A dedicated device for calibration of relaxation time measurements of a medical magnetic resonance imaging system

Abstract

The utility model relates to a kind of special equipment for medical magnetic resonance imaging (MRI) system relaxation time measurement result calibration, including relaxation time standard mould, optical fiber temperature measurement system and control computer. Using relaxation time standard mould can use enough large magnetic resonance free attenuation signal area when carrying out T1, T2 relaxation time measurement calculation, avoid the influence of image boundary signal aliasing on calibration result;Using optical fiber temperature measurement system, the temperature in relaxation time standard mould can be directly measured, the change of temperature in mould is real-time displayed and recorded, the corresponding correction relationship of test temperature and T1 relaxation time standard value, T2 relaxation time standard value is established, the correction value of T1, T2 relaxation time measurement value and corresponding standard value under different calibration temperature is given, the calibration of clinical human tissue T1, T2 relaxation time measurement result is realized, and measurement result accuracy and consistency are promoted, promote its clinical application.

Description

Technical Field

[0001] This utility model relates to a special device in the field of medical testing phantoms, and in particular to a special device for calibrating the relaxation time measurement results of medical magnetic resonance imaging systems. Background Technology

[0002] Magnetic resonance imaging (MRI) is primarily used clinically to obtain morphological information about lesions. With the elucidation of the correspondence between different human tissues and parameters such as relaxation time and diffusion, obtaining functional and quantitative information about organs or tissues through MRI has become an important clinical research direction. This type of research generally employs quantitative magnetic resonance imaging (qMRI), which analyzes the raw signals of target areas in MRI images to obtain information representing metabolic characteristics, such as T1 and T2 relaxation times of the corresponding human tissues. This provides technical support for early disease diagnosis and etiology / pathogenesis research in clinical practice. In recent years, qMRI technology has gradually moved from scientific research to routine clinical application, and different manufacturers have implemented T1 and T2 relaxation time measurement functions on their mainstream MRI equipment. However, due to the lack of calibration and standardization of relaxation time measurement results, the relaxation time data obtained from different brands and devices vary greatly, and the reproducibility of measurement results is poor. This makes it difficult to interpret qMRI measurement results statistically and apply them clinically, hindering the clinical promotion and effectiveness of qMRI technology.

[0003] To accurately determine the values ​​of T1 and T2 relaxation times, numerous research teams both domestically and internationally have conducted research on T1 and T2 relaxation time standard materials. Currently, only products from Caliber MRI (USA) and Gold Standard (UK) are available capable of calibrating T1 and T2 relaxation time measurements. Caliber MRI's flagship product is the Premium System Phantom, a 231 mm diameter phantom that includes a copper sulfate module for measuring field homogeneity, a nickel chloride module for measuring T1, a manganese chloride module for measuring T2, and a proton density module. The advantages of this phantom are that it can simultaneously test some imaging performance parameters, and the solution temperature within the phantom can be calculated using imaging methods. The disadvantages are that the T1 and T2 relaxation times are measured using different standard materials, and the measurement results may differ due to factors such as the homogeneity of the static magnetic field. Furthermore, the measurement module filled with the T1 and T2 relaxation time standard materials has a small geometric size, limiting the usable magnetic resonance free decay signal region when calculating T1 and T2 relaxation times, which may cause deviations in the measurement results due to signal aliasing at image boundaries. Moreover, the solution temperature within the phantom is indirectly calculated using imaging methods and is not the actual temperature within the phantom; a correction relationship between the standard values ​​of the T1 and T2 relaxation time standard materials and the temperature has not been established. All three of these factors can cause deviations in the standard values ​​used for calibrating the T1 and T2 relaxation time standard materials and in the calibration results.

[0004] GOLD Standard's flagship product is the MultiSample 120E, a cylindrical phantom with a diameter of 120mm that can hold up to 24 standard 10mL polypropylene bottles filled with standard solutions for diffusion or relaxation measurements. Compared to CaliberMRI products, this phantom offers several advantages: first, it provides a wider variety of T1 and T2 relaxation time standards, allowing for calibration coverage of a broader range of T1 and T2 relaxation times; second, it uses the same standard materials for both T1 and T2 relaxation times, avoiding the influence of factors such as static magnetic field homogeneity on the measurement results. However, it also has disadvantages: first, it cannot measure temperature within the phantom itself, relying solely on thermal paper applied to the phantom surface to characterize temperature changes, making it impossible to establish a correction relationship between the standard values ​​of the T1 and T2 relaxation time standards and temperature; second, the relatively small size of the polypropylene bottles filled with both T1 and T2 relaxation time standards may lead to measurement inaccuracies due to signal aliasing at image boundaries.

[0005] Furthermore, neither of the aforementioned foreign phantoms provides a temperature correction method for the standard values ​​of T1 and T2 relaxation times, nor does it provide how to use the standard values ​​to correct the T1 and T2 relaxation time measurement results of the medical magnetic resonance imaging system being calibrated.

[0006] In view of the defects of the existing technology, the inventor, through continuous research, design, and repeated trial production and improvement, has finally created this utility model with practical value. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of existing technologies and provide a new type of dedicated device for calibrating relaxation time measurement results in medical magnetic resonance imaging systems. The technical problem to be solved is to ensure that a sufficiently large magnetic resonance free decay signal region is used when performing relaxation time measurement calculations, so as to avoid the influence of image boundary signal aliasing on the calibration results, thus making it more suitable for practical use.

[0008] Another objective of this invention is to overcome the shortcomings of existing technologies and provide a new specialized device for calibrating relaxation time measurement results in medical magnetic resonance imaging systems. The technical problem to be solved is to enable direct measurement of the temperature inside the phantom, real-time display and recording of temperature changes inside the phantom, thereby establishing a correction relationship and correction method between the test temperature of the relaxation time standard material and the relaxation time standard value, thus making it more suitable for practical use.

[0009] Another objective of this invention is to provide a dedicated device for calibrating relaxation time measurement results of medical magnetic resonance imaging systems. The technical problem to be solved is to enable it to correct the relaxation time measurement results of clinical human tissue magnetic resonance imaging, thereby making it more suitable for practical use.

[0010] The purpose of this utility model and the technical problem it solves are achieved by the following technical solution. According to this utility model, a special device for calibrating relaxation time measurement results in a medical magnetic resonance imaging system includes a relaxation time standard phantom, a fiber optic temperature measurement system, and a control computer. The relaxation time standard phantom and the fiber optic temperature measurement system are connected in a tight-fitting manner, and the fiber optic temperature measurement system and the control computer are connected via fiber optic communication.

[0011] Furthermore, the relaxation time standard phantom consists of a sealing cover at the top, a phantom shell at the bottom, and a relaxation time standard unit disposed inside the phantom shell; The sealing cap is cylindrical. Multiple internally threaded through holes with internal threads are evenly arranged along the edge of the upper surface of the sealing cap. An optical fiber through hole is provided at the center of the upper surface of the sealing cap. A groove is etched in the middle of the optical fiber through hole and a sealing gasket is embedded in the groove. The lower surface of the sealing cap is provided with multiple counterclockwise threaded mounting holes. The multiple counterclockwise threaded mounting holes are evenly distributed with the optical fiber through hole as the center of symmetry. The depth of each counterclockwise threaded mounting hole is within the thickness of the sealing cap. A circular upper groove is etched near the edge of the lower surface of the sealing cap. The circular upper groove is concentric with the lower surface of the sealing cap. The mold shell is an open-top cylindrical shell, including an outer edge and a main body. The outer diameter of the outer edge is the same as the outer diameter of the sealing cap. Near the outer edge, the outer edge of the mold shell has multiple internally threaded fixing holes, each corresponding to a set of internally threaded through holes. The depth of these holes is within the thickness range of the outer edge of the mold shell. A circular lower groove is located on the outer edge of the mold shell, corresponding to the upper circular groove. The two grooves are identical in position and size, and the lower circular groove is concentric with the outer edge of the mold shell. A sealing gasket is embedded in the lower circular groove. Apply a small amount of silicone grease to the ring. The thickness of this sealing gasket should be greater than the combined depth of the upper and lower circular grooves. The diameter of the inner edge of the mold shell should be the same as the inner diameter of the main body of the mold shell. Use plastic screws to pass through multiple internal threaded through holes and corresponding internal threaded fixing holes and tighten them to assemble the sealing cap and the mold shell into one piece. When using the relaxation time standard mold, the mold shell should be filled with pure water to ensure that there are no air bubbles in the relaxation time standard mold after the sealing cap and the mold shell are assembled into one piece. The inner diameter of the mold shell should be greater than 12cm and the depth should be greater than 10cm.

[0012] Furthermore, the relaxation time standard unit consists of multiple identical cylindrical reagent bottles. Each reagent bottle comprises a bottle body and a cap, which are tightly connected by threads. Each bottle is filled with different T1 and T2 relaxation time standard substances. A sealing gasket is embedded inside the cap of each bottle. When the cap is tightened clockwise, the sealing gasket presses against the top of the bottle opening, ensuring no liquid exchange between the T1 and T2 relaxation time standard substances inside the bottle and the pure water in the phantom shell. Each reagent bottle cap has a counter-clockwise thread. After the bottle is filled with the T1 and T2 relaxation time standard substances and the cap is tightened, each bottle is fixed to the lower surface of the cap by inserting it into the counter-clockwise threaded mounting hole on the lower surface of the cap and tightening it. After each bottle is fixed to the cap, it can be inserted into the phantom shell without contacting the inner wall of the phantom shell. Each reagent bottle has an inner diameter greater than 3 cm and a height greater than 5 cm.

[0013] Furthermore, the standard substances filled with different T1 and T2 relaxation times are composed of manganese chloride or nickel chloride solutions of different concentrations. In actual use, different concentrations of manganese chloride or nickel chloride solutions are selected according to the T1 and T2 relaxation time ranges to be calibrated. When the concentration of manganese chloride solution is 0.0113mM~1.5996mM, the corresponding standard value range of T1 relaxation time is 2478ms~82ms and the corresponding standard value range of T2 relaxation time is 553ms~5ms. When the concentration of nickel chloride solution is 0.29mM~65.3mM, the corresponding standard value range of T1 relaxation time is 1937ms~21ms and the corresponding standard value range of T2 relaxation time is 1521ms~15ms.

[0014] Furthermore, the fiber optic temperature measurement system consists of a main unit, a fiber optic temperature probe, and a housing for the probe. The main unit receives the optical signal transmitted by the probe and converts it into a temperature value. The fiber optic temperature probe is based on the principle of a fluorescent fiber optic temperature sensor and is compatible with the measurement environment of 1.5T and above medical superconducting magnetic resonance imaging systems. It has a temperature measurement accuracy of ±0.1℃ and a measurement range covering 0℃ to 50℃. The fiber optic cable of the probe is longer than 5 meters to ensure that the main unit and control computer can be located outside the shielded room of the medical magnetic resonance imaging system when performing relaxation time measurements using a relaxation time standard phantom. The fiber optic temperature probe passes through the fiber optic cable for temperature measurement. The probe housing ensures that the fluorescent fiber optic temperature sensor at the front end of the fiber optic temperature probe is completely outside the probe housing. Then, adhesive is used to fill the gap between the fiber optic temperature probe and the probe housing, achieving both a fixed probe and a waterproof seal. The probe housing is a hollow acrylic tube, with an outer diameter larger than the inner diameter after the sealing gasket is installed in the fiber optic through-hole. This ensures a tight fit between the probe housing and the sealing gasket after insertion into the fiber optic through-hole, preventing pure water leakage from the phantom housing when the relaxation time standard phantom is placed flat in a medical superconducting magnetic resonance imaging system for relaxation time measurement.

[0015] Furthermore, the control computer communicates with the device host via a data cable. The fiber optic temperature measurement software is installed in the control computer and is used to control the device host to collect temperature data and record the temperature measurement results. The fiber optic temperature measurement software can also calibrate the temperature measurement results of the fiber optic temperature probe. It uniformly selects and provides 5 to 10 standard ambient temperatures within the measurement range of 0℃ to 50℃. By linearly fitting the measurement results of the fiber optic temperature probe with the standard ambient temperatures, it can calibrate and correct the temperature measurement results of the fiber optic temperature probe.

[0016] The objective of this utility model and the technical problem it solves are achieved by the following technical solution. A method for calibrating relaxation time measurement results in a medical magnetic resonance imaging system, according to this utility model, includes the following steps: Step 1: Calibrate the relaxation time standard values ​​of different T1 and T2 relaxation time standard substances filled in each reagent bottle. Specifically, magnetic resonance spectroscopy is used to determine the relaxation time standard values. This method is traceable to national time and frequency standards, thus ensuring the accuracy of the determination results. When using magnetic resonance spectroscopy to determine the T1 and T2 relaxation times of the T1 and T2 relaxation time standard substances, first, the static magnetic field strength of the magnetic resonance spectroscopy test environment is set to the static magnetic field strength when the T1 and T2 relaxation time standard substances are used. Then, the T1 relaxation time of the T1 and T2 relaxation time standard substances is calibrated using inversion recovery sequences, and the T1 relaxation time is calibrated using CPMG sequences. The T2 relaxation time of T1 and T2 relaxation time standard materials; before determining the standard values ​​of relaxation time of different T1 and T2 relaxation time standard materials, the relaxation time standard phantom needs to be placed in the magnetic resonance spectroscopy test environment in advance so that the pure water in the phantom shell, the different T1 and T2 relaxation time standard materials filled in each reagent bottle and the test environment reach thermal equilibrium; when determining the standard values ​​of relaxation time of different T1 and T2 relaxation time standard materials, the temperature in the relaxation time standard phantom is measured simultaneously using a fiber optic temperature measurement system. The temperature measurement results are used to establish the correction curves of the relaxation time standard values ​​of different T1 and T2 relaxation time standard materials as a function of test temperature. Step 2: Use calibrated T1 and T2 relaxation time standard materials to calibrate the T1 relaxation time and T2 relaxation time measurement results of the medical magnetic resonance imaging system.

[0017] Furthermore, the inversion recovery sequence first applies a 180° pulse in the X direction, with magnetization vector M Z Flip it to the negative Z-axis direction, and then let the magnetization vector M Z After free relaxation and a period of time TI, a 90° pulse is applied again. The amplitude of the FID signal at this time is detected and recorded. By changing TI multiple times, the magnetization vector M is plotted. z The curve of TI changing, then according to M z (TI)=M0(1-2e -TI / T1 T1 is calculated by fitting. In the inversion recovery sequence, the repetition time needs to be long enough, preferably greater than 4000 milliseconds, and the echo time should be as short as possible, but preferably greater than 10 milliseconds. In formula M z (TI)=M0(1-2e -TI / T1 )middle: M z (TI): The magnetization vector in the Z-direction of the magnetic resonance spectroscopy test environment is denoted as M. z M z It is a function of TI, and its function expression is M0(1-2e -TI / T1 ); M0: The inversion recovery sequence applies a 180° pulse in the X direction, causing the magnetization vector M... Z After flipping to the negative Z-axis direction, this point is recorded as time 0. At this time, the magnetization vector in the Z-direction of the magnetic resonance spectroscopy test environment is denoted as M0. TI: Time interval; e -TI / T1 e is an exponential function, where -TI / T1 is the exponent and e is the natural constant; T1: refers to the T1 relaxation time of a substance, which is the spin-lattice relaxation time of the atomic nucleus (i.e., the longitudinal relaxation time).

[0018] Furthermore, the CPMG sequence consists of one 90° radio frequency pulse in the X direction and multiple 180° radio frequency pulses in the Y direction. After transmitting the 90° radio frequency pulse in the X direction, a 180° radio frequency pulse is applied along the Y direction at TE intervals. Each 180° pulse generates an FID signal. Multiple such FID (free induction attenuation) signals are acquired, and the echo signal amplitude envelope is plotted according to formula M. xy (t)=M xy (0)e -t / T2 (t=nTE, n=1,2,3,...,20) The T2 relaxation time is calculated using fitting. In CPMG sequences, the repetition time needs to be sufficiently long, typically greater than 4000 milliseconds; In formula M xy (t)=M xy (0)e -t / T2 (t=nTE, n=1,2,3,…,20): M xy (t): The CPMG sequence emits a 90° RF pulse in the X direction of the magnetic resonance spectroscopy test environment, followed by a 180° RF pulse in the Y direction every TE time; an FID signal is generated after each 180° RF pulse; M xy (t) is the line connecting the peak values ​​of multiple FID signals in the XY plane, generally called the envelope of the echo signal amplitude, M xy M(t) is a function of time t, which can be expressed as M xy (0)e -t / T2 The zero point of time t is the starting point at which the CPMG sequence emits a 90° radio frequency pulse in the X direction of the magnetic resonance spectroscopy test environment. M xy (0): The starting time point at which the CPMG sequence emits a 90° radio frequency pulse in the X direction of the magnetic resonance spectroscopy test environment is recorded as 0. At this time, the magnetization vector on the XY plane of the magnetic resonance spectroscopy test environment is denoted as M. xy (0); TE: Echo Time e -t / T2 e is an exponential function, where -t / T² is the exponent and e is the natural constant. T2: refers to the T2 relaxation time of matter, which is the spin-spin relaxation time of the atomic nucleus (i.e., transverse relaxation time). nTE: The time point of the nth TE, where n is the number of 180° pulses emitted.

[0019] Further: The method for establishing correction curves of the relaxation time standard values ​​of different T1 and T2 relaxation time standard substances as a function of test temperature using the temperature measurement results of the fiber optic temperature measurement system (2) is as follows: Step 1.1: Temperature measurement. For inversion recovery sequence or CPMG sequence, before starting the sequence scan, start the fiber optic temperature measurement system to measure the temperature of pure water in the phantom shell. Record the pure water temperature H1 and the ambient temperature H2 of the magnetic resonance spectroscopy test environment. If the temperature difference between H1 and H2 is within ±0.1 degrees Celsius, the measurement and calibration of the T1 relaxation time standard value and the T2 relaxation time standard value can begin. Use the pure water temperature H1 as the test temperature for the current relaxation time measurement. Step 1.2: Establish correction curves between test temperature and T1 and T2 relaxation time standard values. For the fixed measurement results of the relaxation time standard values ​​of T1 and T2 relaxation time standard materials, establish a comparison table of test temperature and T1 relaxation time standard values ​​and test temperature and T2 relaxation time standard values ​​for the same standard material under the same static magnetic field strength. Establish linear correction curves between test temperature and T1 and T2 relaxation time standard values. According to the experimental results, as the test temperature changes, the temperature change coefficient of T1 and T2 relaxation time standard values ​​with increasing temperature is approximately +2% / ℃. It should be emphasized that the linear correction curves of T1 and T2 relaxation time standard values ​​and test temperature obtained under different static magnetic field strengths of magnetic resonance spectroscopy methods are different.

[0020] Furthermore, step 2 specifically includes the following steps: Step 2.1: Place the relaxation time standard phantom in the shielding room of the medical magnetic resonance imaging system to be calibrated in advance, so that the pure water in the phantom shell 1-2 and the different T1 and T2 relaxation time standard substances filled in each reagent bottle reach thermal equilibrium with the temperature of the shielding room. Step 2.2: Place the relaxation time standard phantom in the imaging coil. The inner diameter of the imaging coil should be 1-2-1 larger than the edge of the phantom shell and each reagent bottle should be in the middle of the imaging coil. Use the medical magnetic resonance imaging system to be calibrated to scan its commonly used T1 and T2 relaxation time measurement sequences to obtain the T1 relaxation time measurement value and T2 relaxation time measurement value of the different T1 and T2 relaxation time standard substances filled in each reagent bottle. At the same time, following the above...A method for calibrating relaxation time measurement results in a medical magnetic resonance imaging system, obtaining the calibration temperatures of T1 and T2 relaxation time standard materials during measurement; Step 2.3: Based on the static magnetic field strength of the medical magnetic resonance imaging system and the calibration temperature of the obtained T1 and T2 relaxation time standard materials, the calibration temperature is substituted into the temperature correction curve of the corresponding concentration of manganese chloride or nickel chloride solution to obtain the standard value of T1 relaxation time and the standard value of T2 relaxation time at the calibration temperature. Step 2.4: Provide the correction values ​​for the measured values ​​of T1 relaxation time and T2 relaxation time at the calibration temperature, that is, subtract the corresponding measured value of T1 relaxation time or T2 relaxation time from the standard value of T1 relaxation time or T2 relaxation time at the calibration temperature.

[0021] This invention has significant advantages and beneficial effects compared with the prior art. It has at least the following advantages: 1. The reagent bottle filled with the equivalent material for T1 and T2 relaxation times has an inner diameter of not less than 3 cm and a height of not less than 5 cm, and the cross-section is a regular circle. This ensures that the relaxation time standard phantom can acquire a sufficient number of cross-sectional images when calibrating the medical magnetic resonance imaging system being calibrated. The region of interest for the cross-sectional imaging corresponding to each reagent bottle is large enough to ensure that a sufficiently large magnetic resonance free decay signal region is used when calculating T1 and T2 relaxation times, and to avoid the influence of image boundary signal aliasing on the calibration results. 2. This patent uses a fiber optic temperature measurement system compatible with a superconducting magnetic resonance imaging system, which can directly measure the temperature inside the relaxation time standard phantom when the relaxation time standard values ​​of T1 and T2 relaxation time standard materials are set, and display and record the temperature change inside the phantom in real time, thereby establishing a corresponding correction relationship between the test temperature and the T1 relaxation time standard value and the T2 relaxation time standard value. 3. Using a fiber optic temperature measurement system compatible with the superconducting magnetic resonance imaging environment, the temperature inside the relaxation time standard phantom can be directly measured when calibrating the measurement results of the medical magnetic resonance imaging system using the relaxation time standard phantom. The measured calibration temperature is used to establish the standard values ​​of T1 relaxation time and T2 relaxation time for different T1 and T2 relaxation time standard materials during calibration using interpolation. This provides correction values ​​for the measured T1 and T2 relaxation times at different calibration temperatures and their corresponding standard values, thereby calibrating the T1 and T2 relaxation time measurement results of clinical human tissues. 4. Since the length of the reagent bottle is shorter than the depth of the relaxation time standard phantom shell, a pure water imaging area is reserved in the lower part of the relaxation time standard phantom. In actual use, pure water images can be acquired as needed to analyze the image uniformity of the medical magnetic resonance imaging system being tested, and then to analyze the distribution of static magnetic field and radio frequency field.

[0022] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a special device for calibrating relaxation time measurement results of a medical magnetic resonance imaging system according to this utility model.

[0024] Figure 2 This is a schematic diagram of the relaxation time standard phantom structure of this utility model.

[0025] Figure 3 This is a schematic diagram of the structure of the relaxation time standard mold sealing cover of this utility model.

[0026] Figure 4 This is a schematic diagram of the outer shell structure of the relaxation time standard phantom of this utility model.

[0027] Figure 5 This is a schematic diagram of the structure of the relaxation time standard phantom reagent bottle of this utility model.

[0028] Figure 6A This is a schematic diagram of the structure of the relaxation time standard phantom reagent bottle of this utility model.

[0029] Figure 6B This is a structural diagram of the main body of the reagent bottle of the relaxation time standard phantom reagent bottle of this utility model.

[0030] Figure 6C This is a structural diagram of the reagent bottle cap of the relaxation time standard phantom reagent bottle of this utility model.

[0031] Figure 7 This is a schematic diagram of the fiber optic temperature measurement system and control computer of this utility model and patent.

[0032] Figure 8 This is a graph showing the results of Molly sequence measurement of T1 relaxation time of target human tissue (brain tissue) within the circular region of interest in this invention.

[0033] in: 1: Relaxation Time Standard Molecular 1-1: Sealing cap 1-1-1: First internal thread through hole; 1-1-2: Second internal thread through hole 1-1-3: Third internal thread through hole; 1-1-4: Fourth internal thread through hole 1-1-5: Fifth internal thread through hole; 1-1-6: Sixth internal thread through hole 1-1-7: Seventh internal thread through hole; 1-1-8: Eighth internal thread through hole 1-1-9: Ninth internal thread through hole; 1-1-10: Tenth internal thread through hole 1-1-11: Fiber Optic Through-Hole 1-1-12: First counterclockwise threaded mounting hole; 1-1-13: Second counterclockwise threaded mounting hole 1-1-14: Third counterclockwise threaded mounting hole; 1-1-15: Fourth counterclockwise threaded mounting hole 1-1-16: Circular groove 1-2: Outer shell of the phantom 1-2-1: Edge of the outer shell of the mold 1-2-1-1: First internal thread fixing hole; 1-2-1-2: Second internal thread fixing hole 1-2-1-3: Third internal thread fixing hole; 1-2-1-4: Fourth internal thread fixing hole 1-2-1-5: Fifth internal thread fixing hole; 1-2-1-6: Sixth internal thread fixing hole 1-2-1-7: Seventh internal thread fixing hole; 1-2-1-8: Eighth internal thread fixing hole 1-2-1-9: Ninth internal thread fixing hole; 1-2-1-10: Tenth internal thread fixing hole 1-2-1-11: Circular lower groove 1-2-2: Main body of the mold shell 1-3: Standard Unit of Relaxation Time 1-3-1: First reagent bottle; 1-3-2: Second reagent bottle 1-3-3: Third reagent bottle; 1-3-4: Fourth reagent bottle 1-3-4-1: Fourth reagent bottle cap 1-3-4-2: Main body of the fourth reagent bottle 2: Fiber optic temperature measurement system 2-1: Main unit of the device 2-2: Fiber optic temperature probe 2-3: Fiber optic temperature probe housing 3: Controlling the computer 3-1: Data cable 3-2: Fiber Optic Temperature Measurement Software Detailed Implementation

[0034] To further illustrate the technical means and effects adopted by this utility model to achieve the intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, method, steps, features, and effects of a special device for calibrating relaxation time measurement results of a medical magnetic resonance imaging system according to this utility model.

[0035] Please see Figure 1 As shown in the figure, a special device for calibrating relaxation time measurement results of a medical magnetic resonance imaging system according to a preferred embodiment of the present invention mainly includes a relaxation time standard phantom 1, an optical fiber temperature measurement system 2, and a control computer 3. The relaxation time standard phantom 1 and the optical fiber temperature measurement system 2 are connected in a tight fit manner, and the optical fiber temperature measurement system 2 and the control computer 3 are connected in an optical fiber communication manner.

[0036] Please see Figure 2 As shown, the relaxation time standard phantom 1 consists of a sealing cover 1-1 located at the top, a phantom shell 1-2 located at the bottom, and a relaxation time standard unit 1-3 disposed inside the phantom shell 1-2; Please see Figure 3 As shown, the sealing cover 1-1 is a cylinder. Multiple internally threaded through holes with internal threads are evenly arranged on the edge of the upper surface of the sealing cover 1-1. An optical fiber through hole 1-1-11 is provided at the center of the upper surface of the sealing cover 1-1. A groove is etched in the middle of the optical fiber through hole 1-1-11 and a sealing gasket is embedded in the groove. The lower surface of the sealing cover 1-1 is provided with multiple counterclockwise threaded mounting holes. The multiple counterclockwise threaded mounting holes are evenly distributed with the optical fiber through hole 1-1-11 as the center of symmetry. The depth of each counterclockwise threaded mounting hole is within the thickness of the sealing cover 1-1. A circular upper groove 1-1-16 is etched near the edge of the lower surface of the sealing cover 1-1. The circular upper groove 1-1-16 is concentric with the lower surface of the sealing cover 1-1. As Figure 3 As shown, in a specific embodiment of this utility model, 10 internally threaded through holes with internal threads are evenly arranged on the upper surface edge of the sealing cover 1-1, namely: the first internally threaded through hole 1-1-1, the second internally threaded through hole 1-1-2, the third internally threaded through hole 1-1-3, the fourth internally threaded through hole 1-1-4, the fifth internally threaded through hole 1-1-5, the sixth internally threaded through hole 1-1-6, the seventh internally threaded through hole 1-1-7, the eighth internally threaded through hole 1-1-8, the ninth internally threaded through hole 1-1-9, and the tenth internally threaded through hole 1-1-10. See Figure 4As shown, the mold shell 1-2 is an open cylindrical shell, including the mold shell edge 1-2-1 and the mold shell body 1-2-2. The outer diameter of the mold shell edge 1-2-1 is the same as the outer diameter of the sealing cap 1-1. Near the outer edge of the mold shell edge 1-2-1, and corresponding to multiple internally threaded through holes, multiple internally threaded fixing holes are provided. The depth of these internally threaded fixing holes is within the thickness range of the mold shell edge 1-2-1. A circular lower groove 1-2-1-11 is provided on the mold shell edge 1-2-1 at a position corresponding to the circular upper groove 1-1-16. The two grooves are the same in position and size, and the circular lower groove 1-2-1-11 is concentric with the mold shell edge 1-2-1. -11 contains a sealing gasket with a small amount of silicone grease applied to it. The thickness of the sealing gasket is slightly greater than the depth of the groove after the upper circular groove 1-1-16 and the lower circular groove 1-2-1-11 are combined. The diameter of the inner edge of the outer shell 1-2-1 is the same as the inner diameter of the outer shell 1-2-2. Plastic screws are used to pass through multiple internal threaded through holes and corresponding internal threaded fixing holes and tighten them to assemble the sealing cap 1-1 and the outer shell 1-2 into one unit. When using the relaxation time standard mold 1, the outer shell 1-2 should be filled with pure water to ensure that after the sealing cap 1-1 and the outer shell 1-2 are assembled into one unit, the relaxation time standard mold 1 is free of air bubbles, and the inner diameter of the outer shell 1-2 is greater than 12cm and the depth is greater than 10cm.

[0037] As Figure 4 As shown, in a specific embodiment of this utility model, the outer edge 1-2-1 of the mold body shell is provided with 10 internally threaded fixing holes near the outer edge and corresponding to 10 internally threaded through holes, namely: the first internally threaded fixing hole 1-2-1-1, the second internally threaded fixing hole 1-2-1-2, the third internally threaded fixing hole 1-2-1-3, the fourth internally threaded fixing hole 1-2-1-4, the fifth internally threaded fixing hole 1-2-1-5, the sixth internally threaded fixing hole 1-2-1-6, the seventh internally threaded fixing hole 1-2-1-7, the eighth internally threaded fixing hole 1-2-1-8, the ninth internally threaded fixing hole 1-2-1-9, and the tenth internally threaded fixing hole 1-2-1-10.

[0038] See Figure 5As shown, relaxation time standard unit 1-3 consists of multiple identical cylindrical reagent bottles. Each reagent bottle comprises a bottle body and a cap, which are tightly connected by threads. Each bottle is filled with different T1 and T2 relaxation time standard substances. A sealing gasket is embedded inside the cap of each bottle. When the cap is tightened clockwise to the bottle body, the sealing gasket is pressed against the top of the bottle opening, ensuring no liquid exchange between the T1 and T2 relaxation time standard substances inside the bottle and the pure water in the outer shell 1-2. Each reagent bottle cap has a counter-clockwise thread, allowing the bottle to be inserted into the sealing cap 1-3 after being filled with the T1 and T2 relaxation time standard substances and the cap tightened. The lower surface is provided with counterclockwise threaded mounting holes and tightened to fix each reagent bottle on the lower surface of the sealing cap 1-1; after each reagent bottle is fixed on the sealing cap 1-1, it can be inserted into the main body of the mold shell 1-2-2 without contacting the inner wall of the main body of the mold shell 1-2-2. The inner diameter of each reagent bottle is greater than 3cm and the height is greater than 5cm.

[0039] As Figure 5 and Figures 6A-6C As shown, in a specific embodiment of this utility model, the relaxation time standard unit 1-3 is composed of four identical cylindrical reagent bottles, namely, the first reagent bottle 1-3-1, the second reagent bottle 1-3-2, the third reagent bottle 1-3-3, and the fourth reagent bottle 1-3-4. Each reagent bottle consists of a reagent bottle body and a test bottle cap, and each reagent bottle body and reagent bottle cap are tightly connected by threads. Figures 6A-6C The fourth test bottle 1-3-4 shown is composed of the body of the fourth reagent bottle 1-3-4-2 and the top cover of the fourth reagent bottle 1-3-4-1, and the two are tightly connected by threads.

[0040] The standard reference materials filled with different T1 and T2 relaxation times are composed of manganese chloride or nickel chloride solutions of different concentrations. In actual use, different concentrations of manganese chloride or nickel chloride solutions are selected according to the T1 and T2 relaxation time ranges to be calibrated. When the concentration of manganese chloride solution is 0.0113mM~1.5996mM, the corresponding standard value range of T1 relaxation time is 2478ms~82ms and the corresponding standard value range of T2 relaxation time is 553ms~5ms. When the concentration of nickel chloride solution is 0.29mM~65.3mM, the corresponding standard value range of T1 relaxation time is 1937ms~21ms and the corresponding standard value range of T2 relaxation time is 1521ms~15ms.

[0041] See Figure 7As shown, the fiber optic temperature measurement system 2 consists of a main unit 2-1, a fiber optic temperature probe 2-2, and a fiber optic temperature probe housing 2-3. The main unit 2-1 receives the optical signal transmitted by the fiber optic temperature probe 2-2 and converts it into a temperature value. The fiber optic temperature probe 2-2 is based on the temperature measurement principle of a fluorescent fiber optic temperature sensor and is compatible with the measurement environment of 1.5T and above medical superconducting magnetic resonance imaging systems. It has a temperature measurement accuracy of ±0.1℃ and a measurement range covering 0℃~50℃. The fiber optic length of the fiber optic temperature probe 2-2 is greater than 5 meters to ensure that when measuring the relaxation time in the relaxation time standard phantom 1, the main unit 2-1 and the control computer 3 can be located outside the shielded room of the medical magnetic resonance imaging system. The fiber optic temperature probe 2-2 passes through the fiber optic temperature probe housing 2-3. 3. Ensure that the fluorescent fiber optic temperature sensor at the front end of the fiber optic temperature probe 2-2 is completely outside the fiber optic temperature probe housing 2-3. Then, fill the gap between the fiber optic temperature probe 2-2 and the fiber optic temperature probe housing 2-3 using glue injection to achieve the effect of fixing the fiber optic temperature probe 2-2 and waterproof sealing. The fiber optic temperature probe housing 2-3 is a hollow acrylic round tube. The outer diameter of the fiber optic temperature probe housing 2-3 is larger than the inner diameter of the fiber optic through hole 1-1-11 after the sealing gasket is installed. This ensures that the fiber optic temperature probe housing 2-3 can form a tight fit with the sealing gasket after being inserted into the fiber optic through hole 1-1-11, thereby preventing pure water leakage from the housing 1-2 of the relaxation time standard phantom 1 when it is placed flat in the medical superconducting magnetic resonance imaging system for relaxation time measurement.

[0042] See Figure 7 As shown, the control computer 3 communicates with the host device 2-1 via data cable 3-1. The fiber optic temperature measurement software 3-2 is installed in the control computer 3 and is used to control the host device 2-1 to collect temperature data and record the temperature measurement results. The fiber optic temperature measurement software 3-2 can also calibrate the temperature measurement results of the fiber optic temperature probe 2-2. It uniformly selects and provides 5 to 10 standard ambient temperatures within the measurement range of 0℃ to 50℃. By linearly fitting the measurement results of the fiber optic temperature probe 2-2 with the standard ambient temperatures, it achieves calibration and correction of the temperature measurement results of the fiber optic temperature probe 2-2.

[0043] A method for calibrating relaxation time measurement results in a medical magnetic resonance imaging system, comprising the following steps: Step 1: Calibrate the relaxation time standard values ​​of different T1 and T2 relaxation time standard substances filled in each reagent bottle. Specifically, magnetic resonance spectroscopy is used to calibrate the relaxation time standard values. This method can be traced back to the national time and frequency standard, thus ensuring the accuracy of the calibration results. When using magnetic resonance spectroscopy to determine the T1 and T2 relaxation times of the T1 and T2 relaxation time standard substances, first, the static magnetic field strength of the magnetic resonance spectroscopy test environment is set to the static magnetic field strength when the T1 and T2 relaxation time standard substances are used. Then, the T1 relaxation time of the T1 and T2 relaxation time standard substances is calibrated using inversion recovery sequences, respectively. During the process, the T2 relaxation time of the T1 and T2 relaxation time standard substances was calibrated using CPMG sequences. Before determining the standard values ​​of the relaxation time of different T1 and T2 relaxation time standard substances, the relaxation time standard phantom 1 needed to be placed in the magnetic resonance spectroscopy test environment to ensure that the pure water in the phantom shell 1-2, the different T1 and T2 relaxation time standard substances filled in each reagent bottle, and the test environment reached thermal equilibrium. When determining the standard values ​​of the relaxation time of different T1 and T2 relaxation time standard substances, the temperature in the relaxation time standard phantom 1 was measured simultaneously using the fiber optic temperature measurement system 2. The temperature measurement results were used to establish correction curves for the relaxation time standard values ​​of different T1 and T2 relaxation time standard substances as a function of the test temperature.

[0044] Step 2: Use calibrated T1 and T2 relaxation time standard materials to calibrate the T1 relaxation time and T2 relaxation time measurement results of the medical magnetic resonance imaging system.

[0045] The inversion recovery sequence first applies a 180° pulse in the X direction, with magnetization vector M Z Flip it to the negative Z-axis direction, and then let the magnetization vector M Z After free relaxation and a period of time TI, a 90° pulse is applied again. The amplitude of the FID signal at this time is detected and recorded. By changing TI multiple times, the magnetization vector M is plotted. z The curve of TI changing, then according to M z (TI)=M0(1-2e -TI / T1 T1 is calculated by fitting. In the inversion recovery sequence, the repetition time needs to be long enough, preferably greater than 4000 milliseconds, and the echo time should be as short as possible, but preferably greater than 10 milliseconds.

[0046] In formula M z (TI)=M0(1-2e -TI / T1 )middle: M z (TI): The magnetization vector in the Z-direction of the magnetic resonance spectroscopy test environment is denoted as M. z M zIt is a function of TI, and its function expression is M0(1-2e -TI / T1 ); M0: The inversion recovery sequence applies a 180° pulse in the X direction, causing the magnetization vector M... Z After flipping to the negative Z-axis direction, this point is recorded as time 0. At this time, the magnetization vector in the Z-direction of the magnetic resonance spectroscopy test environment is denoted as M0. TI: Time interval; e -TI / T1 e is an exponential function, where -TI / T1 is the exponent and e is the natural constant; T1: refers to the T1 relaxation time of a substance, which is the spin-lattice relaxation time of the atomic nucleus (i.e., the longitudinal relaxation time).

[0047] The CPMG sequence consists of a 90° radio frequency pulse in the X direction and multiple 180° radio frequency pulses in the Y direction. After transmitting the 90° radio frequency pulse in the X direction, a 180° radio frequency pulse is applied in the Y direction at TE intervals. Each 180° pulse generates an FID signal. Multiple such FID signals are acquired, and the echo signal amplitude envelope is plotted. According to formula M... xy (t)=M xy (0)e -t / T2 (t=nTE, n=1,2,3,...,20) The T2 relaxation time is calculated using fitting. In CPMG sequences, the repetition time needs to be long enough, typically greater than 4000 milliseconds.

[0048] In M xy (t)=M xy (0)e -t / T2 (t=nTE, n=1,2,3,…,20): M xy (t): The CPMG sequence emits a 90° RF pulse in the X direction of the magnetic resonance spectroscopy test environment, followed by a 180° RF pulse in the Y direction every TE time; an FID signal is generated after each 180° RF pulse; M xy (t) is the line connecting the peak values ​​of multiple FID signals in the XY plane, generally called the envelope of the echo signal amplitude, M xy M(t) is a function of time t, which can be expressed as M xy (0)e -t / T2 The zero point of time t is the starting point at which the CPMG sequence emits a 90° radio frequency pulse in the X direction of the magnetic resonance spectroscopy test environment. M xy (0): The starting time point at which the CPMG sequence emits a 90° radio frequency pulse in the X direction of the magnetic resonance spectroscopy test environment is recorded as 0. At this time, the magnetization vector on the XY plane of the magnetic resonance spectroscopy test environment is denoted as M.xy (0); TE: Echo Time e -t / T2 e is an exponential function, where -t / T² is the exponent and e is the natural constant. T2: refers to the T2 relaxation time of matter, which is the spin-spin relaxation time of the atomic nucleus (i.e., transverse relaxation time). nTE: The time point of the nth TE, where n is the number of 180° pulses emitted.

[0049] The method for establishing correction curves of relaxation time standard values ​​of different T1 and T2 relaxation time standard substances as a function of test temperature using temperature measurement results from fiber optic temperature measurement system 2 is as follows: Step 1.1: Temperature measurement. For inversion recovery sequence or CPMG sequence, before starting sequence scanning, start the fiber optic temperature measurement system 2 to measure the pure water temperature in the phantom shell 1-2. Record the pure water temperature H1 and the ambient temperature H2 of the magnetic resonance spectroscopy test environment at this time. If the temperature difference between H1 and H2 is within ±0.1 degrees Celsius, the measurement and calibration of the T1 relaxation time standard value and the T2 relaxation time standard value can be started. Use the pure water temperature H1 as the test temperature for the current relaxation time measurement. Step 1.2: Establish correction curves between test temperature and T1 and T2 relaxation time standard values. For the fixed measurement results of the relaxation time standard values ​​of T1 and T2 relaxation time standard materials, establish a comparison table of test temperature and T1 relaxation time standard values ​​and test temperature and T2 relaxation time standard values ​​for the same standard material under the same static magnetic field strength. Establish linear correction curves between test temperature and T1 and T2 relaxation time standard values. According to the experimental results, as the test temperature changes, the temperature change coefficient of T1 and T2 relaxation time standard values ​​with increasing temperature is approximately +2% / ℃. It should be emphasized that the linear correction curves of T1 and T2 relaxation time standard values ​​and test temperature obtained under different static magnetic field strengths of magnetic resonance spectroscopy methods are different.

[0050] Step 2 specifically includes the following steps: Step 2.1: Place the relaxation time standard phantom 1 in the shielded room of the medical magnetic resonance imaging system to be calibrated in advance, so that the pure water in the phantom shell 1-2 and the different T1 and T2 relaxation time standard substances filled in each reagent bottle reach thermal equilibrium with the temperature of the shielded room. Step 2.2: Place the relaxation time standard phantom 1 in the imaging coil. The inner diameter of the imaging coil should be larger than the edge 1-2-1 of the phantom shell, and each reagent bottle should be positioned in the middle of the imaging coil. Use the medical magnetic resonance imaging system to be calibrated to scan its commonly used T1 and T2 relaxation time measurement sequences to obtain the T1 relaxation time and T2 relaxation time measurements of the different T1 and T2 relaxation time standard substances filled in each reagent bottle 1-3-1~1-3-4. Simultaneously, following the... The above A method for calibrating relaxation time measurement results in medical magnetic resonance imaging systems. Calibration of standard references for relaxation times T1 and T2 during measurement Quasi-temperature ; Step 2.3: Based on the static magnetic field strength of the medical magnetic resonance imaging system and the calibration temperature of the obtained T1 and T2 relaxation time standard materials, the calibration temperature is substituted into the temperature correction curve of the corresponding concentration of manganese chloride or nickel chloride solution to obtain the standard value of T1 relaxation time and the standard value of T2 relaxation time at the calibration temperature. Step 2.4: Provide the correction values ​​for the measured values ​​of T1 relaxation time and T2 relaxation time at the calibration temperature, that is, subtract the corresponding measured value of T1 relaxation time or T2 relaxation time from the standard value of T1 relaxation time or T2 relaxation time at the calibration temperature.

[0051] A preferred embodiment of this utility model provides a method for calibrating relaxation time measurement results in a medical magnetic resonance imaging system, which mainly includes the following steps: The two-step correction method described in this utility model is detailed below.

[0052] The first step involves obtaining the pure water temperature in relaxation time standard phantom 1 using a fiber optic temperature measurement system, and establishing correction curves between the standard values ​​of relaxation times T1 and T2 and the test temperature. Since the standard substances for relaxation times T1 and T2 can be manganese chloride solution or nickel chloride solution, this paper takes a nickel chloride solution with a concentration of 0.29 mM to 2.52 mM covering the T1 relaxation time range of brain tissue as an example to introduce the process of establishing correction curves between the standard value of relaxation time T1 and the test temperature under a static magnetic field strength of 3.0 T.

[0053] First, the static magnetic field strength of the magnetic resonance spectroscopy (MRS) testing environment was set to 3.0T, and the temperature of the MRS testing environment was gradually increased from 16.0℃ to 26.0℃ using a precision air conditioner. After each temperature adjustment, the relaxation time standard phantom 1 was placed in the MRS testing environment beforehand to ensure that the pure water in the phantom shell and the different T1 and T2 relaxation time standard substances filled in the cylindrical reagent bottle reached thermal equilibrium with the testing environment. Then, the T1 relaxation time of the relaxation time standard substances was calibrated using inversion recovery sequences. When measuring the standard value of T1 relaxation time, the temperature reading of the fiber optic temperature measurement system was recorded before the test began, and it was determined whether the temperature of the solution inside the relaxation time standard phantom 1 had reached thermal equilibrium with the testing environment. The test temperature was then recorded. The correspondence between the standard values ​​of T1 relaxation time of nickel chloride solutions of different concentrations and temperature is shown in Table 1.

[0054] As shown in Table 1, the temperature variation coefficient of the standard value of T1 relaxation time with increasing temperature is approximately +2% / ℃. To obtain more accurate standard values ​​of T1 relaxation time in a 3.0T test environment at different temperatures, a least-squares linear fitting method was used to obtain the fitting curve T1=aH1+b for the standard value of T1 relaxation time of nickel chloride solutions of different concentrations within the temperature range of 16.0℃~26.0℃, where a and b are constant coefficients obtained after least-squares linear fitting. The R-squared values ​​for all linear fittings are... 2 All values ​​are greater than 95%, indicating that the linear fitting results are good.

[0055] In the formula: T1=aH1+b: T1: The standard value of the T1 relaxation time at the corresponding H1 test temperature. H1: Test temperature; a: The slope value in the linear fitting curve. The slope value corresponding to different concentrations of nickel chloride solution is different and can be calculated according to Table 1; b: The intercept value in the linear fitting curve. The intercept values ​​are different for nickel chloride solutions of different concentrations and can be calculated according to Table 1.

[0056] Table 1. Correspondence between standard values ​​of T1 relaxation time and test temperature for nickel chloride solutions of different concentrations The second step, for the medical magnetic resonance imaging system to be calibrated, presents the process for obtaining correction values ​​for T1 and T2 relaxation time measurements when used to measure the T1 and T2 relaxation times of human tissue. Since the T1 and T2 relaxation time standard materials can be manganese chloride solution or nickel chloride solution, taking a 0.29mM~2.52mM nickel chloride solution covering the T1 relaxation time range of brain tissue as an example, the calculation process for the correction value of the T1 relaxation time measurement under a 3.0T static magnetic field strength is introduced.

[0057] First, the static magnetic field strength of the medical magnetic resonance imaging system to be calibrated should be 3.0T. Place the relaxation time standard phantom 1 in the shielding room of the medical magnetic resonance imaging system to be calibrated so that the pure water in the phantom shell and the different T1 and T2 relaxation time standard substances filled in the cylindrical reagent bottle reach thermal equilibrium with the environment of the shielding room, and record the ambient temperature of the shielding room at this time.

[0058] Then, human body temperature was measured using a thermometer, and the commonly used T1 relaxation time measurement sequence (such as the Molly sequence) was scanned using the medical magnetic resonance imaging system to be calibrated. This yielded T1 relaxation time measurements of the target human tissue and T1 relaxation time measurements of nickel chloride solutions at different concentrations using the Molly sequence. Based on the conclusions of the first step, the temperature variation coefficient of the standard T1 relaxation time with increasing temperature is approximately +2% / ℃. Using this temperature variation coefficient, the T1 relaxation time measurements of nickel chloride solutions at different concentrations at human body temperature using the Molly sequence were obtained. The human body temperature was then fitted into the test temperature-T1 relaxation time standard value fitting curve from the first step to obtain the correction results for the T1 relaxation time standard values ​​of nickel chloride solutions at different concentrations, as shown in Table 2.

[0059] Furthermore, using the least squares linear fitting method, linear fitting curves were obtained for the T1 relaxation time of the Molly sequence measurements and the corrected standard values ​​of the T1 relaxation time for nickel chloride solutions with concentrations ranging from 0.29 mM to 2.52 mM at human body temperature. M =cT1 标 +d, where c and d are constant coefficients obtained after least squares linear fitting, c = 1.0418 and d = 117.69 ms, and the linear fitting R0 is... 2 =0.9967.

[0060] Finally, the measured T1 relaxation time values ​​of the target human brain tissue (see...) Figure 8 The mean value (980.5 ms) is substituted into the linear fitting curve T1. M =cT1 标 +d, and the corresponding standard T1 relaxation time value of 828.2ms is obtained. The corrected value of the T1 relaxation time of the target human brain tissue is the difference between the standard value and the measured value, which is -152.3ms. Figure 8 Max represents the maximum T1 relaxation time for all pixels within the circular sensing interest region, Min represents the minimum T1 relaxation time, and Mean represents the mean.

[0061] Table 2. Correspondence between T1 relaxation time, ambient temperature in the shielded room, Molly sequence measurements, and corrected standard values ​​for nickel chloride solutions of different concentrations. The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A dedicated device for calibrating relaxation time measurement results in a medical magnetic resonance imaging system, characterized in that: It includes a relaxation time standard phantom (1), an optical fiber temperature measurement system (2), and a control computer (3). The relaxation time standard phantom (1) and the optical fiber temperature measurement system (2) are connected in a tight fit manner, and the optical fiber temperature measurement system (2) and the control computer (3) are connected in an optical fiber communication manner.

2. The specialized device for calibrating relaxation time measurement results of a medical magnetic resonance imaging system according to claim 1, characterized in that: The relaxation time standard phantom (1) consists of a sealing cover (1-1) at the top, a phantom shell (1-2) at the bottom, and a relaxation time standard unit (1-3) disposed inside the phantom shell (1-2); The sealing cap (1-1) is a cylinder. Multiple internally threaded through holes with internal threads are evenly arranged on the edge of the upper surface of the sealing cap (1-1). An optical fiber through hole (1-1-11) is provided at the center of the upper surface of the sealing cap (1-1). A groove is etched in the middle of the optical fiber through hole (1-1-11) and a sealing gasket is embedded in the groove. The lower surface of the sealing cap (1-1) is provided with multiple counterclockwise threaded mounting holes. The multiple counterclockwise threaded mounting holes are evenly distributed with the optical fiber through hole (1-1-11) as the center of symmetry. The depth of each counterclockwise threaded mounting hole is within the thickness of the sealing cap (1-1). A circular upper groove (1-1-16) is etched near the edge of the lower surface of the sealing cap (1-1). The circular upper groove (1-1-16) is concentric with the lower surface of the sealing cap (1-1). The mold shell (1-2) is an open-top cylindrical shell, including an outer edge (1-2-1) and a main body (1-2-2). The outer diameter of the outer edge (1-2-1) is the same as the outer diameter of the sealing cap (1-1). Near the outer edge of the outer edge (1-2-1), the outer edge (1-2-1) has multiple internally threaded fixing holes, each corresponding to a series of internally threaded through holes. The depth of these internally threaded fixing holes is within the thickness range of the outer edge (1-2-1). A circular lower groove (1-2-1-11) is located on the outer edge (1-2-1) corresponding to the upper circular groove (1-1-16). The two grooves are identical in position and size. The lower circular groove (1-2-1-11) is concentric with the outer edge (1-2-1). -11) contains a sealing gasket with a small amount of silicone grease applied to it. The thickness of the sealing gasket is greater than the depth of the groove after the upper circular groove (1-1-16) and the lower circular groove (1-2-1-11) are combined. The diameter of the inner edge of the outer shell (1-2-1) is the same as the inner diameter of the outer shell (1-2-2). Plastic screws are used to pass through multiple internal threaded through holes and corresponding internal threaded fixing holes and tighten them so that the sealing cap (1-1) and the outer shell (1-2) are assembled into one piece. When using the relaxation time standard mold (1), the outer shell (1-2) should be filled with pure water to ensure that the relaxation time standard mold (1) is free of air bubbles after the sealing cap (1-1) and the outer shell (1-2) are assembled into one piece. The inner diameter of the outer shell (1-2) is greater than 12cm and the depth is greater than 10cm.

3. The specialized device for calibrating relaxation time measurement results of a medical magnetic resonance imaging system according to claim 1, characterized in that: The relaxation time standard unit (1-3) consists of multiple identical cylindrical reagent bottles. Each reagent bottle comprises a bottle body and a cap, which are tightly connected by threads. Each bottle is filled with different T1 and T2 relaxation time standard substances. A sealing gasket is embedded inside the cap of each bottle. The cap is screwed clockwise onto the bottle body, and the sealing gasket is pressed tightly against the top of the bottle opening, ensuring no liquid exchange between the T1 and T2 relaxation time standard substances inside the bottle and the pure water in the phantom shell (1-2). Multiple reagent bottles... Each reagent bottle has a counterclockwise thread on its cap. After the reagent bottle is filled with T1 and T2 relaxation time standard substances and the cap is tightened, each reagent bottle is fixed to the lower surface of the sealing cap (1-1) by inserting it into the counterclockwise threaded mounting hole on the lower surface of the sealing cap (1-1) and tightening it. After each reagent bottle is fixed on the sealing cap (1-1), it can be inserted into the main body of the phantom shell (1-2-2) without contacting the inner wall of the main body of the phantom shell (1-2-2). The inner diameter of each reagent bottle is greater than 3cm and the height is greater than 5cm.

4. A dedicated device for calibrating relaxation time measurement results of a medical magnetic resonance imaging system according to claim 3, characterized in that... The aforementioned standard substances filled with different T1 and T2 relaxation times are composed of manganese chloride or nickel chloride solutions of different concentrations. Different concentrations of manganese chloride or nickel chloride solutions are selected based on the required T1 and T2 relaxation time ranges for calibration. Specifically, when the manganese chloride solution concentration is 0.0113 mM to 1.5996 mM, the corresponding standard T1 relaxation time range is 2478 ms to 82 ms, and the corresponding standard T2 relaxation time range is 553 ms to 5 ms. When the nickel chloride solution concentration is 0.29 mM to 65.3 mM, the corresponding standard T1 relaxation time range is 1937 ms to 21 ms, and the corresponding standard T2 relaxation time range is 1521 ms to 15 ms.

5. A dedicated device for calibrating relaxation time measurement results of a medical magnetic resonance imaging system according to claim 1, characterized in that: The fiber optic temperature measurement system (2) consists of a host device (2-1) for receiving the optical signal transmitted by the fiber optic temperature probe (2-2) and converting it into a temperature value, a fiber optic temperature probe (2-2) based on the temperature measurement principle of a fluorescent fiber optic temperature sensor, and a fiber optic temperature probe housing (2-3). The fiber optic temperature probe (2-2) is compatible with the measurement environment of a 1.5T or higher medical superconducting magnetic resonance imaging system, with a temperature measurement accuracy of ±0.1℃ and a measurement range covering 0℃~50℃. The fiber optic length of the fiber optic temperature probe (2-2) is greater than 5 meters to ensure that when performing relaxation time measurement on the relaxation time standard phantom (1), the host device (2-1) and the control computer (3) can be located in the medical magnetic field. Outside the shielded room of the resonant imaging system, the fiber optic temperature probe (2-2) passes through the fiber optic temperature probe housing (2-3), ensuring that the fluorescent fiber optic temperature sensor at the front end of the fiber optic temperature probe 2-2 is completely outside the fiber optic temperature probe housing (2-3). The gap between the fiber optic temperature probe (2-2) and the fiber optic temperature probe housing (2-3) is filled by injection. The fiber optic temperature probe housing (2-3) is a hollow acrylic round tube. The outer diameter of the fiber optic temperature probe housing (2-3) is larger than the inner diameter after the sealing gasket is installed in the fiber optic through hole (1-1-11), ensuring that the fiber optic temperature probe housing (2-3) can form a tight fit with the sealing gasket after being inserted into the fiber optic through hole (1-1-11).

6. A dedicated device for calibrating relaxation time measurement results of a medical magnetic resonance imaging system according to claim 1, characterized in that... The control computer (3) communicates with the device host (2-1) via the data cable (3-1). The fiber optic temperature measurement software (3-2) used to control the device host (2-1) to collect temperature data and record temperature measurement results and to calibrate the temperature measurement results is installed in the control computer (3).

Images