Construction and detection method of in vitro model of normal and incompetent mitral valve hemodynamics by magnetic resonance imaging

Abstract

The present invention discloses an in vitro model construction and detection method for magnetic resonance imaging hemodynamics of a mitral valve, which comprises: (A) preparing an insufficiency of the mitral valve, (B) assembling the in vitro model, (C) magnetic resonance scanning of the in vitro model, and (D) analyzing the magnetic resonance data of the in vitro model. The present invention constructs an in vitro model that can simulate normal and insufficiency of the mitral valve in vivo, and can be used to test the accuracy and stability of magnetic resonance instruments and hemodynamic sequences, and establishes a set of 4Dflow sequence test specification system.

Description

Technical Field

[0001] The invention belongs to the field of medical equipment, and in particular relates to an in vitro model of magnetic resonance imaging hemodynamics of a normal and insufficiency mitral valve, and a construction and detection method of the in vitro model. Background Art

[0002] Mitral regurgitation is one of the most common heart valve diseases. Severe mitral regurgitation can lead to atrial fibrillation, heart failure, pulmonary hypertension, and even death. Patients with mitral regurgitation and heart failure have a decreased quality of life and an increased risk of rehospitalization and death. Some studies have shown that early surgical valve surgery or transcatheter intervention can improve the prognosis of patients with mitral regurgitation. Therefore, accurate grading of the severity of mitral regurgitation is crucial for patient management and determining the timing of intervention.

[0003] Currently, the commonly used methods for measuring mitral regurgitation in clinical practice are transthoracic echocardiography and cardiac magnetic resonance imaging. However, transthoracic echocardiography has poor interobserver reproducibility, and the results may be inaccurate when measuring unidirectional blood flow using only two-dimensional imaging. Moreover, the results are less accurate when there are complex conditions of mitral regurgitation, such as non-circular or eccentric regurgitation orifices. Cardiac magnetic resonance imaging can indirectly calculate the amount of mitral regurgitation by subtracting the aortic antegrade flow from the left ventricular stroke volume, but the use of indirect methods will be limited when there are multiple valve regurgitations or cardiac shunts. Direct mitral flow measurement using 2D phase-contrast magnetic resonance can overcome the above limitations, but 2D phase-contrast magnetic resonance cannot accurately measure when there are multiple regurgitations or complex shapes of regurgitant orifices.

[0004] 4Dflow is a method that uses phase contrast magnetic resonance technology to perform velocity-encoded imaging and signal acquisition of blood flow in three-dimensional space and at each heartbeat phase, and can non-invasively evaluate hemodynamic changes in the heart and large blood vessels. Its accuracy in flow velocity has been confirmed in an in vitro model. Previous studies have shown that 4Dflow technology has a certain correlation with indirect measurement methods of cardiac magnetic resonance and echocardiography for measuring regurgitation, but there are certain numerical differences in the measurement results of the regurgitation volume among the three methods. At present, there is a lack of a gold standard for the evaluation of mitral regurgitation volume, and there is still controversy over the use of 4Dflow technology for quantitative measurement of mitral regurgitation. The in vitro model can calculate the mitral regurgitation volume by measuring flow velocity, pressure, and volume. In addition, the hemodynamics of the human heart is relatively complex, with various turbulences and backflows, and is also affected by the movement of the heartbeat and breathing. The in vitro model is mainly based on straight pipes with a constant flow rate, so there are large differences between the two. This difference makes 4Dflow heterogeneous among different manufacturers. Therefore, building a set of phantoms that accurately measure 4Dflow in a complex hemodynamic environment is of great significance to the formulation of 4Dflow international sequence standards and norms. Summary of the invention

[0005] The purpose of the present invention is to provide an in vitro model of mitral valve magnetic resonance imaging hemodynamics and its construction and detection method on the basis of the existing technology, which is used to simulate normal and mitral valve insufficiency conditions, and is helpful to test the working performance of magnetic resonance instruments and hemodynamic sequences.

[0006] The purpose of the present invention can be achieved by the following measures:

[0007] An in vitro model construction and detection method for magnetic resonance imaging hemodynamics of the mitral valve comprises the following steps:

[0008] (A) Preparation of an incomplete mitral valve: The medical mitral valve bioprosthesis is expanded by pulling to 1.2 to 3 times of its original diameter and then continuously pulled to maintain its diameter at the expanded size, thereby obtaining an incomplete mitral valve with misaligned leaflets;

[0009] (B) Assembling the in vitro model: placing and fixing the medical mitral valve bioprosthesis or the incomplete mitral valve obtained in step (A) into the magnetic resonance phantom pipe, and placing the magnetic resonance phantom pipe into the in vitro model; the in vitro model comprises a magnetic resonance phantom pipe, a coordination module, a catheter control unit, a water storage tank, a pulse pump device and an electrocardiogram control system, wherein the outlet of the magnetic resonance phantom pipe is connected to the liquid inlet of the coordination module through a reflux line I; the coordination module comprises a coordination liquid container and a pressure regulating unit, and the pressure regulating unit regulates the pressure in the coordination liquid container. The pressure presents periodic changes to simulate the pressure changes of heart beating; the liquid outlet of the coordination module is connected to the liquid inlet of the water tank through a pipeline, the water tank can be filled with blood simulation liquid, the liquid outlet of the water tank is connected to the inlet of the pulse pump device through a pipeline, the outlet of the pulse pump device is connected to the inlet of the magnetic resonance phantom pipeline through a pipeline, and the outlet of the magnetic resonance phantom pipeline is directly connected to the liquid inlet of the water tank through a reflux pipeline II; the catheter control unit is respectively connected to the magnetic resonance phantom pipeline, the coordination module and the electrocardiogram control system through a circuit;

[0010] (C) Magnetic resonance scanning of the in vitro model: starting the in vitro model of step (B), allowing the blood simulation fluid in the water storage tank to enter the magnetic resonance phantom pipe through the pulse pump device, and return to the water storage tank through the return pipe I or the return pipe II, and the magnetic resonance phantom pipe is filled with a medical mitral valve bioprosthesis or the incomplete mitral valve prepared in step (A); using a 3T magnetic resonance system, using a 4Dflow sequence to scan the model, and obtain magnetic resonance imaging data of the mitral valve in the magnetic resonance phantom pipe;

[0011] (D) In ​​vitro model magnetic resonance data analysis: The magnetic resonance imaging data are analyzed using magnetic resonance analysis software, and the data are preprocessed for bias correction and signal aliasing correction. The forward peak flow velocity, forward flow, regurgitant peak flow velocity and regurgitant flow through the medical mitral valve bioprosthesis and the insufficiency of the mitral valve are then measured respectively.

[0012] In step (A), preferably, the medical mitral valve bioprosthesis can be expanded by pulling to 1.3 to 2 times of its original diameter and continuously pulled for 10 to 60 minutes, or expanded by pulling to a diameter of 40 to 50 mm and continuously pulled. The continuous pulling time can be maintained at 10 to 60 minutes, especially 30 minutes, so that the diameter of the bioprosthesis is maintained at the size after pulling and expansion, that is, a mitral valve with insufficiency is obtained.

[0013] In step (B), the medical mitral valve bioprosthesis or the insufficiency of the mitral valve can be fixed in the magnetic resonance phantom channel by using a flexible resin.

[0014] In the in vitro model, silicone tubes are preferably used as the pipes between the magnetic resonance phantom pipe, the coordination module, the water reservoir and the pulse pump device.

[0015] In the in vitro model, a check valve I may be provided on the pipeline between the pulse pump device and the magnetic resonance phantom pipeline, a shut-off valve I may be provided on the pipeline between the coordination module and the water tank or on the return pipeline I, and a check valve II and a shut-off valve II may be provided on the return pipeline II.

[0016] The reflux circuit I and the coordination module can be used to simulate the situation in which the heart beats and causes the mitral valve to produce regurgitation. The coordination module includes a coordination liquid container and a pressure regulating unit, and the pressure regulating unit regulates the pressure in the coordination liquid container to show periodic changes to simulate the pressure changes of the heart beating. Furthermore, the water flow in the in vitro model flows at a uniform speed under the action of the pulse pump, and the pressure regulating unit of the coordination module causes the pressure in the coordination liquid container to show periodic changes to simulate the pressure changes of the heart beating, thereby producing a changing pressure on the pipeline structure of the valve at the front end, so that under a higher rear pressure, it exceeds the pressure provided by the front water pump, thereby producing regurgitation in the incompletely closed mitral valve structure. The pressure regulating unit includes but is not limited to a piston structure, a piston-like structure or a shrinkable airbag structure.

[0017] As a bypass, the return line II is a continuous constant speed pipeline, which provides a basis and reference for the acquisition and analysis of magnetic resonance imaging data. Generally, the return line I and the return line II are not opened at the same time.

[0018] The pulse pump device in the in vitro model is MRI-compatible and comes with a control unit that allows control of peak flow, stroke volume, heart rate, and flow waveform.

[0019] The water tank in the in vitro model is filled with blood simulation fluid, which is mainly composed of 50% to 70% distilled water and 50% to 30% glycerol. In a preferred embodiment, the blood simulation fluid is composed of 60% distilled water and 40% glycerol.

[0020] The catheter control unit is connected to the magnetic resonance phantom pipe through a circuit and further connected to the ECG control system. It can obtain magnetic resonance imaging data through the magnetic head coil arranged outside the magnetic resonance phantom pipe, and obtain relevant data for obtaining forward peak flow velocity, forward flow, reflux peak flow velocity and reflux flow through the forward signal circuit and the backward signal circuit. The catheter control unit is connected to the coordination module through a circuit and further connected to the ECG control system, and can obtain the periodic pressure changes in the coordination liquid container to simulate the heart beat, and feed it back to the ECG control system and the 3T magnetic resonance system.

[0021] In step (C), a 3T magnetic resonance system can be used, a 24-channel body coil and retrospective cardiac gating can be used, and the model can be scanned using a 4Dflow sequence. The trigger signals collected or generated by the catheter control unit and the control unit of the pulse pump device are synchronized to the 3T magnetic resonance system through the ECG control system for ECG signal data acquisition and ECG gating.

[0022] In step (D), the CVI42 magnetic resonance analysis software can be used to perform data analysis on the in vitro model 4Dflow scanning results, and the data can be preprocessed, namely, bias correction and signal aliasing correction. The forward peak flow velocity, forward flow, regurgitant peak flow velocity and regurgitant flow through the medical mitral valve bioprosthesis and the insufficiency of the mitral valve are measured respectively.

[0023] A method for calculating the forward peak flow velocity and the forward peak flow rate is as follows: a measurement plane is generated at the point where the flow velocity of the forward jet in each phase in the magnetic resonance phantom pipeline is the maximum, and the measurement plane is made perpendicular to the jet direction; the outline of the jet passing through the plane is automatically circled and adjusted on the newly generated measurement plane; and the forward peak flow velocity and the forward flow rate can be obtained after software analysis.

[0024] A method for calculating the regurgitation peak flow velocity and regurgitation volume is as follows: a measurement plane is generated 1 to 2 cm distal to the regurgitation orifice of the incompletely closed mitral valve, and the measurement plane is made perpendicular to the direction of the regurgitation jet. The contour of the regurgitation jet passing through the plane is automatically circled and adjusted on the newly generated measurement plane, and the regurgitation peak flow velocity and regurgitation volume can be obtained after software analysis.

[0025] The present invention also includes an in vitro model of MRI hemodynamics of mitral valve, which includes an MRI phantom pipeline, a coordination module, a catheter control unit, a water storage tank, a pulse pump device and an ECG control system, wherein the outlet of the MRI phantom pipeline is connected to the liquid inlet of the coordination module through a return pipeline I; the coordination module includes a coordination liquid container and a pressure regulating unit, the pressure regulating unit regulates the pressure in the coordination liquid container to present a periodic change to simulate the pressure change of the heart beating; the liquid outlet of the coordination module is connected to the liquid inlet of the water storage tank through a pipeline, the water storage tank can be filled with blood simulation liquid, the liquid outlet of the water storage tank is connected to the inlet of the pulse pump device through a pipeline, the outlet of the pulse pump device is connected to the inlet of the MRI phantom pipeline through a pipeline, and the outlet of the MRI phantom pipeline is directly connected to the liquid inlet of the water storage tank through a return pipeline II; the catheter control unit is respectively connected to the MRI phantom pipeline, the coordination module and the ECG control system through a circuit. The specific components and their connection methods in the in vitro model are as described above.

[0026] Beneficial effects of the present invention:

[0027] The in vitro model of mitral valve magnetic resonance imaging hemodynamics provided by the present invention and its construction and detection method can be used to simulate normal and mitral valve regurgitation conditions, can be used to test the accuracy and stability of magnetic resonance instruments and hemodynamic sequences, and establish a set of 4Dflow sequence test specification system, which is helpful to test the working performance of magnetic resonance instruments and hemodynamic sequences. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a diagram of the structure of a medical mitral bioprosthesis;

[0029] Figure 2 is a schematic diagram of an in vitro model of MRI hemodynamics of the mitral valve;

[0030] In the figure, 1-medical mitral valve bioprosthesis or incomplete mitral valve, 2-magnetic resonance phantom pipeline, 3-coordination module, 4-catheter control unit, 5-water storage tank, 6-pulse pump device, 7-ECG control system, 11-check valve I, 12-cut-off valve I, 13-cut-off valve II, 14-check valve II, 21-return pipeline I, 22-return pipeline II, 23-forward signal circuit, 24-backward signal circuit, 25-coordination module signal circuit, 26-catheter control circuit, 27-pulse pump signal circuit, 31-control room, 32-magnetic resonance environment. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0032] A structure of a medical mitral valve bioprosthesis Figure 1 The structure of an in vitro model of normal and regurgitant mitral valve MRI hemodynamics is shown in Figure 2 As shown, it includes a magnetic resonance phantom pipeline 2, a coordination module 3, a catheter control unit 4, a water storage tank 5, a pulse pump device 6 and an ECG control system 7. The magnetic resonance phantom pipeline 2, the coordination module 3, the water storage tank 4 and the pulse pump device 6 are connected by a silicone tube.

[0033] A medical mitral valve bioprosthesis or an incomplete mitral valve is fixed by flexible resin in the magnetic resonance phantom pipe 2. The outlet of the magnetic resonance phantom pipe 2 is connected to the liquid inlet of the coordination module 3 through a reflux pipeline I.

[0034] The coordination module 3 includes a coordination liquid container and a pressure regulating unit, and the coordination liquid container is used to temporarily store the blood simulation liquid. The pressure regulating unit can be a piston-like structure or a shrinkable airbag structure. The water flow in the in vitro model flows at a uniform speed under the action of the pulse pump. The pressure regulating unit of the coordination module makes the pressure in the coordination liquid container change periodically to simulate the pressure change of the heart beating, thereby generating a changing pressure on the pipeline structure of the valve at the front end, so that under a higher rear pressure, it exceeds the pressure provided by the front water pump, thereby generating regurgitation in the incomplete mitral valve structure.

[0035] The liquid outlet of the coordination module 3 is connected to the liquid inlet of the water storage tank 5 through a pipeline. A cut-off valve I is provided on the pipeline between the coordination module 3 and the water storage tank 5 or on the return pipeline I. The water storage tank 5 is filled with 20L of blood simulation liquid, which is composed of 60% distilled water and 40% glycerol, and the density of the simulation liquid is about 1.20g / cm 3 , T1 value is about 900 mesc, which is mainly used for liquid inflow and recovery of the in vitro model. The liquid outlet of the water storage tank 5 is connected to the inlet of the pulse pump device 6 through a pipeline.

[0036] The pulse pump device is compatible with magnetic resonance and has a control unit that can control peak flow, stroke volume, heart rate and flow waveform. The outlet of the pulse pump device 6 is connected to the inlet of the magnetic resonance phantom pipeline 2 through a pipeline. A check valve I is provided on the pipeline between the pulse pump device 6 and the magnetic resonance phantom pipeline 2.

[0037] The outlet of the magnetic resonance phantom pipe 2 is directly connected to the liquid inlet of the water storage tank 5 through the return pipe II. A check valve II and a cut-off valve II are provided on the return pipe II.

[0038] The catheter control unit 4 is connected to the magnetic resonance phantom pipe 2, the coordination module 3 and the ECG control system 7 respectively through circuits.

[0039] Preparation of incomplete mitral valve: Take a 30mm diameter medical mitral valve bioprosthesis, use forceps to expand it to a diameter of 45mm by external traction and maintain it for 30 minutes. After recovery, the diameter of the medical bioprosthesis is measured to be maintained at 45mm, and the leaflets are incompletely coapted.

[0040] In vitro model assembly: According to different measurement conditions, the medical mitral valve bioprosthesis or the prepared incomplete mitral valve is respectively placed in and fixed in the magnetic resonance phantom pipe, and the magnetic resonance phantom pipe is placed in the in vitro model.

[0041] In vitro model MRI scanning: The in vitro model was started, and the blood simulation fluid in the water tank entered the MRI phantom pipe through the pulse pump device, and returned to the water tank through the return pipe I or return pipe II according to the demand. The MRI phantom pipe was equipped with a medical mitral valve bioprosthesis or an insufficiency of the mitral valve. The MRI experiment was performed on a 3T MRI system (United Imaging MR790), using a 24-channel body coil and retrospective cardiac gating. The model was scanned using the 4Dflow sequence. The control unit generated a trigger signal and synchronized it to the MRI scanning system for ECG signal data acquisition and ECG gating. MRI data were obtained in the MRI phantom pipe equipped with a medical mitral valve bioprosthesis or an insufficiency of the mitral valve. The 4Dflow scanning sequence used a retrospective ECG trigger, three-dimensional, time-resolved phase contrast, and gradient echo pulse sequence. The time resolution is 40 ms, the repetition time is 20.8 ms, the echo time is 2.86 ms, the flip angle is 8°, and the voxel size is 3 × 3 × 5 mm. 3 , the speed encoding is 150cm / s, and the scanning time is 8-15 minutes.

[0042] In vitro model MRI data analysis: CVI42 MRI analysis software was used to analyze the 4Dflow scanning results of the in vitro model, and the data was preprocessed, namely bias correction and signal aliasing correction. The forward peak flow velocity, forward flow, regurgitant peak flow velocity and regurgitant volume through the medical mitral valve bioprosthesis and the insufficiency of the mitral valve were measured respectively. The forward peak flow velocity and forward peak flow were calculated as follows: a measurement plane was generated at the maximum flow velocity of the forward jet in each phase of the MRI phantom tube, and the measurement plane was perpendicular to the jet direction. The newly generated measurement plane was automatically circled and the outline of the jet passing through the plane was manually adjusted. After software analysis, the forward peak flow velocity and forward flow were obtained. The regurgitant peak flow velocity and regurgitant volume were calculated as follows: a measurement plane was generated 1 to 2 cm away from the distal end of the regurgitant orifice of the insufficiency of the mitral valve, and the measurement plane was perpendicular to the regurgitant jet direction. The contour of the regurgitant jet passing through the newly generated measurement plane is automatically circled and manually adjusted, and the regurgitant peak velocity and regurgitant flow can be obtained after software analysis. Under actual test conditions: using cardiac magnetic resonance 4Dflow measurement, it can be obtained that the normal mitral valve forward peak velocity is 1.22m / s, the abnormal mitral valve forward peak velocity is 0.78m / s, the abnormal mitral valve forward flow is 385.15ml / s, the abnormal mitral valve regurgitant peak velocity is 0.53m / s, and the abnormal mitral valve regurgitant flow is 115.5ml / s. The management flow monitoring system measured: the normal mitral valve forward peak velocity is 1.30m / s, and the abnormal mitral valve forward peak velocity is 0.76m / s.

[0043] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structural transformation made using the contents of the present invention specification, or directly or indirectly applied to the technical field attached to other related products, are also included in the patent protection scope of the present invention.

Claims

1. A method for constructing and detecting an in vitro model of normal and incompetent mitral valve hemodynamics by magnetic resonance imaging, characterized in that The steps include: (A) Preparation of an incomplete mitral valve: The medical mitral valve bioprosthesis is expanded by pulling to 1.2 to 3 times of its original diameter and then continuously pulled to maintain its diameter at the expanded size, thereby obtaining an incomplete mitral valve with misaligned leaflets; (B) Assembling the in vitro model: placing a medical mitral valve bioprosthesis or the incomplete mitral valve obtained in step (A) into and fixing it in a magnetic resonance phantom pipe, and placing the magnetic resonance phantom pipe into the in vitro model; the in vitro model comprises a magnetic resonance phantom pipe (2), a coordination module (3), a catheter control unit (4), a water storage tank (5), a pulse pump device (6) and an electrocardiogram control system (7); the outlet of the magnetic resonance phantom pipe (2) is connected to the liquid inlet of the coordination module (3) through a reflux pipeline I (21); the coordination module (3) comprises a coordination liquid container and a pressure regulating unit, and the pressure regulating unit regulates the pressure in the coordination liquid container to present a periodic change for simulating The pressure change of the simulated heart beat; the liquid outlet of the coordination module (3) is connected to the liquid inlet of the water tank (5) through a pipeline, the water tank (5) can be filled with blood simulation liquid, the liquid outlet of the water tank (5) is connected to the inlet of the pulse pump device (6) through a pipeline, the outlet of the pulse pump device (6) is connected to the inlet of the magnetic resonance phantom pipeline (2) through a pipeline, and the outlet of the magnetic resonance phantom pipeline (2) is directly connected to the liquid inlet of the water tank (5) through a reflux pipeline II (22); the catheter control unit (4) is respectively connected to the magnetic resonance phantom pipeline (2), the coordination module (3) and the electrocardiogram control system (7) through a circuit; (C) Magnetic resonance scanning of the in vitro model: starting the in vitro model of step (B), allowing the blood simulation fluid in the water storage tank (5) to enter the magnetic resonance phantom pipe (2) through the pulse pump device (6), and return to the water storage tank (5) through the return pipe I (21) or the return pipe II (22), wherein the magnetic resonance phantom pipe (2) contains a medical mitral valve bioprosthesis or the incomplete mitral valve obtained in step (A); using a 3T magnetic resonance system and a 4D flow sequence to scan the model, and obtain magnetic resonance imaging data of the mitral valve in the magnetic resonance phantom pipe (2); (D) In ​​vitro model magnetic resonance data analysis: The magnetic resonance imaging data are analyzed using magnetic resonance analysis software, and the data are preprocessed for bias correction and signal aliasing correction. The forward peak flow velocity, forward flow, regurgitant peak flow velocity and regurgitant flow through the medical mitral valve bioprosthesis and the insufficiency of the mitral valve are then measured respectively.

2. The method according to claim 1, characterized in that In step (A), the medical mitral valve bioprosthesis is expanded by pulling to 1.3 to 2 times of its original diameter and the pulling is continued for 10 to 60 minutes, or expanded by pulling to a diameter of 40 to 50 mm and the pulling is continued for 10 to 60 minutes so that the diameter is maintained at the size after the pulling and expansion, thereby obtaining an incomplete mitral valve.

3. The method according to claim 1, characterized in that: In step (B), the medical mitral valve bioprosthesis or the insufficiency of the mitral valve is fixed in the magnetic resonance phantom pipe by using a flexible resin; the pipes between the magnetic resonance phantom pipe (2), the coordination module (3), the water storage tank (5) and the pulse pump device (6) are silicone tubes.

4. The method according to claim 1, characterized in that A check valve I (11) is provided on the pipeline between the pulse pump device (6) and the magnetic resonance phantom pipeline (2), a shut-off valve I (12) is provided on the pipeline between the coordination module (3) and the water storage tank (5) or on the return pipeline I (21), and a check valve II (14) and a shut-off valve II (13) are provided on the return pipeline II (22).

5. The method according to claim 1, characterized in that In the in vitro model, the pulse pump device is compatible with magnetic resonance and has a control unit, which can control the peak flow, stroke volume, heart rate and flow waveform; the water storage tank is filled with blood simulation fluid, and the blood simulation fluid is mainly composed of 50% to 70% distilled water and 50% to 30% glycerol.

6. The method according to claim 1, characterized in that In step (C), a 3T magnetic resonance system is used, a 24-channel body coil and retrospective cardiac gating are used, and a 4D flow sequence is used to scan the model. The trigger signals collected or generated by the catheter control unit (4) and the control unit of the pulse pump device are synchronized to the 3T magnetic resonance system through the ECG control system (7) to perform ECG signal data acquisition and ECG gating.

7. The method according to claim 1, characterized in that In step (C), the 4D flow scan sequence uses a retrospective ECG-triggered, three-dimensional, time-resolved phase contrast and gradient echo pulse sequence, with a time resolution of 40 ms, a repetition time of 20.8 ms, an echo time of 2.86 ms, a flip angle of 8°, and a voxel size of 3×3×5 mm. 3 , the speed encoding is 150cm / s, and the scanning time is 8 to 15 minutes.

8. The method according to claim 1, characterized in that In step (D), the CVI42 magnetic resonance analysis software is used to perform data analysis on the 4D flow scanning results of the in vitro model; the forward peak flow velocity and the forward peak flow rate are calculated by: generating a measurement plane at the maximum flow velocity of each phase of the forward jet in the magnetic resonance phantom pipe (2) and making the measurement plane perpendicular to the jet direction, automatically circling and adjusting the outline of the jet passing through the plane on the newly generated measurement plane, and obtaining the forward peak flow velocity and the forward flow rate after software analysis; the regurgitation peak flow velocity and the regurgitation flow rate are calculated by: generating a measurement plane 1 to 2 cm away from the distal end of the regurgitation orifice of the incompletely closed mitral valve, and making the measurement plane perpendicular to the regurgitation jet direction, automatically circling and adjusting the outline of the regurgitation jet passing through the plane on the newly generated measurement plane, and obtaining the regurgitation peak flow velocity and the regurgitation flow rate after software analysis.

9. An in vitro model of normal and regurgitant mitral valve hemodynamics using magnetic resonance imaging, characterized in that: It comprises a magnetic resonance phantom pipeline (2), a coordination module (3), a catheter control unit (4), a water storage tank (5), a pulse pump device (6) and an electrocardiogram control system (7); a medical mitral valve bioprosthesis or an incompletely closed mitral valve is fixed in the magnetic resonance phantom pipeline (2); the outlet of the magnetic resonance phantom pipeline (2) is connected to the liquid inlet of the coordination module (3) through a return pipeline I (21); the coordination module (3) comprises a coordination liquid container and a pressure regulating unit, the pressure regulating unit regulating the pressure in the coordination liquid container to present a periodic change to simulate the pressure change of the heart beat; the coordination module (3) The liquid outlet is connected to the liquid inlet of the water storage tank (5) through a pipeline. The water storage tank (5) can be filled with blood simulation liquid. The liquid outlet of the water storage tank (5) is connected to the inlet of the pulse pump device (6) through a pipeline. The outlet of the pulse pump device (6) is connected to the inlet of the magnetic resonance phantom pipeline (2) through a pipeline. The outlet of the magnetic resonance phantom pipeline (2) is directly connected to the liquid inlet of the water storage tank (5) through a reflux pipeline II (22). The catheter control unit (4) is respectively connected to the magnetic resonance phantom pipeline (2), the coordination module (3) and the electrocardiogram control system (7) through a circuit.

10. The in vitro model of mitral valve hemodynamics by magnetic resonance imaging according to claim 9, characterized in that: The medical mitral valve bioprosthesis or the incomplete mitral valve is fixed in the magnetic resonance phantom pipeline by using a flexible resin; the pipelines between the magnetic resonance phantom pipeline (2), the coordination module (3), the water storage tank (5) and the pulse pump device (6) are silicone tubes; a check valve I (11) is provided on the pipeline between the pulse pump device (6) and the magnetic resonance phantom pipeline (2); a shut-off valve I (12) is provided on the pipeline between the coordination module (3) and the water storage tank (5) or on the return pipeline I (21); and a check valve II (14) and a shut-off valve II (13) are provided on the return pipeline II (22).

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