CN113281368B - Magnetic resonance elasticity measurement method, device, computer equipment, system and storage medium - Google Patents
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Abstract
The invention relates to the technical field of magnetic resonance, and discloses a magnetic resonance elastic measurement method, a device, computer equipment, a system and a storage medium.
Description
Technical Field
The invention belongs to the technical field of magnetic resonance, and particularly relates to a magnetic resonance elasticity measurement method, a magnetic resonance elasticity measurement device, computer equipment, a magnetic resonance elasticity measurement system and a magnetic resonance elasticity measurement storage medium.
Background
Elasticity is an important mechanical parameter of biological tissues, and characterizes the deformation difficulty of the tissues under the action of mechanical external force. The elastic change of the tissue is closely related to the physiological and pathological states, so that normal and abnormal tissues can be distinguished. In traditional medicine, a doctor qualitatively judges the elastic size of tissues through palpation, and further diagnoses lesions. In recent years, non-invasive elastography based on nuclear magnetic resonance has been widely used for disease assessment of organs such as liver fibrosis grade, breast, brain and skeletal muscle.
The basic principle of magnetic resonance elastography is to detect particle displacement of an object under the action of external force by using a magnetic resonance technology, solve the inverse problem of elastography based on displacement information, and obtain the elastic coefficient distribution of the object by an inversion fitting algorithm. Specifically, the existing nuclear magnetic resonance elastic quantification technology mainly comprises the following three steps: (1) generating shear waves in the object; (2) Converting particle displacement under the action of shear waves into magnetic resonance phase images through motion sensitive gradient coding by using a phase contrast imaging pulse sequence; (3) And obtaining the elastic coefficient distribution of the object by an inversion fitting algorithm based on an inverse problem model of elastic mechanics.
The existing magnetic resonance elastography system mainly comprises the following parts: (a) a magnetically compatible shear wave generating device; (B) a high performance magnetic resonance imaging system; (C) elastography post-processing software. Due to the specificity of the magnetic resonance elastography technology, the shear wave generating device is required to have magnetic compatibility on one hand, and a high-performance gradient field, a high signal-to-noise ratio rapid scanning sequence and the like are also required on the other hand. Therefore, only a few manufacturers currently offer mr elastography devices, which are very expensive. There are few hospitals in China to carry out magnetic resonance elastography detection, so that single detection of patients is quick and quick in thousands of yuan, hospital equipment is tense, and queuing time of patients is long.
In view of the above prior art problems, the applicant previously disclosed a single-sided magnet-based magnetic resonance elasticity measurement scheme (CN 202011140597.1, a low-field nmr elasticity measurement method and system, publication date: 2021, month 1, day 22) that generates a shear wave in tissue by an externally applied simple harmonic vibration excitation device and measures the magnetic resonance signals of two regions (i.e., region 1 and region 2 as shown in fig. 1) along the propagation direction of the shear wave. Because the natural gradient field of the unilateral magnet encodes the motion of the shear wave, the motion speed of the shear wave can be calculated through the magnetic resonance signals measured in the two areas, and the elastic modulus is further obtained. However, since the shear wave generating device generates the shear wave and simultaneously generates the longitudinal wave inevitably, the vibration direction of the longitudinal wave is along the wave propagation direction, and a gradient field exists along the longitudinal wave direction in the single-side magnet system (as shown in fig. 1) and the gradient field strength is far greater than the gradient field strength perpendicular to the direction, the longitudinal wave is encoded by the gradient field, and the vibration information of the longitudinal wave is reflected in the measured magnetic resonance signal, so that the longitudinal wave can interfere with the elastic measurement result, and the measurement accuracy is affected.
Disclosure of Invention
In order to solve the technical problem that longitudinal waves can cause interference to an elastic measurement result in the existing magnetic resonance elastic measurement scheme based on a single-side magnet, the invention aims to provide a novel magnetic resonance elastic measurement method, a novel magnetic resonance elastic measurement device, a novel magnetic resonance elastic measurement system, a novel magnetic resonance elastic measurement storage medium, a novel magnetic resonance elastic measurement computer device, a novel magnetic resonance elastic measurement system and a novel magnetic resonance elastic storage medium, influences of the longitudinal waves on the elastic measurement result can be overcome, measurement accuracy is ensured, and practical application and popularization are facilitated.
In a first aspect, the present invention provides a magnetic resonance elasticity measurement method, comprising:
acquiring N groups of magnetic resonance signals obtained by measuring a detected object, wherein the N groups of magnetic resonance signals are in one-to-one correspondence with N equidistant positions of a motion module from the detected object, each group of magnetic resonance signals in the N groups of magnetic resonance signals comprises M spin echo signals obtained by applying elastic measurement pulse sequence sampling by a magnetic resonance spectrometer after shear waves propagate to a measurement area and when the motion module is away from the corresponding position of the detected object, the detected object is positioned in the measurement area, the motion module comprises a magnet and a radio frequency coil, N represents a positive integer not less than 5, and M represents a positive integer not less than 10;
Performing phase extraction operation on each spin echo signal in the N groups of magnetic resonance signals to obtain corresponding phase information;
generating a two-dimensional phase information graph containing N.M phase information according to all phase information obtained by taking phases, wherein the phase information of an ith row and an jth column in the two-dimensional phase information graph corresponds to the jth spin echo signal obtained by sampling at the ith position in the N equidistant positions one by one, i represents a positive integer not more than N, and j represents a positive integer not more than M;
zero padding operation is carried out on the periphery of the two-dimensional phase information graph to generate a two-dimensional matrix containing P, Q and P represents a positive integer greater than N, and Q represents a positive integer greater than M;
performing two-dimensional Fourier transform on the two-dimensional matrix to obtain frequency domain information;
selecting frequency information corresponding to the frequency of the shear wave and corresponding to the interested wavelength of the shear wave from the frequency domain information;
performing inverse Fourier transform on the selected frequency information to obtain a new information diagram from which the longitudinal wave interference is removed;
according to the new information graph, calculating the wavelength of the shear wave;
the young's modulus for characterizing the elasticity of the object to be examined is calculated according to the following formula:
E＝3ρλ 2 f 2
Where ρ represents the density of the object, λ represents the wavelength of the shear wave, and f represents the frequency of the shear wave.
Based on the above summary of the invention, a novel magnetic resonance elastic measurement scheme capable of effectively reducing interference of longitudinal waves on elastic measurement can be provided, namely after a plurality of groups of magnetic resonance signals obtained by measuring an object to be detected are acquired, a new information diagram from which the interference of the longitudinal waves is removed can be obtained through phase-taking operation, zero-filling operation, two-dimensional Fourier transform, key frequency information selection and inverse Fourier transform in sequence, then based on the new information diagram, the elastic coefficient representing the object to be detected is obtained through calculation of the wavelength and Young modulus of the shear waves, and because the effective removal of the interference of the longitudinal waves is realized in the elastic measurement process, the influence of the longitudinal waves on elastic measurement results can be overcome, the measurement accuracy is ensured, and the practical application and popularization are facilitated.
In one possible design, selecting frequency information corresponding to the frequency of the shear wave from the frequency domain information includes:
the time dimension frequency step delta f is calculated according to the following formula t ：
Wherein Q represents the total column number of the two-dimensional matrix, and Δt represents the sampling interval time of the M spin echo signals;
According to the time dimension frequency step delta f t The time dimension center distance L is calculated according to the following formula t ：
Where round () represents a rounding function and f represents the frequency of the shear wave;
in the frequency domain information, selecting the distance center in the time dimension as L t As frequency information corresponding to the frequency of the shear wave.
In one possible design, selecting frequency information corresponding to a wavelength of interest of the shear wave from the frequency domain information includes:
the space dimension frequency step delta f is calculated according to the following formula s ：
Wherein P represents the total number of rows of the two-dimensional matrix, and Δs represents the equidistant values of the N equidistant positions;
according to the spatial dimension frequency step delta f s The space dimension center distance range L is calculated according to the following formula s,min ,L s,max ]：
In the formula, round () represents a rounding function, λ min Represents the minimum value of the wavelength of interest of the shear wave, lambda max Representing a wavelength maximum of interest of the shear wave;
in the frequency domain information, selecting a distance center between [ L ] in the space dimension s,min ,L s,max ]As frequency information corresponding to the frequency of the shear wave.
In one possible design, the calculating the wavelength of the shear wave according to the new information graph includes:
Taking any row vector from the new information graph as a reference vector R;
and extracting other row vectors U relative to the reference vector R row by row from the new information graph, and calculating corresponding time shift values relative to the reference vector R by solving the following objective function for each other row vector U:
Min f(s)＝||R(t)-U(t-y)||
wherein y represents a time shift value to be solved, t represents a time abscissa of the reference vector R and other row vectors U, s represents equidistant positions corresponding to the other row vectors U and belonging to the N equidistant positions, i represents an open root number of a sum of squares of components after vector difference, and Min f(s) represents a minimum value of an optimization problem f(s);
according to the time shift values y of the other row vectors U and the equidistant positions s corresponding to the other row vectors U one by one, obtaining a linear relation by least square fitting: y=b×s+c, where c represents another coefficient to be determined;
the wavelength lambda of the shear wave is calculated according to the following formula:
where f represents the frequency of the shear wave.
In a second aspect, the invention provides a magnetic resonance elasticity measurement device, which comprises a signal acquisition unit, a phase extraction operation unit, an information graph generation unit, a zero filling operation unit, a fourier transform unit, a frequency information selection unit, an inverse fourier transform unit, a wavelength calculation unit and a young modulus calculation unit which are sequentially connected in a communication manner;
The signal acquisition unit is used for acquiring N groups of magnetic resonance signals obtained by measuring an object to be detected, wherein the N groups of magnetic resonance signals are in one-to-one correspondence with N equidistant positions of a motion module from the object to be detected, each group of magnetic resonance signals in the N groups of magnetic resonance signals comprises M spin echo signals obtained by applying elastic measurement pulse sequence sampling by a magnetic resonance spectrometer after shear waves propagate to a measurement area and when the motion module is away from the corresponding position of the object to be detected, the object to be detected is positioned in the measurement area, the motion module comprises a magnet and a radio frequency coil, N represents a positive integer not less than 5, and M represents a positive integer not less than 10;
the phase extraction operation unit is used for carrying out phase extraction operation on each spin echo signal in the N groups of magnetic resonance signals to obtain corresponding phase information;
the information map generating unit is configured to generate a two-dimensional phase information map including n×m phase information according to all phase information obtained by phase extraction, where phase information of an ith row and an jth column in the two-dimensional phase information map corresponds to a jth spin echo signal obtained by sampling at an ith position in the N equidistant positions one by one, i represents a positive integer not greater than N, and j represents a positive integer not greater than M;
The zero-filling operation unit is used for performing zero-filling operation on the periphery of the two-dimensional phase information graph to generate a two-dimensional matrix containing P and Q elements, wherein P represents a positive integer greater than N, and Q represents a positive integer greater than M;
the Fourier transform unit is used for performing two-dimensional Fourier transform on the two-dimensional matrix to obtain frequency domain information;
the frequency information selecting unit is used for selecting frequency information which corresponds to the frequency of the shear wave and corresponds to the interested wavelength of the shear wave from the frequency domain information;
the inverse Fourier transform unit is used for performing inverse Fourier transform on the selected frequency information to obtain a new information diagram from which the longitudinal wave interference is removed;
the wavelength calculation unit is used for calculating the wavelength of the shear wave according to the new information graph;
the young modulus calculation unit is used for calculating young modulus for representing elasticity of the detected object according to the following formula:
E＝3ρλ 2 f 2
where ρ represents the density of the object, λ represents the wavelength of the shear wave, and f represents the frequency of the shear wave.
In a third aspect, the present invention provides a computer device comprising a memory communicatively coupled to a processor, wherein the memory is configured to store a computer program, and the processor is configured to read the computer program and perform a magnetic resonance elasticity measurement method as described in the first aspect or any one of the first aspects.
In a fourth aspect, the invention provides a magnetic resonance elasticity measurement system, which comprises a nuclear magnetic resonance subsystem, a mechanical vibration excitation device, a probe module and a control console, wherein the nuclear magnetic resonance subsystem comprises a magnetic resonance spectrometer, a radio frequency power amplifier, a preamplifier and a transceiver transfer switch, the mechanical vibration excitation device comprises a waveform generator and a power amplifier, and the probe module comprises a magnet, a radio frequency coil, a vibration generator, a transmission rod, a linear reciprocating mechanism and a probe shell;
the radio frequency signal output end of the magnetic resonance spectrometer is electrically connected with the radio frequency signal input end of the radio frequency power amplifier, the radio frequency signal output end of the radio frequency power amplifier is electrically connected with the first switching end of the transmit-receive change-over switch, the echo signal input end of the preamplifier is electrically connected with the second switching end of the transmit-receive change-over switch, the echo signal output end of the preamplifier is electrically connected with the echo signal input end of the nuclear magnetic resonance spectrometer, the controlled end of the transmit-receive change-over switch is electrically connected with the gate control signal output end of the nuclear magnetic resonance spectrometer, and the switching public end of the transmit-receive change-over switch is electrically connected with the radio frequency coil;
The synchronous control signal output end of the magnetic resonance spectrometer is electrically connected with the controlled end of the waveform generator, the sine wave signal output end of the waveform generator is electrically connected with the signal input end of the power amplifier, and the signal output end of the power amplifier is electrically connected with the signal input end of the vibration generator;
the magnet and the radio frequency coil are respectively positioned in the probe shell and are used as a movement module to be fixed on a movable part of the linear reciprocating mechanism, the vibration generator is fixed in the probe shell, the vibration output end of the vibration generator is fixedly connected with one end of the transmission rod, and the other end of the transmission rod sequentially passes through the magnet, the radio frequency coil and the probe shell in a movable way so as to be used for contacting an external detected object;
the linear reciprocating mechanism is fixed inside the probe housing and is used for driving the movable part to do linear reciprocating motion far away from or close to the detected object inside the probe housing 36;
the console is respectively in communication connection with the magnetic resonance spectrometer and the linear reciprocating mechanism, and is used for respectively sending a plurality of elasticity measurement control instructions to the magnetic resonance spectrometer and the linear reciprocating mechanism, receiving a plurality of groups of magnetic resonance signals acquired by the magnetic resonance spectrometer and measured for the detected object, and completing data processing, wherein the data processing comprises executing the magnetic resonance elasticity measurement method possibly designed according to any one of the first aspect or the first aspect.
In one possible design, the number of elastic measurement control instructions includes:
a first control instruction is sent to the linear reciprocating mechanism when measurement starts so as to drive the motion module to reach a preset initial position away from the detected object;
a second control instruction is sent to the magnetic resonance spectrometer after the first control instruction is sent, so that the magnetic resonance spectrometer is started to control the waveform generator to generate a sine wave signal, and the vibration generator is driven by the power amplifier to output simple harmonic vibration, wherein the frequency of the sine wave signal and/or the simple harmonic vibration is equal to the frequency of a shear wave;
a third control instruction is sent to the magnetic resonance spectrometer after the second control instruction is sent, so that the magnetic resonance spectrometer is started to apply elastic measurement pulse sequence sampling to obtain a group of magnetic resonance signals containing a plurality of spin echo signals;
a fourth control instruction is sent to the linear reciprocating mechanism after the third control instruction is sent, so that the motion module is driven to respectively reach a plurality of equidistant positions from the detected object;
and a fifth control instruction is sent to the magnetic resonance spectrometer after the fourth control instruction is sent, so that the magnetic resonance spectrometer is started to apply elastic measurement pulse sequence sampling to obtain a plurality of groups of magnetic resonance signals corresponding to the equidistant positions one by one.
In one possible design, the third control instruction sent to the magnetic resonance spectrometer after the second control instruction is sent includes:
and after the second control instruction is sent and when the preset time is up, the control instruction is sent to the magnetic resonance spectrometer so as to start the magnetic resonance spectrometer to sample by applying an elastic measurement pulse sequence to obtain a group of magnetic resonance signals containing a plurality of spin echo signals.
In a fifth aspect, the present invention provides a storage medium having instructions stored thereon which, when run on a computer, perform a magnetic resonance elasticity measurement method as set forth in the first aspect or any one of the first aspects.
In a sixth aspect, the invention provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the magnetic resonance elasticity measurement method as described above in the first aspect or any one of the possible designs of the first aspect.
The invention has the technical effects that:
(1) The invention provides a novel magnetic resonance elasticity measurement scheme capable of effectively reducing interference of longitudinal waves on elasticity measurement, namely after a plurality of groups of magnetic resonance signals obtained by measuring an object to be detected are acquired, a new information diagram from which the interference of the longitudinal waves is removed can be obtained through phase-taking operation, zero-filling operation, two-dimensional Fourier transform, key frequency information selection and Fourier inverse transform in sequence, then the elasticity coefficient representing the object to be detected is obtained through calculation of the wavelength and Young modulus of shear waves based on the new information diagram, and the influence of the longitudinal waves on the elasticity measurement result can be overcome due to the fact that the effective removal of the interference of the longitudinal waves is realized in the elasticity measurement process, the measurement accuracy is ensured, and the method is convenient for practical application and popularization;
(2) The elastic measurement can be realized based on low-field nuclear magnetic resonance, and the traditional magnetic resonance system is simplified according to specific requirements, so that the system is lighter and more convenient, and better economic benefit can be generated.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of the principle of prior art shear wave based elasticity measurement.
Fig. 2 is a schematic flow chart of the magnetic resonance elasticity measurement method provided by the invention.
Fig. 3 is a timing diagram of an elasticity measurement pulse sequence provided by the present invention.
Fig. 4 is an exemplary diagram of a two-dimensional phase information map provided by the present invention.
Fig. 5 is an exemplary diagram of a new information diagram from which the longitudinal wave interference has been removed, provided by the present invention.
Fig. 6 is an exemplary graph of a fitting relationship between time shift amounts and equidistant positions provided by the present invention.
Fig. 7 is a schematic structural diagram of a magnetic resonance elasticity measurement device provided by the invention.
Fig. 8 is a schematic structural diagram of a computer device provided by the present invention.
Fig. 9 is a schematic structural diagram of a magnetic resonance elasticity measurement system provided by the present invention.
Fig. 10 is a detailed schematic diagram of the probe module in the mr elastometry system provided by the present invention.
In the above figures: 31-magnet; 32-a radio frequency coil; 33-a vibration generator; 34-a transmission rod; 35-a linear reciprocating mechanism; 36-a probe housing; 100-an object to be inspected.
Detailed Description
The invention will be further elucidated with reference to the drawings and to specific embodiments. The present invention is not limited to these examples, although they are described in order to assist understanding of the present invention. Specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments of the present invention. This invention may, however, be embodied in many alternate forms and should not be construed as limited to the embodiments set forth herein.
It should be understood that for the term "and/or" that may appear herein, it is merely one association relationship that describes an associated object, meaning that there may be three relationships, e.g., a and/or B, may represent: a alone, B alone, and both a and B; for the term "/and" that may appear herein, which is descriptive of another associative object relationship, it means that there may be two relationships, e.g., a/and B, it may be expressed that: a alone, a alone and B alone; in addition, for the character "/" that may appear herein, it is generally indicated that the context associated object is an "or" relationship.
As shown in fig. 2 to 6, the magnetic resonance elasticity measurement method provided in the first aspect of the present embodiment may be, but is not limited to, executed by a console (which may send a plurality of elasticity measurement control instructions to a magnetic resonance spectrometer in the magnetic resonance subsystem and a linear reciprocating mechanism in the probe module respectively) in a magnetic resonance elasticity measurement system (including, but not limited to, a nuclear magnetic resonance subsystem, a mechanical vibration excitation device, a probe module, a console, etc.), and receive a plurality of sets of magnetic resonance signals acquired by the magnetic resonance spectrometer and measured for a detected object, and complete data processing, so as to overcome the influence of longitudinal waves on the elasticity measurement result, and ensure measurement accuracy. The magnetic resonance elasticity measurement method may include, but is not limited to, the following steps S1 to S9.
S1, acquiring N groups of magnetic resonance signals obtained by measuring an object to be detected, wherein the N groups of magnetic resonance signals are in one-to-one correspondence with N equidistant positions of a motion module from the object to be detected, each group of magnetic resonance signals in the N groups of magnetic resonance signals comprises M spin echo signals obtained by sampling an elastic measurement pulse sequence by a magnetic resonance spectrometer after shear waves propagate to a measurement area and when the motion module is away from the corresponding position of the object to be detected, the object to be detected is positioned in the measurement area, the motion module comprises a magnet and a radio frequency coil, N represents a positive integer not less than 5, and M represents a positive integer not less than 10.
In the step S1, the N sets of magnetic resonance signals are derived from the magnetic resonance spectrometer, and may be, but not limited to, directly acquired by signal transmission. Since the spin echo signals are sampled when the shear wave propagates to the measurement region and the object to be detected is located in the measurement region, the gradient field of the magnet can be used to encode the proton operation of the shear wave on the object to be detected, so that the obtained M spin echo signals can be used in the elasticity measurement scheme of the present embodiment. The specific implementation of the propagation of the shear wave to the measurement area is conventional in the prior art, see the applicant's prior disclosure; the specific implementation mode of the magnetic resonance spectrometer for obtaining the spin echo signal by applying the elastic measurement pulse sequence sampling is also the conventional mode, and can be referred to the conventional nuclear magnetic resonance technology; the elastometric pulse sequence may be, but is not limited to, a sampled self-rotating Echo sequence (Spin Echo, SE) or a CPMG sequence (aNMR pulse sequencenamed by several scientists Carr, purcell, meiboost and Gill, i.e. nuclear magnetic resonance sequences named by Carr, purcell, meiboost and Gill et al), which may utilize the natural gradient of a single-sided magnet to achieve encoding of proton motion. For example, the object to be detected may be an elastic mold body made of agar, N takes a value of 30, the N equidistant positions are 80.0 mm, 81.5 mm, 83.0 mm, 118.5 mm and 120.0mm (i.e. the distance Δs is 1.5 mm) of the moving mold set from the agar object, the frequency of the shear wave is set to be 50Hz, the elastic measurement pulse sequence adopts a CPMG sequence, the echo interval time is set to be 0.5ms, and a set of magnetic resonance signals including m=128 spin echo signals are obtained by sampling the CPMG sequence at each equidistant position, as shown in fig. 3.
S2, performing phase extraction operation on each spin echo signal in the N groups of magnetic resonance signals to obtain corresponding phase information.
In the step S2, the phase fetching operation may specifically be to retain phase information in the spin echo signal.
S3, generating a two-dimensional phase information graph containing N.M phase information according to all phase information obtained by taking phases, wherein the phase information of an ith row and an jth column in the two-dimensional phase information graph corresponds to the jth spin echo signal obtained by sampling at the ith position in the N equidistant positions one by one, i represents a positive integer not greater than N, and j represents a positive integer not greater than M.
In the step S3, for example, for 30×128 spin echo signals, a two-dimensional phase information chart containing 30×128 phases is obtained, and as shown in fig. 4, it is obvious that there is a vibration condition of shear waves and longitudinal waves in the agar object. In addition, since the phase information of the ith row and the jth column in the two-dimensional phase information graph corresponds to the jth spin echo signal sampled at the ith position in the N equidistant positions one by one, the transverse dimension of the two-dimensional phase information graph is a time dimension, and the longitudinal dimension is a space dimension.
S4, performing zero filling operation on the periphery of the two-dimensional phase information graph to generate a two-dimensional matrix containing P, wherein P represents a positive integer greater than N, and Q represents a positive integer greater than M.
In the step S4, for example, for a two-dimensional phase information map including 30×128 phases, a two-dimensional matrix of 256×2000 (i.e., p=256, q=2000) may be generated by a zero-padding operation. Likewise, the transverse dimension of the two-dimensional matrix is still the time dimension, and the longitudinal dimension is still the space dimension.
S5, performing two-dimensional Fourier transform on the two-dimensional matrix to obtain frequency domain information.
In the step S5, the two-dimensional fourier transform is an integral transform that helps to analyze the frequency domain components of the signal. The obtained frequency domain information still has two-dimensional characteristics: the transverse dimension is still the time dimension, and the longitudinal dimension is still the space dimension.
S6, selecting frequency information which corresponds to the frequency of the shear wave and corresponds to the interested wavelength of the shear wave from the frequency domain information.
In the step S6, specifically, frequency information corresponding to the frequency of the shear wave is selected from the frequency domain information, including, but not limited to, the following steps S611 to S613.
S611, calculating according to the following formula to obtain a time dimension frequency step delta f t ：
Where Q represents the total number of columns of the two-dimensional matrix, and Δt represents the sampling interval time of the M spin echo signals.
In the step S611, for example, when q=2000 and the sampling interval time Δt is 0.5ms, the calculated time dimension frequency step Δf is calculated t 1.
S612 according toThe time dimension frequency step delta f t The time dimension center distance L is calculated according to the following formula t ：
Where round () represents a rounding function and f represents the frequency of the shear wave.
In the step S612, for example, when the frequency f of the shear wave is 50Hz, the obtained time dimension center distance L is calculated t 50.
S613, selecting the distance center in the time dimension as L in the frequency domain information t As frequency information corresponding to the frequency of the shear wave.
In the step S613, the selecting operation of the frequency information is to reserve the frequency information with the frequency f in the frequency domain information, and the frequency information of the other columns is set to zero.
In the step S6, specifically, frequency information corresponding to the wavelength of interest of the shear wave is selected from the frequency domain information, including, but not limited to, the following steps S621 to S623.
S621, calculating to obtain a space dimension frequency step length delta f according to the following formula s ：
Where P represents the total number of rows of the two-dimensional matrix and Δs represents the equidistant values of the N equidistant positions.
In the step S621, for example, when p=256 and the equidistant value Δs is 1.5mm, the calculated spatial dimension frequency step Δf is calculated s 2.6.
S622, according to the space dimension frequency step length delta f s The space dimension center distance range L is calculated according to the following formula s,min ,L s,max ]：
In the formula, round () represents a rounding function, λ min Represents the minimum value of the wavelength of interest of the shear wave, lambda max Representing a wavelength maximum of interest of the shear wave.
In the step S622, for example, when lambda min 0.01m, lambda max At 0.06m, the L is calculated s,min Is 6, L s,max 38.
S623, selecting a distance center between [ L ] in the space dimension in the frequency domain information s,min ,L s,max ]As frequency information corresponding to the frequency of the shear wave.
In the step S623, the selection operation of the frequency information is to reserve the distance center of [ L ] in the frequency domain information s,min ,L s,max ]And setting the frequency information of the other rows to zero according to the frequency information of the rows in the range.
S7, performing inverse Fourier transform on the selected frequency information to obtain a new information diagram from which the longitudinal wave interference is removed.
In the step S7, as shown in fig. 5 for example, it is apparent that there is only a vibration condition of the shear wave in the agar object, and the interference of the longitudinal wave has been removed. In addition, the new information map can be seen to be identical to the two-dimensional phase information map: the transverse dimension is the time dimension and the longitudinal dimension is the space dimension.
S8, calculating the wavelength of the shear wave according to the new information graph.
In step S8, specifically, the wavelength of the shear wave is calculated according to the new information map, including, but not limited to, the following steps S81 to S84.
S81, taking any row vector from the new information graph as a reference vector R.
S82, other row vectors U relative to the reference vector R are extracted row by row from the new information graph, and for each other row vector U, the corresponding time shift value relative to the reference vector R is obtained by solving the following objective function calculation:
Min f(s)＝||R(t)-U(t-y)||
where y represents a time-shift value to be solved, t represents a time abscissa of the reference vector R and other row vectors U, s represents equidistant positions corresponding to the other row vectors U and belonging to the N equidistant positions, i represents an open root number of a sum of squares of components after vector difference, and Min f(s) represents a minimum value of the optimization problem f(s).
In the step S82, the specific process of solving is the existing conventional mathematical manner.
S83, according to time translation values y of a plurality of other row vectors U and a plurality of equidistant positions s corresponding to the other row vectors U one by one, obtaining a linear relation through least square fitting: y=b×s+c, where c represents another coefficient to be determined.
In the step S83, the least square fitting method is a conventional fitting method. For example, as shown in FIG. 6, when the N equidistant positions are 80.0, 81.5, 83.0, & gt118.5 and 120.0mm (i.e. the distance Δs is 1.5 mm) from the agar object by the motion module, the slope coefficient b can be fitted to be 5.9ms/cm. Further, since the coefficient c is not useful in the subsequent calculation, the value thereof may not be sized.
S84, calculating the wavelength lambda of the shear wave according to the following formula:
where f represents the frequency of the shear wave.
In the step S84, when the frequency f of the shear wave is 50Hz, the calculated wavelength λ may be 3.3866cm.
S9, calculating the Young modulus for representing the elasticity of the detected object according to the following formula:
E＝3ρλ 2 f 2
where ρ represents the density of the object, λ represents the wavelength of the shear wave, and f represents the frequency of the shear wave.
In said step S9, the principle of calculation of said young 'S modulus can be found in the applicant' S prior publication. For example, when agar density is 1000kg/m 3 And the elastic coefficient of the agar mold body is 11.2Kpa, which is close to the actual situation.
Therefore, through the magnetic resonance elasticity measurement method described in detail in the steps S1 to S9, a novel magnetic resonance elasticity measurement scheme capable of effectively reducing interference of longitudinal waves on elasticity measurement can be provided, namely after a plurality of groups of magnetic resonance signals obtained by measuring an object to be detected are acquired, a new information diagram from which the interference of the longitudinal waves is removed can be obtained through phase-taking operation, zero-filling operation, two-dimensional Fourier transformation, key frequency information selection and inverse Fourier transformation in sequence, and then based on the new information diagram, the elasticity coefficient representing the object to be detected is obtained through calculation of the wavelength and Young modulus of the shear waves.
As shown in fig. 7, a second aspect of the present embodiment provides a virtual device for implementing the method of the first aspect or any one of the possible designs of the first aspect, where the virtual device includes a signal acquisition unit, a phase extraction operation unit, an information map generation unit, a zero filling operation unit, a fourier transform unit, a frequency information selection unit, an inverse fourier transform unit, a wavelength calculation unit, and a young's modulus calculation unit that are sequentially connected in communication;
The signal acquisition unit is used for acquiring N groups of magnetic resonance signals obtained by measuring an object to be detected, wherein the N groups of magnetic resonance signals are in one-to-one correspondence with N equidistant positions of a motion module from the object to be detected, each group of magnetic resonance signals in the N groups of magnetic resonance signals comprises M spin echo signals obtained by applying elastic measurement pulse sequence sampling by a magnetic resonance spectrometer after shear waves propagate to a measurement area and when the motion module is away from the corresponding position of the object to be detected, the object to be detected is positioned in the measurement area, the motion module comprises a magnet and a radio frequency coil, N represents a positive integer not less than 5, and M represents a positive integer not less than 10;
the phase extraction operation unit is used for carrying out phase extraction operation on each spin echo signal in the N groups of magnetic resonance signals to obtain corresponding phase information;
the information map generating unit is configured to generate a two-dimensional phase information map including n×m phase information according to all phase information obtained by phase extraction, where phase information of an ith row and an jth column in the two-dimensional phase information map corresponds to a jth spin echo signal obtained by sampling at an ith position in the N equidistant positions one by one, i represents a positive integer not greater than N, and j represents a positive integer not greater than M;
The zero-filling operation unit is used for performing zero-filling operation on the periphery of the two-dimensional phase information graph to generate a two-dimensional matrix containing P and Q elements, wherein P represents a positive integer greater than N, and Q represents a positive integer greater than M;
the Fourier transform unit is used for performing two-dimensional Fourier transform on the two-dimensional matrix to obtain frequency domain information;
the frequency information selecting unit is used for selecting frequency information which corresponds to the frequency of the shear wave and corresponds to the interested wavelength of the shear wave from the frequency domain information;
the inverse Fourier transform unit is used for performing inverse Fourier transform on the selected frequency information to obtain a new information diagram from which the longitudinal wave interference is removed;
the wavelength calculation unit is used for calculating the wavelength of the shear wave according to the new information graph;
the young modulus calculation unit is used for calculating young modulus for representing elasticity of the detected object according to the following formula:
E＝3ρλ 2 f 2
where ρ represents the density of the object, λ represents the wavelength of the shear wave, and f represents the frequency of the shear wave.
The working process, working details and technical effects of the foregoing apparatus provided in the second aspect of the present embodiment may refer to the first aspect or any one of the possible designs of the method in the first aspect, which are not described herein again.
As shown in fig. 8, a third aspect of the present embodiment provides a computer device for executing the method of the first aspect or any one of the possible designs of the first aspect, where the memory is configured to store a computer program, and a processor, where the processor is configured to read the computer program and execute the magnetic resonance elasticity measurement method of the first aspect or any one of the possible designs of the first aspect. By way of specific example, the Memory may include, but is not limited to, random-Access Memory (RAM), read-Only Memory (ROM), flash Memory (Flash Memory), first-in first-out Memory (First Input First Output, FIFO), and/or first-in last-out Memory (First Input Last Output, FILO), etc.; the processor may not be limited to use with a microprocessor of the STM32F105 family. In addition, the computer device may include, but is not limited to, a power module, a display screen, and other necessary components.
The working process, working details and technical effects of the foregoing computer device provided in the third aspect of the present embodiment may refer to the first aspect or any one of the possible designs of the method in the first aspect, which are not described herein again.
As shown in fig. 9 to 10, a fourth aspect of the present embodiment provides a magnetic resonance elasticity measurement system applying the method of the first aspect or any one of the possible designs of the first aspect, including a nuclear magnetic resonance subsystem, a mechanical vibration excitation device, a probe module and a console, where the nuclear magnetic resonance subsystem includes a magnetic resonance spectrometer, a radio frequency power amplifier, a preamplifier and a transceiver switch, the mechanical vibration excitation device includes a waveform generator and a power amplifier, and the probe module includes a magnet 31, a radio frequency coil 32, a vibration generator 33, a transmission rod 34, a linear reciprocating mechanism 35 and a probe housing 36.
The radio frequency signal output end of the magnetic resonance spectrometer is electrically connected with the radio frequency signal input end of the radio frequency power amplifier, the radio frequency signal output end of the radio frequency power amplifier is electrically connected with the first switching end of the transmit-receive change-over switch, the echo signal input end of the preamplifier is electrically connected with the second switching end of the transmit-receive change-over switch, the echo signal output end of the preamplifier is electrically connected with the echo signal input end of the nuclear magnetic resonance spectrometer, the controlled end of the transmit-receive change-over switch is electrically connected with the gate control signal output end of the nuclear magnetic resonance spectrometer, and the switching public end of the transmit-receive change-over switch is electrically connected with the radio frequency coil 32. The specific principles of operation of the aforementioned magnetic resonance spectrometer, radio frequency power amplifier, preamplifier, transmit-receive switch and radio frequency coil 32 are fundamental principles of existing magnetic resonance systems, which can all be implemented with existing equipment.
The synchronous control signal output end of the magnetic resonance spectrometer is electrically connected with the controlled end of the waveform generator, the sine wave signal output end of the waveform generator is electrically connected with the signal input end of the power amplifier, and the signal output end of the power amplifier is electrically connected with the signal input end of the vibration generator 33. In the scanning stage, the magnetic resonance spectrometer is responsible for emitting a radio frequency signal (the radio frequency signal is amplified by the radio frequency power amplifier, then the radio frequency coil excites the detected object, then the radio frequency coil receives the magnetic resonance signal, the magnetic resonance signal is collected and processed by the spectrometer after being amplified by the preamplifier), and simultaneously emits a synchronous control signal, so that the waveform generator is controlled to generate a sine wave signal with specific frequency and specific intensity, the sine wave signal is amplified by the power amplifier and then drives the vibration generator 33 to work, and finally vibration is transmitted into the detected object 100 through the transmission rod 34, so that shear waves with corresponding frequency are generated inside the detected object 100.
The magnet 31 and the radio frequency coil 32 are respectively positioned in the probe housing 36 and are fixed on the movable part of the linear reciprocating mechanism 35 as a movement module, the vibration generator 33 is fixed in the probe housing 36, the vibration output end of the vibration generator 33 is fixedly connected with one end of the transmission rod 34, and the other end of the transmission rod 34 sequentially passes through the magnet 31, the radio frequency coil 32 and the probe housing 36 to be used for contacting an external detected object 100; the linear reciprocating mechanism 35 is fixed inside the probe housing 36, and is configured to drive the movable portion to reciprocate linearly inside the probe housing 36 away from or toward the object 100. The magnet 31 may preferably be a single-sided magnet of special design so as to have a natural gradient field, which can be used for motion encoding without the need for gradient power amplifiers and gradient coils in conventional magnetic resonance systems; the rf coil 32 is used as a signal probe, preferably a specially designed transceiver integrated dual-frequency rf coil. The linear reciprocating mechanism 35 is configured to drive the motion module to be located at a plurality of equidistant positions from the object 100 under the control of the console, so as to start the magnetic resonance spectrometer to sample by applying an elastic measurement pulse sequence to obtain a plurality of groups of magnetic resonance signals corresponding to the plurality of equidistant positions one by one; the linear reciprocating mechanism 35 may be implemented using a conventional mechanism, such as a vertical lift mechanism. In addition, the other end of the transmission rod 34 preferably passes through the center holes of the magnet 31 and the radio frequency coil 32.
The console is respectively connected to the magnetic resonance spectrometer and the linear reciprocating mechanism 35 in a communication manner, and is configured to send a plurality of elastic measurement control instructions to the magnetic resonance spectrometer and the linear reciprocating mechanism 35, and receive a plurality of sets of magnetic resonance signals acquired by the magnetic resonance spectrometer and measured for the object 100 to be detected, so as to complete data processing, where the data processing includes, but is not limited to, executing the magnetic resonance elastic measurement method according to the first aspect or any one of the first aspects.
In one possible design, the number of elastic measurement control instructions includes, but is not limited to, the following:
a first control command sent to the linear reciprocating mechanism 35 at the beginning of measurement so as to drive the movement module to reach a preset initial position from the object 100 to be inspected;
a second control instruction is sent to the magnetic resonance spectrometer after the first control instruction is sent, so that the magnetic resonance spectrometer is started to control the waveform generator to generate a sine wave signal, and the vibration generator 33 is driven by the power amplifier to output simple harmonic vibration, wherein the frequency of the sine wave signal and/or the simple harmonic vibration is equal to the frequency of a shear wave;
A third control instruction is sent to the magnetic resonance spectrometer after the second control instruction is sent, so that the magnetic resonance spectrometer is started to apply elastic measurement pulse sequence sampling to obtain a group of magnetic resonance signals containing a plurality of spin echo signals;
a fourth control command sent to the linear reciprocating mechanism 35 after the third control command is sent, so as to drive the movement modules to respectively reach a plurality of equidistant positions from the object 100 to be inspected;
and a fifth control instruction is sent to the magnetic resonance spectrometer after the fourth control instruction is sent, so that the magnetic resonance spectrometer is started to apply elastic measurement pulse sequence sampling to obtain a plurality of groups of magnetic resonance signals corresponding to the equidistant positions one by one.
In one possible design, the third control instruction sent to the magnetic resonance spectrometer after the second control instruction is sent includes: and after the second control instruction is sent and when the preset time is up, the control instruction is sent to the magnetic resonance spectrometer so as to start the magnetic resonance spectrometer to sample by applying an elastic measurement pulse sequence to obtain a group of magnetic resonance signals containing a plurality of spin echo signals. The purpose of the delayed transmission of the aforementioned control command is to ensure that the shear wave has propagated to the measurement area and has stabilized, the preset time τ being for example 200ms.
The working process, working details and technical effects of the foregoing measurement system provided in the fourth aspect of the present embodiment may refer to the first aspect or any one of the possible designs of the method in the first aspect, which are not described herein again. In addition, the elastic measurement can be realized based on low-field nuclear magnetic resonance, and the traditional magnetic resonance system is simplified according to specific requirements, so that the system is lighter and more convenient, and better economic benefit can be generated.
A fifth aspect of the present embodiment provides a storage medium storing instructions comprising the method of the first aspect or any one of the possible designs of the first aspect, i.e. instructions stored on the storage medium, which when run on a computer, perform a magnetic resonance elasticity measurement method as described in the first aspect or any one of the possible designs of the first aspect. The storage medium refers to a carrier for storing data, and may include, but is not limited to, a computer readable storage medium including a floppy disk, an optical disk, a hard disk, a flash Memory, a flash disk, and/or a Memory Stick (Memory Stick), where the computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable devices.
The working process, working details and technical effects of the foregoing storage medium provided in the fifth aspect of the present embodiment may refer to the first aspect or any one of the possible designs of the method in the first aspect, which are not described herein again.
A sixth aspect of the present embodiment provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the magnetic resonance elasticity measurement method as described in the first aspect or any one of the possible designs of the first aspect. Wherein the computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some of the technical features thereof can be replaced by equivalents. Such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Finally, it should be noted that the invention is not limited to the alternative embodiments described above, but can be used by anyone in various other forms of products in the light of the present invention. The above detailed description should not be construed as limiting the scope of the invention, which is defined in the claims and the description may be used to interpret the claims.
Claims (10)
1. A method of magnetic resonance elastography, comprising:
acquiring N groups of magnetic resonance signals obtained by measuring a detected object, wherein the N groups of magnetic resonance signals are in one-to-one correspondence with N equidistant positions of a motion module from the detected object, each group of magnetic resonance signals in the N groups of magnetic resonance signals comprises M spin echo signals obtained by applying elastic measurement pulse sequence sampling by a magnetic resonance spectrometer after shear waves propagate to a measurement area and when the motion module is away from the corresponding position of the detected object, the detected object is positioned in the measurement area, the motion module comprises a magnet and a radio frequency coil, N represents a positive integer not less than 5, and M represents a positive integer not less than 10;
performing phase extraction operation on each spin echo signal in the N groups of magnetic resonance signals to obtain corresponding phase information;
generating a two-dimensional phase information graph containing N.M phase information according to all phase information obtained by taking phases, wherein the phase information of an ith row and an jth column in the two-dimensional phase information graph corresponds to the jth spin echo signal obtained by sampling at the ith position in the N equidistant positions one by one, i represents a positive integer not more than N, and j represents a positive integer not more than M;
Zero padding operation is carried out on the periphery of the two-dimensional phase information graph to generate a two-dimensional matrix containing P, Q and P represents a positive integer greater than N, and Q represents a positive integer greater than M;
performing two-dimensional Fourier transform on the two-dimensional matrix to obtain frequency domain information;
selecting frequency information corresponding to the frequency of the shear wave and corresponding to the interested wavelength of the shear wave from the frequency domain information;
performing inverse Fourier transform on the selected frequency information to obtain a new information diagram from which the longitudinal wave interference is removed;
according to the new information graph, calculating the wavelength of the shear wave;
the young's modulus for characterizing the elasticity of the object to be examined is calculated according to the following formula:
E＝3ρλ 2 f 2
where ρ represents the density of the object, λ represents the wavelength of the shear wave, and f represents the frequency of the shear wave.
2. The magnetic resonance elasticity measurement method of claim 1, wherein selecting frequency information corresponding to a frequency of the shear wave from the frequency domain information includes:
the time dimension frequency step delta f is calculated according to the following formula t ：
Wherein Q represents the total column number of the two-dimensional matrix, and Δt represents the sampling interval time of the M spin echo signals;
According to the time dimension frequency step delta f t The time dimension center distance L is calculated according to the following formula t ：
Where round () represents a rounding function and f represents the frequency of the shear wave;
in the frequency domain information, selecting the distance center in the time dimension as L t As frequency information corresponding to the frequency of the shear wave.
3. The magnetic resonance elasticity measurement method of claim 1, wherein selecting frequency information corresponding to a wavelength of interest of the shear wave from the frequency domain information includes:
the space dimension frequency step delta f is calculated according to the following formula s ：
Wherein P represents the total number of rows of the two-dimensional matrix, and Δs represents the equidistant values of the N equidistant positions;
according to the spatial dimension frequency step delta f s The space dimension center distance range L is calculated according to the following formula s,min ,L s,max ]：
In the formula, round () represents a rounding function, λ min Represents the minimum value of the wavelength of interest of the shear wave, lambda max Representing a wavelength maximum of interest of the shear wave;
in the frequency domain information, selecting a distance center between [ L ] in the space dimension s,min ,L s,max ]As frequency information corresponding to the frequency of the shear wave.
4. The method of magnetic resonance elastometry of claim 1, wherein calculating the wavelength of the shear wave from the new information map comprises:
taking any row vector from the new information graph as a reference vector R;
and extracting other row vectors U relative to the reference vector R row by row from the new information graph, and calculating corresponding time shift values relative to the reference vector R by solving the following objective function for each other row vector U:
Min f(s)＝||R(t)-U(t-y)||
wherein y represents a time shift value to be solved, t represents a time abscissa of the reference vector R and other row vectors U, s represents equidistant positions corresponding to the other row vectors U and belonging to the N equidistant positions, i represents an open root number of a sum of squares of components after vector difference, and Min f(s) represents a minimum value of an optimization problem f(s);
according to the time shift values y of the other row vectors U and the equidistant positions s corresponding to the other row vectors U one by one, obtaining a linear relation by least square fitting: y=b×s+c, where c represents another coefficient to be determined;
the wavelength lambda of the shear wave is calculated according to the following formula:
Where f represents the frequency of the shear wave.
5. The magnetic resonance elasticity measurement device is characterized by comprising a signal acquisition unit, a phase extraction operation unit, an information graph generation unit, a zero filling operation unit, a Fourier transformation unit, a frequency information selection unit, an inverse Fourier transformation unit, a wavelength calculation unit and a Young modulus calculation unit which are sequentially connected in a communication mode;
the signal acquisition unit is used for acquiring N groups of magnetic resonance signals obtained by measuring an object to be detected, wherein the N groups of magnetic resonance signals are in one-to-one correspondence with N equidistant positions of a motion module from the object to be detected, each group of magnetic resonance signals in the N groups of magnetic resonance signals comprises M spin echo signals obtained by applying elastic measurement pulse sequence sampling by a magnetic resonance spectrometer after shear waves propagate to a measurement area and when the motion module is away from the corresponding position of the object to be detected, the object to be detected is positioned in the measurement area, the motion module comprises a magnet and a radio frequency coil, N represents a positive integer not less than 5, and M represents a positive integer not less than 10;
the phase extraction operation unit is used for carrying out phase extraction operation on each spin echo signal in the N groups of magnetic resonance signals to obtain corresponding phase information;
The information map generating unit is configured to generate a two-dimensional phase information map including n×m phase information according to all phase information obtained by phase extraction, where phase information of an ith row and an jth column in the two-dimensional phase information map corresponds to a jth spin echo signal obtained by sampling at an ith position in the N equidistant positions one by one, i represents a positive integer not greater than N, and j represents a positive integer not greater than M;
the zero-filling operation unit is used for performing zero-filling operation on the periphery of the two-dimensional phase information graph to generate a two-dimensional matrix containing P and Q elements, wherein P represents a positive integer greater than N, and Q represents a positive integer greater than M;
the Fourier transform unit is used for performing two-dimensional Fourier transform on the two-dimensional matrix to obtain frequency domain information;
the frequency information selecting unit is used for selecting frequency information which corresponds to the frequency of the shear wave and corresponds to the interested wavelength of the shear wave from the frequency domain information;
the inverse Fourier transform unit is used for performing inverse Fourier transform on the selected frequency information to obtain a new information diagram from which the longitudinal wave interference is removed;
the wavelength calculation unit is used for calculating the wavelength of the shear wave according to the new information graph;
The young modulus calculation unit is used for calculating young modulus for representing elasticity of the detected object according to the following formula:
E＝3ρλ 2 f 2
where ρ represents the density of the object, λ represents the wavelength of the shear wave, and f represents the frequency of the shear wave.
6. A computer device comprising a memory and a processor in communication, wherein the memory is adapted to store a computer program and the processor is adapted to read the computer program and to perform a magnetic resonance elasticity measurement method according to any one of claims 1-4.
7. The magnetic resonance elasticity measurement system is characterized by comprising a nuclear magnetic resonance subsystem, a mechanical vibration excitation device, a probe module and a control console, wherein the nuclear magnetic resonance subsystem comprises a magnetic resonance spectrometer, a radio frequency power amplifier, a preamplifier and a transceiver change-over switch, the mechanical vibration excitation device comprises a waveform generator and a power amplifier, and the probe module comprises a magnet (31), a radio frequency coil (32), a vibration generator (33), a transmission rod (34), a linear reciprocating mechanism (35) and a probe shell (36);
the radio frequency signal output end of the magnetic resonance spectrometer is electrically connected with the radio frequency signal input end of the radio frequency power amplifier, the radio frequency signal output end of the radio frequency power amplifier is electrically connected with the first switching end of the transceiving change-over switch, the echo signal input end of the preamplifier is electrically connected with the second switching end of the transceiving change-over switch, the echo signal output end of the preamplifier is electrically connected with the echo signal input end of the magnetic resonance spectrometer, the controlled end of the transceiving change-over switch is electrically connected with the gating signal output end of the magnetic resonance spectrometer, and the switching public end of the transceiving change-over switch is electrically connected with the radio frequency coil (32);
The synchronous control signal output end of the magnetic resonance spectrometer is electrically connected with the controlled end of the waveform generator, the sine wave signal output end of the waveform generator is electrically connected with the signal input end of the power amplifier, and the signal output end of the power amplifier is electrically connected with the signal input end of the vibration generator (33);
the magnet (31) and the radio frequency coil (32) are respectively positioned in the probe shell (36) and are fixed on the movable part of the linear reciprocating mechanism (35) as a movement module, the vibration generator (33) is fixed in the probe shell (36), the vibration output end of the vibration generator (33) is fixedly connected with one end of the transmission rod (34), and the other end of the transmission rod (34) sequentially passes through the magnet (31), the radio frequency coil (32) and the probe shell (36) in a movable mode so as to be used for contacting an external detected object (100);
the linear reciprocating mechanism (35) is fixed inside the probe housing (36) and used for driving the movable part to do linear reciprocating motion far away from or close to the detected object (100) inside the probe housing (36);
the console is respectively in communication connection with the magnetic resonance spectrometer and the linear reciprocating mechanism (35) and is used for respectively sending a plurality of elasticity measurement control instructions to the magnetic resonance spectrometer and the linear reciprocating mechanism (35) and receiving a plurality of groups of magnetic resonance signals acquired by the magnetic resonance spectrometer and measured for the detected object (100) to complete data processing, wherein the data processing comprises executing the magnetic resonance elasticity measurement method according to any one of claims 1-4.
8. The magnetic resonance elastometry system of claim 7, wherein the number of elastometry control instructions comprise:
a first control command sent to the linear reciprocating mechanism (35) at the beginning of measurement so as to drive the motion module to reach a preset initial position away from the detected object (100);
a second control instruction is sent to the magnetic resonance spectrometer after the first control instruction is sent, so that the magnetic resonance spectrometer is started to control the waveform generator to generate a sine wave signal, and the vibration generator (33) is driven by the power amplifier to output simple harmonic vibration, wherein the frequency of the sine wave signal and/or the simple harmonic vibration is equal to the frequency of a shear wave;
a third control instruction is sent to the magnetic resonance spectrometer after the second control instruction is sent, so that the magnetic resonance spectrometer is started to apply elastic measurement pulse sequence sampling to obtain a group of magnetic resonance signals containing a plurality of spin echo signals;
a fourth control command sent to the linear reciprocating mechanism (35) after the third control command is sent so as to drive the motion module to respectively reach a plurality of equidistant positions from the detected object (100);
And a fifth control instruction is sent to the magnetic resonance spectrometer after the fourth control instruction is sent, so that the magnetic resonance spectrometer is started to apply elastic measurement pulse sequence sampling to obtain a plurality of groups of magnetic resonance signals corresponding to the equidistant positions one by one.
9. The magnetic resonance elastometry system of claim 8, wherein a third control instruction sent to the magnetic resonance spectrometer after sending the second control instruction comprises:
and after the second control instruction is sent and when the preset time is up, the control instruction is sent to the magnetic resonance spectrometer so as to start the magnetic resonance spectrometer to sample by applying an elastic measurement pulse sequence to obtain a group of magnetic resonance signals containing a plurality of spin echo signals.
10. A storage medium having instructions stored thereon which, when executed on a computer, perform the magnetic resonance elastometry method of any of claims 1-4.
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