Method and apparatus for measuring relaxation time of magnetic resonance overlapping peaks based on selective excitation

Abstract

This invention discloses a method and apparatus for measuring the relaxation time of overlapping peaks in magnetic resonance based on selective excitation, comprising: acquiring one-dimensional nuclear magnetic resonance (NMR) data of a sample. 1 H-spectrum, based on one-dimensional nuclear magnetic resonance 1 The H-scan determines the pulse width and power corresponding to the 90-degree hard pulse of the sample, obtains the pure chemical shift spectrum of the sample, and identifies the center frequency of the proton to be selectively excited, in order to set the longitudinal relaxation time measurement sequence and the transverse relaxation time measurement sequence. The longitudinal and transverse relaxation time measurement sequences are then input into an NMR spectrometer containing the sample, respectively, to acquire a series of selectively excited inversion recovery spectra and a series of selectively excited spin echo spectra. The longitudinal and transverse relaxation times of the proton to be selectively excited are obtained by performing exponential function fitting using the least squares method based on the signal intensity. This invention has significant advantages in signal selectivity and resolution.

Description

Technical Field

[0001] This invention relates to the field of nuclear magnetic resonance, and more specifically to a method and apparatus for measuring the relaxation time of overlapping peaks in magnetic resonance based on selective excitation. Background Technology

[0002] Nuclear magnetic resonance (NMR) technology provides a non-destructive method for identifying and confirming the structure and composition of substances. Relaxation time is an important parameter in NMR experiments, divided into longitudinal relaxation (T1) and transverse relaxation (T2), playing a crucial role in refining experimental parameters, identifying and accurately quantifying substances, analyzing molecular dynamics, and exploring chemical reaction kinetics. However, due to J-coupling splitting, conventional one-dimensional proton spectrum peaks overlap significantly, leading to errors in relaxation time measurement. Combining pure chemical shift spectroscopy with relaxation measurement can effectively solve this problem, but its application is limited due to its long sampling time and low sensitivity. Summary of the Invention

[0003] The present application addresses the technical problem of accurately measuring the relaxation time of complex samples with overlapping spectral peaks, as mentioned above. The purpose of this application is to propose a method and apparatus for measuring the relaxation time of overlapping magnetic resonance peaks based on selective excitation, thereby resolving the technical problems mentioned in the background section.

[0004] In a first aspect, the present invention provides a method for measuring the relaxation time of overlapping peaks in magnetic resonance based on selective excitation, comprising the following steps:

[0005] Obtain one-dimensional NMR of the sample 1 H-spectrum, based on one-dimensional nuclear magnetic resonance 1 H-spectroscopy determines the pulse width and power corresponding to the 90-degree hard pulse of the sample, obtains the pure chemical shift spectrum of the sample, and identifies the center frequency of the protons to be selectively excited.

[0006] Based on the pulse width and power corresponding to the 90-degree hard pulse of the sample and the center frequency to be selected, a longitudinal relaxation time measurement sequence and a transverse relaxation time measurement sequence are set. The longitudinal relaxation time measurement sequence includes a 180-degree hard pulse applied after a first waiting time, a 90-degree hard pulse applied after a time τ, two subsequent adiabatic pulses in opposite directions combined with a spatial coding gradient, and a 180-degree selective pulse placed between the two opposite adiabatic pulses combined with coherent path selection gradients on both sides. The transverse relaxation time measurement sequence includes a 90-degree hard pulse applied after a second waiting time, followed by two τ... eA 180-degree hard pulse is applied in the middle of time / 2 and repeated m times within the decay time Δ. This is followed by two adiabatic pulses in opposite directions, coupled with a spatial coding gradient, and a 180-degree selective pulse positioned between the two opposite adiabatic pulses, coupled with coherent path selection gradients on both sides, where Δ=mτ. e ;

[0007] The longitudinal relaxation time measurement sequence and the transverse relaxation time measurement sequence were respectively input into the nuclear magnetic resonance spectrometer on which the sample was placed, and a series of selective excitation inversion recovery spectra and a series of selective excitation spin echo spectra were acquired respectively.

[0008] The longitudinal relaxation time and transverse relaxation time of the proton to be selectively excited were obtained by performing exponential function fitting using the least squares method based on the spectral intensity of a series of selectively excited inversion recovery spectra and a series of selectively excited spin echo spectra.

[0009] Preferably, the generation process of a 180-degree selective pulse is as follows:

[0010] One-dimensional nuclear magnetic resonance of the sample 1 The center position of the protons to be selectively excited in the H spectrum is set as the center frequency of the selective 180-degree pulse, based on the one-dimensional nuclear magnetic resonance... 1 The signal distribution in the H spectrum determines the waveform type and excitation bandwidth of the selective 180-degree pulse, and the waveform corresponding to the selective 180-degree pulse is generated based on the excitation bandwidth.

[0011] Preferably, the generation process of two adiabatic pulses in opposite directions is as follows:

[0012] According to one-dimensional nuclear magnetic resonance 1 The signal distribution and overlap in the H spectrum are determined by the sweep frequency range, power, and duration of two adiabatic pulses in opposite directions, where the sweep frequency range is determined by the sample length, gradient, and gyromagnetic ratio.

[0013] Preferably, the intensity of the spatial coding gradient is set according to the corresponding adiabatic pulse, and the intensity and duration of the coherent path selection gradient are set.

[0014] Preferably, the width and power of the 90-degree hard pulse in the longitudinal relaxation time measurement sequence and the transverse relaxation time measurement sequence are based on one-dimensional nuclear magnetic resonance. 1 The pulse width and power corresponding to the 90-degree hard pulse of the sample determined by the H spectrum.

[0015] Preferably, time τ and decay time Δ are a series of delays that increase in size and are both far from 5T1.

[0016] Preferably, both the first and second waiting times are greater than five times the longitudinal relaxation time.

[0017] Secondly, the present invention provides a magnetic resonance overlapping peak relaxation time measurement device based on selective excitation, comprising:

[0018] The parameter determination module is configured to acquire one-dimensional NMR of the sample. 1 H-spectrum, based on one-dimensional nuclear magnetic resonance 1 H-spectroscopy determines the pulse width and power corresponding to the 90-degree hard pulse of the sample, obtains the pure chemical shift spectrum of the sample, and identifies the center frequency of the protons to be selectively excited.

[0019] The sequence setting module is configured to set a longitudinal relaxation time measurement sequence and a transverse relaxation time measurement sequence based on the pulse width and power corresponding to the 90-degree hard pulse of the sample and the center frequency to be selected. The longitudinal relaxation time measurement sequence includes a 180-degree hard pulse applied after a first waiting time, a 90-degree hard pulse applied after a time τ, two subsequent adiabatic pulses in opposite directions combined with a spatial coding gradient, and a 180-degree selective pulse set between the two opposite adiabatic pulses combined with coherent path selection gradients on both sides. The transverse relaxation time measurement sequence includes a 90-degree hard pulse applied after a second waiting time, followed by two τ... e A 180-degree hard pulse is applied in the middle of time / 2 and repeated m times within the decay time Δ. This is followed by two adiabatic pulses in opposite directions, coupled with a spatial coding gradient, and a 180-degree selective pulse positioned between the two opposite adiabatic pulses, coupled with coherent path selection gradients on both sides, where Δ=mτ. e ;

[0020] The acquisition module is configured to acquire a series of selective excitation inversion recovery spectra and a series of selective excitation spin echo spectra by inputting longitudinal relaxation time measurement sequences and transverse relaxation time measurement sequences into a nuclear magnetic resonance spectrometer containing a sample.

[0021] The fitting module is configured to perform exponential function fitting using the least squares method based on the spectral signal intensities of a series of selectively excited inversion recovery spectra and a series of selectively excited spin echoes, respectively, to obtain the longitudinal relaxation time and transverse relaxation time of the protons to be selectively excited.

[0022] Thirdly, the present invention provides an electronic device including one or more processors; and a storage device for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the method as described in any implementation of the first aspect.

[0023] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method as described in any of the implementations of the first aspect.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The magnetic resonance overlapping peak relaxation time measurement method proposed in this invention has greatly improved the sensitivity of the spectrum obtained based on the relaxation time of selectively excited protons. Even at a concentration of a few millimoles per liter, the relaxation time of protons can be accurately measured.

[0026] (2) The sequence used in the magnetic resonance overlapping peak relaxation time measurement method based on selective excitation proposed in this invention does not require any phase cycling, only a single scan is needed, and the measurement time is almost the same as that of traditional methods.

[0027] (3) The magnetic resonance overlapping peak relaxation time measurement method proposed in this invention, when used to measure the longitudinal relaxation time T1, obtains a series of spectra that selectively excite the proton to be measured, suppress the proton signal that overlaps with it, extract the target spectral peak with complete waveform, and accurately obtain the longitudinal relaxation time of the proton by fitting the T1 curve according to the spectral peak intensity.

[0028] (4) The magnetic resonance overlapping peak relaxation time measurement method proposed in this invention, when used to measure the longitudinal relaxation time T2, obtains a series of spectra that selectively excite the proton to be measured, suppress the proton signal that overlaps with it, extract the target spectral peak with complete waveform, and accurately obtain the transverse relaxation time of the proton by fitting the T2 curve according to the spectral peak intensity. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is an exemplary device architecture diagram in which an embodiment of this application can be applied;

[0031] Figure 2 This is a flowchart illustrating an embodiment of the magnetic resonance overlapping peak relaxation time measurement method based on selective excitation in this application.

[0032] Figure 3This is a schematic diagram of the relaxation time measurement sequence of the selectively excited magnetic resonance overlapping peak relaxation time measurement method according to an embodiment of this application, wherein... Figure 3 (a) is the longitudinal relaxation time measurement sequence. Figure 3 (b) is the transverse relaxation time measurement sequence;

[0033] Figure 4 Comparison of longitudinal relaxation time T1 measurements using conventional IR and selective excitation method GEM-IR for overlapping peaks in mixed samples of butanol and butyric acid. Figure 4 (a) shows the result of longitudinal relaxation time T1 measured by conventional IR method. Figure 4 (b) shows the results of longitudinal relaxation time T1 measured by the selective excitation method GEM-IR;

[0034] Figure 5 Comparison of transverse relaxation time (T2) measurements for overlapping peaks in a mixed sample of butanol and butyric acid using conventional CPMG and selective excitation method GEM-CPMG. Figure 5 (a) is the spectrum of transverse relaxation time T2 measured by the conventional CPMG method. Figure 5 (b) is the spectrum of transverse relaxation time T2 measured by the selective excitation method GEM-CPMG;

[0035] Figure 6 Comparison of longitudinal relaxation time T1 and transverse relaxation time T2 obtained by fitting conventional IR and selective excitation method GEM-IR, as well as conventional CPMG and selective excitation method GEM-CPMG to the overlapping peaks of mixed samples of butanol and butyric acid.

[0036] Figure 7 This is a schematic diagram of a magnetic resonance overlapping peak relaxation time measurement device based on selective excitation, as an embodiment of this application.

[0037] Figure 8 This is a schematic diagram of the structure of a computer device suitable for implementing the electronic devices of the present application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0039] Figure 1An exemplary device architecture 100 is shown that can be applied to the selectively excited magnetic resonance overlapping peak relaxation time measurement method or the selectively excited magnetic resonance overlapping peak relaxation time measurement device according to the embodiments of this application.

[0040] like Figure 1 As shown, the device architecture 100 may include terminal device 101, terminal device 2 102, terminal device 3 103, network 104, and server 105. Network 104 serves as the medium for providing communication links between terminal device 101, terminal device 2 102, terminal device 3 103, and server 105. Network 104 may include various connection types, such as wired or wireless communication links or fiber optic cables, etc.

[0041] Users can use terminal device 101, terminal device 2 102, and terminal device 3 103 to interact with server 105 via network 104 to receive or send messages, etc. Various applications, such as data processing applications and file processing applications, can be installed on terminal device 101, terminal device 2 102, and terminal device 3 103.

[0042] Terminal devices 101, 102, and 103 can be either hardware or software. When terminal devices 101, 102, and 103 are hardware, they can be various electronic devices, including but not limited to smartphones, tablets, laptops, and desktop computers. When terminal devices 101, 102, and 103 are software, they can be installed in the aforementioned electronic devices. They can be implemented as multiple software programs or software modules (e.g., software or software modules used to provide distributed services) or as a single software program or software module. No specific limitations are imposed here.

[0043] Server 105 can be a server that provides various services, such as a background data processing server that processes files or data uploaded by terminal device 101, terminal device 202, and terminal device 303. The background data processing server can process the acquired files or data and generate processing results.

[0044] It should be noted that the magnetic resonance overlap peak relaxation time measurement method based on selective excitation provided in this application embodiment can be executed by server 105, or by terminal device 101, terminal device 2 102, or terminal device 3 103. Correspondingly, the magnetic resonance overlap peak relaxation time measurement device based on selective excitation can be set in server 105, or in terminal device 101, terminal device 2 102, or terminal device 3 103.

[0045] It should be understood that Figure 1The number of terminal devices, networks, and servers shown is merely illustrative. Any number of terminal devices, networks, and servers can be included depending on implementation needs. If the data being processed does not need to be retrieved remotely, the above architecture may not include a network, requiring only servers or terminal devices.

[0046] Figure 2 An embodiment of this application provides a method for measuring the relaxation time of magnetic resonance overlapping peaks based on selective excitation, comprising the following steps:

[0047] S1, Obtain one-dimensional NMR of the sample. 1 H-spectrum, based on one-dimensional nuclear magnetic resonance 1 H-spectroscopy determines the pulse width and power corresponding to the 90-degree hard pulse of the sample, obtains the pure chemical shift spectrum of the sample, and identifies the center frequency of the protons to be selectively excited.

[0048] Specifically, the selectively excited magnetic resonance overlapping peak relaxation time measurement method proposed in the embodiments of this application is named GEM-IR / CPMG, which acquires one-dimensional nuclear magnetic resonance data of the sample. 1 H-spectroscopy is used to determine the pulse width and power corresponding to the 90-degree hard pulse of the sample. A pure chemical shift spectrum of the sample is obtained to facilitate the identification of the center frequency of the protons to be selectively excited among overlapping peaks.

[0049] S2, based on the pulse width and power corresponding to the 90-degree hard pulse of the sample and the center frequency to be selected, set the longitudinal relaxation time measurement sequence and the transverse relaxation time measurement sequence. The longitudinal relaxation time measurement sequence includes a 180-degree hard pulse applied after the first waiting time, a 90-degree hard pulse applied after time τ, two subsequent adiabatic pulses in opposite directions combined with a spatial coding gradient, and a 180-degree selective pulse set between the two opposite adiabatic pulses combined with coherent path selection gradients on both sides. The transverse relaxation time measurement sequence includes a 90-degree hard pulse applied after the second waiting time, followed by two τ... e A 180-degree hard pulse is applied in the middle of time / 2 and repeated m times within the decay time Δ. This is followed by two adiabatic pulses in opposite directions, coupled with a spatial coding gradient, and a 180-degree selective pulse positioned between the two opposite adiabatic pulses, coupled with coherent path selection gradients on both sides, where Δ=mτ. e .

[0050] In a specific embodiment, the process of generating a 180-degree selective pulse is as follows:

[0051] One-dimensional nuclear magnetic resonance of the sample 1 The center position of the protons to be selectively excited in the H spectrum is set as the center frequency of the selective 180-degree pulse, based on the one-dimensional nuclear magnetic resonance...1 The signal distribution in the H spectrum determines the waveform type and excitation bandwidth of the selective 180-degree pulse, and the waveform corresponding to the selective 180-degree pulse is generated based on the excitation bandwidth.

[0052] In a specific embodiment, the generation process of two adiabatic pulses in opposite directions is as follows:

[0053] According to one-dimensional nuclear magnetic resonance 1 The signal distribution and overlap in the H spectrum are determined by the sweep frequency range, power, and duration of two adiabatic pulses in opposite directions, where the sweep frequency range is determined by the sample length, gradient, and gyromagnetic ratio.

[0054] In a specific embodiment, the intensity of the spatial coding gradient is set according to the corresponding adiabatic pulse, and the intensity and duration of the coherent path selection gradient are set.

[0055] In a specific embodiment, the width and power of the 90-degree hard pulse in the longitudinal relaxation time measurement sequence and the transverse relaxation time measurement sequence are based on one-dimensional nuclear magnetic resonance. 1 The pulse width and power corresponding to the 90-degree hard pulse of the sample determined by the H spectrum.

[0056] In a specific embodiment, time τ and decay time Δ are a series of delays that increase in size and are all far from 5T1.

[0057] In a specific embodiment, both the first waiting time and the second waiting time are greater than five times the longitudinal relaxation time.

[0058] Specifically, by setting the relevant parameters of the relaxation time measurement sequence, the one-dimensional nuclear magnetic resonance (NMR) is transformed. 1 The center position of the protons to be selectively excited in the H spectrum is set as the center frequency of the selective 180-degree pulse, based on the one-dimensional nuclear magnetic resonance... 1 Based on the signal distribution in the H-spectrum, the waveform type and excitation bandwidth of the selective 180-degree pulse are set. A specific waveform is generated according to the excitation bandwidth, and its duration and power are obtained to achieve a more perfect target nuclear peak shape. The intensity and duration of the coherence path selection gradient G2 are set to perform coherence path selection, thereby eliminating signals caused by imperfections in the selective 180-degree pulse. This is based on the one-dimensional nuclear magnetic resonance... 1 The signal distribution and overlap in the H-spectrum are determined by setting the sweep range, power, and duration of two opposite adiabatic pulses, where the sweep range is determined by the sample length, gradient, and gyromagnetic ratio. After these settings, the following results are obtained: Figure 3 The relaxation time measurement sequence shown is as follows, in which Figure 3 (a) is the longitudinal relaxation time measurement sequence. Figure 3(b) is the transverse relaxation time measurement sequence. The sequence used in the embodiments of this application requires no phase cycling and only single-scan sampling. The first and second waiting times are the inversion recovery times. This sequence can selectively excite a unique proton from multiple overlapping signals in a single scan while preserving relevant coupling details. In the presence of a magnetic field gradient, two adiabatic pulses are used in conjunction with a spatially encoded gradient to generate a chemical shift selective filter, with a selective 180-degree pulse in the middle that only inverts the spin to be measured, refocusing J coupling, thereby achieving selective excitation. Therefore, it has significant advantages in signal selectivity and resolution.

[0059] S3. Input the longitudinal relaxation time measurement sequence and the transverse relaxation time measurement sequence into the nuclear magnetic resonance spectrometer on which the sample is placed, and acquire a series of selective excitation inversion recovery spectra and a series of selective excitation spin echo spectra, respectively.

[0060] S4. Based on the spectrum intensity of a series of selectively excited inversion recovery spectra and a series of selectively excited spin echo spectra, the least squares method is used to fit an exponential function to obtain the longitudinal relaxation time and transverse relaxation time of the proton to be selectively excited.

[0061] In the longitudinal relaxation time measurement experiment, after a first waiting time d1 (d1>5T1), a 180-degree hard pulse is applied, flipping the magnetization vector from the z-axis to the -z-axis. After a time evolution of τ, a 90-degree hard pulse is applied, with its width and power using the pulse width and power corresponding to the 90-degree hard pulse of the sample measured in step S1, flipping the magnetization vector to the xy plane. τ is a series of delays increasing in size. The setting of τ is extremely important for T1, and it is crucial to minimize the longitudinal magnetization vector M. z The values ​​have a relatively uniform distribution, with the points at the beginning being denser and the points at the end being more sparse. Next, two adiabatic pulses in opposite directions are combined with a spatially encoded gradient, with a 180-degree selective pulse in the middle flanked by coherent path selection gradients. This is used to precisely and selectively excite the peak of the proton to be selectively excited, while suppressing the signals of other protons. Subsequently, a series of selectively excited inversion recovery (SOR) spectra are acquired, and then the obtained SOR spectra are fitted with an exponential function using the least squares method based on the signal intensity, thus obtaining the longitudinal relaxation time T1 of the proton. When measuring the longitudinal relaxation time T1, the obtained series of SOR spectra only excite the peak to be measured, suppressing overlapping peaks, extracting the target spectral peak with a complete waveform, and then fitting the longitudinal relaxation time T1 curve.

[0062] In the experiment measuring transverse relaxation time, a second waiting time d2 (d2>5T1) is first passed. Then, the measured 90-degree hard pulse is used as the excitation pulse of the pulse sequence to flip the magnetization vector from the z-axis to the xy-plane, followed by two τ... e A 180-degree hard pulse is applied in the middle of time / 2, and the cycle is repeated m times, τ e The decay time Δ (Δ = mτ) is set to a fixed value. e () is a series of delays increasing in size, to maximize the transverse magnetization vector M. xy The values ​​have a relatively uniform distribution, causing the transverse magnetization vector to decay. Next, two adiabatic pulses in opposite directions are combined with a spatially encoded gradient, with a 180-degree selective pulse in the middle flanked by coherent path selection gradients. This is used to precisely and selectively excite the peak of the proton to be selectively excited, while suppressing the signals of other protons. Subsequently, a series of spectra of selectively excited spin echoes are acquired, and the obtained spectra are then fitted with an exponential function using the least squares method based on the signal intensity, thus obtaining the transverse relaxation time T2 of the proton. When measuring the transverse relaxation time T2, the obtained series of selectively excited spin echo spectra only excite the peak to be measured, suppressing overlapping peaks, extracting the target spectral peak with a complete waveform, and then fitting the transverse relaxation time T2 curve.

[0063] The steps S1-S4 above do not necessarily represent the order of the steps, but are represented by step symbols. The order of the steps can be adjusted.

[0064] The present invention will be described in detail below using specific embodiments.

[0065] This embodiment uses a Varian 500MHz nuclear magnetic resonance spectrometer. The sample is a solution of a mixture of 0.05 mol / L butanol and butyric acid dissolved in heavy water (D2O). Figure 3 The relaxation time measurement sequence is shown.

[0066] Step 1: Acquire one-dimensional NMR data of the sample 1 H spectrum, the pulse width of the 90-degree hard pulse of the sample was 10.8 μs, the power was 58 dB, and the center frequency of the spectrum was -655 Hz;

[0067] Step 2: Measure the center frequency of the protons to be tested in the overlapping peaks. The center frequency of the proton of the methyl group in butanol in the overlapping peaks is -2123.4 Hz, and the center frequency of the proton of the methyl group in butyric acid is -2109.1 Hz.

[0068] Step 3: Set the intensity of the coherent path selection gradient for the GEM-IR / CPMG pulse to G2 = 9G / cm and the duration to 1ms;

[0069] Step 4: Transform the one-dimensional nuclear magnetic resonance image.1 The center positions of the selected protons for butanol and butyric acid in the H spectrum were set as the center frequencies (seltof) of the selective 180-degree pulses. The waveforms of the selective 180-degree pulses were generated using the Pbox program, with the 'rsnob' shape used here. Based on the signal distribution, the excitation bandwidth of the selective 180-degree pulses was adjusted to 100 Hz, resulting in a pulse width of 18.5 ms and a power of 13 dB.

[0070] Step 5: Based on the sample tube length and gyromagnetic ratio, set the sweep frequency range of two adiabatic pulses in opposite directions to ±2500Hz. Use Pbox to generate adiabatic pulses with a power of 18dB and a duration of 100ms.

[0071] Step 6: Set the intensity of the spatial coding gradient G1 according to the corresponding adiabatic pulse, G1 = 0.25G / cm;

[0072] Step 7: Set the waiting time d1 = 10s and the inversion recovery time τ1 = 0.0625s, 0.125s, 0.25s, 0.5s, 1s, 2s, 4s, 8s, 16s, 32s in the longitudinal relaxation recovery section.

[0073] Step 8: Record a series of selective inversion recovery (GEM-IR) spectra;

[0074] Step Nine: Repeat steps Three through Eight;

[0075] Step 10: Set the waiting time d2 = 10s and the decay time Δ = 0.02s, 0.005s, 0.08s, 0.2s, 0.5s, 0.8s, 1.2s, 1.6s, 3.2s, 6.4s in the transverse relaxation decay part;

[0076] Step 11: Record a series of selective spin echo (GEM-CPMG) spectra;

[0077] Step 12: Fit the peak intensities of the excited hydrogen nuclei in the two obtained spectra to obtain the longitudinal relaxation time T1 and the transverse relaxation time T2.

[0078] The above steps do not represent the only possible order of steps, but only one possible order. Depending on the specific experiment, some steps may need to be repeated to adjust the optimal parameters.

[0079] Figure 4 and Figure 5The results of comparing the relaxation time measurement using the selectively excited magnetic resonance overlapping peak method with the traditional method are presented. As can be seen from the figures, the traditional method shows a quintet at 0.75 ppm, which is actually an overlap of two triplets from butanol and butyric acid, leading to inaccurate relaxation measurements. In contrast, the two triplets in the spectrum obtained using the selectively excited magnetic resonance overlapping peak method are perfectly separated, allowing for more accurate relaxation time measurements. Figure 6 This presentation showcases the specific results of a selectively excited magnetic resonance overlapping peak relaxation time measurement method. This method yields relaxation times with higher accuracy and smaller errors. Furthermore, due to the single-scan design, the sampling time is shorter, and spectral sensitivity is preserved. In practical applications, the specific values ​​for the selective 180-degree pulse, adiabatic pulse, inversion recovery time, and decay time must be adjusted based on sample information.

[0080] In summary, the selective excitation-based magnetic resonance overlapping peak relaxation time measurement method provided by this invention can accurately measure the relaxation time of protons in overlapping peaks, facilitating the optimization of NMR experimental parameters and the analysis of molecular dynamics.

[0081] Further reference Figure 7 As an implementation of the methods shown in the above figures, this application provides an embodiment of a magnetic resonance overlapping peak relaxation time measurement device based on selective excitation. This device embodiment is similar to... Figure 2 Corresponding to the method embodiments shown, this device can be specifically applied to various electronic devices.

[0082] This application provides a magnetic resonance overlapping peak relaxation time measurement device based on selective excitation, including:

[0083] Parameter determination module 1 is configured to acquire one-dimensional NMR of the sample. 1 H-spectrum, based on one-dimensional nuclear magnetic resonance 1 H-spectroscopy determines the pulse width and power corresponding to the 90-degree hard pulse of the sample, obtains the pure chemical shift spectrum of the sample, and identifies the center frequency of the protons to be selectively excited.

[0084] Sequence setting module 2 is configured to set a longitudinal relaxation time measurement sequence and a transverse relaxation time measurement sequence based on the pulse width and power corresponding to the 90-degree hard pulse of the sample and the center frequency to be selected. The longitudinal relaxation time measurement sequence includes a 180-degree hard pulse applied after a first waiting time, a 90-degree hard pulse applied after a time τ, two subsequent adiabatic pulses in opposite directions combined with a spatial coding gradient, and a 180-degree selective pulse set between the two opposite adiabatic pulses combined with a coherent path selection gradient on both sides. The transverse relaxation time measurement sequence includes a 90-degree hard pulse applied after a second waiting time, followed by two τ... e A 180-degree hard pulse is applied in the middle of time / 2 and repeated m times within the decay time Δ. This is followed by two adiabatic pulses in opposite directions, coupled with a spatial coding gradient, and a 180-degree selective pulse positioned between the two opposite adiabatic pulses, coupled with coherent path selection gradients on both sides, where Δ=mτ. e ;

[0085] Acquisition module 3 is configured to acquire a series of selective excitation inversion recovery spectra and a series of selective excitation spin echo spectra by inputting longitudinal relaxation time measurement sequences and transverse relaxation time measurement sequences into a nuclear magnetic resonance spectrometer containing a sample.

[0086] Fitting module 4 is configured to perform exponential function fitting using the least squares method based on the spectral signal intensities of a series of selectively excited inversion recovery spectra and a series of selectively excited spin echoes, respectively, to obtain the longitudinal relaxation time and transverse relaxation time of the proton to be selectively excited.

[0087] The following is for reference. Figure 8 It illustrates an electronic device suitable for implementing embodiments of this application (e.g., Figure 1 The diagram shows the structure of a computer device 800 (a server or terminal device). Figure 8 The electronic device shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of this application.

[0088] like Figure 8As shown, the computer device 800 includes a central processing unit (CPU) 801 and a graphics processing unit (GPU) 802, which can perform various appropriate actions and processes according to programs stored in read-only memory (ROM) 803 or programs loaded from storage section 809 into random access memory (RAM) 804. The RAM 804 also stores various programs and data required for the operation of the computer device 800. The CPU 801, GPU 802, ROM 803, and RAM 804 are interconnected via bus 805. An input / output (I / O) interface 806 is also connected to bus 805.

[0089] The following components are connected to I / O interface 806: an input section 807 including a keyboard, mouse, etc.; an output section 808 including an LCD, speakers, etc.; a storage section 809 including a hard disk, etc.; and a communication section 810 including a network interface card, such as a LAN card or modem. The communication section 810 performs communication processing via a network such as the Internet. A drive 811 may also be connected to I / O interface 806 as needed. A removable medium 812, such as a hard disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 811 as needed so that computer programs read from it can be installed into storage section 809 as needed.

[0090] In particular, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 810, and / or installed from removable medium 812. When the computer program is executed by central processing unit (CPU) 801 and graphics processing unit (GPU) 802, the functions defined in the methods of this application are performed.

[0091] It should be noted that the computer-readable medium described in this application can be a computer-readable signal medium, a computer-readable medium, or any combination thereof. A computer-readable medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor device, or any combination thereof. More specific examples of a computer-readable medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this application, a computer-readable medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution device, apparatus, or device. In this application, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media can also be any computer-readable medium other than a computer-readable medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution device, apparatus, or apparatus. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0092] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0093] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using dedicated hardware-based means to perform the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0094] The modules described in the embodiments of this application can be implemented in software or hardware. These modules can also be located within a processor.

[0095] In another aspect, this application also provides a computer-readable medium, which may be included in the electronic device described in the above embodiments; or it may exist independently and not assembled into the electronic device. The computer-readable medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to: acquire one-dimensional nuclear magnetic resonance imaging of a sample. 1 H-spectrum, based on one-dimensional nuclear magnetic resonance 1 H-spectroscopy determines the pulse width and power corresponding to the 90-degree hard pulse of the sample, obtains the pure chemical shift spectrum of the sample, and identifies the center frequency of the protons to be selectively excited. Based on the pulse width and power corresponding to the 90-degree hard pulse of the sample and the center frequency to be selected, a longitudinal relaxation time measurement sequence and a transverse relaxation time measurement sequence are set. The longitudinal relaxation time measurement sequence includes a 180-degree hard pulse applied after a first waiting time, a 90-degree hard pulse applied after a time τ, two subsequent adiabatic pulses in opposite directions combined with a spatial coding gradient, and a 180-degree selective pulse placed between the two opposite adiabatic pulses, with coherent path selection gradients on both sides. The transverse relaxation time measurement sequence includes a 90-degree hard pulse applied after a second waiting time, followed by two subsequent adiabatic pulses in opposite directions combined with a spatial coding gradient, and a 180-degree selective pulse placed between the two opposite adiabatic pulses, with coherent path selection gradients on both sides. e A 180-degree hard pulse is applied in the middle of time / 2 and repeated m times within the decay time Δ. This is followed by two adiabatic pulses in opposite directions, coupled with a spatial coding gradient, and a 180-degree selective pulse positioned between the two opposite adiabatic pulses, coupled with coherent path selection gradients on both sides, where Δ=mτ. eThe longitudinal relaxation time measurement sequence and the transverse relaxation time measurement sequence were respectively input into a nuclear magnetic resonance spectrometer containing the sample, and a series of selective excitation inversion recovery spectra and a series of selective excitation spin echo spectra were acquired. Based on the spectral signal intensity of the series of selective excitation inversion recovery spectra and the series of selective excitation spin echo spectra, the longitudinal relaxation time and transverse relaxation time of the proton to be selectively excited were obtained by least squares method exponential function fitting.

[0096] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for measuring the relaxation time of overlapping peaks in magnetic resonance based on selective excitation, characterized in that, Includes the following steps: Obtain one-dimensional NMR of the sample 1 H-spectrum, based on the one-dimensional nuclear magnetic resonance spectrum 1 H-spectroscopy determines the pulse width and power corresponding to the 90-degree hard pulse of the sample, obtains the pure chemical shift spectrum of the sample, and identifies the center frequency of the protons to be selectively excited. Based on the pulse width and power corresponding to the 90-degree hard pulse of the sample and the center frequency to be selected, a longitudinal relaxation time measurement sequence and a transverse relaxation time measurement sequence are set. The longitudinal relaxation time measurement sequence includes a 180-degree hard pulse applied after a first waiting time, a 90-degree hard pulse applied after a time τ, two subsequent adiabatic pulses in opposite directions combined with a spatial coding gradient, and a 180-degree selective pulse set between the two opposite adiabatic pulses combined with coherent path selection gradients on both sides. The transverse relaxation time measurement sequence includes a 90-degree hard pulse applied after a second waiting time, followed by two subsequent adiabatic pulses in opposite directions combined with a spatial coding gradient, and a 180-degree selective pulse set between the two opposite adiabatic pulses combined with a coherent path selection gradient on both sides. e A 180-degree hard pulse is applied in the middle of time / 2 and repeated m times within the decay time Δ. This is followed by two adiabatic pulses applied in opposite directions, coupled with a spatial coding gradient. A 180-degree selective pulse is placed between these two opposite adiabatic pulses, coupled with coherent path selection gradients on both sides, where Δ=mτ e ; The longitudinal relaxation time measurement sequence and the transverse relaxation time measurement sequence were respectively input into a nuclear magnetic resonance spectrometer containing the sample, and a series of selective excitation inversion recovery spectra and a series of selective excitation spin echo spectra were acquired respectively. The longitudinal relaxation time and transverse relaxation time of the proton to be selectively excited are obtained by performing exponential function fitting using the least squares method based on the spectrum intensity of the series of selectively excited inversion recovery and the spectrum signal intensity of the series of selectively excited spin echoes.

2. The method for measuring the relaxation time of overlapping magnetic resonance peaks based on selective excitation according to claim 1, characterized in that, The generation process of the 180-degree selective pulse is as follows: The sample was subjected to one-dimensional nuclear magnetic resonance. 1 The center position of the protons to be selectively excited in the H spectrum is set as the center frequency of the selective 180-degree pulse, according to the one-dimensional nuclear magnetic resonance... 1 The signal distribution in the H spectrum determines the waveform type and excitation bandwidth of the selective 180-degree pulse, and the waveform corresponding to the selective 180-degree pulse is generated based on the excitation bandwidth.

3. The method for measuring the relaxation time of overlapping magnetic resonance peaks based on selective excitation according to claim 1, characterized in that, The generation process of the two adiabatic pulses in opposite directions is as follows: According to one-dimensional nuclear magnetic resonance 1 The signal distribution and overlap in the H spectrum are determined by setting the sweep frequency range, power, and duration of the two adiabatic pulses in opposite directions, wherein the sweep frequency range is determined by the sample length, gradient, and gyromagnetic ratio.

4. The method for measuring the relaxation time of overlapping magnetic resonance peaks based on selective excitation according to claim 1, characterized in that, The intensity of the spatial coding gradient is set according to the corresponding adiabatic pulse, and the intensity and duration of the coherent path selection gradient are also set.

5. The method for measuring the relaxation time of overlapping magnetic resonance peaks based on selective excitation according to claim 1, characterized in that, The width and power of the 90-degree hard pulse in the longitudinal and transverse relaxation time measurement sequences are based on the one-dimensional nuclear magnetic resonance (NMR) data. 1 The pulse width and power corresponding to the 90-degree hard pulse of the sample determined by the H spectrum.

6. The method for measuring the relaxation time of overlapping magnetic resonance peaks based on selective excitation according to claim 1, characterized in that, The time τ and decay time Δ are a series of delays that increase in size and are all far from 5T1.

7. The method for measuring the relaxation time of overlapping magnetic resonance peaks based on selective excitation according to claim 1, characterized in that, Both the first waiting time and the second waiting time are greater than five times the longitudinal relaxation time.

8. A magnetic resonance overlapping peak relaxation time measurement device based on selective excitation, characterized in that, include: The parameter determination module is configured to acquire one-dimensional NMR of the sample. 1 H-spectrum, based on the one-dimensional nuclear magnetic resonance spectrum 1 H-spectroscopy determines the pulse width and power corresponding to the 90-degree hard pulse of the sample, obtains the pure chemical shift spectrum of the sample, and identifies the center frequency of the protons to be selectively excited. The sequence setting module is configured to set a longitudinal relaxation time measurement sequence and a transverse relaxation time measurement sequence based on the pulse width and power corresponding to the 90-degree hard pulse of the sample and the center frequency to be selected. The longitudinal relaxation time measurement sequence includes a 180-degree hard pulse applied after a first waiting time, a 90-degree hard pulse applied after a time τ, two subsequently applied adiabatic pulses in opposite directions with spatial coding gradients, and a 180-degree selective pulse set between the two opposite adiabatic pulses with coherent path selection gradients on both sides. The transverse relaxation time measurement sequence includes a 90-degree hard pulse applied after a second waiting time, followed by two τ... e A 180-degree hard pulse is applied in the middle of time / 2 and repeated m times within the decay time Δ. This is followed by two adiabatic pulses applied in opposite directions, coupled with a spatial coding gradient. A 180-degree selective pulse is placed between these two opposite adiabatic pulses, coupled with coherent path selection gradients on both sides, where Δ=mτ e ; The acquisition module is configured to acquire a series of selective excitation inversion recovery spectra and a series of selective excitation spin echo spectra by inputting the longitudinal relaxation time measurement sequence and the transverse relaxation time measurement sequence into a nuclear magnetic resonance spectrometer on which the sample is placed. The fitting module is configured to perform exponential function fitting using the least squares method based on the spectrum intensity of the series of selectively excited inversion recovery spectra and the spectrum signal intensity of the series of selectively excited spin echoes, respectively, to obtain the longitudinal relaxation time and transverse relaxation time of the proton to be selectively excited.

9. An electronic device, comprising: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the method as described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-7.

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