier, and the measurement sequence pulse signal output end of the radio frequency power amplifier is electrically connected to the transceiver.
  • the first switching terminal of the transfer switch, the pre-saturation pulse signal output terminal of the radio frequency power amplifier is electrically connected to the secondary radio frequency coil, and the echo signal input terminal of the preamplifier is electrically connected to the second switching terminal of the transceiver switch.
  • the echo signal output end of the preamplifier is electrically connected to the echo signal input end of the nuclear magnetic resonance spectrometer, and the controlled end of the transceiving switch is communicatively connected to the control signal output end of the nuclear magnetic resonance spectrometer.
  • the switching common terminal of the transceiving switch is electrically connected to the main radio frequency coil;
  • the main radio frequency coil is used as a signal transceiver component of the radio frequency subsystem to transmit 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 the echo signal from the detection area;
  • the secondary radio frequency coil is used as a signal transmitting component of the radio frequency subsystem, and before or during transmitting the measurement sequence pulse signal, transmits a pre-saturation pulse signal from the nuclear magnetic resonance spectrometer, so as to generate a signal covering the
  • the radio frequency field of the non-interested region within the detection region is made so that some or all of the magnetization vectors in the non-interested region are parallel to the static magnetic field.
  • a new type of nuclear magnetic resonance measurement system that can achieve the effect of region-selective excitation can be provided.
  • a pre-saturation pulse signal is transmitted through the secondary radio frequency coil to generate a radio frequency field covering the non-interested area in the detection area, so that some or all of the magnetization vectors in the non-interested area can be compared with the magnetization vector generated by the magnet.
  • the static magnetic field is parallel, so that the useless signal generated in the non-interesting area and which will interfere with the echo signal generated in the area of interest can be weakened or disappeared during measurement, so as to achieve the effect of area-selective excitation and solve the problem of current unilateral magnet NMR.
  • the system has the problem of inaccurate fat detection due to the imperfect excitation area.
  • it is based on low-field nuclear magnetic resonance and the traditional magnetic resonance system is simplified for specific needs, it can make the system more lightweight and convenient, and can also produce better economic benefits; no imaging, short measurement time, and high accuracy; based on Nuclear magnetic resonance technology, the measurement process is highly streamlined, not easily affected by the operator's manipulation, and has strong repeatability; the measurement process is not easily affected by motion.
  • the radio frequency subsystem further includes a radio frequency field shielding plate, wherein the radio frequency field shielding plate is arranged in a peripheral area of the main radio frequency coil and is parallel to the main radio frequency coil;
  • the radio frequency field shielding plate is used for shielding the main radio frequency coil from generating the pulse vector magnetic field for the non-interest region when the main radio frequency coil transmits the measurement sequence pulse signal.
  • the radio frequency field shielding plate adopts a flat plate structure made of metal material, a folding fan structure or any combination of them.
  • the nuclear magnetic resonance measurement system further includes a bed, a shielding bin and a mobile probe, wherein the shielding bin includes a built-in metal shielding layer;
  • the shielding bin is covered on the manned bed surface of the bed body, and has an opening and closing structure, so that the human body to be inspected enters the space surrounded by the manned bed surface and the shielding bin;
  • the mobile probe is arranged in the space surrounded by the manned bed surface and the shielding bin, and can be moved in the left-right direction, the head-to-foot direction and/or the front-rear direction of the human body to be inspected through a mechanical drive mechanism, so as to The localization detection of the organs to be inspected in the body is performed outside the human body to be inspected.
  • the bed body is grounded, and the metal shielding layer in the shielding box is electrically connected to the bed body through a detachable connection structure on the opening and closing edge when the box body is closed, so that the metal shield The shielding layer is grounded through the bed.
  • the shielding compartment includes a trunk shielding compartment/and a leg shielding compartment, wherein the trunk shielding compartment and the leg shielding compartment can be combined to form a closed structure for covering the body below the neck ;
  • the trunk shielding bin includes a flexible neckline and a shielding sleeve part, wherein the flexible neckline is used for the head of the human body to be inspected to extend out of the bin, and the shielding sleeve part is used for the to-be-inspected body
  • the arm portion of the human body extends out of the bin so that the arm portion can hold the grounding handle.
  • the grounding handle is made of conductive material and grounded through a surge protection circuit.
  • 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 around the manned bed surface and the shielding bin. in the space and away from the mobile probe;
  • Each noise measurement coil in the at least one noise measurement coil is respectively electrically connected to the noise signal input end of the preamplifier, and the noise signal output end of the preamplifier is electrically connected to the signal input end of the phase synthesizer, so the The signal output end of the phase synthesizer is electrically connected to the noise signal input end of the nuclear magnetic resonance spectrometer;
  • the nuclear magnetic resonance spectrometer is further used for, before collecting the echo signal, according to the first noise signal received from the main radio frequency coil and the at least one noise measurement when the radio frequency power amplifier is turned off the second noise signal of the coil, to determine the signal correlation between the first noise signal and the second noise signal;
  • the nuclear magnetic resonance spectrometer is further configured to determine, 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 the echo signal is collected.
  • the noise signal appears in the echo signal from the main radio frequency coil, and then the determined noise signal is subtracted from the echo signal to obtain a new echo signal with noise reduction.
  • the shielding bin is hinged to the edge of the manned bed surface of the bed body through a hinge structure.
  • the magnet adopts a unilateral magnet structure, wherein the unilateral magnet structure has an ergonomic curved surface that fits with the body surface adjacent to the target sample organ.
  • the present invention provides a new type of nuclear magnetic resonance measurement system that can achieve area-selective excitation effects, that is, by arranging parallel secondary radio frequency coils in the peripheral area of the main radio frequency coil of the radio frequency subsystem, and transmitting the measurement sequence Before or during the pulse signal, a pre-saturation pulse signal is transmitted through the secondary radio frequency coil to generate a radio frequency field covering the non-interested area in the detection area, so that part or all of the magnetization vector in the non-interested area can be generated with the magnet.
  • the static magnetic field is parallel to the static magnetic field, which can weaken or disappear the useless signal generated in the non-interesting area and interfere with the echo signal generated in the area of interest during measurement, so as to achieve the effect of regional selective excitation and solve the problem of the current unilateral magnet nuclear magnetic field.
  • the resonance system has the problem of inaccurate fat detection due to the unsatisfactory excitation area;
  • FIG. 1 is a schematic structural diagram of a low-field nuclear magnetic resonance organ fat non-invasive quantitative detection system in the prior art.
  • FIG. 2 is an exemplary simulation diagram of an excitation region of a single-sided magnet nuclear magnetic resonance system in the prior art.
  • FIG. 3 is a schematic structural diagram of the nuclear magnetic resonance measurement system provided by the present invention.
  • FIG. 4 is a first timing diagram of the measurement sequence pulse signal and the pre-saturation pulse signal provided by the present invention.
  • FIG. 5 is a second timing diagram of the measurement sequence pulse signal and the pre-saturation pulse signal provided by the present invention.
  • FIG. 6 is a schematic cross-sectional view of the human body provided by the present invention.
  • FIG. 7 is a schematic diagram of the first arrangement of the primary radio frequency coil and the secondary radio frequency coil provided by the present invention.
  • FIG. 8 is a schematic diagram of a second arrangement of the primary radio frequency coil and the secondary radio frequency coil provided by the present invention.
  • FIG. 9 is a schematic three-dimensional structural diagram of the unilateral magnet structure provided by the present invention.
  • FIG. 10 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.
  • FIG. 11 is a schematic diagram of the specific structure of the RF field shielding plate provided by the present invention, wherein, FIG. 11(a) is a single-layer flat plate structure, FIG. 11(b) is a single-layer folding fan structure, and FIG. 11(c) is the lower flat plate and the The combined structure of the upper folding fan, Figure 11(d) is a double-layer flat plate structure, and Figure 11(e) is a double-layer folding fan structure.
  • FIG. 12 is a schematic diagram of the arrangement of the main radio frequency coil, the sub radio frequency coil and the radio frequency field shielding plate provided by the present invention.
  • Fig. 13 is a schematic diagram of the first use structure of the bed body and the shielding bin provided by the present invention.
  • Fig. 14 is a schematic diagram of the second use structure of the bed body and the shielding bin provided by the present invention.
  • Fig. 15 is a schematic view of the opened structure of the bed body and the shielding bin provided by the present invention.
  • FIG. 16 is a schematic three-dimensional structure diagram of the mobile probe provided by the present invention.
  • first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, a first element could be referred to as a second element, and similarly a second element could be referred to as a first element, without departing from the scope of the exemplary embodiments of this invention.
  • the nuclear magnetic resonance measurement system suitable for non-invasive quantitative detection of organs includes a radio frequency subsystem and a magnet 2 , wherein the magnet 2 is used in the detection area A static magnetic field is generated inside;
  • the radio frequency subsystem includes a nuclear magnetic resonance spectrometer, a radio frequency power amplifier, a preamplifier, a transceiver switch and a radio frequency coil group, wherein the radio frequency coil group includes a main radio frequency coil 151 and a secondary radio frequency coil 152, the secondary radio frequency coil 152 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 and the pre-saturation pulse signal output end of the nuclear magnetic resonance spectrometer are respectively electrically connected to the signal input ends 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 transceiving switch, and the pre-saturation pulse
  • the nuclear magnetic resonance spectrometer is used to generate the measurement sequence pulse signal shown in Figure 4 or 5 (which is the current conventional method)
  • the radio frequency power amplifier is used to amplify the to-be-transmitted the measurement sequence pulse signal and the pre-saturation pulse signal
  • the preamplifier is used for amplifying the received echo signal
  • the transceiver switch is used for switching control of the gate signal, so that the main The radio frequency coil 151 can not only transmit the measurement sequence pulse signal, but also asynchronously receive the echo signal, which can be,
  • the frequency of the pulse vector magnetic field is adjustable to match Larmor frequency (which is the 1H gyromagnetic ratio multiplied by the field strength of the static magnetic field) at different locations within the ROI (Region of Interest).
  • the radio frequency field generated by the secondary radio frequency coil 152 is also adjustable.
  • the measurement sequence can be transmitted before the measurement sequence pulse signal is transmitted as shown in FIG. 4 or after the measurement sequence is transmitted as shown in FIG. 5 .
  • the pre-saturation pulse signal (which preferably can realize a pulse signal with a flip angle of 90 degrees) is continuously applied, so that some or all of the magnetization vectors in the non-interested region are parallel to the static magnetic field, so that During the measurement, the useless signal generated by the non-interested region (such as subcutaneous fat, etc.) and which will interfere with the echo signal generated by the region of interest (such as the liver, etc.) is weakened or eliminated, so as to achieve region-selective excitation Effect.
  • the arc 300 is the excitation area (ie, the detection area) of the main RF coil 151 .
  • the number of the secondary radio frequency coils 152 may be two, and they are arranged symmetrically in the outer peripheral area of the main radio frequency coil 151 and horizontally arranged on the line together with the main radio frequency coil 151 As shown in FIG. 8 , the number of the secondary radio frequency coils 152 can be four, and they are arranged symmetrically in the outer peripheral area of the main radio frequency coil 151, and the main radio frequency coil 151 are arranged horizontally on the coil base 153 together.
  • the magnet 2 is set as a portable magnet, and the portable magnet is arranged in at least a unilateral magnet structure, wherein the unilateral magnet structure has an ergonomic curved surface that fits with the adjacent body surface of the target sample organ , as shown in Figure 9.
  • 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.
  • the excitation area of the static magnetic field can reach a depth of 12 cm from the surface of the magnet and 9 cm under the skin, which can also achieve good selectivity for patients with a thick subcutaneous fat layer;
  • the field excitation region of the static magnetic field is highly selective in the region of the depth of interest, which can avoid signals from internal organs other than the liver.
  • the magnets 2 can also be permanent magnets, electromagnets or their hybrids.
  • a new type of nuclear magnetic resonance measurement system that can achieve the effect of region-selective excitation is provided, that is, by arranging parallel secondary radio frequency coils in the peripheral region of the main radio frequency coil of the radio frequency subsystem , and before or in the process of transmitting the measurement sequence pulse signal, the pre-saturation pulse signal is transmitted through the secondary radio frequency coil to generate a radio frequency field covering the non-interesting area in the detection area, which can make the part of the non-interesting area or the non-interesting area.
  • All the magnetization vectors are parallel to the static magnetic field generated by the magnet, so that the useless signals generated in the non-interesting area and which will interfere with the echo signal generated in the area of interest can be weakened or disappeared during measurement, so as to achieve the effect of regional selective excitation. It solves the problem of inaccurate fat detection caused by the unsatisfactory excitation area in the current unilateral magnet NMR system.
  • the measurement process is highly streamlined, not easily affected by the operator's manipulation, and has strong repeatability; the measurement process is not easily affected by motion.
  • the radio frequency subsystem further includes a radio frequency field shielding plate 16 , wherein the radio frequency field shielding plate 16 is arranged in the peripheral area of the main radio frequency coil 151 and is connected with the main radio frequency coil 151 Parallel; the radio frequency field shielding plate 16 is used to shield the main radio frequency coil 151 from generating the pulse vector magnetic field for the non-interest region when the main radio frequency coil 151 transmits the measurement sequence pulse signal.
  • 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 time-varying magnetic field (which can be referred to as the main RF current).
  • the RF field shielding plate 16 is a complete metal body, the currents induced on the shielding body flow in the manner of multi-circulation paths and change with the change of the main magnetic field.
  • the main magnetic field enters the radio frequency field shielding plate 16 in a direction almost perpendicular to the The area on the radio frequency field shielding plate 16, therefore, in the area close to the radio frequency field shielding plate 16, the component of the main magnetic field is mainly the y component, so in the area of the radio frequency field shielding plate 16, the magnetic field generated by the induced current is the same as the The main magnetic fields are superimposed on each other in the y direction, so that the main magnetic field is greatly weakened in a certain area on the RF field shielding plate 16, and in the x direction of the area close to the RF field shielding plate 16, part of the area is superimposed with the main magnetic field It is enhanced, and part of the area is weakened.
  • the main magnetic field has less component in the x-direction of the area close to the RF field shielding plate 16, and the induced current x-direction component is also weaker, the y-direction component of this area is greatly weakened.
  • the main magnetic field is 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 stimulating useless signals such as body surface fat, etc. Regioselective excitation effect. As shown in FIG.
  • the RF field shielding plate 16 can be, but is not limited to, a flat plate structure made of metal material, a folding fan structure or any combination thereof, wherein, by using the folding fan structure, the induced current circulation can be increased Therefore, the induced magnetic field in the area close to the radio frequency field shielding plate 16 is increased, and the ability to weaken the main magnetic field in the area close to the radio frequency field shielding plate 16 is improved.
  • the arrangement positions of the radio frequency field shielding plate 16 and the secondary radio frequency coil 152 in the outer peripheral region of the main radio frequency coil 151 can be, for example, as shown in FIG. 12 .
  • the nuclear magnetic resonance measurement system further includes a bed 3, a shielding bin 4 and a mobile probe 5, wherein the shielding bin 4 includes a built-in metal shielding layer; the shielding bin 4 Covered on the manned bed surface 31 of the bed body 3, and has an opening and closing structure, so that the human body to be inspected enters the space surrounded by the manned bed surface 31 and the shielding bin 4; the mobile probe 5 is arranged in the space surrounded by the manned bed surface 31 and the shielding compartment 4, and can be moved in the left-right direction, the head-to-foot direction and/or the front-rear direction of the human body to be inspected through a mechanical drive mechanism, so as to be able to move in all directions.
  • the shielding bin 4 includes a built-in metal shielding layer
  • the shielding bin 4 Covered on the manned bed surface 31 of the bed body 3, and has an opening and closing structure, so that the human body to be inspected enters the space surrounded by the manned bed surface 31 and the shielding bin 4
  • the positioning detection of the organs to be inspected in the body is performed outside the human body to be inspected.
  • the bed 3 is used to carry the human body 100 to be inspected.
  • the shielding chamber 4 can also effectively protect the mobile probe 5, which can be made of hard material and sandwiched with the metal shielding layer, such as a metal mesh. , metal film or metal sheet; the shielding chamber 4 can be hinged to the edge of the manned bed surface of the bed body 3 through a hinge structure, so as to open and allow the human body 100 to enter.
  • the mobile probe 5 is used to load the radio frequency coil set, the radio frequency field shielding plate 16 and the magnet 2, etc., so that the mechanical drive mechanism can be used in the left and right directions of the human body to be inspected, the head of the human body to be inspected, and the like during inspection. Moving in the direction of the feet and/or in the front-rear direction realizes accurate positioning of the organs to be inspected in the body outside the human body to be inspected 100 , as shown in FIG. 16 .
  • the bed body 3 is grounded, and the metal shielding layer in the shielding bin 4 is electrically connected to the bed body 3 through a detachable connection structure 34 located on the opening and closing edge when the bin body is closed, so that the metal shield The 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 reed or a plug is matched with a reserved slot, so as to achieve the overall electrical conduction between the shielding compartment 4 and the entire hospital bed, and ensure that the shielding compartment 4 is fully connected. shielding effect.
  • the shielding compartment 4 includes a trunk shielding compartment 41/and a leg shielding compartment 42, wherein the trunk shielding compartment 41 and the leg shielding compartment 42 can be combined to cover the neck
  • the trunk shielding box 41 includes a flexible neckline 411 and a shielding sleeve part 412, wherein the flexible neckline 411 is used for the head of the human body to be examined to protrude out of the box, and the shielding The sleeve part 412 is used for the arm part of the human body to be examined to extend out of the chamber, so that the arm part can hold the grounding handle 6 . As shown in FIG.
  • the trunk shielding compartment 41 and the leg shielding compartment 42 may be combined to form a closed structure for covering the body below the neck; and as shown in FIG. 14 , the trunk shielding compartment may only be formed by the trunk shielding compartment 41 constitute a semi-closed structure (that is, a semi-open shielding bin structure).
  • the flexible neckline 411 is used to cooperate with the neck of the human body 100 to be inspected; the shielding sleeve portion 412 is used to cooperate with the arm of the human body to be inspected 100, which can help the human body to be inspected 100 to be fixed for testing Posture; the grounding handle 16 is used to eliminate noise that may be introduced by the human body.
  • the grounding handle 6 is made of conductive material and is grounded through a surge protection circuit.
  • the human body 100 to be inspected can hold the grounding handle 6 to ground the noise signal conducted through the human body so as to eliminate it.
  • the surge protection circuit can be designed as an RC parallel filter circuit, so as to form a high-pass filter with a cutoff frequency of about 60Hz, that is, the filter circuit has a high impedance at 60Hz and a very low impedance at the target frequency.
  • the human body releases the noise induced by the human body by touching the metal rod. If the grounding metal rod is directly touched without the protection circuit, and this ground is connected to the ground of the outer shielding and power amplifier components, it may transmit an instant through the shielding layer.
  • High voltage or high current (mainly power frequency) is dangerous 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, and the high-pass filter is on the power frequency. With a large impedance, it can prevent the passage of large currents, thereby protecting the human body.
  • 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 around the manned bed surface and the shielding bin.
  • the noise measurement coil in the at least one noise measurement coil is electrically connected to the noise signal input end of the preamplifier, and the noise signal output end of the preamplifier is electrically connected is connected to the signal input end of the phase synthesizer, and the signal output end of the phase synthesizer is electrically connected to the noise signal input end of the nuclear magnetic resonance spectrometer;
  • the nuclear magnetic resonance spectrometer is also used for, before collecting echo signals,
  • the first noise signal is determined according to the first noise signal from the main RF coil 151 and the second noise signal from the at least one noise measurement coil, which are received with the RF power amplifier turned off The signal correlation with the second noise signal;
  • the nuclear magnetic resonance spectrometer is further configured to, when collecting echo signals, according to the signal correlation between the first noise signal and the second noise signal and from
  • the at least one noise measurement coil includes four noise measurement coils. Since the signal received by the coil is related to its distance from the signal source, the farther the signal is, the lower the signal, so the noise measurement coil is placed When in the shielding chamber 4, it needs to be set far away from the mobile probe, so as to ensure that the magnetic resonance signal/echo signal received by it is negligible; and the noise signal exists in the environment, so it can be considered that the noise measurement
  • the coil is only picking up the noise signal.
  • the phase synthesizer is used for synthesizing noise signals from different noise measuring coils, and then receiving and processing by the nuclear magnetic resonance spectrometer; therefore, when the at least one noise measuring coil has only one noise measuring coil, the Set the phase synthesizer.
  • the determination process of the signal correlation can use the existing technology, such as linear fitting or nonlinear fitting technology; the determination method of the noise signal in the echo signal can still use the existing technology.
  • the shielding box 4 can block most of the noise from the surrounding environment, due to the incomplete closed structure or open structure of the shielding box 4, part of the ambient noise will be introduced through the human body, the shielding box 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, and the accuracy of the measurement results can be further ensured.

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Abstract

一种适用于器官无创定量检测的核磁共振测量***，提供一种能够达成区域选择性激发效果的核磁共振测量***，通过在射频子***的主射频线圈（151）的外周区域中布置平行的副射频线圈（152），并在发射测量序列脉冲信号之前或过程中，通过副射频线圈（152）来发射预饱和脉冲信号以产生覆盖检测区域内非感兴趣区的射频场，可使得非感兴趣区内的部分或全部磁化矢量与磁体（2）产生的静态磁场平行，进而在测量时可使非感兴趣区产生的且会对感兴趣区产生的回波信号造成干扰的无用信号减弱或消失，达到区域选择性激发效果，解决当前单边磁体核磁共振***因存在激发区域不理想而导致脂肪检测不准的问题。

Description

一种适用于器官无创定量检测的核磁共振测量*** 技术领域
本发明属于核磁共振技术领域，具体地涉及一种适用于器官无创定量检测的核磁共振测量***。
背景技术
在传统的医疗设备中，能够用于人体器官检测(例如肝检测等)的技术手段主要有超声检测、核磁共振检测和穿刺检测。但是它们自身各有局限性，如：(a)超声检测：传统的超声检测仪器，只可进行定性测量，无法满足脂肪含量30％以下时的检测需求；另一类为基于超声的脂肪肝及肝纤维化定量检测产品，主要局限是易受超声穿透性不足的影响，在针对肥胖类患者检测时，成功率低；(b)核磁共振检测，可采用磁共振Dixon技术定量脂肪、磁共振弹性成像技术(Magnetic Resonance Elastography,MRE)测量肝脏纤维化，虽然在检测精度上满足要求，但价格高昂，医院采购动辄500万甚至更高，单次检测费用以江苏为例在3000元左右，价格高昂，无法广泛用于早中期的脂肪肝监测；(c)穿刺检测，例如肝穿检测，这一检测手段在准确性上有着绝对的最高精度，是临床检测的金标准，但该种检测手段对人体的伤害极大，仅适用于绝对必要情况，无法广泛应用，且对样本的提取以及技师操作水平均有极高要求。
现有专利CN201911101865.6《一种基于磁共振原理的器官脂肪无创定量检测方法》公开了一种基于单边磁体核磁共振***的器官脂肪无创检测技术。如图1所示，该技术采用外部计算机(即由显示器和数据处理器构成的计算机设备)和一个射频RF子***以及一个便携式单边永磁体模块，构建起了一个低场核磁共振器官脂肪无创定量检测***，该***具有便携和低成本等优势，可以实现非侵入性和安全的器官脂肪定量检测。但是由于采用了单边永磁体，其磁场极不均匀，导致其激发区域为非规则的面。如图2所示一种单边磁体核磁共振***的激发区域示模拟图，其激发区域近似为马鞍形，选择性差，且激发深度有限。此激发区域可能不能完全落在待检器官上。例如该马鞍形激发区域中，其下部区域可能会激发体表脂肪层，其顶端可能会激发到肝脏以外的器官，导致检测误差。
由此针对单边磁体核磁共振***所存在激发区域不理想的情况，有必要提供一种新型的核磁共振测量***结构，以便改善因非理想激发区域导致脂肪检测不准的问题。
发明内容
为了解决现有单边磁体核磁共振***因存在激发区域不理想而导致脂肪检测不准的问题，本发明目的在于提供一种适用于器官无创定量检测的新型核磁共振测量***。
第一方面，本发明提供了一种适用于器官无创定量检测的核磁共振测量***，包括有射频子***和磁体，其中，所述磁体用于在检测区域内产生静态磁场；
所述射频子***包括有核磁共振谱仪、射频功率放大器、前置放大器、收发转换开关和射频线圈组，其中，所述射频线圈组包括有主射频线圈和副射频线圈，所述副射频线圈布置在所述主射频线圈的外周区域中且与所述主射频线圈平行；
所述核磁共振谱仪的测量序列脉冲信号输出端和预饱和脉冲信号输出端分别电连接所述射频功率放大器的信号输入端，所述射频功率放大器的测量序列脉冲信号输出端电连接所述收发转换开关的第一切换端，所述射频功率放大器的预饱和脉冲信号输出端电连接所述副射频线圈，所述前置放大器的回波信号输入端电连接所述收发转换开关的第二切换端，所述前置放大器的回波信号输出端电连接所述核磁共振谱仪的回波信号输入端，所述收发转换开关的受控端通信连接所述核磁共振谱仪的控制信号输出端，所述收发转换开关的切换公共端电连接所述主射频线圈；
所述主射频线圈用于作为所述射频子***的信号收发部件，发射来自所述核磁共振谱仪的测量序列脉冲信号，以便在所述检测区域内产生与所述静态磁场相交的脉冲向量磁场，并接收来自所述检测区域的回波信号；
所述副射频线圈用于作为所述射频子***的信号发射部件，在发射所述测量序列脉冲信号之前或过程中，发射来自所述核磁共振谱仪的预饱和脉冲信号，以便产生覆盖所述检测区域内非感兴趣区的射频场，使得所述非感兴趣区内的部分或全部磁化矢量与所述静态磁场平行。
基于上述发明内容，可提供一种能够达成区域选择性激发效果的新型核磁共振测量***，即通过在射频子***的主射频线圈的外周区域中布置平行的副射频线圈，并在发射测量序列脉冲信号之前或过程中，通过该副射频线圈来发射预饱和脉冲信号以产生覆盖检测区域内非感兴趣区的射频场，可使得所述非感兴趣区内的部分或全部磁化矢量与磁体产生的静态磁场平行，进而在测量时可使非感兴趣区产生的且会对感兴趣区产生的回波信号造成干扰的无用信号减弱或消失，达到区域选择性激发效果，解决当前单边磁体核磁共振***因存在激发区域不理想而导致脂肪检测不准的问题。此外，由于是基于低场核磁共振且针对特定需求对传统磁共振***做了简化，可使得***更加轻巧便捷，也能产生更好的经济效益；无需成像，测量时间短，准确性高；基于核磁共振技术，测量过程流程化程度高，不易受操作者手法的影响，可重复性强；测量过程不易受运动影响。
在一个可能的设计中，所述射频子***还包括有射频场屏蔽板，其中，所述射频场屏蔽板布置在所述主射频线圈的外周区域中且与所述主射频线圈平行；
所述射频场屏蔽板用于在所述主射频线圈发射所述测量序列脉冲信号时，屏蔽所述主射频线圈对所述非感兴趣区产生所述脉冲向量磁场。
在一个可能的设计中，所述射频场屏蔽板采用由金属材质制成的平板结构、折叠扇结构或它们的任意组合结构。
在一个可能的设计中，所述核磁共振测量***还包括有床体、屏蔽仓和移动式探头，其 中，所述屏蔽仓包括有内设的金属屏蔽层；
所述屏蔽仓覆盖在所述床体的载人床面上，并具有开合结构，以便待检人体进入由所述载人床面和所述屏蔽仓包围的空间中；
所述移动式探头设置在由所述载人床面和所述屏蔽仓包围的空间中，并通过机械驱动机构能够在待检人体的左右方向、头脚方向和/或前后方向上移动，以便在所述待检人体外部对体内待检器官进行定位检测。
在一个可能的设计中，所述床体接地，所述屏蔽仓中的金属屏蔽层在仓体闭合时通过位于开合边缘上的可拆卸连接结构与所述床体电连接，以便所述金属屏蔽层通过所述床体接地。
在一个可能的设计中，所述屏蔽仓包括有躯干屏蔽仓/和腿部屏蔽仓，其中，所述躯干屏蔽仓和所述腿部屏蔽仓可组合构成用于覆盖颈部以下身体的封闭结构；
所述躯干屏蔽仓包括有柔性领口和屏蔽袖套部，其中，所述柔性领口用于供所述待检人体的头部伸出仓外，所述屏蔽袖套部用于供所述待检人体的手臂部伸出仓外，以便使所述手臂部可持握接地把手。
在一个可能的设计中，所述接地把手由导电材质制成，并通过浪涌保护电路接地。
在一个可能的设计中，所述核磁共振测量***还包括有相位合成器和至少一个噪声测量线圈，其中，所述至少一个噪声测量线圈布置在由所述载人床面和所述屏蔽仓包围的空间中且远离所述移动式探头设置；
所述至少一个噪声测量线圈中的各个噪声测量线圈分别电连接所述前置放大器的噪声信号输入端，所述前置放大器的噪声信号输出端电连接所述相位合成器的信号输入端，所述相位合成器的信号输出端电连接所述核磁共振谱仪的噪声信号输入端；
所述核磁共振谱仪还用于在采集回波信号前，根据在关闭所述射频功率放大器情况下所接收到的且来自所述主射频线圈的第一噪声信号和来自所述至少一个噪声测量线圈的第二噪声信号，确定出所述第一噪声信号与所述第二噪声信号的信号相关性；
所述核磁共振谱仪还用于在采集回波信号时，根据所述第一噪声信号与所述第二噪声信号的信号相关性和来自所述至少一个噪声测量线圈的第三噪声信号，确定出在来自所述主射频线圈的回波信号中的噪声信号，然后在所述回波信号中减除确定的所述噪声信号，得到降噪的新回波信号。
在一个可能的设计中，所述屏蔽仓通过合页结构铰接所述床体的载人床面边沿。
在一个可能的设计中，所述磁体采用单边磁体结构，其中，所述单边磁体结构具有与目标检样器官相邻身体表面贴合的人体工程学弧曲面。
本发明创造的有益效果：
(1)本发明创造提供了一种可达成区域选择性激发效果的新型核磁共振测量***，即通过在射频子***的主射频线圈的外周区域中布置平行的副射频线圈，并在发射测量序列脉 冲信号之前或过程中，通过该副射频线圈来发射预饱和脉冲信号以产生覆盖检测区域内非感兴趣区的射频场，可使得所述非感兴趣区内的部分或全部磁化矢量与磁体产生的静态磁场平行，进而在测量时可使非感兴趣区产生的且会对感兴趣区产生的回波信号造成干扰的无用信号减弱或消失，达到区域选择性激发效果，解决当前单边磁体核磁共振***因存在激发区域不理想而导致脂肪检测不准的问题；
(2)由于是基于低场核磁共振且针对特定需求对传统磁共振***做了简化，可使得***更加轻巧便捷，也能产生更好的经济效益；无需成像，测量时间短，准确性高；基于核磁共振技术，测量过程流程化程度高，不易受操作者手法的影响，可重复性强；测量过程不易受运动影响；
(3)还可以通过在射频子***的主射频线圈的外周区域中布置平行的射频场屏蔽板，可以屏蔽主射频线圈的部分射频场，进而实现对体表脂肪等无用信号不激发目的，进一步达到区域选择性激发效果；
(4)通过主动噪声控制设计，可以降低核磁共振应用对于噪声的敏感度，进一步确保测量结果的准确性。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是现有技术中低场核磁共振器官脂肪无创定量检测***的结构示意图。
图2是现有技术中单边磁体核磁共振***的激发区域示范模拟图。
图3是本发明提供的核磁共振测量***的结构示意图。
图4是本发明提供的测量序列脉冲信号与预饱和脉冲信号的第一种时序示意图。
图5是本发明提供的测量序列脉冲信号与预饱和脉冲信号的第二种时序示意图。
图6是本发明提供的人体横断位截面示意图。
图7是本发明提供的主射频线圈和副射频线圈的第一种布置示意图。
图8是本发明提供的主射频线圈和副射频线圈的第二种布置示意图。
图9是本发明提供的单边磁体结构的立体结构示意图。
图10是本发明提供的主射频线圈与射频场屏蔽板的磁场分解示意图。
图11是本发明提供的射频场屏蔽板的具体结构示意图，其中，图11(a)为单层平板结构，图11(b)为单层折叠扇结构，图11(c)为下层平板与上层折叠扇的组合结构，图11(d)为双层平板结构，图11(e)为双层折叠扇结构。
图12是本发明提供的主射频线圈、副射频线圈和射频场屏蔽板的布置示意图。
图13是本发明提供的床体和屏蔽仓的第一种使用结构示意图。
图14是本发明提供的床体和屏蔽仓的第二种使用结构示意图。
图15是本发明提供的床体和屏蔽仓的打开结构示意图。
图16是本发明提供的移动式探头的立体结构示意图。
具体实施方式
下面结合附图及具体实施例来对本发明作进一步阐述。在此需要说明的是，对于这些实施例方式的说明虽然是用于帮助理解本发明，但并不构成对本发明的限定。本文公开的特定结构和功能细节仅用于描述本发明示例的实施例。然而，可用很多备选的形式来体现本发明，并且不应当理解为本发明限制在本文阐述的实施例中。
应当理解，尽管本文可能使用术语第一、第二等等来描述各种单元，但是这些单元不应当受到这些术语的限制。这些术语仅用于区分一个单元和另一个单元。例如可以将第一单元称作第二单元,并且类似地可以将第二单元称作第一单元，同时不脱离本发明示例的实施例的范围。
应当理解，对于本文中可能出现的术语“和/或”，其仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，单独存在B，同时存在A和B三种情况；对于本文中可能出现的术语“/和”，其是描述另一种关联对象关系，表示可以存在两种关系，例如，A/和B，可以表示：单独存在A，单独存在A和B两种情况；另外，对于本文中可能出现的字符“/”，一般表示前后关联对象是一种“或”关系。
应当理解，在本文中若将单元称作与另一个单元“连接”、“相连”或“耦合”时，它可以与另一个单元直相连接或耦合，或中间单元可以存在。相対地，在本文中若将单元称作与另一个单元“直接相连”或“直接耦合”时，表示不存在中间单元。另外，应当以类似方式来解释用于描述单元之间的关系的其他单词(例如，“在……之间”对“直接在……之间”,“相邻”对“直接相邻”等等)。
应当理解，本文使用的术语仅用于描述特定实施例，并不意在限制本发明示例的实施例。若本文所使用的，单数形式“一”、“一个”以及“该”意在包括复数形式，除非上下文明确指示相反意思。还应当理解，若术语“包括”、“包括了”、“包含”和/或“包含了”在本文 中被使用时,指定所声明的特征、整数、步骤、操作、单元和/或组件的存在性,并且不排除一个或多个其他特征、数量、步骤、操作、单元、组件和/或他们的组合存在性或增加。
应当理解，还应当注意到在一些备选可能设计中，所出现的功能/动作可能与附图出现的顺序不同。例如,取决于所涉及的功能/动作,实际上可以实质上并发地执行,或者有时可以以相反的顺序来执行连续示出的两个图。
应当理解，在下面的描述中提供了特定的细节,以便于对示例实施例的完全理解。然而,本领域普通技术人员应当理解可以在没有这些特定细节的情况下实现示例实施例。例如可以在框图中示出***，以避免用不必要的细节来使得示例不清楚。在其他实例中，可以不以非必要的细节来示出众所周知的过程、结构和技术，以避免使得示例实施例不清楚。
如图3～9所示，本实施例第一方面提供的所述适用于器官无创定量检测的核磁共振测量***，包括有射频子***和磁体2，其中，所述磁体2用于在检测区域内产生静态磁场；所述射频子***包括有核磁共振谱仪、射频功率放大器、前置放大器、收发转换开关和射频线圈组，其中，所述射频线圈组包括有主射频线圈151和副射频线圈152，所述副射频线圈152布置在所述主射频线圈151的外周区域中且与所述主射频线圈151平行；所述核磁共振谱仪的测量序列脉冲信号输出端和预饱和脉冲信号输出端分别电连接所述射频功率放大器的信号输入端，所述射频功率放大器的测量序列脉冲信号输出端电连接所述收发转换开关的第一切换端，所述射频功率放大器的预饱和脉冲信号输出端电连接所述副射频线圈152，所述前置放大器的回波信号输入端电连接所述收发转换开关的第二切换端，所述前置放大器的回波信号输出端电连接所述核磁共振谱仪的回波信号输入端，所述收发转换开关的受控端通信连接所述核磁共振谱仪的控制信号输出端，所述收发转换开关的切换公共端电连接所述主射频线圈151；所述主射频线圈151用于作为所述射频子***的信号收发部件，发射来自所述核磁共振谱仪的测量序列脉冲信号，以便在所述检测区域内产生与所述静态磁场相交的脉冲向量磁场，并接收来自所述检测区域的回波信号；所述副射频线圈152用于作为所述射频子***的信号发射部件，在发射所述测量序列脉冲信号之前或过程中，发射来自所述核磁共振谱仪的预饱和脉冲信号，以便产生覆盖所述检测区域内非感兴趣区的射频场，使得所述非感兴趣区内的部分或全部磁化矢量与所述静态磁场平行。
如图3～9所示，在所述核磁共振测量***的具体结构中，所述核磁共振谱仪用于通过现有常规方式产生如图4或5所示的测量序列脉冲信号(其为现有扫描序列脉冲信号，用以激发目标检样中的氢原子并产生可检测信号，又称磁共振信号或回波信号)和预饱和脉冲信号，以便驱动一个或多个所述主射频线圈151和一个或多个所述副射频线圈152，并对接收到的回波信号进行测量处理，实现器官无创定量检测目的，其可采用现有仪器设备实现；所述射频功率放大器用于放大待发射的所述测量序列脉冲信号和所述预饱和脉冲信号；所述前置放大器用于放大接收的所述回波信号；所述收发转换开关用于通过门控信号的切换控制，使所述主射频线圈151既可发射所述测量序列脉冲信号，也能异步接收所述回波信号，其可以但不限于为一个单刀双掷开关。
所述主射频线圈151在所述检测区域内产生的脉冲向量磁场与所述静态磁场正交时，激发产生回波信号的效率最高，并且该脉冲向量磁场的频率是可调的，用以匹配感兴趣区ROI(Region of Interest)内不同位置的拉莫尔Larmor频率(其为1H旋磁比乘以所述静态磁场的场强)。所述副射频线圈152产生的射频场也是可调节的，在其射频场覆盖范围内，可如图4所示在发射所述测量序列脉冲信号之前或如图5所示在发射所述测量序列脉冲信号的整个过程中持续施加所述预饱和脉冲信号(其优选可实现90度翻转角的脉冲信号)，使所述非感兴趣区内的部分或全部磁化矢量与所述静态磁场平行，以便在测量时使所述非感兴趣区(例如皮下脂肪等)产生的且会对所述感兴趣区(例如肝脏等)产生的回波信号造成干扰的无用信号减弱或消失，达到区域选择性激发效果。如图6所示，在人体横断位截面示意图中，弧线300为所述主射频线圈151的激发区域(即所述检测区域)，在未做饱和的情况下，此区域内所有信号都会被接收，即所述弧线300中实线段302为所述感兴趣区(即待检器官200)，所述弧线300中虚线段301为所述非感兴趣区(也即待饱和区)，来自所述非感兴趣区的信号将会对测量结果造成极大的误差，而如果通过所述副射频线圈152对所述非感兴趣区进行预饱和，可使来自所述非感兴趣区的信号极大地降低或消失。此外，如图7所示，所述副射频线圈152的数目可以为两个，并左右对称地布置在所述主射频线圈151的外周区域中，以及与所述主射频线圈151一起水平布置在线圈底座153上；如图8所示，所述副射频线圈152的数目可以为四个，并上下及左右对称地布置在所述主射频线圈151的外周区域中，以及与所述主射频线圈151一起水平布置在所述线圈底座153上。
所述磁体2设为便携式磁体，所述便携式磁体的设置方式至少采用有单边磁体结构，其中，所述单边磁体结构具有与目标检样器官相邻身体表面贴合的人体工程学弧曲面，如图9所示。所述磁体2产生的所述静态磁场用于极化目标检样的感兴趣区域内的氢原子。采用如图9所示的单边磁体结构，可使所述静态磁场的激发区域深度达距磁体表面12cm，可达皮下9cm，对于皮下脂肪层厚的患者也可以达到很好的选择性；所述静态磁场的场激发区域在感兴趣深度区域的选择性较高，可以避开肝脏以外内脏的信号。此外，所述磁体2还可以是永磁体、电磁体或者它们的混合型。
由此通过前述核磁共振测量***的详细描述，提供了一种可达成区域选择性激发效果的新型核磁共振测量***，即通过在射频子***的主射频线圈的外周区域中布置平行的副射频线圈，并在发射测量序列脉冲信号之前或过程中，通过该副射频线圈来发射预饱和脉冲信号以产生覆盖检测区域内非感兴趣区的射频场，可使得所述非感兴趣区内的部分或全部磁化矢量与磁体产生的静态磁场平行，进而在测量时可使非感兴趣区产生的且会对感兴趣区产生的回波信号造成干扰的无用信号减弱或消失，达到区域选择性激发效果，解决当前单边磁体核磁共振***因存在激发区域不理想而导致脂肪检测不准的问题。此外，由于是基于低场核磁共振且针对特定需求对传统磁共振***做了简化，可使得***更加轻巧便捷，也能产生更好的经济效益；无需成像，测量时间短，准确性高；基于核磁共振技术，测量过程流程化程度高，不易受操作者手法的影响，可重复性强；测量过程不易受运动影响。
在一个可能的设计中，所述射频子***还包括有射频场屏蔽板16，其中，所述射频场屏蔽板16布置在所述主射频线圈151的外周区域中且与所述主射频线圈151平行；所述射频 场屏蔽板16用于在所述主射频线圈151发射所述测量序列脉冲信号时，屏蔽所述主射频线圈151对所述非感兴趣区产生所述脉冲向量磁场。如图10所示，所述射频场屏蔽板16可由金属制成，其工作原理如下：当所述主射频线圈151中通过射频电流时，射频电流产生一个随时间变化的磁场(可称为主磁场)，并在所述射频场屏蔽板16中感应出与射频线圈电流流向相同的电流，并在所述射频场屏蔽板16中以涡流的形式流动，这个感应的电流产生的一个磁场与射频电流产生的磁场相互叠加，由于所述射频场屏蔽板16为一个完整的金属体，因此屏蔽体上感应的电流以多循环路径的方式流动，并随主磁场的变化而变化，这些路径的电流产生的磁场大部分叠加在y方向，而在x方向的叠加效应较弱；在靠近所述射频场屏蔽板16的区域，主磁场几乎以垂直于所述射频场屏蔽板16的方向进入所述射频场屏蔽板16上的区域，因此在靠近所述射频场屏蔽板16的区域上，主磁场的分量主要为y分量，因此在所述射频场屏蔽板16的区域，感应电流产生的磁场与主磁场在y方向相互叠加，从而导致主磁场在所述射频场屏蔽板16上一定的区域被大幅削弱，而靠近所述射频场屏蔽板16的区域的x方向上，部分区域与主磁场叠加得到增强，部分区域被削弱，由于主磁场在靠近所述射频场屏蔽板16的区域x方向上分量较少，而感应电流x方向的分量也较弱，使得此区域在y方向分量的大幅削弱导致主磁场在靠近所述射频场屏蔽板16的一定区域得到大幅的削减。由此可通过调节所述射频场屏蔽板16与所述主射频线圈151的距离，达成屏蔽所述主射频线圈151部分射频场的目的，进而实现对体表脂肪等无用信号不激发目的，达到区域选择性激发效果。如图11所示，所述射频场屏蔽板16可以但不限于采用由金属材质制成的平板结构、折叠扇结构或它们的任意组合结构，其中，通过采用折叠扇结构，可增加感应电流循环的路径，从而增加了靠近所述射频场屏蔽板16的区域中的感应磁场，提高了削弱靠近所述射频场屏蔽板16的区域中主磁场的能力。此外，所述射频场屏蔽板16与所述副射频线圈152在所述主射频线圈151的外周区域的布置位置，可举例如图12所示。
在一个可能的设计中，所述核磁共振测量***还包括有床体3、屏蔽仓4和移动式探头5，其中，所述屏蔽仓4包括有内设的金属屏蔽层；所述屏蔽仓4覆盖在所述床体3的载人床面31上，并具有开合结构，以便待检人体进入由所述载人床面31和所述屏蔽仓4包围的空间中；所述移动式探头5设置在由所述载人床面31和所述屏蔽仓4包围的空间中，并通过机械驱动机构能够在待检人体的左右方向、头脚方向和/或前后方向上移动，以便在所述待检人体外部对体内待检器官进行定位检测。如图13～15所示，所述床体3用于承载所述待检人体100。所述屏蔽仓4除用于屏蔽外界干扰信号外，还能有效对所述移动式探头5起到保护作用，其可由硬质材质制成，并夹设有所述金属屏蔽层，例如金属网、金属薄膜或金属薄板；所述屏蔽仓4可通过合页结构铰接所述床体3的载人床面边沿，以便开合并使所述待检人体100进入。所述移动式探头5用于装载所述射频线圈组、所述射频场屏蔽板16和所述磁体2等，以便在检测时由所述机械驱动机构在所述待检人体的左右方向、头脚方向和/或前后方向上移动，实现在所述待检人体100的外部对体内待检器官进行准确定位，如图16所示。具体地，所述床体3接地，所述屏蔽仓4中的金属屏蔽层在仓体闭合时通过位于开合边缘上的可拆卸连接结构34与所述床体3电连接，以便所述金属屏蔽层通过所述床体3接地。所述可拆卸连接结构34可以但不限于采用簧片或插头与预留插槽向配合的结构，以便达成所述屏蔽仓4与整个病床的整体电性导通，确保所述屏蔽仓4的屏蔽效果。
在一个可能的设计中，所述屏蔽仓4包括有躯干屏蔽仓41/和腿部屏蔽仓42，其中，所述躯干屏蔽仓41和所述腿部屏蔽仓42可组合构成用于覆盖颈部以下身体的封闭结构；所述躯干屏蔽仓41包括有柔性领口411和屏蔽袖套部412，其中，所述柔性领口411用于供所述待检人体的头部伸出仓外，所述屏蔽袖套部412用于供所述待检人体的手臂部伸出仓外，以便使所述手臂部可持握接地把手6。如图13所示，所述躯干屏蔽仓41和所述腿部屏蔽仓42可组合构成用于覆盖颈部以下身体的封闭结构；而如图14所示，也可只有由所述躯干屏蔽仓41构成的半封闭结构(也即半开放式屏蔽仓结构)。所述柔性领口411用于与所述待检人体100的颈部配合；所述屏蔽袖套部412用于与所述待检人体100的手臂部配合，可以帮助所述待检人体100固定测试姿势；所述接地把手16用于消除人体可能导入的噪声，具体地，所述接地把手6由导电材质制成，并通过浪涌保护电路接地。由此可使所述待检人体100在测量时通过握住所述接地把手6，来对通过人体传导的噪声信号进行接地从而消除。详细地，所述浪涌保护电路可设计为RC并联滤波电路，以便形成一个截止频率约60Hz的高通滤波器，即此滤波电路在60Hz具有很高的阻抗，而在目标频率具有很低的阻抗，人体通过触摸金属拉杆以释放来自人体感应的的噪声，如果不通过保护电路直接触摸接地金属杆，而这个地又和外层屏蔽以及功率放大等部件的地相连，可能会通过屏蔽层传送瞬间高压或大电流(主要是工频)对人造成危险，由于来自人体的噪声通常为高频噪声，电容在目标频率具有很低的阻抗，因此可以释放噪声到地上，高通滤波器在工频上具有很大的阻抗，可以防止大电流通过，从而保护人体。
在一个可能的设计中，所述核磁共振测量***还包括有相位合成器和至少一个噪声测量线圈，其中，所述至少一个噪声测量线圈布置在由所述载人床面和所述屏蔽仓包围的空间中且远离所述移动式探头设置；所述至少一个噪声测量线圈中的各个噪声测量线圈分别电连接所述前置放大器的噪声信号输入端，所述前置放大器的噪声信号输出端电连接所述相位合成器的信号输入端，所述相位合成器的信号输出端电连接所述核磁共振谱仪的噪声信号输入端；所述核磁共振谱仪还用于在采集回波信号前，根据在关闭所述射频功率放大器情况下所接收到的且来自所述主射频线圈151的第一噪声信号和来自所述至少一个噪声测量线圈的第二噪声信号，确定出所述第一噪声信号与所述第二噪声信号的信号相关性；所述核磁共振谱仪还用于在采集回波信号时，根据所述第一噪声信号与所述第二噪声信号的信号相关性和来自所述至少一个噪声测量线圈的第三噪声信号，确定出在来自所述主射频线圈151的回波信号中的噪声信号，然后在所述回波信号中减除确定的所述噪声信号，得到降噪的新回波信号。如图3所示，所述至少一个噪声测量线圈包括有四个噪声测量线圈，由于线圈接收到的信号与其至信号源的距离有关，越远则信号越低，因此所述噪声测量线圈摆放在所述屏蔽仓4内时，需远离所述移动式探头设置，以便保证其接收到的磁共振信号/回波信号可忽略不计；而噪声信号存在于环境中，所以可以认为所述噪声测量线圈只在采集噪声信号。所述相位合成器用于对来自不同噪声测量线圈的噪声信号进行合成，然后再由所述核磁共振谱仪进行接收处理；因此当所述至少一个噪声测量线圈只有一个噪声测量线圈时，可缺省设置所述相位合成器。所述信号相关性的确定过程可采用现有技术，例如线性拟合或非线性拟合技术；所述回波信号中的噪声信号的确定方式依然可采用现有技术。虽然所述屏蔽仓4能够阻挡大部分来自周围环境中的噪声，但由于所述屏蔽仓4的不完全封闭结构或开放式结构，部分环境 噪声会通过人体、屏蔽仓或病床等被引入，因此通过前述的主动噪声控制设计，可以降低核磁共振应用对于噪声的敏感度，进一步确保测量结果的准确性。
以上所描述的实施例仅仅是示意性的，若涉及到作为分离部件说明的单元，其可以是或者也可以不是物理上分开的；若涉及到作为单元显示的部件，其可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。本领域普通技术人员在不付出创造性的劳动的情况下，即可以理解并实施。
以上实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换。而这些修改或者替换，并不使相应技术方案的本质脱离本发明实施例技术方案的精神和范围。
最后应说明的是，本发明不局限于上述可选的实施方式，任何人在本发明的启示下都可得出其他各种形式的产品。上述具体实施方式不应理解成对本发明的保护范围的限制，本发明的保护范围应当以权利要求书中界定的为准，并且说明书可以用于解释权利要求书。

Claims (10)

  1. 一种适用于器官无创定量检测的核磁共振测量***，其特征在于，包括有射频子***和磁体(2)，其中，所述磁体(2)用于在检测区域内产生静态磁场；
    所述射频子***包括有核磁共振谱仪、射频功率放大器、前置放大器、收发转换开关和射频线圈组，其中，所述射频线圈组包括有主射频线圈(151)和副射频线圈(152)，所述副射频线圈(152)布置在所述主射频线圈(151)的外周区域中且与所述主射频线圈(151)平行；
    所述核磁共振谱仪的测量序列脉冲信号输出端和预饱和脉冲信号输出端分别电连接所述射频功率放大器的信号输入端，所述射频功率放大器的测量序列脉冲信号输出端电连接所述收发转换开关的第一切换端，所述射频功率放大器的预饱和脉冲信号输出端电连接所述副射频线圈(152)，所述前置放大器的回波信号输入端电连接所述收发转换开关的第二切换端，所述前置放大器的回波信号输出端电连接所述核磁共振谱仪的回波信号输入端，所述收发转换开关的受控端通信连接所述核磁共振谱仪的控制信号输出端，所述收发转换开关的切换公共端电连接所述主射频线圈(151)；
    所述主射频线圈(151)用于作为所述射频子***的信号收发部件，发射来自所述核磁共振谱仪的测量序列脉冲信号，以便在所述检测区域内产生与所述静态磁场相交的脉冲向量磁场，并接收来自所述检测区域的回波信号；
    所述副射频线圈(152)用于作为所述射频子***的信号发射部件，在发射所述测量序列脉冲信号之前或过程中，发射来自所述核磁共振谱仪的预饱和脉冲信号，以便产生覆盖所述检测区域内非感兴趣区的射频场，使得所述非感兴趣区内的部分或全部磁化矢量与所述静态磁场平行。
  2. 如权利要求1所述的核磁共振测量***，其特征在于，所述射频子***还包括有射频场屏蔽板(16)，其中，所述射频场屏蔽板(16)布置在所述主射频线圈(151)的外周区域中且与所述主射频线圈(151)平行；
    所述射频场屏蔽板(16)用于在所述主射频线圈(151)发射所述测量序列脉冲信号时，屏蔽所述主射频线圈(151)对所述非感兴趣区产生所述脉冲向量磁场。
  3. 如权利要求2所述的核磁共振测量***，其特征在于，所述射频场屏蔽板(16)采用由金属材质制成的平板结构、折叠扇结构或它们的任意组合结构。
  4. 如权利要求1所述的核磁共振测量***，其特征在于，所述核磁共振测量***还包括有床体(3)、屏蔽仓(4)和移动式探头(5)，其中，所述屏蔽仓(4)包括有内设的金属屏蔽层；
    所述屏蔽仓(4)覆盖在所述床体(3)的载人床面(31)上，并具有开合结构，以便待检人体进入由所述载人床面(31)和所述屏蔽仓(4)包围的空间中；
    所述移动式探头(5)设置在由所述载人床面(31)和所述屏蔽仓(4)包围的空间中，并通过机械驱动机构能够在待检人体的左右方向、头脚方向和/或前后方向上移动，以便在所述待检人体外部对体内待检器官进行定位检测。
  5. 如权利要求4所述的核磁共振测量***，其特征在于，所述床体(3)接地，所述屏 蔽仓(4)中的金属屏蔽层在仓体闭合时通过位于开合边缘上的可拆卸连接结构(34)与所述床体(3)电连接，以便所述金属屏蔽层通过所述床体(3)接地。
  6. 如权利要求4所述的核磁共振测量***，其特征在于，所述屏蔽仓(4)包括有躯干屏蔽仓(41)/和腿部屏蔽仓(42)，其中，所述躯干屏蔽仓(41)和所述腿部屏蔽仓(42)可组合构成用于覆盖颈部以下身体的封闭结构；
    所述躯干屏蔽仓(41)包括有柔性领口(411)和屏蔽袖套部(412)，其中，所述柔性领口(411)用于供所述待检人体的头部伸出仓外，所述屏蔽袖套部(412)用于供所述待检人体的手臂部伸出仓外，以便使所述手臂部可持握接地把手(6)。
  7. 如权利要求6所述的核磁共振测量***，其特征在于，所述接地把手(6)由导电材质制成，并通过浪涌保护电路接地。
  8. 如权利要求4所述的核磁共振测量***，其特征在于，所述核磁共振测量***还包括有相位合成器和至少一个噪声测量线圈，其中，所述至少一个噪声测量线圈布置在由所述载人床面(31)和所述屏蔽仓(4)包围的空间中且远离所述移动式探头(5)设置；
    所述至少一个噪声测量线圈中的各个噪声测量线圈(5)分别电连接所述前置放大器的噪声信号输入端，所述前置放大器的噪声信号输出端电连接所述相位合成器的信号输入端，所述相位合成器的信号输出端电连接所述核磁共振谱仪的噪声信号输入端；
    所述核磁共振谱仪还用于在采集回波信号前，根据在关闭所述射频功率放大器情况下所接收到的且来自所述主射频线圈(151)的第一噪声信号和来自所述至少一个噪声测量线圈的第二噪声信号，确定出所述第一噪声信号与所述第二噪声信号的信号相关性；
    所述核磁共振谱仪还用于在采集回波信号时，根据所述第一噪声信号与所述第二噪声信号的信号相关性和来自所述至少一个噪声测量线圈的第三噪声信号，确定出在来自所述主射频线圈(151)的回波信号中的噪声信号，然后在所述回波信号中减除确定的所述噪声信号，得到降噪的新回波信号。
  9. 如权利要求4所述的核磁共振测量***，其特征在于，所述屏蔽仓(4)通过合页结构铰接所述床体(3)的载人床面边沿。
  10. 如权利要求1所述的核磁共振测量***，其特征在于，所述磁体(2)采用单边磁体结构，其中，所述单边磁体结构具有与目标检样器官相邻身体表面贴合的人体工程学弧曲面。
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CN117890840A (zh) * 2022-10-09 2024-04-16 无锡鸣石峻致医疗科技有限公司 一种具有空间选择性的磁共振***及其工作方法
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