CN109085522B - Method and device for acquiring magnetic resonance diffusion weighted imaging and spectrum signals - Google Patents
Method and device for acquiring magnetic resonance diffusion weighted imaging and spectrum signals Download PDFInfo
- Publication number
- CN109085522B CN109085522B CN201810708108.4A CN201810708108A CN109085522B CN 109085522 B CN109085522 B CN 109085522B CN 201810708108 A CN201810708108 A CN 201810708108A CN 109085522 B CN109085522 B CN 109085522B
- Authority
- CN
- China
- Prior art keywords
- signals
- magnetic resonance
- diffusion
- excited state
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- G01R33/5602—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse
-
- 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
- G01R33/561—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
Abstract
The embodiment of the application discloses a method and a device for acquiring a magnetic resonance diffusion weighted imaging signal and a spectrum signal. The method utilizes the effective time gap between the excitation and the acquisition of the magnetic resonance diffusion weighted spectrum signals, the characteristic that water molecules and metabolites have different frequency spectrum frequencies and the characteristic that binomial pulses have the characteristic of selectively exciting substances with different frequencies, and can realize the joint acquisition of the magnetic resonance diffusion weighted imaging signals and the spectrum signals in the same signal acquisition sequence by the application of three excitation pulses and two signal acquisition modules. Therefore, the method saves the magnetic resonance scanning time and improves the scanning efficiency. Furthermore, the diffusion-weighted imaging signal and the diffusion-weighted spectrum signal are signals acquired after one excitation, and the two acquired signals can be ensured to be signals from the same body part of a patient, so that the complete registration of the diffusion-weighted imaging and the diffusion-weighted spectrum can be ensured, and accurate clinical diagnosis can be ensured.
Description
Technical Field
The present application relates to the field of magnetic resonance technology, and in particular, to a method and an apparatus for acquiring a magnetic resonance diffusion weighted imaging signal and a spectrum signal.
Background
Magnetic Resonance Weighted Imaging (DWI) Imaging provides tissue contrast that is different from conventional Magnetic Resonance Imaging (DWI) images and can provide potentially unique information about the survival and development of brain tissue. It is very sensitive to the identification of acute cerebral infarction and other brain acute lesions, and can provide information on lesions such as tumor, infection, trauma and demyelination.
The diffusion weighted imaging utilizes the random and irregular Brownian motion characteristics of water molecules in tissues to carry out imaging, is a non-invasive method capable of detecting the diffusion motion of the water molecules in living tissues, and can provide the functional state characteristics of various tissues of a human body at the molecular level.
Dispersion Weighted Spectroscopy (DWS) is a method for measuring the dispersion characteristics of various metabolites in vivo by non-invasively collecting dispersion Weighted spectral signals, and a detection method for measuring the molecular composition and the spatial configuration of the metabolites by using chemical shift in magnetic resonance is successfully applied to the cerebral infarction research, so that a new thought is provided for the research of the pathophysiology of the cerebral infarction.
Currently, combining magnetic resonance diffusion-weighted imaging and diffusion-weighted spectroscopy techniques can provide more valuable diagnostic results.
Currently, the acquisition of the diffusion weighted imaging signal and the spectral signal is implemented by separate signal acquisition sequences. This acquisition mode is not conducive to increasing the magnetic resonance scan time. Moreover, the diffusion-weighted imaging signals and the spectrum signals obtained by independently acquiring the diffusion-weighted imaging signals and the spectrum signals respectively are relatively discrete, so that the magnetic resonance diffusion-weighted imaging and the spectrum cannot be completely registered, thereby bringing troubles to clinical diagnosis.
Disclosure of Invention
In view of this, the embodiments of the present application provide a method and an apparatus for acquiring magnetic resonance diffusion weighted imaging and spectrum signals, so as to integrate a magnetic resonance diffusion weighted imaging signal acquisition process and a magnetic resonance diffusion weighted spectrum signal acquisition process into one signal acquisition sequence, thereby achieving the purposes of saving magnetic resonance scanning time and improving scanning efficiency on one hand, and improving the degree of registration of magnetic resonance diffusion weighted imaging and spectrum on the other hand.
In order to achieve the above purpose, the embodiments of the present application adopt the following technical solutions:
a method of acquiring magnetic resonance diffusion weighted imaging signals and spectroscopy signals, comprising:
applying a first excitation pulse to excite a plane of interest of a magnetic resonance scanning object so that water molecules and metabolites in the plane of interest are both in an excited state;
applying a second excitation pulse to maintain the water molecules in an excited state and to maintain the metabolites in a suppressed state;
acquiring water molecule signals in an excited state to obtain magnetic resonance diffusion weighted imaging signals;
applying a third excitation pulse to excite the metabolite in an excited state and to place the water molecules in a suppressed state;
and collecting substance peak signals of the metabolites in the excited state to obtain dispersion weighted spectrum signals.
Optionally, after the applying the first excitation pulse and before the applying the second excitation pulse, the method further includes:
a first partial diffusion encoding gradient pulse is applied to first diffusion encode the water molecule and metabolite signals in the excited state.
Optionally, after the applying the second excitation pulse and before the acquiring the water molecule signal in the excited state, the method further includes:
applying a second partial diffusion coding gradient pulse to carry out second diffusion coding on the water molecule signals in the excited state;
the acquiring of water molecule signals in an excited state to obtain magnetic resonance diffusion weighted imaging signals specifically comprises:
and acquiring water molecule signals which are subjected to second diffusion coding and in an excited state to obtain magnetic resonance diffusion weighted imaging signals.
Optionally, after the applying the third excitation pulse and before the acquiring the substance peak signal of the metabolite in the excited state, the method further includes:
applying a third part diffusion coding gradient pulse to carry out third diffusion coding on the substance peak signal of the metabolite in the excited state;
the collecting of the substance peak signal of the metabolite in the excited state to obtain the dispersion weighted spectrum signal specifically includes:
and collecting substance peak signals of the metabolites which are subjected to the third dispersion coding and are in an excited state to obtain dispersion weighted spectrum signals.
Optionally, the second excitation pulse and the third excitation pulse are both binomial pulses.
An apparatus for acquiring magnetic resonance diffusion weighted imaging signals and spectroscopy signals, comprising:
the first excitation module is used for applying a first excitation pulse to excite an interested plane of a magnetic resonance scanning object, so that water molecules and metabolites in the interested plane are in an excited state;
the second excitation module is used for applying a second excitation pulse so as to enable the water molecules to be in an excited state continuously and enable the metabolites to be in a suppressed state;
the diffusion weighted imaging signal acquisition module is used for acquiring water molecule signals in an excited state to obtain magnetic resonance diffusion weighted imaging signals;
the third excitation module is used for applying a third excitation pulse to excite the metabolites to be in an excited state and enable water molecules to be in a suppression state;
and the dispersion weighted spectrum signal acquisition module is used for acquiring substance peak signals of the metabolites in the excited state to obtain dispersion weighted spectrum signals.
Optionally, the apparatus further comprises:
and the first diffusion coding gradient module is used for performing first diffusion coding on water molecule and metabolite signals in an excited state after the first excitation pulse is applied and before the second excitation pulse is applied.
Optionally, the apparatus further comprises:
the second diffusion coding gradient module is used for performing second diffusion coding on the water molecule signals in the excited state after the second excitation pulse is applied and before the water molecule signals in the excited state are collected;
the diffusion weighted imaging signal acquisition module is specifically used for acquiring water molecule signals which are subjected to second diffusion coding and are in an excited state so as to obtain magnetic resonance diffusion weighted imaging signals.
Optionally, the apparatus further comprises:
the third diffusion coding gradient module is used for performing third diffusion coding on the substance peak signal of the metabolite in the excited state after the third excitation pulse is applied and before the substance peak signal of the metabolite in the excited state is acquired;
the dispersion weighted spectrum signal acquisition module is specifically used for:
and collecting substance peak signals of the metabolites which are subjected to the third dispersion coding and are in an excited state to obtain dispersion weighted spectrum signals.
Optionally, the second excitation module and the third excitation module are both binomial pulse modules.
Compared with the prior art, the embodiment of the application has the following beneficial effects:
based on the fact that a period of time elapses from signal excitation to signal acquisition in a magnetic resonance dispersion weighted spectrum signal scanning sequence, the acquisition method provided by the embodiment of the present application acquires magnetic resonance dispersion weighted imaging signals before acquiring magnetic resonance spectrum signals after excitation of a plane of interest of a magnetic resonance scanning object by using an effective time gap between excitation and acquisition of magnetic resonance spectrum signals, so that magnetic resonance dispersion weighted imaging signals and magnetic resonance dispersion weighted spectrum signals can be obtained in one magnetic resonance spectrum signal scanning sequence, that is, the embodiment of the present application integrates an acquisition process of magnetic resonance dispersion weighted imaging signals into a magnetic resonance dispersion weighted spectrum signal scanning sequence, so that the acquisition method provided by the embodiment of the present application can obtain magnetic resonance dispersion weighted imaging signals and magnetic resonance dispersion weighted spectrum signals in one magnetic resonance dispersion weighted spectrum scanning sequence, therefore, the acquisition method provided by the embodiment of the application integrates the magnetic resonance diffusion weighted imaging signal acquisition process and the magnetic resonance diffusion weighted spectrum signal acquisition process into a signal acquisition sequence. Therefore, compared with the prior art, the acquisition method provided by the embodiment of the application saves the time for acquiring the magnetic resonance diffusion weighted imaging signal, thereby saving the magnetic resonance scanning time and improving the scanning efficiency.
Furthermore, the magnetic resonance diffusion weighted imaging signal and the magnetic resonance spectrum signal acquired by the embodiment of the application are acquired after one excitation, and the two acquired signals can be ensured to be from the signals of the same body part of the patient, so that the complete registration of the magnetic resonance diffusion weighted imaging and the spectrum can be ensured, and the accurate clinical diagnosis can be ensured.
Drawings
In order that the detailed description of the present application may be clearly understood, a brief description of the drawings that will be used when describing the detailed description of the present application will be provided. It is to be understood that these drawings are merely illustrative of some of the embodiments of the application.
Figure 1 is a schematic diagram of a magnetic resonance system employed in an embodiment of the present application;
figure 2 is a schematic diagram of a magnetic resonance signal scan sequence employed in an embodiment of the present application;
FIG. 3 is a schematic flowchart of a method for acquiring magnetic resonance diffusion-weighted imaging signals and spectroscopic signals according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a pulse sequence employed in a gradient echo planar imaging method;
FIG. 5 is a schematic diagram of a pulse sequence employed by the excitation echo acquisition method;
figure 6 is a schematic diagram of another magnetic resonance signal scan sequence employed in an embodiment of the present application;
FIG. 7 is a schematic flow chart diagram illustrating an alternative embodiment of a method for acquiring magnetic resonance diffusion weighted imaging signals and spectroscopic signals provided by an embodiment of the present application;
FIG. 8 is a schematic diagram of a control apparatus for performing a method for acquiring magnetic resonance diffusion weighted imaging signals and spectroscopic signals in accordance with an embodiment of the present application;
fig. 9 is a schematic structural diagram of an acquisition apparatus for magnetic resonance diffusion weighted imaging signals and spectrum signals according to an embodiment of the present application.
Detailed Description
At present, a magnetic resonance diffusion weighted imaging signal acquisition process and a magnetic resonance diffusion weighted spectrum signal acquisition process are two completely independent signal acquisition processes. Thus, the magnetic resonance scanning time is the sum of the magnetic resonance diffusion weighted imaging signal scanning time and the diffusion weighted spectrum signal scanning time, which results in longer magnetic resonance signal acquisition time and lower magnetic resonance scanning efficiency.
In addition, because the acquisition process of the magnetic resonance diffusion weighted imaging signal and the acquisition process of the magnetic resonance diffusion weighted spectrum signal are completely independent, the time difference exists between the acquisition time of the diffusion weighted imaging signal and the acquisition time of the diffusion weighted spectrum signal, so that the acquired diffusion weighted imaging signal and the diffusion weighted spectrum signal are relatively discrete, and if the patient moves in the interval time of the scanning magnetic resonance diffusion weighted imaging signal and the scanning magnetic resonance diffusion weighted spectrum signal, the acquired magnetic resonance diffusion weighted imaging signal and the magnetic resonance diffusion weighted spectrum signal may not come from the signal of the same body area of the patient, so that the magnetic resonance diffusion weighted imaging and the diffusion weighted spectrum cannot be completely registered, thereby bringing troubles to clinical diagnosis.
In the process of solving the technical problems, the inventor of the present application has made the following research findings: in a magnetic resonance diffusion-weighted spectroscopy signal scan sequence, the diffusion-weighted spectroscopy signals are not acquired immediately after signal excitation, but rather a period of time elapses from signal excitation to diffusion-weighted spectroscopy signal acquisition. The acquisition of the magnetic resonance diffusion weighted imaging signal is immediately acquired after excitation, and the acquisition of the magnetic resonance diffusion weighted imaging signal and the acquisition of the excitation pulse of the magnetic resonance diffusion weighted spectrum signal can be shared. Furthermore, water and metabolites have different spectral frequencies, and thus water or metabolites may be selectively excited when appropriate excitation pulses are utilized.
Based on the above research, the embodiments of the present application utilize the effective time gap between excitation and acquisition of the magnetic resonance dispersion weighted spectrum signals to acquire the magnetic resonance dispersion weighted imaging signals before acquiring the magnetic resonance dispersion weighted spectrum signals after excitation of the interest plane of the magnetic resonance scanning object, so that the magnetic resonance dispersion weighted imaging signals and the magnetic resonance dispersion weighted spectrum signals can be obtained in a magnetic resonance dispersion weighted spectrum signal scanning sequence, that is, the embodiments of the present application integrate the acquisition process of the magnetic resonance dispersion weighted imaging signals into the magnetic resonance dispersion weighted spectrum signal scanning sequence, so that the embodiments of the present application provide the acquisition method of the magnetic resonance dispersion weighted imaging signals and the dispersion weighted spectrum signals can obtain the magnetic resonance dispersion weighted imaging signals and the magnetic resonance dispersion weighted spectrum signals in a magnetic resonance dispersion weighted spectrum scanning sequence, therefore, the acquisition method provided by the embodiment of the application integrates the magnetic resonance diffusion weighted imaging signal acquisition process and the magnetic resonance diffusion weighted spectrum signal acquisition process into a signal acquisition sequence. Therefore, compared with the prior art, the acquisition method provided by the embodiment of the application saves the time for acquiring the magnetic resonance diffusion weighted imaging signal, thereby saving the magnetic resonance scanning time and improving the scanning efficiency.
In addition, the magnetic resonance diffusion weighted imaging signal and the magnetic resonance diffusion weighted spectrum signal acquired by the embodiment of the application are acquired after one-time excitation, and the two acquired signals can be ensured to be from the signals of the same body part of a patient, so that the complete registration of the magnetic resonance diffusion weighted imaging and the magnetic resonance diffusion weighted spectrum can be ensured, and accurate clinical diagnosis can be ensured.
The following detailed description of specific embodiments of the present application is provided in conjunction with the accompanying drawings.
A magnetic resonance system 10 employed in an embodiment of the present application will first be described with reference to figure 1. Referring to fig. 1, the magnetic resonance system includes a magnetic resonance scanner 11, a console 12, peripheral devices 13, a DWI processing module 14, and a DWS processing module 15.
The internal components of the magnetic resonance scanner 11 include, for example: a magnet 111 generating a static magnetic field (B0), sets of magnetic field gradient coil windings 112 for superimposing selected magnetic field gradients on the static magnetic field, a radio frequency transmit coil 113 for generating a radio frequency field (B1), a radio frequency receive coil 114 for detecting magnetic resonance signals transmitted from the scanned subject, and a patient bed 115 for housing the scanned subject.
The console 12 is used for operator control of the magnetic resonance scan and can display the resulting magnetic resonance imaging and magnetic resonance spectra.
The peripheral device 13 includes a gradient power amplifier 131, a radio frequency power amplifier 132, a receiving unit 133, a gate control unit 134, a radio frequency control unit 135, a gradient control unit 136, a patient bed control unit 137, a sequence control unit 138, and the like.
The DWI processing module 14 is configured to, after receiving the DWI signal from the receiving unit 133, perform image processing, such as fourier transform, on the DWI signal to generate a DWI image.
The DWS processing module 15 is configured to receive the DWS signal from the receiving unit 133, and then perform image processing, such as fourier transform, on the DWS signal to generate a DWS spectrum.
The magnetic resonance diffusion weighted imaging signal and the diffusion weighted spectrum signal acquisition method provided by the embodiment of the application only relate to the magnetic resonance scanner 11, the console 12 and the peripheral equipment 13 in the magnetic resonance system 10 shown in fig. 1, and do not relate to the DWI processing module 14 for image processing and the DWS processing module 15 for spectrum processing.
In addition, in order to solve the above technical problem, the magnetic resonance signal scanning sequence adopted by the present application is as shown in fig. 2. In the signal scan pulse sequence, RF represents an excitation pulse sequence, and ACQ represents a signal acquisition segment sequence. The sequence of excitation pulses comprises a first excitation pulse 21, a second excitation pulse 22 and a third excitation pulse 23, wherein:
the first excitation pulse 21 may excite all substances in a plane of interest of the subject of a magnetic resonance scan such that all substances in the plane of interest are in an excited state. Wherein all substances on the plane of interest include water molecules and various chemical metabolites.
The second excitation pulse 22 may retain the water molecule signal in the excited state and suppress the substance peak signal of the metabolite, leaving the substance peak signal in the suppressed state.
The third excitation pulse 23 may excite the substance peak signal of the metabolite and suppress the water molecule signal.
As an example, second excitation pulse 22 and third excitation pulse 23 may both be binomial pulses that may selectively excite species having different frequencies. Thus, water and metabolites having different frequencies are selectively excited using the binomial pulse, so that a water signal and a substance peak signal of the metabolite are collected after different excitations.
Based on the magnetic resonance system 10 shown in fig. 1 and the magnetic resonance signal scanning sequence shown in fig. 2, a flow chart of the method for acquiring magnetic resonance diffusion weighted imaging signals and spectrum signals provided by the present application is shown in fig. 3, and includes the following steps:
s301: a first excitation pulse is applied to excite a plane of interest of a magnetic resonance scanning subject such that water molecules and metabolites within the plane of interest are both in an excited state.
It should be noted that in the embodiment of the present application, the first excitation pulse may be a pulse with a flip angle of 90 °, which can activate all the substances on the excitation plane to make all the substances in the excited state.
The substance in an excited state flips along the magnetization vector in the direction of the main magnetic field (Z-direction) to a plane perpendicular to the direction of the main magnetic field, i.e. the X-Y plane. The signal lying in the X-Y plane can be captured by the received signal and can thus be acquired.
In the present example, all substances on the excitation plane include water and various metabolites. Thus, after application of the first excitation pulse, the magnetization vector of the water and metabolites in the direction of the main magnetic field (Z-direction) in the excitation plane is flipped onto a plane perpendicular to the direction of the main magnetic field, i.e. the X-Y plane.
S302: a second excitation pulse is applied to keep the water molecules in the excited state and the metabolites in the inhibited state.
Due to the different excitation frequencies of water molecules and metabolites, suitable pulses such as binomial pulses can be selected to excite one species and suppress the other species, i.e., one species flips over and the other does not.
In an embodiment of the application, the second excitation pulse may be a binomial pulse, and the binomial pulse is capable of keeping a magnetization vector of water molecules in a direction of the main magnetic field (Z direction) on a plane perpendicular to the direction of the main magnetic field, and the metabolite is flipped from the plane perpendicular to the direction of the main magnetic field (Z direction). That is, the second excitation pulse does not act on the water molecules, thereby maintaining the water molecules in an excited state after the first excitation, while the second excitation pulse acts on the metabolites to flip from a plane perpendicular to the direction of the main magnetic field to a direction along the direction of the main magnetic field (Z direction) back to an unexcited state. Thus, after excitation by the second excitation pulse, the water molecules remain in the excited state, while the metabolites flip to the suppressed state.
S303: and acquiring water molecule signals in an excited state to obtain magnetic resonance diffusion weighted imaging signals.
Since the magnetization vector of the water molecules in the direction of the main magnetic field (Z direction) is maintained in a plane perpendicular to the direction of the main magnetic field, the water molecule signal can be captured by the receiving coil. Therefore, water molecule signals in an excited state can be acquired, and magnetic resonance diffusion weighted imaging signals are obtained. The magnetic resonance diffusion weighted imaging signal is subjected to Fourier transform to obtain magnetic resonance diffusion weighted imaging.
S304: a third excitation pulse is applied to excite the metabolite in an excited state and to place the water molecules in a suppressed state.
In an embodiment of the present application, the third excitation pulse may also be a binomial pulse, and the binomial pulse is capable of flipping a magnetization vector of a water molecule in the direction of the main magnetic field (Z direction) into the direction of the main magnetic field (Z direction), such that a magnetization vector of a metabolite in the direction of the main magnetic field (Z direction) is flipped into a plane perpendicular to the direction of the main magnetic field. That is, the third excitation pulse does not act on the metabolite so that the metabolite is maintained in the suppressed state after the second excitation, and the third excitation pulse acts on the water molecule to turn it from a plane perpendicular to the direction of the main magnetic field to a direction along the direction of the main magnetic field (Z direction) to return to the unexcited state. Thus, after excitation by the third excitation pulse, water molecules are in a suppressed state, while metabolites are excited to an excited state.
S305: and collecting substance peak signals of the metabolites in the excited state to obtain dispersion weighted spectrum signals.
The metabolite in the excited state flips its magnetization vector in the direction of the main magnetic field (Z-direction) in a plane perpendicular to the direction of the main magnetic field. The substance peak signal of the metabolite can thus be captured by the receiving coil. Therefore, the substance peak signals of the metabolites in the excited state can be collected, so as to obtain the magnetic resonance diffusion weighted spectrum signals. The magnetic resonance dispersion weighted spectrum can be obtained by Fourier transform of the magnetic resonance dispersion weighted spectrum signal.
The above is a specific implementation manner of the method for acquiring a magnetic resonance diffusion weighted imaging signal and a spectrum signal provided in the embodiment of the present application. In this particular implementation, the combined acquisition of magnetic resonance dispersion weighted imaging signals and spectroscopic signals in the same signal acquisition sequence can be achieved by the application of three excitation pulses and two signal acquisition modules, taking advantage of the time gap between excitation and acquisition of magnetic resonance dispersion weighted spectroscopic signals, the different spectral frequencies of water molecules and metabolites of the species, and the selective excitation of different frequency species by the binomial pulses. The acquisition process of the magnetic resonance dispersion weighted imaging signal and the acquisition method of the dispersion weighted spectrum signal provided by the embodiment of the application can obtain the magnetic resonance dispersion weighted imaging signal and the magnetic resonance dispersion weighted spectrum signal in a magnetic resonance dispersion weighted spectrum scanning sequence, so that the acquisition method provided by the embodiment of the application integrates the magnetic resonance dispersion weighted imaging signal acquisition process and the magnetic resonance dispersion weighted spectrum signal acquisition process into a signal acquisition sequence. Therefore, compared with the prior art, the acquisition method provided by the embodiment of the application saves the time for acquiring the magnetic resonance diffusion weighted imaging signal, thereby saving the magnetic resonance scanning time and improving the scanning efficiency.
In addition, the magnetic resonance diffusion weighted imaging signal and the magnetic resonance diffusion weighted spectrum signal acquired by the embodiment of the application are acquired after one-time excitation, and the two acquired signals can be ensured to be from the signals of the same body part of a patient, so that the complete registration of the magnetic resonance diffusion weighted imaging and the magnetic resonance diffusion weighted spectrum can be ensured, and accurate clinical diagnosis can be ensured.
In addition, in the embodiment of the application, the water signal and the substance peak signal of the metabolite are separated through the binomial excitation pulse, specifically, the substance peak signal of the metabolite is suppressed before the water signal is collected, and the water signal is suppressed before the dispersion weighted spectrum signal is collected, so that the collected dispersion weighted imaging signal and the collected spectrum signal are relatively pure, the imaging signal is not influenced by the substance peak signal, the spectrum signal is not influenced by the dispersion water signal, and the quality of DWI and DWS is favorably improved.
In order to enable the acquired signals to be directly used for magnetic resonance diffusion imaging and spectroscopy, as an alternative embodiment of the present application, a diffusion encoding gradient pulse may be applied after each application of an excitation pulse to achieve spatial encoding of the excitation signals. See in particular the examples below.
A specific implementation of this alternative embodiment of the present application is described below with Echo Planar Imaging (EPI) as an example of magnetic resonance diffusion weighted Imaging and excitation Echo Acquisition (STEAM) as an example of magnetic resonance diffusion weighted spectroscopy.
First, the concepts of gradient echo planar imaging and excitation echo acquisition are introduced.
The gradient echo planar imaging is a fast imaging sequence widely applied at present, after one-time radio frequency excitation, a series of gradient echoes are generated by using a fast inverse gradient and are respectively subjected to phase coding, the gradient echoes are filled into a corresponding k space, and imaging is realized through Fourier transform. Figure 3 shows a schematic diagram of a gradient echo pulse sequence, also called gradient echo pulse sequence timing diagram, showing the time sequence of the application of the various pulses. For example, the line labeled RF represents an RF pulse, the RF pulse in fig. 4 being a 90 ° pulse. Mark GX、GYAnd GZThe lines of (a) represent gradient pulses applied along the x-axis, y-axis and z-axis directions, respectively, and the line labeled ACQ corresponds to the magnetic resonance diffusion weighted imaging signal acquisition segment.
The excitation echo acquisition method is a commonly used spectrum sequence, three planes which are perpendicular to each other are excited by three 90-degree excitation pulses, spectrum signals are limited at the vertical junction of the three planes, namely a focus area of interest, the excitation echo signals in the area are obtained, and curves of different chemical substance peaks in rectangular coordinates, which are frequency distribution curves, namely magnetic resonance spectrogram, are obtained through Fourier transform. The corresponding magnetic resonance spectrum is shown in fig. 5.
In this alternative embodiment, a magnetic resonance scan sequence is employed as shown in figure 6. The pulse sequence in fig. 6 comprises three excitation pulses: the first excitation pulse is a 90 ° pulse, and the second and third excitation pulses are binomial pulses. Mark GX、GYAnd GZThe lines of (a) represent gradient pulses applied along the x-axis, y-axis and z-axis directions, respectively, and the line labeled ACQ corresponds to the magnetic resonance diffusion weighted imaging and spectroscopy signal acquisition segments.
As can be seen from the scanning sequence shown in fig. 6, in the magnetic resonance scanning sequence shown in fig. 6, the magnetic resonance dispersion weighted imaging signal and the acquired magnetic resonance dispersion weighted spectrum signal share a first excitation pulse, and as can be seen from the ACQ line, the signal acquisition sequence of the magnetic resonance dispersion weighted imaging is inserted before the signal acquisition sequence of the magnetic resonance dispersion weighted spectrum by using the idle time period of the signal acquisition sequence of the magnetic resonance dispersion weighted spectrum, so as to achieve the effects of saving the acquisition time and improving the efficiency of the magnetic resonance scanning.
Based on fig. 6, a flow chart of an alternative implementation of the method for acquiring magnetic resonance diffusion weighted imaging signals and spectrum signals provided by the embodiment of the present application is shown in fig. 7, and includes the following steps:
s701: a first excitation pulse is applied to excite a plane of interest of a magnetic resonance scanning subject such that water molecules and metabolites within the plane of interest are both in an excited state.
This step is the same as S301, and for the sake of brevity, it will not be described in detail here, and for specific information, see S301.
S702: a first partial diffusion encoding gradient pulse is applied to first diffusion encode the water molecule and metabolite signals in the excited state.
It should be noted that diffusion weighted imaging and spectroscopy are imaging of molecular motion labeling, primarily by applying a pair of diffusion gradient pulses of equal area and opposite direction of action. The pair of diffusion gradient pulses are set to be denoted by a and B, respectively. Then the phase dispersion is started through A, and the convergence is started through B, the overall effect is that the accumulated phase dispersion of static molecules is 0, the dispersed molecules generate an accumulated phase dispersion phi due to the movement, the phase dispersion degrees of different dispersed molecules are different, and the acquired signal intensity reflects the dispersion degrees of different molecules. It should be noted that any random diffusion motion will result in a dephasing, and the strength of the dephasing represents the strength of the diffusion weighting.
Thus, in this step, the first partial-diffusion-encoding gradient pulse is used to dephase the signals of water molecules and metabolites in the excited state.
S703: a second excitation pulse is applied to keep the water molecules in the excited state and the metabolites in the inhibited state.
This step is the same as S302, and for brevity, will not be described in detail here, for specific information see S302.
S704: and applying a second partial diffusion coding gradient pulse to perform second diffusion coding on the water molecule signals in the excited state.
It should be noted that, in the embodiment of the present application, the first partial diffusion encoding gradient pulse and the second partial diffusion encoding gradient pulse need to be paired. The second partial diffusion coded gradient pulse is used to echo the water signal.
S705: and acquiring water molecule signals which are subjected to second diffusion coding and in an excited state to obtain magnetic resonance diffusion weighted imaging signals.
S706: a third excitation pulse is applied to excite the metabolite in an excited state and to place the water molecules in a suppressed state.
The step is the same as S304, and for brevity, detailed description is omitted here, and for specific information, refer to S304.
S707: and applying a third partial diffusion coding gradient pulse to carry out third diffusion coding on the substance peak signals of the metabolites in the excited state.
In the embodiment of the present application, the first partial diffusion encoding gradient pulse and the third partial diffusion encoding gradient pulse need to be present in pairs.
The third diffusion-coded gradient pulse is used to repolymerize the metabolite signal while dissipating the residual water signal.
S708: and collecting substance peak signals of the metabolites which are subjected to the third dispersion coding and are in an excited state to obtain dispersion weighted spectrum signals.
The above provides an alternative implementation of the method for acquiring magnetic resonance diffusion weighted imaging signals and spectroscopic signals according to the embodiments of the present application. In this alternative embodiment, a diffusion encoding gradient pulse is applied after each application of an excitation pulse to achieve spatial encoding of the excitation signal, which enables the acquired signals to be used directly for magnetic resonance diffusion imaging and spectroscopy.
The method for acquiring magnetic resonance diffusion weighted imaging signals and spectroscopic signals of the above-described embodiment may be performed by the control apparatus shown in fig. 8. The control device shown in fig. 8 includes a processor (processor810, communication Interface 820, memory 830, bus 840), processor810, communication Interface 820, memory 830 communicating with each other via bus 840.
The memory 830 may store logic instructions for acquiring magnetic resonance diffusion weighted imaging signals and spectroscopy signals, and may be a non-volatile memory (non-volatile memory), for example. The processor810 may invoke logic instructions to perform the acquisition of magnetic resonance dispersion weighted imaging signals and spectroscopy signals in the memory 830 to perform the magnetic resonance dispersion weighted imaging signal and spectroscopy signal acquisition methods described above. As an embodiment, the logic instructions for acquiring the magnetic resonance diffusion weighted imaging signals and the spectrum signals may be a program corresponding to control software, and when the processor executes the instructions, the control device may correspondingly display a functional interface corresponding to the instructions on a display interface.
The functions of the logic instructions for acquisition of the magnetic resonance diffusion weighted imaging signals and the spectroscopic signals may be stored in a computer readable storage medium if implemented in the form of software functional units and sold or used as a stand-alone product. Based on such understanding, the technical solutions of the present disclosure may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the methods according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The logic instructions for acquiring the magnetic resonance diffusion weighted imaging signals and the spectrum signals can be called as a magnetic resonance diffusion weighted imaging signal and spectrum signal acquisition device, and the device can be divided into various functional modules. See in particular the examples below.
The following describes a specific implementation of the apparatus for acquiring magnetic resonance diffusion weighted imaging signals and spectrum signals according to the embodiment of the present application.
Figure 9 is a schematic diagram of an acquisition device for magnetic resonance diffusion weighted imaging signals and spectroscopy signals. As shown in fig. 9, the apparatus includes:
a first excitation module 91 for applying a first excitation pulse to excite a plane of interest of a magnetic resonance scanning object, so that water molecules and metabolites in the plane of interest are in an excited state;
a second excitation module 93 for applying a second excitation pulse to retain water molecules in an excited state and to suppress a substance peak signal of a metabolite so that the substance peak signal is in a suppressed state;
a diffusion weighted imaging signal acquisition module 95, configured to acquire water molecule signals in an excited state to obtain magnetic resonance diffusion weighted imaging signals;
a third excitation module 97 for applying a third excitation pulse to excite a substance peak signal of the metabolite and suppress a water molecule signal;
and a dispersion weighted spectrum signal acquisition module 99 for acquiring the substance peak signal of the metabolite in the excited state to obtain a dispersion weighted spectrum signal.
As an optional embodiment of the present application, the apparatus may further include:
a first diffusion coding gradient module 92 for performing a first diffusion coding of water molecules and metabolite signals in an excited state after applying the first excitation pulse and before applying the second excitation pulse.
As another alternative embodiment of the present application, the apparatus may further include:
a second diffusion coding gradient module 94, configured to perform second diffusion coding on the water molecule signal in the excited state after applying the second excitation pulse and before collecting the water molecule signal in the excited state;
the diffusion weighted imaging signal acquisition module 95 is specifically configured to acquire the water molecule signal after the second diffusion coding and in the excited state, so as to obtain a magnetic resonance diffusion weighted imaging signal.
As still another optional embodiment of the present application, the apparatus may further include:
a third diffusion coding gradient module 98, configured to perform third diffusion coding on the substance peak signal of the metabolite in the excited state after applying the third excitation pulse and before collecting the substance peak signal of the metabolite in the excited state;
the dispersion weighted spectrum signal acquisition module 99 is specifically configured to:
and collecting substance peak signals of the metabolites which are subjected to the third dispersion coding and are in an excited state to obtain dispersion weighted spectrum signals.
As yet another alternative embodiment of the present application, the second excitation module and the third excitation module are both binomial pulse modules.
In the device provided by the specific implementation mode, the characteristic that substances of water molecules and metabolites have different frequency spectrums and substances with different frequencies are selectively excited by binomial pulses by utilizing the effective time gap between the excitation and the acquisition of the magnetic resonance dispersion weighted spectrum signals is utilized, and the magnetic resonance dispersion weighted imaging signals and the spectrum signals can be jointly acquired in the same signal acquisition sequence through the application of three excitation pulses and two signal acquisition modules. The acquisition process of the magnetic resonance dispersion weighted imaging signal and the acquisition method of the dispersion weighted spectrum signal provided by the embodiment of the application can obtain the magnetic resonance dispersion weighted imaging signal and the magnetic resonance dispersion weighted spectrum signal in a magnetic resonance dispersion weighted spectrum scanning sequence, so that the acquisition method provided by the embodiment of the application integrates the magnetic resonance dispersion weighted imaging signal acquisition process and the magnetic resonance dispersion weighted spectrum signal acquisition process into a signal acquisition sequence. Therefore, compared with the prior art, the acquisition method provided by the embodiment of the application saves the time for acquiring the magnetic resonance diffusion weighted imaging signal, thereby saving the magnetic resonance scanning time and improving the scanning efficiency.
In addition, the magnetic resonance diffusion weighted imaging signal and the magnetic resonance diffusion weighted spectrum signal acquired by the embodiment of the application are acquired after one-time excitation, and the two acquired signals can be ensured to be from the signals of the same body part of a patient, so that the complete registration of the magnetic resonance diffusion weighted imaging and the magnetic resonance diffusion weighted spectrum can be ensured, and accurate clinical diagnosis can be ensured.
The foregoing is a detailed description of the present application.
Claims (10)
1. A method of acquiring magnetic resonance diffusion weighted imaging signals and spectroscopy signals, comprising:
applying a first excitation pulse to excite a plane of interest of a magnetic resonance scanning object so that water molecules and metabolites in the plane of interest are both in an excited state;
applying a second excitation pulse to maintain the water molecules in an excited state and to maintain the metabolites in a suppressed state;
acquiring water molecule signals in an excited state to obtain magnetic resonance diffusion weighted imaging signals;
applying a third excitation pulse to excite the metabolite in an excited state and to place the water molecules in a suppressed state;
and collecting substance peak signals of the metabolites in the excited state to obtain dispersion weighted spectrum signals.
2. The method of claim 1, wherein after said applying a first excitation pulse and before said applying a second excitation pulse, further comprising:
a first partial diffusion encoding gradient pulse is applied to first diffusion encode the water molecule and metabolite signals in the excited state.
3. The method of claim 2, wherein after the applying the second excitation pulse and before the acquiring water molecule signals in an excited state, further comprising:
applying a second partial diffusion coding gradient pulse to carry out second diffusion coding on the water molecule signals in the excited state;
the acquiring of water molecule signals in an excited state to obtain magnetic resonance diffusion weighted imaging signals specifically comprises:
and acquiring water molecule signals which are subjected to second diffusion coding and in an excited state to obtain magnetic resonance diffusion weighted imaging signals.
4. The method of claim 3, wherein after said applying a third excitation pulse and before said acquiring a substance peak signal of a metabolite in an excited state, further comprising:
applying a third part diffusion coding gradient pulse to carry out third diffusion coding on the substance peak signal of the metabolite in the excited state;
the collecting of the substance peak signal of the metabolite in the excited state to obtain the dispersion weighted spectrum signal specifically includes:
and collecting substance peak signals of the metabolites which are subjected to the third dispersion coding and are in an excited state to obtain dispersion weighted spectrum signals.
5. The method of any of claims 1-4, wherein the second excitation pulse and the third excitation pulse are both binomial pulses.
6. An apparatus for acquiring magnetic resonance diffusion weighted imaging signals and spectroscopy signals, comprising:
the first excitation module is used for applying a first excitation pulse to excite an interested plane of a magnetic resonance scanning object, so that water molecules and metabolites in the interested plane are in an excited state;
the second excitation module is used for applying a second excitation pulse so as to enable the water molecules to be in an excited state continuously and enable the metabolites to be in a suppressed state;
the diffusion weighted imaging signal acquisition module is used for acquiring water molecule signals in an excited state to obtain magnetic resonance diffusion weighted imaging signals;
the third excitation module is used for applying a third excitation pulse to excite the metabolites to be in an excited state and enable water molecules to be in a suppression state;
and the dispersion weighted spectrum signal acquisition module is used for acquiring substance peak signals of the metabolites in the excited state to obtain dispersion weighted spectrum signals.
7. The apparatus of claim 6, further comprising:
and the first diffusion coding gradient module is used for performing first diffusion coding on water molecule and metabolite signals in an excited state after the first excitation pulse is applied and before the second excitation pulse is applied.
8. The apparatus of claim 7, further comprising:
the second diffusion coding gradient module is used for performing second diffusion coding on the water molecule signals in the excited state after the second excitation pulse is applied and before the water molecule signals in the excited state are collected;
the diffusion weighted imaging signal acquisition module is specifically used for acquiring water molecule signals which are subjected to second diffusion coding and are in an excited state so as to obtain magnetic resonance diffusion weighted imaging signals.
9. The apparatus of claim 8, further comprising:
the third diffusion coding gradient module is used for performing third diffusion coding on the substance peak signal of the metabolite in the excited state after the third excitation pulse is applied and before the substance peak signal of the metabolite in the excited state is acquired;
the dispersion weighted spectrum signal acquisition module is specifically used for:
and collecting substance peak signals of the metabolites which are subjected to the third dispersion coding and are in an excited state to obtain dispersion weighted spectrum signals.
10. The apparatus of any one of claims 6-9, wherein the second excitation module and the third excitation module are both binomial pulse modules.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810708108.4A CN109085522B (en) | 2018-07-02 | 2018-07-02 | Method and device for acquiring magnetic resonance diffusion weighted imaging and spectrum signals |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810708108.4A CN109085522B (en) | 2018-07-02 | 2018-07-02 | Method and device for acquiring magnetic resonance diffusion weighted imaging and spectrum signals |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109085522A CN109085522A (en) | 2018-12-25 |
| CN109085522B true CN109085522B (en) | 2021-07-09 |
Family
ID=64836878
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810708108.4A Active CN109085522B (en) | 2018-07-02 | 2018-07-02 | Method and device for acquiring magnetic resonance diffusion weighted imaging and spectrum signals |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109085522B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115656900B (en) * | 2022-11-02 | 2023-06-23 | 佛山瑞加图医疗科技有限公司 | Method and device for reducing influence of system error on magnetic resonance imaging |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6078176A (en) * | 1996-11-08 | 2000-06-20 | General Electric Company | Fast spin echo pulse sequence for diffusion weighted imaging |
| US9470770B2 (en) * | 2011-02-15 | 2016-10-18 | Koninklijke Philips N.V. | Magnetic resonance spectroscopy with automatic phase and B0 correction using interleaved water reference scan |
| EP2699926B1 (en) * | 2011-04-21 | 2015-07-29 | Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. | Spatially encoded phase-contrast mri |
| EP2933651B1 (en) * | 2014-04-17 | 2020-03-18 | Albert-Ludwigs-Universität Freiburg | MRI Method of Hybrid Acquisition in 3D TSE |
| DE102014219320B4 (en) * | 2014-09-24 | 2016-06-16 | Siemens Healthcare Gmbh | Reconstruction of an MR image taking into account the chemical shift |
| JP6708525B2 (en) * | 2016-08-31 | 2020-06-10 | 株式会社日立製作所 | Magnetic resonance measuring apparatus and image processing method |
| CN106249183B (en) * | 2016-09-24 | 2018-10-12 | 中国科学院武汉物理与数学研究所 | One kind is based on spectrum as integrated hyperpolarization xenon magnetic resonance method |
| CN107271937B (en) * | 2017-07-04 | 2019-07-23 | 南京拓谱医疗科技有限公司 | A kind of synchronous acquisition and calibration method of three-dimensional multi-parameter weighted magnetic resonance imaging |
-
2018
- 2018-07-02 CN CN201810708108.4A patent/CN109085522B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN109085522A (en) | 2018-12-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7592810B2 (en) | MRI methods for combining separate species and quantifying a species | |
| Sinha et al. | In vivo diffusion‐weighted MRI of the breast: potential for lesion characterization | |
| Nguyen et al. | T2prep three‐dimensional spiral imaging with efficient whole brain coverage for myelin water quantification at 1.5 tesla | |
| Raya et al. | Methods and applications of diffusion imaging of vertebral bone marrow | |
| Posse et al. | Enhancement of temporal resolution and BOLD sensitivity in real-time fMRI using multi-slab echo-volumar imaging | |
| US5771893A (en) | Method and apparatus for nuclear magnetic resonance imaging of physiological function information | |
| US8030921B2 (en) | Methods for fat signal suppression in magnetic resonance imaging | |
| US7514927B2 (en) | MR multi-slice steady state free precession imaging | |
| US20080211499A1 (en) | Low Power Decoupling for Multi-Nuclear Spectroscopy | |
| EP1751572A1 (en) | Contrast prepared mri involving non-cartesian trajectories with oversampling of the center of k-space | |
| JPS63262145A (en) | Method and system for separating spectrum component | |
| US5283526A (en) | Method for performing single and multiple slice magnetic resonance spectroscopic imaging | |
| US5010300A (en) | Multi-axis pre-saturated spin echo phase encoded spectroscopy | |
| CN109242847B (en) | Magnetic resonance diffusion weighted imaging method and device | |
| CN108324275B (en) | Method and device for acquiring magnetic resonance imaging signal and spectrum signal | |
| CN109085522B (en) | Method and device for acquiring magnetic resonance diffusion weighted imaging and spectrum signals | |
| Mani et al. | Multi‐band‐and in‐plane‐accelerated diffusion MRI enabled by model‐based deep learning in q‐space and its extension to learning in the spherical harmonic domain | |
| Liu et al. | Nuts and bolts of CEST MR imaging | |
| EP1790991A2 (en) | Data processing system and data processing method involving a Wiener filter | |
| JP3699963B2 (en) | Magnetic resonance imaging system | |
| JP4718698B2 (en) | Magnetic resonance imaging system | |
| JPH10305021A (en) | Formation of pulse sequence for nuclear spin tomography and nuclear spin tomographic apparatus | |
| EP4067927B1 (en) | Method and system for magnetic resonance elastography | |
| US20220091208A1 (en) | Methods, systems, and computer readable media for in vivo phase incrementing magnetic resonance spectroscopic imaging (pi-mrsi) for multi-biomarker imaging and for simultaneous imaging of zero quantum-->double quantum (zq-->dq) and dq-->zq coherence pathways | |
| JPH11104106A (en) | Magnetic resonance diagnostic device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |