Non-diagnostic method for simultaneous targeted detection of magnetic resonance signals of methylmalonic acid and lactic acid molecules in brain and application

Abstract

The invention discloses a non-diagnostic method for simultaneous targeted detection of magnetic resonance signals of methylmalonic acid and lactic acid molecules in the brain, and the method employs a J editing method, and comprises the following steps: i, employing a spatially selective 90-degree radio frequency pulse to simultaneously excite the magnetic resonance signals of methylmalonic acid and lactic acid molecules; step ii, simultaneously controlling quantum states of a lactic acid and methylmalonic acid molecule tetra-spinning system by using a J editing technology; and step iii, realizing repolymerization of methylmalonic acid and lactic acid signals by using layer selection pulses with spatial selectivity, and further collecting magnetic resonance signals of methylmalonic acid and lactic acid molecules at the same time. The invention also discloses application of the method in non-diagnostic-purpose detection of the magnetic resonance signal specificity of methylmalonic acid and lactic acid molecules in the human brain.

Description

Technical Field

[0001] This invention belongs to the field of magnetic resonance medicine, specifically relating to a method and application for simultaneously and targetedly detecting magnetic resonance signals of methylmalonic acid and lactate molecules in the human brain for non-diagnostic purposes. Background Technology

[0002] Methylmalonic acidemia (MMA) is an autosomal recessive inherited congenital organic acid metabolism disorder caused by abnormally high levels of methylmalonic acid (MMA) in the blood and urine due to defects in the metabolism of methylmalonyl-CoA mutase (MCM) or its coenzyme cobalamin (Cbl; also known as vitamin B12). Abnormal accumulation of MMA can cause multi-system damage, primarily affecting the central nervous system. Lactic acid (Lac) is an important intermediate metabolite in the metabolism of carbohydrates and non-essential amino acids, and is a product of anaerobic glycolysis of glucose. MMA patients, due to their congenital metabolic disorder, may experience secondary lactate elevation. In clinical medicine, the concentrations of methylmalonic acid and lactate in patients are primarily assessed using gas chromatography and mass spectrometry to detect levels in ex vivo samples such as urine, blood, or cerebrospinal fluid. However, in vitro blood and urine organic acid detection can only reflect the metabolic changes of MMA in the human metabolic cycle, and it is difficult to achieve quantitative detection of MMA and Lac in the lesion area of ​​the patient's brain.

[0003] Magnetic resonance spectroscopy (MRS) is a non-invasive technique for detecting the types, structures, amounts, and spatial distribution of metabolites in living tissues and organs. Due to its non-invasiveness and high sensitivity, it is currently one of the most direct and effective non-invasive methods for detecting energy metabolism in living cells, and can provide information on the metabolic state of brain tissue at the molecular level. However, because MMA molecules and Lac molecules have similar structures and differ in their amounts within the body, their distribution in vivo varies. 1 Signals generated in H-magnetic resonance spectroscopy (MRS) have similar frequencies and are prone to overlap. This signal overlap makes it difficult for traditional magnetic resonance detection techniques to accurately distinguish between MMA and Lac, especially when both need to be detected simultaneously. This indistinguishable signal interference can severely affect the accuracy and reliability of the detection. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and application for simultaneously and precisely targeting the magnetic resonance imaging (MRI) signals of methylmalonic acid (MMA) and lactate molecules in the human brain for non-diagnostic purposes using J-editing techniques. This invention utilizes J-editing technology to manipulate the molecular states of lactate molecules while precisely controlling the evolution of the molecular states of methylmalonic acid (MMA) molecules. This achieves simultaneous and precise observation of the MRI signals of methylmalonic acid and lactate molecules in the living human brain, and effectively distinguishes between the two molecules. Experiments have demonstrated that this method is rapid, non-invasive, applicable to living organisms, and exhibits good stability and sensitivity in the measurement results.

[0005] This invention provides a method for targeted detection of methylmalonic acid and lactate molecules in the brain using J-editing for non-diagnostic purposes, the method comprising:

[0006] Step i: Simultaneously excite the magnetic resonance signals of methylmalonic acid and lactic acid molecules using a spatially selective 90-degree radio frequency pulse (excitation pulse);

[0007] Step ii: Simultaneously manipulate the quantum state of the four-spin system of lactic acid and methylmalonic acid molecules using J-editing technology;

[0008] Step iii: Re-aggregate the signals of methylmalonic acid and lactic acid using spatially selective layer-selective pulses, and then simultaneously acquire the magnetic resonance signals of methylmalonic acid and lactic acid molecules.

[0009] Specifically, this invention targets the methylene group in MMA and Lac molecules. 1 The spin coupling characteristic of H led to the design of, for example Figure 3 The pulse sequence shown is mainly composed of "signal suppression", "signal editing" and "magnetic resonance spectroscopy" modules. The signal suppression module mainly consists of outer volume suppression (OVS) and water suppression (WS) parts. The signal editing module mainly consists of multiple saturation pulses and gradient pulses at specific frequencies (the resonance frequency of the proton on the methine group of methylmalonic acid). The magnetic resonance spectroscopy module consists of layer-selective pulses and gradient pulses.

[0010] In step i, the excitation pulse used to excite the target molecule signal refers to a spatially selective layer-selective pulse, the purpose of which is to excite the magnetic resonance signal in a specific region of interest. Before applying the excitation pulse to excite the magnetic resonance signals of methylmalonic acid and lactic acid molecules, it is necessary to apply volumetric external suppression (OVS) and water suppression (WS) techniques to suppress the voxel-extra-voxel magnetic resonance signal and the water signal, thereby improving the subsequent target signal detection intensity. Specifically, the volumetric external suppression (OVS) is mainly achieved by spatially selective saturation pulses and diffraction gradients, the purpose of which is to suppress all magnetic resonance signals outside the selected voxel; the saturation pulse is used to saturate the voxel-extra-voxel magnetic resonance signal, reducing magnetization; the diffraction gradient is used to reduce the coherence of the voxel-extra-voxel magnetic resonance signal. The water suppression WS uses frequency-selective saturation pulses and gradient pulses to suppress the signal of water molecules, such as Chemical Shift Selective Saturation (CHESS) or Water Suppression Enhanced through T1 Effects (WET) technology; water molecule suppression can also be achieved by using multiple small-angle radio frequency pulses and gradient pulses, such as VAPOR (VAriable Power radiofrequency pulses with Optimized Relaxation delays) technology.

[0011] In step i, the radio frequency pulse used to simultaneously excite the magnetic resonance signals of methylmalonic acid and lactic acid molecules has a time range of 1 to 5 ms and a flip angle range of 45 to 135 degrees; preferably, the excitation pulse has a time of 2.5 ms and a flip angle of 90 degrees; the external volume suppression (OVS) can consist of 4 to 16 saturation pulses, each with a time range of 2 to 16 ms; preferably, the external volume suppression module has 8 saturation pulses, each with a time of 8 ms.

[0012] In one specific embodiment, the water suppression used in this invention is WET technology, which includes 2 to 8 saturation pulses, the amplitude of which ranges from 10 to 100 Hz, and the flip angle of each saturation pulse ranges from 45 degrees to 180 degrees; preferably, WET includes three saturation pulses, all of which have an amplitude of 35 Hz and flip angles of 89.2 degrees, 83.4 degrees and 160.8 degrees respectively.

[0013] In step ii, the present invention considers the evolution of both the lactic acid four-spin system and the methylmalonic acid four-spin system.

[0014] Under the excitation pulse in step i, the quantum state of the four-spin lactic acid molecule transforms from the thermal equilibrium state I1z+I2z+I3z+I4z to a single-quantum coherent state. The J-coupling between protons on the methyl and methine atoms of the lactic acid molecule is 6.96 Hz. When the echo time (TE) is the reciprocal of the J-coupling between protons on the methyl and methine atoms of the lactic acid molecule, i.e., TE = 1 / J (TE = 144 ms), under the action of a partial resonance saturation pulse, two layer-selection pulses, and a gradient pulse, the quantum state of the lactic acid molecule will transform into -I1x-I2x-I3x-I4x or -I1y-I2y-I3y-I4y. At this time, the signal of the lactic acid molecule is an inverted doublet, where Ijx, Ijy, and Ijz (j = 1~4) refer to the product operators of the j-th nuclear spin of the lactic acid molecule in the x, y, and z directions, respectively.

[0015] Under the excitation pulse in step i, the quantum state of the methylmalonic acid molecule transforms from the thermal equilibrium state S1z+S2z+S3z+S4z to a single quantum coherent state. The J-coupling between the protons on the methyl and methine groups of methylmalonic acid is 7.14 Hz. Since methylmalonic acid and lactic acid molecules have similar chemical structures, both containing an AX3 spin system consisting of three protons on the methyl group and one proton on the methine group, and they have similar J-coupling constants, when methylmalonic acid uses the J-coupling constant of the lactic acid molecule, i.e., TE = 1 / J (TE = 144 ms), under the action of two layer-selection pulses and a gradient pulse, methylmalonic acid and lactic acid molecules exhibit consistent quantum state evolution. Because the frequency center of the saturation pulse in the signal editing module is placed on the methine of methylmalonic acid, i.e., the frequency resonance saturation pulse, the quantum state of methylmalonic acid remains in the single quantum coherent state S1x+S2x+S3x+S4x or S1y+S2y+S3y+S4y. At this time, the signal of methylmalonic acid is a positive doublet, where Sjx, Sjy and Sjz (j=1~4) refer to the product operators of the j-th nuclear spin of the methylmalonic acid molecule in the x, y and z directions, respectively.

[0016] In step ii, the fat signal was suppressed by spin-spin relaxation under the action of a long TE pulse sequence. In summary, the J-editing technique was used to suppress water peaks and fat signals while achieving targeted detection of lactic acid and methylmalonic acid.

[0017] In step ii, the saturation pulse used in the J-editing technique can consist of one or more long-duration hard pulses or shaped pulses to saturate a magnetic resonance signal at a specific frequency. The duration of the saturation pulse is 5 to 50 ms, and the frequency center is located at the chemical shift of the proton on the methine group of methylmalonic acid. Preferably, the duration of the saturation pulse used in this invention is 15 ms. In experiments involving healthy subjects and patients, the frequency center of the saturation pulse is located at 3.2 ppm in the 1H MRS spectrum of the human brain; in a methylmalonic acid aqueous film at 25 degrees Celsius, the frequency center of the saturation pulse is at 3.18 ppm in the 1H MRS spectrum.

[0018] In step ii, a partial resonance saturation pulse refers to a saturation pulse whose coverage deviates from the resonance frequency of a specific molecule, thus the spin system of that molecule is not affected by the saturation pulse. A frequency resonance saturation pulse refers to a saturation pulse whose coverage is centered on the resonance frequency of a specific molecule, causing the spin system of that molecule to evolve under the influence of the saturation pulse.

[0019] In one specific embodiment, in step ii, the duration of the two saturation pulses used in the J-editing technique is 15 milliseconds, and the frequency center of the saturation pulses is located in the human brain. 1 The H MRS spectrum showed 3.22 ppm; the 180-degree layer-selection pulse was a sinc pulse with a duration of 5 milliseconds and a flip angle of 180 degrees.

[0020] In steps ii and iii, the layer selection pulse includes shape pulses such as sinc pulses and adiabatic pulses, used to refocus the magnetic resonance signal in the region of interest. The time range of the layer selection pulse is 1 to 10 ms, and the flip angle range is 150 to 210 degrees. Preferably, the shape of the layer selection pulse is a sinc pulse, the time is 5 milliseconds, and the flip angle is 180 degrees.

[0021] To detect the magnetic resonance signals of methylmalonic acid and lactic acid molecules of interest, conventional T1 or T2 weighted sequences can be used to locate the position of a living organism in a magnetic field. This knowledge is common knowledge in the field and will not be elaborated further in this invention.

[0022] Methylmalonic acid and lactic acid molecules 1 H magnetic resonance signals include their J coupling value, chemical shift of the proton on the methyl group, and signal intensity.

[0023] The present invention also provides the application of the above method in the specific detection of magnetic resonance signals of methylmalonic acid and lactate molecules in in vitro solutions and / or human brain for non-diagnostic purposes.

[0024] The beneficial effects of this invention include: Based on magnetic resonance technology, this invention has a significant characteristic and innovation that distinguishes it from other previous magnetic resonance spectroscopy techniques: namely, it uses the J-editing method to effectively distinguish and target the magnetic resonance signals of methylmalonic acid (MMA) and lactate (Lac) molecules in the human brain. This invention's method can rapidly, non-invasively, and without radiation measure the magnetic resonance signals of MMA and Lac molecules in the human brain, exhibiting excellent accuracy, sensitivity, and stability. It has significant application value in biology and medicine, and represents a novel and original technology.

[0025] This invention utilized J-editing technology in aqueous membranes and in patients of different genders. Inverted lactate signals and positive methylmalonic acid signals were observed in both aqueous membranes and patients. Notably, the chemical shifts and J-coupling of the methylmalonic acid and lactate peaks measured in the patient brains were consistent with those in the aqueous membrane, indicating good accuracy and stability of the method. Furthermore, this invention detected methylmalonic acid and lactate molecules in the brains of normal volunteers using the J-editing method. Since the methylmalonic acid content in the brains of normal volunteers (less than 1 μmol / L) was much lower than that in patients, no methylmalonic acid and lactate molecules were detected in normal volunteers compared to patients, demonstrating the good sensitivity of this invention. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0027] Figure 1 (a) is a schematic diagram of the molecular structure of methylmalonic acid of the present invention. Figure 1 (b) is a schematic diagram of the molecular structure of lactic acid of the present invention.

[0028] Figure 2 This is a flowchart illustrating the specific implementation of the method of the present invention.

[0029] Figure 3 This is a schematic diagram of the pulse sequence used in this invention for the precise observation of magnetic resonance signals of MMA and Lac molecules in living organisms. Gx, Gy, and Gz represent the pulse gradient channels in the x, y, and z directions, respectively.

[0030] Figure 4 This is a schematic diagram of the main steps in a specific embodiment of the present invention.

[0031] Figure 5This is a conventional T1-weighted plot of the aqueous film sample (a mixed solution of MMA and Lac, both with a concentration of 20 mmol / L) in Example 1 of this invention. Figure 5 (a)), Conventional magnetic resonance spectrum ( Figure 5 (b) below) and using Figure 3 Pulse-based magnetic resonance spectra (PMR spectra) Figure 5 (b) Above). Among them, MMA-CH and MMA-CH3 refer to the magnetic resonance signals of the protons on the methine and methyl groups of the MMA molecule; Lac-CH and Lac-CH3 refer to the magnetic resonance signals on the methine and methyl groups of the Lac molecule.

[0032] Figure 6 This is a standard T1-weighted plot of a 10-year-old male subject with methylmalonic acidemia in Example 2 of the present invention. Figure 6 (a)) Using conventional magnetic resonance spectroscopy on the subjects ( Figure 6 (b) below), Figure 3 Pulse-based magnetic resonance spectra (PMR spectra) Figure 6 (b) Above) and their enlarged views ( Figure 6 (c)).

[0033] Figure 7 This is a standard T1-weighted plot of the 8-year-old female subject with methylmalonic acidemia in Example 3 of the present invention. Figure 7 (a)) Using conventional magnetic resonance spectroscopy on the subjects ( Figure 7 (b) below), Figure 3 Pulse-based magnetic resonance spectra (PMR spectra) Figure 7 (b) Above) and their enlarged views ( Figure 7 (c)).

[0034] Figure 8 This is a standard T1-weighted plot of a 10-year-old male normal volunteer in Example 4 of the present invention. Figure 8 (a)) Using conventional magnetic resonance spectroscopy on the subjects ( Figure 8 (b) below), Figure 3 Pulse-based magnetic resonance spectra (PMR spectra) Figure 8 (b) Above) and their enlarged views ( Figure 8 (c)). Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the specific embodiments and accompanying drawings. Except for the contents specifically mentioned below, the processes, conditions, and experimental methods for implementing the present invention are all common knowledge and general knowledge in the art, and the present invention does not have any particular limitations.

[0036] This invention belongs to the field of magnetic resonance imaging (MRI) technology and discloses a non-diagnostic MRI method for targeted detection of methylmalonic acid (MMA) and lactic acid (Lac) signals in the human brain using J-edit spectroscopy. This method utilizes J-editing technology to manipulate the quantum states of the Lac four-spin system while precisely controlling the quantum state evolution of MMA molecules, achieving targeted detection of the MRI signals of MMA and Lac molecules. Because MMA and Lac molecules have similar chemical structures, their MRI signals overlap significantly in conventional in vivo spectroscopy, which... 1 The H MRS method cannot effectively distinguish between MMA and Lac, while J editing technology can precisely manipulate the quantum states of MMA and Lac, thereby enabling accurate detection of MMA and Lac magnetic resonance signals in the human brain. This invention provides a rapid, non-invasive, and radiation-free method for measuring the magnetic resonance signals of MMA and Lac molecules in the human brain, exhibiting excellent accuracy and sensitivity. It has significant potential applications in the early diagnosis and treatment monitoring of methylmalonic acidemia.

[0037] This invention provides a method for simultaneously targeting and detecting magnetic resonance signals of methylmalonic acid and lactate molecules in the brain using J-editing for non-diagnostic purposes. The method includes the following steps:

[0038] Step i: Simultaneously excite the magnetic resonance signals of methylmalonic acid and lactic acid molecules using spatially selective 90-degree radio frequency pulses;

[0039] Step ii: Simultaneously manipulate the quantum state of the four-spin system of lactic acid and methylmalonic acid molecules using J-editing technology;

[0040] Step iii: Re-aggregate the signals of methylmalonic acid and lactic acid using spatially selective 180-degree radio frequency pulses, and then simultaneously acquire the magnetic resonance signals of methylmalonic acid and lactic acid molecules.

[0041] Figure 2 The flowchart of the method of the present invention includes: (1) external signal suppression and water suppression; (2) manipulating the quantum state of Lac molecules using J editing technology, while precisely controlling the evolution of MMA quantum state; (3) detection of magnetic resonance signals of MMA and Lac molecules; under the above conditions, the pulse shown is applied to a living organism to achieve precise observation of the magnetic resonance signals of methylmalonic acid and lactic acid molecules in a real living organism.

[0042] In the specific implementation process, the main steps of the implementation method applied to living organisms are as follows: Figure 4 As shown:

[0043] 1. Use T1 or T2 magnetic resonance weighted sequences to locate the position of tissues in the magnetic field and select the region of interest.

[0044] 2. Apply Figure 3 The pulse shown demonstrates precise observation of the magnetic resonance signals of methylmalonic acid and lactic acid molecules in actual living organisms.

[0045] Example 1

[0046] Experimental subjects: a mixed solution of MMA and Lac, both at a concentration of 20 mmol / L, with a sample volume of 45 mL.

[0047] Measurement instrument: Siemens 3T Skyra NMR spectrometer, with Siemens 64-channel head coil used as the probe coil.

[0048] Measurement method: Figure 3 The pulse sequence shown.

[0049] The experimental steps are as follows:

[0050] 1. The position of the water film sample in the magnetic field was located using a conventional T1-weighted sequence, and the region of the water film sample to be tested was selected. See the water film magnetic resonance image and the selected region. Figure 5 a.

[0051] 2. Apply Figure 3 The pulse sequence shown has the following specific experimental parameters: spin recovery time (TR) of 2000 ms, echo time (TE) of 144 ms, average number of pulses of 64, flip angle of 90°, region of interest size of 30 × 10 × 10 cubic millimeters, saturation pulse shape in the signal editing module of Gaussian pulse, duration of 15000 microseconds, and RF center of 3.18 ppm. During the experiment, the center frequency and duration of the saturation pulse can be finely adjusted to optimize the magnetic resonance signals of methylmalonic acid and lactic acid molecules.

[0052] Experimental results are as follows Figure 5 As shown, where Figure 5 a is a T1-weighted magnetic resonance image of a mixture of methylmalonic acid and lactic acid; Figure 5 b represents the regular sequence (bottom) and its utilization. Figure 3 The magnetic resonance spectrum of the pulse sequence (top). As can be seen from the figure, the conventional sequence... 1 The H MRS spectrum showed overlap between lactic acid and methylmalonic acid signals, which, compared with the conventional sequence, was observed using... Figure 3 Pulse sequences were obtained targeting methylmalonic acid and lactate. 1 In the H MRS spectrum, the signal of methylmalonic acid is a positive doublet (around 1.2 ppm), while the signal of lactic acid is an inverted doublet (around 1.3 ppm).

[0053] Example 2

[0054] Experimental subjects: A 9-year-old male MUT gene mutation patient clinically diagnosed with methylmalonic acidemia.

[0055] Measurement instrument: Siemens 3T Skyra NMR spectrometer, with Siemens 64-channel head coil used as the probe coil.

[0056] Measurement method: Figure 3 The pulse sequence shown.

[0057] The experimental steps are as follows:

[0058] 1. Magnetic resonance imaging (MRI) images of the patient's brain were acquired using conventional three-dimensional T1-weighted sequences, and regions of interest (lesion locations) were selected. In vivo brain MRI images and regions of interest are shown below. Figure 6 a.

[0059] 2. Apply Figure 3 The pulse sequence shown has the following specific experimental parameters: Repetition Time (TR) of 2000 ms, Echo Time (TE) of 144 ms, average number of pulses of 64, flip angle of 90°, region of interest size of 20×20×20 mm, placed in the occipital lobe lesion area of ​​the brain, saturation pulse shape in the signal editing module of Gaussian pulse, duration of 15000 microseconds, and radio frequency center of 3.22 ppm. During the experiment, the center frequency and duration of the saturation pulse can be finely adjusted to optimize the magnetic resonance signals of methylmalonic acid and lactate molecules.

[0060] Experimental results are as follows Figure 6 As shown. Among them, Figure 6 a represents the patient's T1-weighted magnetic resonance image and the selected region. Figure 6 To the left of b is the regular sequence (bottom) and the sequence utilizing... Figure 3 Magnetic resonance spectra acquired in the region of interest using a pulse sequence (top). Figure 6 The right side of b is a magnified view of the spectrum on the left (magnified region: 0-2.5 ppm). In the conventional sequence... 1 The H MRS spectrum showed significant signal overlap between methylmalonic acid and molecules such as lactic acid and lipids; using Figure 3 Pulse sequences were obtained targeting methylmalonic acid and lactate. 1 In the H MRS spectrum, an inverted lactic acid molecule signal (around 1.36 ppm) and a forward methylmalonic acid signal (around 1.26 ppm) can be seen, and the J coupling between their two peaks is similar to that of the water film.

[0061] Example 3

[0062] Experimental subjects: An 8-year-old female MUT gene mutation patient clinically diagnosed with methylmalonic acidemia.

[0063] Measurement instrument: Siemens 3T Skyra NMR spectrometer, with Siemens 64-channel head coil used as the probe coil.

[0064] Measurement method: Figure 3 The pulse sequence shown.

[0065] The experimental steps are as follows:

[0066] 1. Magnetic resonance imaging (MRI) images of the patient's brain were acquired using conventional three-dimensional T1-weighted sequences, and regions of interest (lesion locations) were selected. In vivo brain MRI images and regions of interest are shown below. Figure 7 a.

[0067] 2. Apply Figure 3 The pulse sequence shown has the following specific experimental parameters: Repetition Time (TR) of 2000 ms, Echo Time (TE) of 144 ms, average number of pulses of 64, flip angle of 90°, region of interest size of 20×20×20 mm, placed in the right cerebellar lesion area (shown as high signal on T2WI and T2-FLAIR on conventional cranial MRI), saturation pulse shape in the signal editing module is a Gaussian pulse, duration of 15000 microseconds, and radio frequency center of 3.22 ppm. During the experiment, the center frequency and duration of the saturation pulse can be finely adjusted to optimize the magnetic resonance signals of methylmalonic acid and lactate molecules.

[0068] Experimental results are as follows Figure 7 As shown. Among them, Figure 7 a represents the patient's T1-weighted magnetic resonance image and the selected region. Figure 7 To the left of b is the regular sequence (bottom) and the sequence utilizing... Figure 3 Magnetic resonance spectra acquired in the region of interest using a pulse sequence (top). Figure 7 The right side of b is a magnified view of the spectrum on the left (magnified region: 0-2.5 ppm). In the conventional sequence... 1 The H MRS spectrum showed significant signal overlap between methylmalonic acid and molecules such as lactic acid and lipids; using Figure 3 Pulse sequences were obtained targeting methylmalonic acid and lactate. 1 In the H MRS spectrum, an inverted lactic acid molecule signal (around 1.36 ppm) and a forward methylmalonic acid signal (around 1.26 ppm) can be seen, and the J coupling between their two peaks is similar to that of the water film.

[0069] Example 4

[0070] Experimental subjects: normal volunteers, 10-year-old male subjects.

[0071] Measurement instrument: Siemens 3T Skyra NMR spectrometer, with Siemens 64-channel head coil used as the probe coil.

[0072] Measurement method: Figure 3 The pulse sequence shown.

[0073] The experimental steps are as follows:

[0074] Magnetic resonance imaging (MRI) images of the brains of normal volunteers were acquired using conventional three-dimensional T1-weighted sequences, and regions of interest were selected. In vivo brain MRI images and regions of interest are shown below. Figure 8 a.

[0075] Apply Figure 3 The pulse sequence shown has the following specific experimental parameters: Repetition Time (TR) of 2000 ms, Echo Time (TE) of 144 ms, average number of pulses of 64, flip angle of 90°, region of interest size of 20 × 20 × 20 mm, saturation pulse shape in the signal editing module of Gaussian pulse, duration of 15000 microseconds, and RF center of 3.22 ppm. During the experiment, the center frequency and duration of the saturation pulse can be fine-tuned to optimize the magnetic resonance signals of methylmalonic acid and lactic acid molecules.

[0076] Experimental results are as follows Figure 7 As shown. Among them, Figure 8 a represents a T1-weighted magnetic resonance image and selected region from a healthy volunteer. Figure 8 To the left of b is the regular sequence (bottom) and the sequence utilizing... Figure 3 Magnetic resonance spectra acquired in the region of interest using a pulse sequence (top). Figure 8 The right side of b is a magnified view of the spectrum on the left (magnified region: 0-2.5 ppm). In the conventional sequence... 1 The H MRS spectrum showed severe signal overlap among molecules such as lipids; using Figure 3 Pulse sequence obtained 1 No signals of methylmalonic acid and lactic acid molecules were observed in the H MRS spectrum.

[0077] The scope of protection of this invention is not limited to the above embodiments. Any variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of this invention are included in this invention and are protected by the appended claims.

Claims

1. A method for simultaneously and targetedly detecting magnetic resonance signals of methylmalonic acid and lactate molecules in the brain for non-diagnostic purposes, characterized in that, The method utilizes the J-editing method and includes the following steps: Step i: Simultaneously excite the magnetic resonance signals of methylmalonic acid and lactic acid molecules using spatially selective 90-degree radio frequency pulses; Step ii: Simultaneously manipulate the quantum state of the four-spin system of lactic acid and methylmalonic acid molecules using J-editing technology; Step iii: Re-aggregate the signals of methylmalonic acid and lactic acid using spatially selective layer-selective pulses, and then simultaneously acquire the magnetic resonance signals of methylmalonic acid and lactic acid molecules.

2. The method as described in claim 1, characterized in that, Before step i, it is also necessary to apply volumetric external suppression (OVS) and water suppression (WS) pulses to improve the detection intensity of subsequent target signals by suppressing the voxel-external magnetic resonance signal and the water signal. The volumetric external suppression (OVS) pulse uses a spatially selective saturation pulse and a diffraction gradient to selectively suppress the voxel-based magnetic resonance signal; the saturation pulse is used to saturate the voxel-based magnetic resonance signal and reduce magnetization; the diffraction gradient is used to reduce the coherence of the voxel-based magnetic resonance signal. The water suppression WS pulse uses frequency-selective saturation pulses and gradient pulses to selectively suppress water signals. The water suppression WS pulse includes water suppression techniques such as chemical shift-selective saturation pulses, T1 effect-enhanced water suppression techniques, or a combination of multiple small-angle radio frequency pulses and gradient pulses to suppress water signals.

3. The method as described in claim 2, characterized in that, In step i, the time range of the radio frequency pulse used to simultaneously excite the magnetic resonance signals of methylmalonic acid and lactic acid molecules is 1 to 5 ms, and the flip angle range is 45 to 135 degrees. The volumetric external suppression (OVS) comprises 4 to 16 saturation pulses, each saturation pulse having a time range of 2 to 16 ms. The T1 effect-enhanced water suppression technique comprises 2 to 8 saturation pulses, the amplitude of which ranges from 10 to 100 Hz, and the flip angle of each saturation pulse ranges from 45 degrees to 180 degrees.

4. The method as described in claim 1, characterized in that, In step ii, under the action of the radio frequency pulse in step i, the four-spin systems of the methylmalonic acid molecule and the lactic acid molecule undergo quantum state evolution, transforming from a thermal equilibrium state to a single quantum coherent state. The echo time TE is set to the reciprocal of the coupling of the lactic acid molecule J, i.e., TE = 1 / J. Under the action of the partial resonance saturation pulse, two layer-selection pulses and gradient pulse, the quantum state of the four-spin system of the lactic acid molecule transforms from the thermal equilibrium state I1z+I2z+I3z+I4z to -I1x-I2x-I3x-I4x or -I1y-I2y-I3y-I4y. Under the action of the frequency resonance saturation pulse, two layer-selection pulses and gradient pulse, the quantum state of the four-spin system of the methylmalonic acid molecule remains in the single quantum coherent state S1x+S2x+S3x+S4x or S1y+S2y+S3y+S4y. Ijx, Ijy, and Ijz, j = 1 to 4, represent the product operators of the j-th nuclear spin of the lactic acid molecule in the x, y, and z directions, respectively; Sjx, Sjy, and Sjz, j = 1 to 4, represent the product operators of the j-th nuclear spin of the methylmalonic acid molecule in the x, y, and z directions, respectively.

5. The method as described in claim 4, characterized in that, The signal of the single quantum coherence state of the lactic acid molecule is an inverted doublet, and the signal of the single quantum coherence state of the methylmalonic acid molecule is a positive doublet; and / or, The partial resonance saturation pulse and / or the frequency resonance saturation pulse include one or more hard pulses or shaped pulses, the time range of the saturation pulse is 5 to 50 ms, and the frequency center is located at the chemical shift of the proton on the methine of methylmalonic acid.

6. The method as described in claim 5, characterized in that, The layer selection pulse includes shape pulses such as sinc pulses and adiabatic pulses. The time range of the layer selection pulse is 1 to 10 ms, and the flip angle range is 150 to 210 degrees.

7. The method as described in claim 1, characterized in that, The pulse sequence used in the method includes a signal suppression module, a signal editing module, and a magnetic resonance spectroscopy module; the signal suppression module includes volumetric external suppression pulses and water suppression pulses; the signal editing module includes saturation pulses and gradient pulses of the resonance frequencies of multiple protons on the methine group of methylmalonic acid; and the magnetic resonance spectroscopy module includes layer-selective pulses and gradient pulses.

8. The method as described in claim 1, characterized in that, The methylmalonic acid and lactic acid molecules 1 H magnetic resonance signals include J coupling value, chemical shift of protons on methyl groups, and signal intensity.

9. The application of the method according to any one of claims 1-8 in the specific detection of magnetic resonance signals of methylmalonic acid and lactate molecules in in vitro solutions and / or human brain for non-diagnostic purposes.

Images