WO2025097750A1 - Multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system and use method therefor - Google Patents

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 quantitative system and its use method Technical Field

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 use method thereof.

Background Art

Magnetic resonance imaging (MRI) can be used for multi-parameter and multi-nuclides imaging. Imaging of endogenous nuclides such as ²³ Na, ³¹ P, and ³⁵ Cl can provide a lot of information that ¹ H imaging cannot provide. At the same time, exogenous nuclides such as ¹⁹ F and ¹³ C have no background signals in the body, which is conducive to being used as probes such as targeting agents and tracers for in vivo research.

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 injection, subcutaneous injection 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 radio frequency 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, taking ³¹ P spectrum imaging as an example, the relative content of two phosphorus-containing substances is usually used based on spectral data to characterize the changes of a functional event, which is not conducive to longitudinal, long-term, and quantitative comparison of the functional status of the subject or the development of the disease.

In magnetic resonance spectroscopy (NMR), internal or external standards are usually used to calibrate the content of substances in a mixture system. However, the effective RF field volume of the RF coil used in NMR is small. For example, the RF coil commonly used for sample tubes with an outer diameter of 5 mm is used. Its effective RF field is distributed in a volume of about 2 cm in height and 5 mm in diameter. The RF field is relatively uniform, and the quantification process of substances does not need to consider the inhomogeneity of the RF field. However, the RF coil volume in MRI is large, and sometimes a surface coil is used to excite and/or receive signals. The RF field is not uniform, resulting in uneven distribution of the intensity of the collected image signal even for a uniform system. Therefore, the RF field uniformity correction is required to quantify the content of substances in MRI.

Chinese patent document CN116098605B proposes a water phantom for multi-nuclide synchronous integrated magnetic resonance imaging and its use method, which can provide feature points and structural similarity features for multi-nuclide magnetic resonance image fusion and solve the problem of multimodal image registration. However, the multiple water phantoms used are mixtures with the same solute concentration and cannot be used to quantify the content information of different nuclides. In addition, the thickness of the internal partition of the water phantom is designed according to the magnetic rotation ratio of the pre-imaging nuclides, which requires high processing accuracy. There is no system or method for synchronous quantification of multiple nuclides in the existing literature for multi-nuclide synchronous magnetic resonance imaging scenarios.

Summary of the invention

The present invention provides 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, and is helpful for longitudinally observing changes in the molecular level of a target area.

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

Furthermore, a cross partition I and partition II are arranged in half of the area on one side of container 2, container 3..., container n, the angle ɑ between partition I and partition II is an acute angle, and the thickness of partition I and partition II is a resolution of ¹ H.

Furthermore, the volume of 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.

Furthermore, in the mixture in container one, the concentration of each pre-imaged nuclide is higher than the estimated concentration of the corresponding nuclide in the organism, such as 50% higher.

Furthermore, the concentration gradient of the non- ^1H pre-imaging nuclide filled in container 2, container 3, ..., container n is set according to the concentration distribution range of the nuclide in the organism reported in the literature, the maximum concentration of the non- ^1H pre-imaging nuclide is 20% higher than the maximum estimated concentration of the nuclide in the organism, and the minimum value is equivalent to the estimated lowest concentration in the organism. The non- ^1H pre-imaging nuclide in container 2, container 3, ..., container n has an equal concentration gradient distribution (the concentration difference is equal and always constant), and the concentrations are marked as _C2 , _C3 , ..., _Cn , respectively.

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.

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

A method for using a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system, the method for using is as follows:

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;

Step 2: Container 2, container 3, ..., container n are placed coplanarly and non-colinearly around the imaging site, and imaged simultaneously with the imaging site to obtain an image of the non- ^1H pre-imaging nuclide in the corresponding area;

Step 3: Correct the image obtained in the second step using the radio frequency field correction coefficient distribution map obtained in the first step, thereby obtaining an image corrected for non- ^1H pre-imaging nuclides in the corresponding area;

The fourth step is to calculate the concentrations of different pre-imaging radionuclides in the region of interest of the image of the corrected imaging site in turn according to the fitting method.

Furthermore, in the fourth step, the concentrations of different pre-imaging nuclides in the region of interest of the image of the corrected imaging part are calculated, and the specific method is as follows:

(1) Selecting a region of interest ROI ₁ in the image region after correction of the imaging part, and calculating the signal intensity S ₁ in ROI ₁ ; selecting regions of interest ROI _j , j=2, ..., n, in the image regions after correction of container 2, container 3, ..., container n, respectively, and calculating the signal intensity S _j in ROI _j ;

(2) Using the signal intensity _Sj and the known concentration of the pre-imaging nuclide in the corresponding container, fit the linear equation S=k*C+b 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 region of interest ROI ₁ of the imaging site;

(4) Repeat steps (1) to (3) to quantify different non- ^1H pre-imaging radionuclides in turn.

Further, 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 pixel of container one point by point are equal;

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.

Further, 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;

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.

Beneficial effects of the present invention:

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 helpful for longitudinal observation of changes at the molecular level in the target area and for subsequent longitudinal comparison of the functional status of the detected part or the development of the disease of the detected object.

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 helpful for the registration 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.

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

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

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

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

FIG3 is a schematic diagram showing the positions of the sealed container and the imaging area for quantitative nuclide concentration;

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

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 ROI ₁ , 11. Region of interest ROI ₂ , 12. Region of interest ROI ₃ , 13. Region of interest ROI ₄ , 14. Region of interest ROI ₅ .

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

This example takes the synchronous magnetic resonance imaging of three radionuclides ¹ H, ²³ Na, and ³¹ P in rabbit thigh muscle tissue as an 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 concentrations of the two radionuclides ²³ Na and ³¹ P in the area of interest of muscle tissue.

As shown in Fig. 1-2, a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system includes 5 sealed containers, each of which is provided with a water inlet 6, through which a mixture containing all pre-imaging nuclides is added into the sealed container; the 5 sealed containers are numbered as container 1, container 2, container 3, container 4, and container 5, respectively, wherein container 2, container 3, container 4, and container 5 are used for quantitative nuclide concentration.

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 radio frequency coil used for imaging. Container 2 2, container 3 3, container 4 4 and container 5 5 are all cylindrical and relatively small in volume, with a diameter of 1.5 cm and a height of 5 cm. Crossed partitions I7 and II8 are fixed inside. The angle ɑ between partitions I7 and II8 is 42°, which can be an acute angle in practice. In the half area of the two partitions close to the side of the cylinder, the upper and lower ends of partitions I7 and II8 are spaced from the sealed container, dividing the sealed container into multiple subspaces.

The five sealed containers are all filled with a uniform mixture containing all pre-imaging nuclides ²³ Na and ³¹ P, wherein container 1 is used for radio frequency field uniformity correction; the pre-imaging nuclides ²³ Na and ³¹ P filled in container 2, container 3, container 4 and container 5 all maintain a known concentration gradient, and the concentration gradient number is 4, which is used to quantify the concentration of ²³ Na and ³¹ P nuclides in the area to be imaged.

The mixture consists of: the solutes are creatine phosphate and sodium chloride (NaCl), the solvent is water (H ₂ O), agarose powder is added, stirred evenly while heating, and gradually cooled to form a semi-solid water mimetic, and the mass fraction of agarose is 4%.

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

In the mixture 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; the concentrations of creatine phosphate are 5 mmol/L, 55 mmol/L, 105 mmol/L and 155 mmol/L respectively.

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

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

Step 2, as shown in FIG3 , container 2 2 , container 3 3 , container 4 4 and container 5 5 are placed coplanarly and non-colinearly around the imaging site 9 , fixed with elastic straps, and imaged simultaneously with the imaging site 9 to obtain images of ²³ Na and ³¹ P-containing compounds in the corresponding regions;

Step 3: Use the radio frequency field correction coefficient distribution map to correct the images of ²³ Na and ³¹ P-containing compounds obtained in the second step. The correction method is as follows: the radio frequency field correction coefficient distribution map is multiplied point by point with the images of ²³ Na and ³¹ P-containing compounds according to the pixel coordinate position to obtain the images of ²³ Na and ³¹ P-containing compounds corrected in the corresponding area. The schematic diagram of the images of the imaging part 9, container two 2, container three 3, container four 4 and container five 5 after correction is shown in FIG4 ;

Step 4: Calculate the concentration of different radionuclides in the region of interest of the corrected imaging part in turn according to the fitting method, as follows:

(1) As shown in FIG. 4 , a region of interest ROI ₁ 10 is drawn in the image region after correction of the imaging part 9, and the signal average value of the region of interest ROI ₁ 10 is calculated and marked as signal intensity S ₁ ; regions of interest ROI _j (j=2, 3, ..., 5) are drawn in the image regions after correction of container 2 2 , container 3 3 , container 4 4 and container 5 5 , respectively, and marked as region of interest ROI ₂ 11 , region of interest ROI ₃ 12 , region of interest ROI ₄ 13 , and region of interest ROI ₅ 14 , and the signal average values in the four regions of interest are calculated respectively, and marked as signal intensity S _j (j=2, 3, ..., 5) in sequence;

(2) Using the signal intensity _Sj and the known concentration of pre-imaging nuclides in the four sealed containers, the linear equation S=k*C+b is fitted 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;

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

Repeat steps (1) to (3) to quantify the pre-imaging nuclides ²³ Na and ³¹ P, respectively.

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 principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

A multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system, characterized in that: it comprises n sealed containers, n≥5 and is an integer, the n sealed containers are sequentially numbered as container one, container two, container three, ..., container n; the sealed containers are all filled with a mixture containing all pre-imaging nuclides, wherein container one is used for radio frequency field uniformity correction, and the non- ^1H pre-imaging nuclides filled in container two, container three ..., container n all maintain a known concentration gradient, and the number of concentration gradients is n-1, which is used to quantify the concentrations of different non- ^1H pre-imaging nuclides in a region to be imaged. According to claim 1, a multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system is characterized in that: a cross partition I and a partition II are arranged in the half area of one side of container two, container three..., container n, the angle ɑ between partition I and partition II is an acute angle, and the thickness of partition I and partition II is a resolution of ¹ H. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1 is characterized in that the volume of container one can fill more than 75% of the effective volume of the radio frequency coil used for imaging. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1 is characterized in that: in the mixture of container one, the concentration of each pre-imaging nuclide is higher than the estimated concentration of the corresponding nuclide in the organism. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1 is characterized in that: the non- ^1H pre-imaging nuclides in container 2, container 3, ..., container n are distributed in equal concentration gradients, the maximum concentration of the non- ^1H pre-imaging nuclides is 20% higher than the maximum estimated concentration of the nuclides in the organism, and the minimum value is equivalent to the estimated minimum concentration in the organism. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1 is 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. The multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to claim 1 is characterized in that: in the mixture, the nuclear magnetic resonance peaks of all nuclides are single peaks; when imaging the exogenous probe, one of the substances in the mixture is selected as the exogenous probe. The method for using the multi-nuclide synchronous integrated magnetic resonance imaging nuclide quantification system according to any one of claims 1 to 7 is characterized in that it comprises the following steps: 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; Step 2: Container 2, container 3, ..., container n are placed coplanarly and non-colinearly around the imaging site, and imaged simultaneously with the imaging site to obtain an image of the non- ^1H pre-imaging nuclide in the corresponding area; Step 3: Correct the image obtained in the second step using the radio frequency field correction coefficient distribution map obtained in the first step, thereby obtaining an image corrected for non- ^1H pre-imaging nuclides in the corresponding area; The fourth step is to calculate the concentrations of different non- ^1H pre-imaging nuclides in the region of interest of the image of the corrected imaging site in turn according to the fitting method. The method of use according to claim 8, characterized in that in the fourth step, the concentrations of different non- ^1H pre-imaging nuclides in the region of interest of the image of the corrected imaging site are calculated by the following specific method: (1) Selecting a region of interest ROI ₁ in the image region after correction of the imaging part, and calculating the signal intensity S ₁ in ROI ₁ ; selecting regions of interest ROI _j , j=2, ..., n, in the image regions after correction of container 2, container 3, ..., container n, respectively, and calculating the signal intensity S _j in ROI _j ; (2) Using the signal intensity _Sj and the known concentration of the pre-imaging nuclide in the corresponding container, fit the linear equation S=k*C+b 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 ROI ₁ of the imaging site; (4) Repeat steps (1) to (3) to quantify different non- ^1H pre-imaging radionuclides in turn. The method of use according to claim 8 is 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 a 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.