Multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system and use method therefor

Abstract

The present invention provides a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system and a use method therefor. The quantification system comprises n sealing containers, n ≥ 5 and being an integer. The n sealing containers are sequentially marked as container 1, container 2, container 3, …, and container n. The sealing containers are filled with a mixture containing all pre-imaging nuclides, and non-1H pre-imaging nuclides with which container 2, container 3, …, and container n are filled maintain a known concentration gradient, with the concentration gradient number being n-1. When the quantification system is used, a radio-frequency field correction coefficient distribution diagram is calculated on the basis of an image of container 1; the remaining containers are placed around an imaging part and imaged at the same time, and the radio-frequency field correction coefficient distribution diagram is used to correct the obtained images; and finally, the concentrations of different non-1H pre-imaging nuclides of a region of interest are sequentially calculated according to a fitting method. The concentration of the pre-imaging nuclide obtained in the present invention is an absolute concentration, facilitating the longitudinal observation of the change in the molecular level of the region of interest.

Description

Multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system and its use method Technical Field

[0001] The present invention relates to the field of magnetic resonance imaging, and in particular to a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system and a method for using the same. Background Art

[0002] Magnetic resonance imaging (MRI) can be multi-parameter and multi-nuclide imaging. 23 Na, 31 P. 35 Imaging of radionuclides such as Cl can provide many 1 H imaging cannot provide information. 19 F. 13 Since radionuclides such as C have no background signal in the body, they are advantageous for use as probes such as targeting agents and tracers for in vivo research.

[0003] The content (concentration) of endogenous substances will change dynamically with the development of functional status or disease; exogenous probes are generally injected into the subject through intravenous, subcutaneous or intratumoral injection, and then reach the target area through the blood circulation system or other mechanisms. The excitation and acquisition process of the nuclear magnetic resonance signal is modulated by the RF pulse flip angle and the receiving link amplifier. The obtained spectral signal or image pixel intensity information is a relative value, not an absolute value. For example, 31 Taking P spectrum imaging as an example, the relative contents of two phosphorus-containing substances are usually used based on spectral data to characterize the changes in a certain functional event, which is not conducive to longitudinal, long-term, quantitative comparison of the functional status of the subjects or the development of the disease.

[0004] Magnetic resonance spectroscopy (NMR) typically uses internal or external standards to calibrate the content of substances in mixtures. However, the effective RF field volume of the radiofrequency coils used in NMR is small. For example, a common RF coil for sample tubes with an outer diameter of 5 mm has an effective RF field distribution within a volume approximately 2 cm high and 5 mm in diameter. This results in a relatively uniform RF field, and the quantification of substances does not require consideration of RF field inhomogeneities. However, MRI uses large RF coils and sometimes uses surface coils for excitation and / or reception. This results in an uneven RF field, resulting in uneven signal intensity distribution in acquired images even for homogeneous systems. Therefore, quantifying substance content in MRI requires correction for RF field uniformity.

[0005] Chinese patent document CN116098605B proposes a water phantom for multi-nuclide synchronous integrated magnetic resonance imaging and its use method. This phantom provides feature points and structural similarity features for multi-nuclide MRI image fusion, solving the problem of multimodal image registration. However, the multiple water phantoms used are mixtures of the same solute concentration, making them incapable of quantifying the content of different nuclides. Furthermore, the thickness of the internal partitions of the water phantom is designed based on the magnetic gyrometry ratio of the pre-imaged nuclides, requiring high machining precision. Existing literature does not yet address the system or method for simultaneous quantification of multiple nuclides in multi-nuclide synchronous magnetic resonance imaging scenarios. Summary of the Invention

[0006] The present invention proposes a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system and a method of using the same, which can simultaneously quantify the absolute contents of multiple pre-imaging nuclides, facilitating longitudinal observation of changes at the molecular level in a target area.

[0007] The technical solution of the present invention is achieved as follows: a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system includes n sealed containers, n ≥ 5 and is an integer, the n sealed containers are sequentially numbered as container 1, container 2, container 3, ..., container n; the sealed containers are filled with a mixture containing all pre-imaging nuclides, wherein container 1 is used for radio frequency field uniformity correction, and containers 2, container 3, ..., container n are filled with non- 1 The H pre-imaging nuclides all maintain a known concentration gradient, and the number of concentration gradients is n-1, which is used to quantify the different non- 1 The concentration of H pre-imaging nuclides. The known concentration gradient here refers to known concentrations arranged in a certain order, that is, containers 2, 3, ..., and n are filled with pre-imaging nuclides of known concentrations in a certain order. A concentration gradient number of n-1 means that the concentrations of the pre-imaging nuclides in containers 2, 3, ..., and n are different from each other.

[0008] Furthermore, a cross partition I and a cross partition II are provided in half of one side of container 2, container 3, ..., and container n. The angle ɑ between partition I and partition II is an acute angle. The thickness of partition I and partition II is 1 The resolution of H.

[0009] Furthermore, the volume of the container 1 is a relatively large sealed container, the volume of which can fill more than 75% of the effective volume of the radio frequency coil used for imaging.

[0010] Furthermore, in the mixture in container one, the concentration of each pre-imaging nuclide is higher than the estimated concentration of the corresponding nuclide in the organism, for example, the concentration is 50% higher.

[0011] Furthermore, the container 2, container 3, ..., container n are filled with non 1The concentration gradient of H pre-imaging nuclide is set according to the concentration distribution range of the nuclide in the organism reported in the literature. 1 The maximum concentration of H pre-imaging nuclide is 20% higher than the maximum estimated concentration of this nuclide in the organism, and the minimum is equivalent to the lowest estimated concentration in the organism. 1 The H pre-image nuclides are distributed in equal concentration gradients (the concentration difference is equal and always constant), and the concentrations are marked as C2, C3, ..., C n .

[0012] Furthermore, the resonance frequency of the pre-imaging nuclide in the mixture is consistent with the excitation frequency of the pre-imaging nuclide in the organism.

[0013] Furthermore, in the mixture, the nuclear magnetic resonance peaks of all nuclides are single peaks. 31 When imaging multiple compounds of P, a single peak of phosphate or creatine phosphate is selected in the mixture; when imaging an exogenous probe, one substance in the mixture is selected as the exogenous probe.

[0014] A method for using a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system, the method of use being as follows:

[0015] The first step is to image the first container and calculate a radio frequency field correction coefficient distribution map based on the image of the first container;

[0016] The second step is to place container 2, container 3, container n around the imaging part in the same plane and non-collinearly, and image the imaging part at the same time to obtain the non-collinear 1 Image of H pre-imaging nuclide;

[0017] The third step is to use the RF field correction coefficient distribution map obtained in the first step to correct the image obtained in the second step, so as to obtain the non- 1 H pre-imaging nuclide-corrected image;

[0018] The fourth step is to calculate the concentrations of different pre-imaging radionuclides in the region of interest of the corrected imaging part image in sequence according to the fitting method.

[0019] Furthermore, in the fourth step, the concentrations of different pre-imaging radionuclides in the region of interest of the image of the corrected imaging site are calculated. The specific method is as follows:

[0020] (1) Select the region of interest (ROI) 1 in the image area after correction of the imaging part, and calculate the signal intensity S1 within ROI1; select the region of interest (ROI) in the image area after correction of container 2, container 3, ..., container n respectively. j , j=2,…,n, and calculate ROI j Signal strength S j ;

[0021] (2) Using signal strength S j Fitting the linear equation S=k*C+b to the known concentration of the pre-imaging nuclide in the corresponding container to obtain k and b, where S is the signal intensity, C is the concentration of the pre-imaging nuclide, and b is the system deviation;

[0022] (3) Substitute S1 into the equation fitted in step (2) to calculate the concentration of the region of interest ROI1 of the imaging site;

[0023] (4) Repeat steps (1)-(3) for different non 1 H pre-imaging radionuclides for quantification.

[0024] Furthermore, in the first step, the calculation method is as follows: the data obtained by multiplying the RF field correction coefficient distribution map and the image pixels of container one point by point are equal;

[0025] In the third step: the correction method is as follows: the RF field correction coefficient distribution map is multiplied point by point with the image pixels obtained in the second step to obtain a new image, which is the image of the imaging part after correction.

[0026] Furthermore, in the first step, the calculation method is as follows: the inverse of the pixel value of the container one image constitutes a distribution map of the radio frequency field correction coefficient;

[0027] In the third step, the correction method is as follows: the RF field correction coefficient distribution map and the image obtained in the second step are multiplied point by point according to the corresponding pixel coordinate positions to obtain a corrected image.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention proposes a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system and its use method. The pre-imaging nuclide concentration obtained is an absolute concentration, and the quantification of multiple nuclides can be achieved simultaneously, which is conducive to the longitudinal observation of changes at the molecular level in the target area and the subsequent longitudinal comparison of the functional status of the detected part or the development of the disease of the detected object.

[0030] 2. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system proposed in the present invention can realize the functions in document ZL202310349168.2, which is conducive to the alignment and fusion of multi-nuclide images. However, the thickness of the partition in the sealed container used for nuclide quantification in the present invention is not limited by the magnetic gyroscopic ratio of the nuclide, and the processing accuracy requirement is low.

[0031] 3. The present invention performs uniformity correction on the radio frequency field before quantitative analysis of pre-imaging nuclides, thereby making the quantitative information obtained more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] FIG1 is a top view of a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system;

[0034] FIG2 is a perspective view of a sealed container for quantifying nuclide concentration;

[0035] FIG3 is a schematic diagram showing the positions of the sealed container and the imaging area for quantifying radionuclide concentration;

[0036] FIG4 is a schematic diagram of the image area and the image of the sealed container and the region of interest after correction;

[0037] 1. Container 1, 2. Container 2, 3. Container 3, 4. Container 4, 5. Container 5, 6. Water inlet, 7. Partition I, 8. Partition II, 9. Imaging site, 10. Region of interest ROI1, 11. Region of interest ROI2, 12. Region of interest ROI3, 13. Region of interest ROI4, 14. Region of interest ROI5. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0039] In this example, three radionuclides were used to measure the 1 H. 23 Na, 31 P synchronous magnetic resonance imaging, for example, muscle tissue contains sodium salts ( 23 Na) and phosphorus ( 31 P) compounds, such as creatine phosphate (PCr), adenosine triphosphate (ATP), inorganic phosphorus (Pi), etc., the goal is to quantify the area of ​​interest in muscle tissue 23 Na, 31 PThe concentration of the two nuclides.

[0040] As shown in FIG1-2, a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system includes five sealed containers, each of which is provided with a water inlet 6, through which a mixture containing all pre-imaging nuclides is added to the sealed containers; the five sealed containers are numbered container one 1, container two 2, container three 3, container four 4 and container five 5, respectively, wherein container two 2, container three 3, container four 4 and container five 5 are used for quantitative nuclide concentrations.

[0041] Container 1 is a relatively large cylindrical container with a diameter of 13 cm and a height of 10 cm. Its volume can fill 75% of the effective volume of the RF coil used for imaging. Containers 2, 3, 4, and 5 are all smaller cylindrical containers with a diameter of 1.5 cm and a height of 5 cm. They are internally fixed with intersecting partitions I7 and II8. The angle α between partitions I7 and II8 is 42°, which can be an acute angle. Within the half of the area on the side closest to the cylinder, partitions I7 and II8 are spaced from the sealed container at their upper and lower ends, dividing the sealed container into multiple sub-spaces.

[0042] All 5 sealed containers are filled with all pre-imaging radionuclides 23 Na, 31 A uniform mixture of P, wherein container 1 is used for radio frequency field uniformity correction; container 2 2, container 3 3, container 4 4 and container 5 5 are filled with pre-imaging nuclides 23 Na, 31 P maintains a known concentration gradient, the number of concentration gradients is 4, which is used to quantify the area to be imaged 23 Na, 31 The concentration of P nuclide.

[0043] The mixture consists of the following components: creatine phosphate and sodium chloride (NaCl) as solutes, water (H2O) as solvent, agarose powder added, stirred evenly while heating, and gradually cooled to form a semi-solid water mimetic, with an agarose mass fraction of 4%.

[0044] In the mixture in container 1, the concentrations of creatine phosphate and sodium chloride were both set to 100 mmol / L.

[0045] In the mixtures of container two 2, container three 3, container four 4 and container five 5: the concentrations of sodium chloride are 10 mmol / L, 60 mmol / L, 110 mmol / L, and 170 mmol / L, respectively; and the concentrations of creatine phosphate are 5 mmol / L, 55 mmol / L, 105 mmol / L, and 155 mmol / L, respectively.

[0046] A method for using a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system comprises the following steps:

[0047] The first step is to image container-1 to obtain an image of container-1, and calculate a radio frequency field correction coefficient distribution map based on the image of container-1; the calculation method is as follows: the reciprocal of the pixel value of the container-1 image constitutes the radio frequency field correction coefficient distribution map;

[0048] Step 2: As shown in FIG3 , container 2, container 3, container 4, and container 5 are placed coplanarly and non-colinearly around the imaging part 9, fixed with elastic straps, and imaged simultaneously with the imaging part 9 to obtain the corresponding area. 23 Na and 31 Image of compound P;

[0049] Step 3: Use the RF field correction coefficient distribution map to correct the data obtained in step 2. 23 Na and 31 The image of compound P is corrected as follows: the distribution of radio frequency field correction coefficients and 23 Na and 31 The image of compound P is multiplied point by point according to the pixel coordinate position to obtain the image in the corresponding area. 23 Na and 31 The image after the P compound is corrected, and the schematic diagram of the imaged portion 9, container two 2, container three 3, container four 4 and container five 5 after the correction is shown in FIG4 ;

[0050] Step 4: Calculate the concentrations of different radionuclides in the ROI of the corrected imaging site in sequence according to the fitting method. The method is as follows:

[0051] (1) As shown in FIG4 , a region of interest (ROI) 110 is drawn in the image region after correction of the imaging part 9, and the average signal value of the region of interest (ROI) 110 is calculated and marked as signal intensity S1; ROIs are drawn in the image regions after correction of container 2, container 3, container 4, and container 5, respectively. j (j=2, 3, ..., 5), marked as region of interest ROI211, region of interest ROI312, region of interest ROI413, region of interest ROI514, respectively, calculate the average signal value in each of the four regions of interest, marked as signal intensity S j (j=2, 3, …, 5);

[0052] (2) Using signal strength S j The linear equation S=k*C+b is fitted to the known concentrations of pre-imaging nuclides in the four sealed containers to obtain the values ​​of k and b, where S is the signal intensity, C is the known concentration of the pre-imaging nuclides, and b is the system deviation;

[0053] (3) Substitute S1 into the fitted equation S1=k*C+b to calculate the image region of interest (ROI) of the imaging site 9. 1 pre-imaging radionuclide concentration.

[0054] Repeat steps (1)-(3) for the pre-imaging nuclides 23 Na, 31 P was quantified.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system, characterized by: The invention comprises n sealed containers, n≥5 and is an integer, the n sealed containers are sequentially numbered as container 1, container 2, container 3, ..., container n; the sealed containers are all filled with a mixture containing all pre-imaging nuclides, wherein container 1 is used for radio frequency field uniformity correction, and container 2, container 3, ..., container n are filled with non- 1 The H pre-imaging nuclides all maintain a known concentration gradient, and the number of concentration gradients is n-1, which is used to quantify the different non- 1 H concentration of the pre-imaging nuclide.

2. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1, characterized in that: A cross partition I and a cross partition II are arranged in the half area of ​​one side of container 2, container 3, ..., and container n. The angle ɑ between partition I and partition II is an acute angle. The thickness of partition I and partition II is 1 The resolution of H.

3. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1, characterized in that: The volume of the container 1 can fill more than 75% of the effective volume of the radio frequency coil used for imaging.

4. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1, characterized in that: The concentration of each pre-imaged nuclide in the mixture in container one is higher than the estimated concentration of the corresponding nuclide in the organism.

5. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1, characterized in that: Non-container 2, container 3, ..., container n 1 H pre-imaging isotropic distribution of radionuclides, non 1 The maximum concentration of H pre-imaging nuclides is 20% higher than the maximum estimated concentration of this nuclide in the organism, and the minimum value is equivalent to the lowest estimated concentration in the organism.

6. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1, characterized in that: The resonance frequency of the pre-imaging nuclide in the mixture is consistent with the excitation frequency of the pre-imaging nuclide in the organism.

7. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1, characterized in that: In the mixture, the nuclear magnetic resonance peaks of all nuclides are single peaks; when imaging with an exogenous probe, one of the substances in the mixture is selected as the exogenous probe.

8. The method for using the multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to any one of claims 1 to 7, characterized in that: The following steps are involved: The first step is to image the container one, and calculate the distribution map of the radio frequency field correction coefficient based on the image of the container one; The second step is to place container 2, container 3, container n in the same plane and not in the same line around the imaging part, and image the imaging part at the same time to obtain the non- 1 H pre-imaging nuclide image; The third step is to use the RF field correction coefficient distribution map obtained in the first step to correct the image obtained in the second step, so as to obtain the non- 1 H pre-imaging nuclide-corrected image; Step 4: Calculate the different non-linearities of the image region of interest after correction in turn according to the fitting method. 1 H concentration of the pre-imaging nuclide.

9. The method of use according to claim 8, characterized in that: In the fourth step, the different non- 1 The concentration of H pre-imaging nuclides is determined by the following method: (1) Select a region of interest ROI1 in the image area after correction of the imaging part, and calculate the signal intensity S1 in ROI1; select regions of interest ROI in the image areas after correction of container 2, container 3, ..., container n respectively. j , j=2,…,n, and calculate ROI j The signal strength S j ; (2) Using signal strength S j Fitting the linear equation S=k*C+b with the known concentration of the pre-imaging nuclide of the corresponding container to obtain k and b, where S is the signal intensity, C is the concentration of the pre-imaging nuclide, and b is the system deviation; (3) Substitute S1 into the equation fitted in step (2) to calculate the concentration of the pre-imaging radionuclide in the region of interest ROI1 of the imaging site; (4) Repeat steps (1) to (3) for different non 1 H pre-imaging radionuclides for quantification.

10. The method of use according to claim 8, characterized in that: In the first step, the calculation method is as follows: the inverse of the pixel value of the container one image constitutes the distribution map of the radio frequency field correction coefficient; In the third step, the correction method is as follows: the RF field correction coefficient distribution map and the image obtained in the second step are corresponding to the pixel coordinate position and multiplied point by point to obtain a corrected image.

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