CN109254255B - Nuclear magnetic resonance transverse relaxation time spectrum measuring method and device and readable storage medium - Google Patents
Nuclear magnetic resonance transverse relaxation time spectrum measuring method and device and readable storage medium Download PDFInfo
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- CN109254255B CN109254255B CN201810952764.9A CN201810952764A CN109254255B CN 109254255 B CN109254255 B CN 109254255B CN 201810952764 A CN201810952764 A CN 201810952764A CN 109254255 B CN109254255 B CN 109254255B
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- 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]
- G01R33/448—Relaxometry, i.e. quantification of relaxation times or spin density
Abstract
The invention provides a nuclear magnetic resonance transverse relaxation time spectrum measuring method, a device and a readable storage medium, wherein the method comprises the following steps: applying a preset pulse sequence to a sample to be detected, wherein the pulse sequence comprises a radio frequency pulse sequence and a gradient pulse sequence; collecting echo signals generated by the sample to be detected according to the pulse sequence; and performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected. Therefore, the influence of inaccurate 180-degree pulse caused by the turning over inaccuracy of the radio frequency field on the measurement of the transverse relaxation nuclear magnetic spectrum can be avoided, the measurement of the transverse relaxation nuclear magnetic spectrum of the sample to be measured can be rapidly realized, and in addition, the precision of the transverse relaxation nuclear magnetic spectrum can be improved.
Description
Technical Field
The invention relates to a petroleum exploration domain, in particular to a nuclear magnetic resonance transverse relaxation time spectrum measuring method and device and a readable storage medium.
Background
After the system in the equilibrium state is subjected to external transient disturbance, the system can return to the original equilibrium state after a certain time, and the period of time which the system goes through is the relaxation time. The nuclear magnetic resonance relaxation time measurement is widely applied to the fields of petroleum, biology, food and chemistry, particularly in the petroleum industry and in petroleum exploration, and the nuclear magnetic resonance logging technology is more and more widely applied because of the characteristics of no damage and accurate measurement of porosity.
In the prior art, the relaxation time of nuclear magnetic resonance logging T2 is first measured, generally by a CPMG pulse sequence. Specifically, a pulse sequence consisting of a 90-degree pulse and a series of 180-degree pulses is applied to a sample to be measured, an echo signal generated by the sample to be measured according to the pulse sequence is collected, and the echo signal is inverted to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured.
However, the measured signal amplitude is too large, so that a relatively long time is required for attenuation, and the 180-degree pulse is inaccurate due to the inaccuracy of the radio frequency field, so that more processing is required to eliminate the inaccuracy. This processing reduces the number of signal acquisitions and reduces the accuracy of the transverse relaxation nuclear magnetic spectrum.
Disclosure of Invention
The invention provides a nuclear magnetic resonance transverse relaxation time spectrum measuring method, a nuclear magnetic resonance transverse relaxation time spectrum measuring device and a readable storage medium, which are used for solving the technical problems that a transverse relaxation nuclear magnetic spectrum is not fast enough when a pulse sequence consisting of 90-degree pulses and a series of 180-degree pulses is adopted to test the transverse relaxation nuclear magnetic spectrum in the prior art, and the precision of the transverse relaxation nuclear magnetic spectrum is reduced to eliminate 180-degree inaccurate couple.
The first aspect of the present invention provides a nuclear magnetic resonance transverse relaxation time spectrum measurement method, including:
applying a preset pulse sequence to a sample to be detected, wherein the pulse sequence comprises a radio frequency pulse sequence and a gradient pulse sequence;
collecting echo signals generated by the sample to be detected according to the pulse sequence;
and performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected.
Further, before the preset pulse sequence is applied to the sample to be tested, the method further includes:
and placing the collected sample in a detection area, and magnetizing the sample to obtain the sample to be detected.
Further, the radio frequency pulse sequence comprises a 30 degree pulse;
the gradient pulse sequence includes at least two gradient magnetic fields that oppose the static magnetic field.
Further, the acquiring the echo signal generated by the sample to be detected according to the pulse sequence includes:
and acquiring an echo signal of the sample to be detected, which is generated according to the pulse sequence, between two gradient magnetic fields in opposite directions.
Further, the radio frequency pulse sequence is connected with the gradient pulse sequence in time sequence.
Another aspect of the present invention provides an nmr transverse relaxation time spectrum measuring apparatus, including:
the pulse sequence applying module is used for applying a preset pulse sequence to a sample to be detected, and the pulse sequence comprises a radio frequency pulse sequence and a gradient pulse sequence;
the echo signal acquisition module is used for acquiring echo signals generated by the sample to be detected according to the pulse sequence;
and the inversion module is used for performing data inversion on the echo signals to obtain the transverse relaxation nuclear magnetic spectrum of the sample to be detected.
Further, the apparatus further comprises:
and the magnetization module is used for placing the collected sample in a detection area, magnetizing the sample and obtaining the sample to be detected.
Further, the radio frequency pulse sequence comprises a 30 degree pulse;
the gradient pulse sequence includes at least two gradient magnetic fields that oppose the static magnetic field.
Further, the echo signal acquisition module includes:
and the echo signal acquisition unit is used for acquiring echo signals generated by the sample to be detected according to the pulse sequence between two gradient magnetic fields in opposite directions. (ii) a
Further, the radio frequency pulse sequence is connected with the gradient pulse sequence in time sequence.
Still another aspect of the present invention provides an apparatus for measuring transverse relaxation time spectrum of nuclear magnetic resonance, comprising: a memory, a processor;
a memory; a memory for storing the processor-executable instructions;
wherein the processor is configured to perform the nuclear magnetic resonance transverse relaxation time spectroscopy measurement method as described above by the processor.
Yet another aspect of the present invention is to provide a computer-readable storage medium, in which computer-executable instructions are stored, and when the computer-executable instructions are executed by a processor, the computer-readable storage medium is used for implementing the nuclear magnetic resonance transverse relaxation time spectrum measurement method as described above.
The invention provides a nuclear magnetic resonance transverse relaxation time spectrum measuring method, a device and a readable storage medium, wherein a preset pulse sequence is applied to a sample to be measured, and the pulse sequence comprises a radio frequency pulse sequence and a gradient pulse sequence; collecting echo signals generated by the sample to be detected according to the pulse sequence; and performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected. Therefore, the measurement of the transverse relaxation nuclear magnetic spectrum of the sample to be measured can be rapidly realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art according to the drawings.
Fig. 1 is a schematic flowchart of a method for measuring transverse relaxation time spectrum of nmr according to an embodiment of the present invention;
fig. 2 is a schematic flowchart of a nmr transverse relaxation time spectrum measurement method according to a second embodiment of the present invention;
fig. 3 is a schematic flowchart of a nmr transverse relaxation time spectrum measurement method according to a third embodiment of the present invention;
fig. 4 is a schematic structural diagram of an apparatus for measuring transverse relaxation time spectrum of nmr according to a fourth embodiment of the present invention;
fig. 5 is a schematic structural diagram of an apparatus for measuring transverse relaxation time spectrum of nmr according to a fifth embodiment of the present invention;
fig. 6 is a schematic structural diagram of an apparatus for measuring transverse relaxation time spectrum of nmr according to a sixth embodiment of the present invention;
fig. 7 is a schematic structural diagram of an apparatus for measuring transverse relaxation time spectrum of nuclear magnetic resonance according to a seventh embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other examples obtained based on the examples in the present invention are within the scope of the present invention.
After the system in the equilibrium state is subjected to external transient disturbance, the system can return to the original equilibrium state after a certain time, and the period of time which the system goes through is the relaxation time. The nuclear magnetic resonance relaxation time measurement is widely applied to the fields of petroleum, biology, food and chemistry, particularly in the petroleum industry and in petroleum exploration, and the nuclear magnetic resonance logging technology is more and more widely applied because of the characteristics of no damage and accurate measurement of porosity.
In the prior art, the relaxation time of nuclear magnetic resonance logging T2 is first measured, generally by a CPMG pulse sequence. Specifically, a pulse sequence consisting of a 90-degree pulse and a series of 180-degree pulses is applied to a sample to be measured, an echo signal generated by the sample to be measured according to the pulse sequence is collected, and the echo signal is inverted to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured.
However, the measured signal amplitude is too large, so that a relatively long time is required for attenuation, and the 180-degree pulse is inaccurate due to the inaccuracy of the radio frequency field, so that more processing is required to eliminate the inaccuracy. This processing reduces the number of signal acquisitions and reduces the accuracy of the transverse relaxation nuclear magnetic spectrum.
In order to solve the technical problem, the invention provides a nuclear magnetic resonance transverse relaxation time spectrum measuring method.
Fig. 1 is a schematic flowchart of a method for measuring transverse relaxation time spectrum of nmr according to an embodiment of the present invention, as shown in fig. 1, the method includes:
Relaxation refers to the phenomenon that when protons resonate under the action of radio frequency pulses and are in a high-energy state, the protons quickly return to the original low-energy state after the radio frequency pulses stop. Under the action of the radio frequency pulse, all protons have the same phase and are arranged in the same direction and precess around the external magnetic field at the same angular velocity (or angular frequency). When the rf pulse is stopped, the protons in the same phase gradually become out of phase with each other. The protons are gradually dispersed in the same phase and finally uniformly distributed, and macroscopically, the process that the transverse magnetization vector of the protons gradually decays from the maximum to 0 is called transverse relaxation process, and the time required by the process is transverse relaxation time.
In this embodiment, in order to obtain the transverse relaxation nuclear magnetic spectrum of the sample to be measured, a preset pulse sequence needs to be applied to the sample to be measured, where the preset pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence, the radio frequency pulse sequence replaces a 90-degree pulse signal, and the gradient pulse sequence replaces a 180-degree pulse signal, so that an influence on the measurement of the transverse relaxation nuclear magnetic spectrum due to inaccuracy of the 180-degree pulse signal can be avoided.
And 102, collecting an echo signal generated by the sample to be detected according to the pulse sequence.
Furthermore, after the excitation of the radio frequency pulse sequence, the protons in the sample to be detected can resonate to absorb the energy of the radio frequency pulse sequence. Therefore, after the emission of the radio frequency pulse sequence is stopped, the protons in the sample to be measured emit an electrical signal according to a specific frequency, and the absorbed energy is released, that is, an echo signal, and in order to realize the measurement of the transverse relaxation nuclear magnetic spectrum of the sample to be measured, the echo signal generated by the sample to be measured according to the pulse sequence also needs to be collected. Specifically, the acquisition of the echo signal may be achieved in any manner, and the present invention is not limited herein.
And 103, performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected.
In this embodiment, after the echo signal is acquired, data inversion may be performed on the echo signal, so that the transverse relaxation nuclear magnetic spectrum of the sample to be measured can be obtained. Specifically, the data inversion of the echo signal may be implemented by any data inversion method, which is not limited herein.
It should be noted that, the sample to be measured includes but is not limited to petroleum, liquid food, etc., when the sample to be measured is a substance such as petroleum, etc., in order to accurately measure its internal components, the data inversion can be performed on the echo signal of the sample to be measured, so as to obtain an accurate transverse relaxation nuclear magnetic spectrum; when the sample to be detected is liquid food, the data inversion can be omitted or performed, and the specific implementation mode can be set by a person skilled in the art according to the current requirement.
In the method for measuring transverse relaxation time spectrum of nuclear magnetic resonance provided by this embodiment, a preset pulse sequence is applied to a sample to be measured, where the pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence; collecting echo signals generated by the sample to be detected according to the pulse sequence; and performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected. Replace 90 degree pulse signal through the radio frequency pulse sequence, replace 180 degree pulse signal through the gradient pulse sequence to can avoid leading to 180 degree pulses inaccurate and giving the influence that measures transverse relaxation nuclear magnetic spectrum and bring because the inaccuracy of wrenching of radio frequency field, and then can be quick realize the measurement to the transverse relaxation nuclear magnetic spectrum of the sample that awaits measuring, in addition, can also improve the precision of transverse relaxation nuclear magnetic spectrum.
Fig. 2 is a schematic flow chart of a nuclear magnetic resonance transverse relaxation time spectrum measurement method according to a second embodiment of the present invention, and on the basis of the second embodiment, as shown in fig. 2, the method includes:
and 204, performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected.
In this embodiment, when the sample is collected, the collected sample can be placed in the detection region, and the sample is magnetized, so that protons in the sample and the magnetic field of the detection region face one direction, and therefore, when a preset pulse sequence is subsequently applied to the sample to be detected, the protons can recover the component of the xy plane more quickly. After a sample to be detected is magnetized, a preset pulse sequence can be applied to the sample to be detected, wherein the pulse sequence comprises a radio frequency pulse sequence and a gradient pulse sequence, echo signals generated by the sample to be detected according to the pulse sequence are collected, data inversion is carried out on the echo signals, and a transverse relaxation nuclear magnetic spectrum of the sample to be detected is obtained.
In the method for measuring transverse relaxation time spectrum of nuclear magnetic resonance provided by this embodiment, the collected sample is magnetized, so that the protons in the sample and the magnetic field of the detection region can all face to one direction, and the measurement rate of transverse relaxation nuclear magnetic spectrum can be further improved.
Further, in any of the above embodiments, the rf pulse sequence includes a 30-degree pulse;
the gradient pulse sequence includes at least two gradient magnetic fields that oppose the static magnetic field.
In this embodiment, in order to obtain the transverse relaxation nuclear magnetic spectrum of the sample to be measured, a preset pulse sequence needs to be applied to the sample to be measured, where the preset pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence, specifically, the radio frequency pulse sequence includes a 30-degree pulse, and a component of an xy plane can be obtained by using the 30-degree pulse (small-angle flip), and meanwhile, the amplitude of an attenuation signal can be reduced, so as to reduce the time for acquiring an echo signal. Further, with the inverse gradient pulse sequence, there is no concern about the effect of inaccurate 180 degree pulses, while increasing the gradient accelerates the completion of the dephasing and rephasing, further reducing the time required to measure the relaxation time of T2.
It should be noted that the radio frequency pulse sequence is temporally connected to the gradient pulse sequence.
The mri transverse relaxation time spectrum measuring method provided by this embodiment can reduce the amplitude of the decay signal by applying the rf pulse sequence including one 30-degree pulse and the gradient pulse sequence including at least two gradient magnetic fields opposite to the static magnetic field to the sample to be measured, thereby reducing the time for acquiring the echo signal, and can accelerate the completion of the dephasing and the rephasing, further reducing the time required for measuring the T2 relaxation time.
Fig. 3 is a schematic flow chart of a nuclear magnetic resonance transverse relaxation time spectrum measurement method according to a third embodiment of the present invention, and as shown in fig. 3, on the basis of any one of the above embodiments, the method further includes:
301, applying a preset pulse sequence to a sample to be detected, wherein the pulse sequence comprises a radio frequency pulse sequence and a gradient pulse sequence;
and 303, performing data inversion on the echo signal to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected.
In this embodiment, in order to obtain the transverse relaxation nuclear magnetic spectrum of the sample to be measured, a preset pulse sequence needs to be applied to the sample to be measured first, where the preset pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence, where the radio frequency pulse sequence replaces a 90-degree pulse signal, and the gradient pulse sequence replaces a 180-degree pulse signal, so that an influence on the measurement of the transverse relaxation nuclear magnetic spectrum due to inaccuracy of the 180-degree pulse signal can be avoided. Furthermore, after the excitation of the radio frequency pulse sequence, the protons in the sample to be detected can resonate to absorb the energy of the radio frequency pulse sequence. Therefore, after the emission of the radio frequency pulse sequence is stopped, the protons in the sample to be measured emit an electrical signal according to a specific frequency, and the absorbed energy is released, that is, an echo signal, and in order to realize the measurement of the transverse relaxation nuclear magnetic spectrum of the sample to be measured, the echo signal generated by the sample to be measured according to the pulse sequence also needs to be collected. Specifically, echo signals generated by the sample to be detected according to the pulse sequence can be collected between two gradient magnetic fields in opposite directions. After the echo signal is collected, data inversion can be carried out on the echo signal, so that the transverse relaxation nuclear magnetic spectrum of the sample to be detected can be obtained. Specifically, the data inversion of the echo signal may be implemented by any data inversion method, which is not limited herein.
In the method for measuring transverse relaxation time spectrum of nuclear magnetic resonance provided by the embodiment, a preset pulse sequence is applied to a sample to be measured, and the pulse sequence comprises a radio frequency pulse sequence and a gradient pulse sequence; collecting echo signals generated by a sample to be detected according to a pulse sequence between two gradient magnetic fields in opposite directions; and performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured. Replace 90 degrees pulse signal through the radio frequency pulse sequence, replace 180 degrees pulse signal through the gradient pulse sequence to can avoid leading to 180 degrees pulse inaccurate and giving the influence that measures transverse relaxation nuclear magnetic spectrum and bring because the inaccuracy of wrenching of radio frequency field, and then can be quick realize the measurement to the transverse relaxation nuclear magnetic spectrum of the sample that awaits measuring, can also improve the precision of transverse relaxation nuclear magnetic spectrum.
Fig. 4 is a schematic structural diagram of an apparatus for measuring transverse relaxation time spectrum of nuclear magnetic resonance according to a fourth embodiment of the present invention, as shown in fig. 4, the apparatus includes:
the pulse sequence applying module 41 is configured to apply a preset pulse sequence to the sample to be detected, where the pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence.
And the echo signal acquisition module 42 is configured to acquire an echo signal generated by the sample to be detected according to the pulse sequence.
And the inversion module 43 is configured to perform data inversion on the echo signal to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured.
Relaxation refers to the phenomenon that when protons resonate under the action of radio frequency pulses and are in a high-energy state, the protons quickly return to the original low-energy state after the radio frequency pulses stop. Under the action of the radio frequency pulse, all protons have the same phase and are arranged in the same direction and precess around the external magnetic field at the same angular velocity (or angular frequency). When the rf pulse is stopped, the protons in the same phase gradually become out of phase with each other. The protons are gradually dispersed in the same phase and finally uniformly distributed, and macroscopically, the process that the transverse magnetization vector of the protons gradually decays from the maximum to 0 is called transverse relaxation process, and the time required by the process is transverse relaxation time.
In this embodiment, in order to obtain the transverse relaxation nuclear magnetic spectrum of the sample to be measured, the pulse sequence applying module 41 needs to apply a preset pulse sequence to the sample to be measured, where the preset pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence, where the radio frequency pulse sequence replaces a 90-degree pulse signal, and the gradient pulse sequence replaces a 180-degree pulse signal, so as to avoid an influence on the measurement of the transverse relaxation nuclear magnetic spectrum due to inaccuracy of the 180-degree pulse signal.
Furthermore, after the excitation of the radio frequency pulse sequence, the protons in the sample to be detected can resonate to absorb the energy of the radio frequency pulse sequence. Therefore, after the emission of the radio frequency pulse sequence is stopped, the protons in the sample to be measured emit an electrical signal according to a specific frequency, and release the absorbed energy, i.e., an echo signal, and in order to implement the measurement of the transverse relaxation nuclear magnetic spectrum of the sample to be measured, the echo signal acquisition module 42 further needs to acquire the echo signal generated by the sample to be measured according to the pulse sequence. Specifically, the acquisition of the echo signal may be achieved in any manner, and the present invention is not limited herein.
After the echo signal acquisition module 42 acquires the echo signal, the inversion module 43 may perform data inversion on the echo signal, so as to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured. Specifically, the data inversion of the echo signal may be implemented by any data inversion method, which is not limited herein.
It should be noted that, the sample to be measured includes but is not limited to petroleum, liquid food, etc., when the sample to be measured is a substance such as petroleum, etc., in order to accurately measure its internal components, the data inversion can be performed on the echo signal of the sample to be measured, so as to obtain an accurate transverse relaxation nuclear magnetic spectrum; when the sample to be detected is liquid food, the data inversion can be omitted or performed, and the specific implementation mode can be set by a person skilled in the art according to the current requirement.
In the nmr transverse relaxation time spectrum measurement apparatus provided in this embodiment, a preset pulse sequence is applied to a sample to be measured, where the pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence; collecting echo signals generated by the sample to be detected according to the pulse sequence; and performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected. Replace 90 degree pulse signal through the radio frequency pulse sequence, replace 180 degree pulse signal through the gradient pulse sequence to can avoid leading to 180 degree pulses inaccurate and giving the influence that measures transverse relaxation nuclear magnetic spectrum and bring because the inaccuracy of wrenching of radio frequency field, and then can be quick realize the measurement to the transverse relaxation nuclear magnetic spectrum of the sample that awaits measuring, in addition, can also improve the precision of transverse relaxation nuclear magnetic spectrum.
Fig. 5 is a schematic structural diagram of an apparatus for measuring transverse relaxation time spectrum of nuclear magnetic resonance according to a fifth embodiment of the present invention, and on the basis of the foregoing embodiment, as shown in fig. 5, the apparatus includes:
the magnetization module 51 is configured to place the acquired sample in a detection region, magnetize the sample, and obtain the sample to be detected;
a pulse sequence applying module 52, configured to apply a preset pulse sequence to the sample to be detected, where the pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence;
an echo signal collecting module 53, configured to collect an echo signal generated by the sample to be detected according to the pulse sequence;
and the inversion module 54 is configured to perform data inversion on the echo signal to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured.
In this embodiment, when a sample is collected, the magnetization module 51 may place the collected sample in the detection region, and magnetize the sample, so that the protons in the sample and the magnetic field of the detection region face one direction, and therefore, when a preset pulse sequence is subsequently applied to the sample to be measured, the protons can recover the component of the xy plane more quickly. After magnetizing the sample to be measured, the pulse sequence applying module 52 may apply a preset pulse sequence to the sample to be measured, where the pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence, the echo signal collecting module 53 collects an echo signal generated by the sample to be measured according to the pulse sequence, and the inversion module 54 performs data inversion on the echo signal to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured.
The nmr transverse relaxation time spectrum measuring device provided by this embodiment magnetizes the collected sample, so that the protons in the sample and the magnetic field in the detection region can all face one direction, and the measurement rate of the transverse relaxation nuclear magnetic spectrum can be further improved.
Further, in any of the above embodiments, the rf pulse sequence includes a 30-degree pulse;
the gradient pulse sequence includes at least two gradient magnetic fields that oppose the static magnetic field.
In this embodiment, in order to obtain the transverse relaxation nuclear magnetic spectrum of the sample to be measured, a preset pulse sequence needs to be applied to the sample to be measured, where the preset pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence, specifically, the radio frequency pulse sequence includes a 30-degree pulse, and a component of an xy plane can be obtained by using the 30-degree pulse (small-angle flip), and meanwhile, the amplitude of an attenuation signal can be reduced, so as to reduce the time for acquiring an echo signal. Further, with the inverse gradient pulse sequence, there is no concern about the effect of inaccurate 180 degree pulses, while increasing the gradient accelerates the completion of the dephasing and rephasing, further reducing the time required to measure the relaxation time of T2.
It should be noted that the radio frequency pulse sequence is temporally connected to the gradient pulse sequence.
The nmr transverse relaxation time spectrum measuring apparatus provided in this embodiment applies a radio frequency pulse sequence including one 30-degree pulse and a gradient pulse sequence including at least two gradient magnetic fields opposite to the static magnetic field to the sample to be measured, thereby reducing the amplitude of the decay signal, reducing the time for acquiring the echo signal, accelerating the completion of the dephasing and the rephasing, and further reducing the time required for measuring the T2 relaxation time.
Fig. 6 is a schematic structural diagram of an apparatus for measuring transverse relaxation time spectrum of nuclear magnetic resonance according to a sixth embodiment of the present invention, and based on any of the above embodiments, as shown in fig. 6, the apparatus further includes:
the pulse sequence applying module 61 is configured to apply a preset pulse sequence to the sample to be detected, where the pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence;
the echo signal acquisition module 62 includes:
the echo signal acquisition unit 601 is used for acquiring echo signals generated by the sample to be detected according to the pulse sequence between two gradient magnetic fields in opposite directions;
and the inversion module 63 is configured to perform data inversion on the echo signal to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured.
In this embodiment, in order to obtain the transverse relaxation nuclear magnetic spectrum of the sample to be measured, the pulse sequence applying module 61 first needs to apply a preset pulse sequence to the sample to be measured, where the preset pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence, where the radio frequency pulse sequence replaces a 90-degree pulse signal, and the gradient pulse sequence replaces a 180-degree pulse signal, so as to avoid an influence on the measurement of the transverse relaxation nuclear magnetic spectrum due to inaccuracy of the 180-degree pulse signal. Furthermore, after the excitation of the radio frequency pulse sequence, the protons in the sample to be detected can resonate to absorb the energy of the radio frequency pulse sequence. Therefore, after the emission of the radio frequency pulse sequence is stopped, the protons in the sample to be measured emit an electrical signal according to a specific frequency, and the absorbed energy is released, that is, an echo signal, and in order to realize the measurement of the transverse relaxation nuclear magnetic spectrum of the sample to be measured, the echo signal generated by the sample to be measured according to the pulse sequence also needs to be collected. Specifically, the echo signal acquiring unit 601 may acquire an echo signal generated by the sample to be measured according to the pulse sequence between two gradient magnetic fields in opposite directions. After the echo signal is acquired, the inversion module 63 may perform data inversion on the echo signal, so as to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured. Specifically, the data inversion of the echo signal may be implemented by any data inversion method, which is not limited herein.
In the nmr transverse relaxation time spectrum measurement apparatus provided in this embodiment, a preset pulse sequence is applied to a sample to be measured, where the pulse sequence includes a radio frequency pulse sequence and a gradient pulse sequence; collecting echo signals generated by a sample to be detected according to a pulse sequence between two gradient magnetic fields in opposite directions; and performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be measured. Replace 90 degrees pulse signal through the radio frequency pulse sequence, replace 180 degrees pulse signal through the gradient pulse sequence to can avoid leading to 180 degrees pulse inaccurate and giving the influence that measures transverse relaxation nuclear magnetic spectrum and bring because the inaccuracy of wrenching of radio frequency field, and then can be quick realize the measurement to the transverse relaxation nuclear magnetic spectrum of the sample that awaits measuring, can also improve the precision of transverse relaxation nuclear magnetic spectrum.
Fig. 7 is a schematic structural diagram of an apparatus for measuring transverse relaxation time spectrum of nuclear magnetic resonance according to a seventh embodiment of the present invention, as shown in fig. 7, the apparatus includes: a memory, a processor;
a memory; a memory for storing the processor-executable instructions;
wherein the processor is configured to perform the nuclear magnetic resonance transverse relaxation time spectroscopy measurement method as described above by the processor.
Yet another embodiment of the present invention further provides a computer-readable storage medium, in which computer-executable instructions are stored, and the computer-executable instructions are executed by a processor to implement the method for measuring transverse relaxation time spectrum of nuclear magnetic resonance as described above.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working process of the apparatus described above may refer to the corresponding process in the foregoing method embodiment, and is not described herein again.
Those of ordinary skill in the art will understand that: all or a portion of the steps of implementing the above-described method embodiments may be performed by hardware associated with program instructions. The program may be stored in a computer-readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (6)
1. A nuclear magnetic resonance transverse relaxation time spectrum measurement method is characterized by comprising the following steps:
applying a preset pulse sequence to a sample to be detected, wherein the pulse sequence comprises a radio frequency pulse sequence and a gradient pulse sequence;
collecting echo signals generated by the sample to be detected according to the pulse sequence;
performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected;
before the preset pulse sequence is applied to the sample to be detected, the method further comprises the following steps:
placing the collected sample in a detection area, and magnetizing the sample to obtain the sample to be detected;
the radio frequency pulse sequence comprises a 30 degree pulse;
the gradient pulse sequence includes at least two gradient magnetic fields that oppose the static magnetic field.
2. The method of claim 1, wherein the collecting the echo signals generated by the sample to be tested according to the pulse sequence comprises:
and acquiring an echo signal of the sample to be detected, which is generated according to the pulse sequence, between two gradient magnetic fields in opposite directions.
3. The method of claim 1, wherein the radio frequency pulse sequence is chronologically contiguous with a gradient pulse sequence.
4. An apparatus for measuring transverse relaxation time spectrum of nuclear magnetic resonance, comprising:
the pulse sequence applying module is used for applying a preset pulse sequence to a sample to be detected, and the pulse sequence comprises a radio frequency pulse sequence and a gradient pulse sequence;
the echo signal acquisition module is used for acquiring echo signals generated by the sample to be detected according to the pulse sequence;
the inversion module is used for performing data inversion on the echo signals to obtain a transverse relaxation nuclear magnetic spectrum of the sample to be detected;
the magnetization module is used for placing the collected sample in a detection area, magnetizing the sample and obtaining the sample to be detected;
the radio frequency pulse sequence comprises a 30 degree pulse;
the gradient pulse sequence includes at least two gradient magnetic fields that oppose the static magnetic field.
5. An apparatus for measuring transverse relaxation time spectrum of nuclear magnetic resonance, comprising: a memory, a processor;
a memory for storing the processor-executable instructions;
wherein the processor is configured to perform the method of nuclear magnetic resonance transverse relaxation time spectroscopy of any of claims 1-3 by the processor.
6. A computer-readable storage medium having stored thereon computer-executable instructions for implementing the mr transverse relaxation time spectroscopy measurement method according to any one of claims 1 to 3 when executed by a processor.
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