Electrical impedance tomography method, device and equipment and readable storage medium

Abstract

The invention discloses an electrical impedance tomography method, device and equipment and a readable storage medium, the electrical impedance tomography method comprises the steps that real-time coordinates of multiple electrodes are obtained through measurement of multiple inertial measurement units, real-time voltages of the multiple electrodes are obtained at the same time, the multiple inertial measurement units and the multiple electrodes are integrated on a flexible patch in a conformal mode, and the multiple inertial measurement units and the multiple electrodes are integrated on the flexible patch in a conformal mode; the flexible patch is attached to the body part of a patient; based on the real-time coordinates of the plurality of electrodes, adopting a grid deformation method or a grid selection method to obtain an instantaneous finite element grid of the body part of the patient; and taking the instantaneous finite element mesh as a forward model, solving the reverse problem equation by using the real-time voltage of the plurality of electrodes, and generating an electrical impedance tomography image of the body part of the patient. According to the method and the device, starting from the source-forward model of the reverse problem of electrical impedance tomography, the obtained instantaneous finite element mesh of the body part of the patient is ensured to be consistent with the real-time topological structure of the electrode, and motion artifacts can be eliminated from the source.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical impedance tomography, and particularly relates to an electrical impedance tomography method, device, equipment and readable storage medium. BACKGROUND

[0002] Electrical impedance tomography (EIT) is a new direction of medical imaging technology, and its basic principle is that different tissues in the human body have different resistances / conductivities under different physiological and pathological conditions, a small safe driving current / voltage is applied to the human body, and the image of the internal resistivity distribution or its change of the human body is reconstructed through the measurement response information of the driving current / voltage in the human body. In recent years, with the development of flexible electronic technology, wearable flexible patches have become a research hotspot. The flexible patch integrates an electrode array and is attached to the surface of the patient's body part to ensure stable electrical coupling between the electrode and the measured surface, adapt to dynamic and irregular working conditions, improve imaging reliability and signal quality, and aims to realize long-term and continuous monitoring of the patient.

[0003] However, in actual application, especially when the flexible patch is worn on the thorax of the patient, the respiratory movement of the patient, body turning, and even slight creep of the skin will cause the flexible patch to stretch, bend or displace as a whole, and then cause the actual position of the electrode in the flexible patch to change, thereby causing motion artifacts and inaccurate positioning of electrical impedance tomography, and other problems, which seriously restricts the application of electrical impedance tomography in the clinic.

[0004] In summary, due to the movement change of the patient's body part, the flexible patch is displaced and deformed, and then the actual position of the electrode in the flexible patch changes, thereby causing motion artifacts and inaccurate positioning of electrical impedance tomography. SUMMARY

[0005] The present application provides an electrical impedance tomography method, device, equipment and readable storage medium, which aims to solve the technical problem that due to the movement change of the patient's body part, the flexible patch is displaced and deformed, and then the actual position of the electrode in the flexible patch changes, thereby causing motion artifacts and inaccurate positioning of electrical impedance tomography.

[0006] In a first aspect, an electrical impedance tomography method is provided, and the electrical impedance tomography method comprises the following steps. Real-time coordinates of a plurality of electrodes are measured by a plurality of inertial measurement units, and real-time voltages of the plurality of electrodes are obtained, wherein the plurality of inertial measurement units and the plurality of electrodes are conformally integrated on a flexible patch, and the flexible patch is attached to a body part of a patient. Based on real-time coordinates of the plurality of electrodes, a grid deformation method or a grid selection method is used to obtain a transient finite element grid of the body part of the patient; With the transient finite element grid as a forward model, real-time voltages of the plurality of electrodes are used to solve a reverse problem equation to generate an electrical impedance tomography image of the body part of the patient.

[0007] Optionally, based on real-time coordinates of the plurality of electrodes, the grid deformation method is used to obtain the transient finite element grid of the body part of the patient, and the method comprises: A preset standard grid corresponding to the body part of the patient is obtained, and the preset standard grid comprises first preset coordinates corresponding to positions of the plurality of electrodes; Based on real-time coordinates of the plurality of electrodes and the corresponding first preset coordinates, a transformation function is constructed; The initial preset coordinates of each grid element of the preset standard grid are converted into new coordinates by using the transformation function, and the preset standard grid after the coordinate conversion is taken as the transient finite element grid of the body part of the patient.

[0008] Optionally, based on real-time coordinates of the plurality of electrodes, the grid selection method is used to obtain the transient finite element grid of the body part of the patient, and the method comprises: A plurality of pre-selected grids are obtained, wherein each pre-selected grid comprises second preset coordinates corresponding to positions of the plurality of electrodes; For each pre-selected grid, a root mean square error between real-time coordinates of the plurality of electrodes and the corresponding second preset coordinates is calculated; The pre-selected grid corresponding to the minimum root mean square error is taken as the transient finite element grid of the body part of the patient.

[0009] Optionally, with the transient finite element grid as a forward model, real-time voltages of the plurality of electrodes are used to solve a reverse problem equation to generate an electrical impedance tomography image of the body part of the patient, and the method comprises: Based on the transient finite element grid, a Jacobian matrix is calculated; Real-time voltages of the plurality of electrodes and the Jacobian matrix are used to solve the reverse problem equation to obtain an electrical conductivity variation of each grid element of the transient finite element grid; The electrical impedance tomography image of the body part of the patient is generated by using the transient finite element grid and a color corresponding to the electrical conductivity variation of each grid element.

[0010] Optionally, the reverse problem equation is: (J T *J+λ*R)*Δσ=J T *(Vm-V0); Wherein, J is the Jacobian matrix, each element J ijSensitivity of real-time voltage of the i-th grid unit to conductivity change of the j-th grid unit, J T is the transpose of the Jacobian matrix, λ is a regularization parameter, R is a regularization matrix, Δσ is the conductivity change to be solved, Vm is the real-time voltage, and V0 is the reference voltage.

[0011] Optionally, the measuring the real-time coordinates of the plurality of electrodes by the plurality of inertial measurement units comprises: selecting one of the plurality of inertial measurement units as a reference inertial measurement unit, and establishing a reference coordinate system with the reference inertial measurement unit as the origin, wherein the reference inertial measurement unit is located directly above a salient point of the body part of the patient; performing coordinate conversion on the relative coordinates of the plurality of electrodes measured by the plurality of inertial measurement units by the reference coordinate system to obtain absolute coordinates of the plurality of electrodes, and taking the absolute coordinates of the plurality of electrodes as the real-time coordinates of the plurality of electrodes measured.

[0012] Optionally, the measuring the real-time coordinates of the plurality of electrodes by the plurality of inertial measurement units comprises: when the number of the inertial measurement units is less than the number of the electrodes, obtaining the real-time coordinates of the plurality of electrodes by spatial interpolation or a deformation model method based on the real-time coordinates of the plurality of electrodes measured by the plurality of inertial measurement units.

[0013] In a second aspect, an embodiment of the present application provides an electrical impedance tomography device, which comprises: a measuring module configured to measure real-time coordinates of a plurality of electrodes by a plurality of inertial measurement units, and simultaneously acquire real-time voltages of the plurality of electrodes, wherein the plurality of inertial measurement units and the plurality of electrodes are conformally integrated on a flexible patch, and the flexible patch is attached to a body part of a patient; a obtaining module configured to obtain an instantaneous finite element grid of the body part of the patient by using a grid deformation method or a grid selection method based on the real-time coordinates of the plurality of electrodes; a generating module configured to use the real-time voltages of the plurality of electrodes to solve a reverse problem equation by taking the instantaneous finite element grid as a forward model, and generate an electrical impedance tomography image of the body part of the patient.

[0014] In a third aspect, an embodiment of the present application provides an electrical impedance tomography device, which comprises a processor, a memory, and an electrical impedance tomography program stored in the memory and executable by the processor, wherein the electrical impedance tomography program, when executed by the processor, implements the steps of the electrical impedance tomography method described above.

[0015] In a fourth aspect, the embodiments of the present application provide a readable storage medium, and the readable storage medium stores an electrical impedance tomography program. When the electrical impedance tomography program is executed by a processor, the steps of the electrical impedance tomography method described above are implemented.

[0016] The technical scheme provided by the embodiments of the present application has the following beneficial effects: In the embodiments of the present application, the real-time coordinates of the plurality of electrodes are measured by a plurality of inertial measurement units, and the real-time voltages of the plurality of electrodes are obtained, wherein the plurality of inertial measurement units are conformally integrated with the plurality of electrodes on a flexible patch, and the flexible patch is attached to a body part of a patient; based on the real-time coordinates of the plurality of electrodes, a transient finite element mesh of the body part of the patient is obtained by using a mesh deformation method or a mesh selection method; and the real-time voltages of the plurality of electrodes are used to solve an inverse problem equation by taking the transient finite element mesh as a forward model, so as to generate an electrical impedance tomography image of the body part of the patient. Through the embodiments of the present application, the real-time coordinates of the plurality of electrodes are measured from the root of the electrical impedance tomography inverse problem, i.e., the forward model, and then the transient finite element mesh of the body part of the patient is obtained by using the mesh deformation method or the mesh selection method, so as to ensure that the transient finite element mesh of the body part of the patient is consistent with the real-time topological structure of the electrodes. Compared with the prior art of using a static fixed finite element mesh as a forward model to generate an electrical impedance tomography image, the motion artifacts can be eliminated from the root, and the accuracy and stability of the electrical impedance tomography under the motion state can be significantly improved, so that long-term continuous monitoring of the patient under the condition of free breathing and slight activity becomes possible. In addition, the plurality of inertial measurement units are conformally integrated with the plurality of electrodes on the flexible patch, which means that even if the flexible patch experiences complex deformation such as stretching, bending and twisting due to the motion change of the body part of the patient, the relative positions between the plurality of inertial measurement units and the plurality of electrodes can remain unchanged, so that the real-time coordinates of the plurality of electrodes can be accurately measured, and the accuracy of the transient finite element mesh of the body part of the patient obtained based on the real-time coordinates of the plurality of electrodes can be ensured, and thus the motion artifacts caused by the mismatch between the static fixed finite element mesh and the actual positions of the electrodes in the imaging of the prior art can be eliminated. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A flowchart of an embodiment of the electrical impedance tomography method of the present application is shown in FIG. 1; Figure 2 An application scenario diagram of an embodiment of the electrical impedance tomography method of the present application is shown in FIG. 2; Figure 3 An application architecture diagram of an embodiment of the electrical impedance tomography method of the present application is shown in FIG. 3; Figure 4 A functional module diagram of an embodiment of the electrical impedance tomography device of the present application is shown in FIG. 4; Figure 5 Fig. 1 is a schematic diagram of a hardware structure of an electrical impedance tomography device according to an embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to enable persons skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative work fall within the scope of protection of the present application.

[0019] In order to make the objects, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0020] In a first aspect, the embodiments of the present application provide an electrical impedance tomography method.

[0021] In an embodiment, with reference to Figure 1 , Figure 1 Fig. 2 is a flowchart of an electrical impedance tomography method according to an embodiment of the present application. As shown in Fig. 2, the electrical impedance tomography method comprises the following steps. Figure 1 In step S10, real-time coordinates of a plurality of electrodes are measured by a plurality of inertial measurement units, and real-time voltages of the plurality of electrodes are obtained, wherein the plurality of inertial measurement units are conformally integrated with the plurality of electrodes on a flexible patch, and the flexible patch is attached to a body part of a patient.

[0022] In the embodiment, for example, the real-time coordinates of 16 EIT electrodes can be measured in real time by 16 micro 9-axis IMUs (inertial measurement units) integrated on the flexible patch. The size of each IMU package is 3 mm x 3 mm x 1 mm. The 16 IMUs and the 16 EIT electrodes are preferably arranged adjacent to each other and conformally integrated on a medical silicone substrate with a thickness of 1.5 mm. In the system initialization stage, first, a reference IMU is fixed at the xiphoid process of the patient as a global static reference point, and a body surface reference coordinate system with the point as the origin is established. Subsequently, the relative positional relationship (including offset vector and rotation matrix) between each IMU and the corresponding EIT electrode is determined by a calibration program. In actual measurement, the IMU obtains three-dimensional space data through the accelerometer, gyroscope and magnetometer, and uses Kalman filtering for data fusion to calculate the attitude (quaternion) and position of each IMU. According to the calibrated relative positional relationship, the absolute three-dimensional coordinates (X i , i , i of each EIT electrode are calculated in combination with the attitude of the IMU and the reference coordinate system.The process is executed every 100 milliseconds, ensuring real-time and accuracy of coordinate measurement.

[0023] In the structure, the EIT electrode and the IMU chip are integrated with the flexible polymer substrate into a multi-layer and integrated structure during the manufacturing process through micro-nano processing technology (such as flexible printed circuit, photolithography, laser-induced graphene) or embedded packaging technology, which means that the leads and interconnections of the electrode and the sensor are also flexible, and the entire device is like a thin layer of "electronic tattoo" or "electronic skin, so that the relative positional relationship between the integrated functional units (electrode and IMU) can be maintained unchanged even when the substrate undergoes complex deformation such as stretching, bending and twisting. Through the conformal integration of the IMU and the electrode, real-time sensing of the electrode topology is realized. Compared with traditional methods, the scheme avoids the limitations of using a fixed coordinate system or post-compensation. The Kalman filtering algorithm effectively suppresses the noise and drift of the IMU data, ensuring the stability of the coordinate measurement. Since the IMU and the electrode are conformally integrated, the relative position of the IMU and the electrode remains unchanged even if the patch is deformed by stretching, bending, etc., so the real-time spatial position of the electrode can be accurately reflected. This "sensing-modeling" integrated design fundamentally solves the model mismatch problem caused by the change of the electrode position in the traditional EIT, provides a reliable foundation for subsequent dynamic mesh updating, and significantly improves the imaging quality in the motion state.

[0024] In step S20, based on the real-time coordinates of the plurality of electrodes, a mesh deformation method or a mesh selection method is used to obtain an instantaneous finite element mesh of the body part of the patient.

[0025] In this embodiment, based on the real-time coordinates of the plurality of electrodes obtained in step S10, an instantaneous finite element mesh is obtained by using a mesh deformation method or a mesh selection method. The mesh deformation method, for example, uses a thin plate spline interpolation algorithm: a preset standard mesh corresponding to the patient's thoracic cavity (containing preset standard coordinates of 16 electrode positions) is obtained, the standard mesh node coordinates and the real-time electrode coordinates are taken as control points, a deformation field function T(x, y, z) = (x', y', z') is calculated, and the function is applied to convert the initial preset coordinates of each mesh element of the preset standard mesh to real-time coordinates. The preset standard mesh after coordinate conversion is used as the instantaneous finite element mesh. The mesh selection method, for example, a grid library containing 100 typical thoracic cavity deformations is constructed in advance through simulation, the root mean square error (RMSE) of the current electrode coordinates and the corresponding coordinates of each grid in the grid library is calculated in real time, and the grid with the smallest RMSE is selected as the instantaneous finite element mesh. Both methods dynamically update the instantaneous finite element mesh of the body part of the patient, ensuring that it is highly consistent with the actual geometric shape of the patch and the electrode.

[0026] The core of the embodiment is the generation of a dynamic finite element mesh, which is the key to solving motion artifacts. The mesh deformation method is based on the principle of elastic deformation, and realizes accurate modeling of continuous deformation through control point mapping, which is suitable for continuous motion such as respiration; the mesh selection method realizes fast response through pattern matching, which is suitable for discrete deformation scenarios. By flexibly using the two methods, the adaptability of the system to different scenarios can be enhanced. Compared with static meshes, by dynamically updating the finite element mesh, the forward model is completely matched with the actual electrode topology, and the motion artifacts caused by model mismatch are eliminated at the root. In the volunteer experiment, the image correlation coefficient is improved by more than 0.45 through dynamic updating of the finite element mesh, which proves that the method can significantly improve the anatomical structure consistency of the image, and the relative changes in lung ventilation distribution are clear and visible, providing a reliable basis for clinical monitoring.

[0027] Step S30, using the instantaneous finite element mesh as the forward model, the real-time voltage of the multiple electrodes is used to solve the inverse problem equation to generate the electrical impedance tomography image of the patient's body part.

[0028] In the embodiment, the instantaneous finite element mesh generated in step S20 is used as the forward model, and the real-time voltage data obtained in step S10 is used to solve the inverse problem equation. For example, first, the Jacobian matrix J can be calculated based on the instantaneous finite element mesh, and each element J ij in the Jacobian matrix J represents the sensitivity of the real-time voltage of the i-th mesh element to the conductivity change of the j-th mesh element, and then the Gauss-Newton method is used to solve the inverse problem equation (J T *J+λ*R)*Δσ=J T *(Vm-V0), where λ is a regularization parameter, R is a regularization matrix, Vm is a real-time voltage, V0 is a reference voltage (which can be the voltage at the initial time or the voltage of the previous frame), and Δσ is the conductivity change to be solved. The conductivity change Δσ of each mesh element is obtained by iterative solution, and finally the EIT image is generated using the instantaneous mesh structure and the color mapping corresponding to Δσ.

[0029] In the embodiment, the inverse problem is solved by dynamically updating the forward model, which ensures the physical consistency of the EIT image reconstruction process. The calculation of the Jacobian matrix depends on the topology of the instantaneous mesh, and the Jacobian matrix calculated using the dynamic mesh can more accurately reflect the spatial relationship between the electrodes and the mesh elements. Compared with static meshes, the accuracy of the conductivity change solution can be significantly improved. In clinical applications, this accurate reconstruction makes the quantitative analysis of lung ventilation distribution more reliable, for example, it can more accurately monitor pathological conditions such as uneven lung ventilation, and the image reconstructed by the dynamic mesh maintains good anatomical structure consistency during deep breathing and turning over, and the lung area is clearly visible.

[0030] In the embodiment, reference is made toFigure 2 , Figure 2 An application scenario diagram of an embodiment of the electrical impedance tomography method of the present application is shown in FIG. 1. As shown in FIG. 1, a flexible patch (with an IMU and electrodes conformally integrated) is worn on the thorax of a patient, and a main processing unit in the system hardware components runs the above-mentioned method of the embodiment to generate EIT images of the patient's chest in real time, which are displayed in real time through a mobile monitoring terminal or a bedside display, and are further applied to scenarios such as ICU intensive care, long-term monitoring in a rehabilitation department, and home remote monitoring. Figure 2 , Figure 3 , Figure 3 An application architecture diagram of an embodiment of the electrical impedance tomography method of the present application is shown in FIG. 2. As shown in FIG. 2, the system corresponding to the electrical impedance tomography method of the present application is divided into a perception layer (a flexible sensor patch), a processing layer (an edge computing unit), and an application layer. The perception layer can optionally integrate an ultrasonic transducer array for synchronous ultrasonic imaging. In addition to being applied to visual display, the EIT images generated in real time by the processing layer can also be applied to trend analysis and management, and intelligent alarm. Figure 3

[0031] Further, in an embodiment, based on the real-time coordinates of the plurality of electrodes, a mesh deformation method is used to obtain the instantaneous finite element mesh of the body part of the patient, including: obtaining a preset standard mesh corresponding to the body part of the patient, the preset standard mesh including first preset coordinates corresponding to the positions of the plurality of electrodes; based on the real-time coordinates of the plurality of electrodes and the corresponding first preset coordinates, a transformation function is constructed; using the transformation function to convert the initial preset coordinates of each mesh element of the preset standard mesh to new coordinates, and using the preset standard mesh after the coordinate conversion as the instantaneous finite element mesh of the body part of the patient.

[0032] In the embodiment, the specific implementation of generating the instantaneous finite element mesh based on the real-time coordinates of the plurality of electrodes using the mesh deformation method is as follows: first, a preset standard mesh corresponding to the thorax of the patient (containing preset standard coordinates of 16 electrode positions, i.e., first preset coordinates) is obtained, which is constructed based on public thoracic anatomy data, and then based on the real-time coordinates of the plurality of electrodes and the preset standard coordinates, a thin plate spline interpolation function T(x, y, z) is constructed, a deformation field function is obtained by solving, the initial preset coordinates of each mesh element of the preset standard mesh are converted to real-time coordinates by applying the deformation field function, and finally the preset standard mesh after the coordinate conversion is used as the instantaneous finite element mesh.

[0033] ​The thin plate spline interpolation method is an interpolation method based on minimum curvature, and can effectively process nonlinear deformation and maintain the smoothness and continuity of the grid. Compared with linear methods such as affine transformation, the thin plate spline can better adapt to the stretching, bending and other deformations of the patch under complex motion. The theoretical basis of the method is the principle of minimum elastic deformation energy, that is, the deformed grid should minimize the deformation energy, which is consistent with the physical properties of biological tissues.

[0034] Further, in an embodiment, based on the real-time coordinates of the plurality of electrodes, the instantaneous finite element grid of the patient's body part is obtained by using a grid selection method, comprising: obtaining a plurality of pre-device selection grids, wherein each pre-device selection grid comprises second preset coordinates corresponding to the positions of the plurality of electrodes; for each pre-device selection grid, calculating the root mean square error between the real-time coordinates of the plurality of electrodes and the corresponding second preset coordinates; the pre-device selection grid corresponding to the minimum root mean square error is taken as the instantaneous finite element grid of the patient's body part.

[0035] In the embodiment, the specific implementation of obtaining the instantaneous finite element grid by using the grid selection method based on the real-time coordinates of the plurality of electrodes is as follows: in the system initialization stage, a grid library containing 100 typical thoracic shapes and patch deformations, i.e. a plurality of pre-device selection grids, is constructed through finite element simulation and body surface deformation experiments. Each grid corresponds to a specific thoracic curvature, patch stretch rate and bending angle. In real-time application, for each pre-device selection grid, the root mean square error between the real-time coordinates of the plurality of electrodes and the corresponding second preset coordinates is calculated, and by comparing the RMSE of all grids, the grid corresponding to the minimum RMSE is selected as the current instantaneous finite element grid.

[0036] The grid selection method is based on the principle of pattern matching, and uses a pre-stored typical deformation grid library to achieve fast response. The theoretical basis is the discrete representation of the deformation space, that is, the actual deformation can be approximated as one of the pre-stored grid library. Compared with the grid deformation method, the grid selection method does not need to calculate the deformation field in real time, and has higher calculation efficiency, and is particularly suitable for regular motion such as respiratory cycle. The grid selection method performs well in respiratory motion monitoring, because the respiratory motion has periodicity, and the pre-stored grid library can well cover the typical deformation state. The grid selection method can achieve high real-time performance on resource-limited embedded devices, and is particularly suitable for long-term continuous monitoring scenarios.

[0037] Further, in an embodiment, step S30 comprises: calculating the Jacobian matrix based on the instantaneous finite element grid; solving the inverse problem equation using the real-time voltages of the plurality of electrodes and the Jacobian matrix to obtain the conductivity change of each grid element of the instantaneous finite element grid; The transient finite element mesh and the color corresponding to the conductivity change of each mesh element are used to generate the electrical impedance tomography image of the patient's body part.

[0038] In this embodiment, the solving process of the inverse problem equation is as follows: first, the Jacobian matrix J is calculated based on the transient finite element mesh, each element J ij represents the sensitivity of the real-time voltage of the i-th mesh element to the conductivity change of the j-th mesh element, and the matrix is calculated by finite element analysis, and the accuracy directly depends on the accuracy of the transient mesh. Then, the regularization parameter λ and the regularization matrix R are introduced to construct the regularization inverse problem equation (J T *J+λ*R)*Δσ=J T *(Vm-V0). The one-step Gauss-Newton method is used for iterative solving, and the conductivity change Δσ to be solved is updated each time until convergence. Finally, Δσ of each mesh element is converted into a color value to generate an EIT image.

[0039] The Jacobian matrix J calculated using the dynamic mesh can more accurately reflect the physical relationship between the electrodes and the mesh elements, and the matching degree of the forward model and the actual measurement data is improved. Compared with the static mesh, the solving accuracy of Δσ is improved by using the Jacobian matrix J calculated using the dynamic mesh to solve the inverse problem equation.

[0040] Further, in an embodiment, the inverse problem equation is: (J T *J+λ*R)*Δσ=J T *(Vm-V0); Wherein, J is the Jacobian matrix, each element J ij represents the sensitivity of the real-time voltage of the i-th mesh element to the conductivity change of the j-th mesh element, J T is the transpose of the Jacobian matrix, λ is the regularization parameter, R is the regularization matrix, Δσ is the conductivity change to be solved, Vm is the real-time voltage, and V0 is the reference voltage.

[0041] In this embodiment, the introduction of the regularization terms λ and R effectively suppresses noise and ill-conditioned problems, ensuring the stability of image reconstruction. The reference voltage V0 can be the voltage at the initial time or the voltage of the previous frame, and the Gauss-Newton method can be used to solve the inverse problem equation, and the conductivity change Δσ is updated each time until convergence.

[0042] Further, in an embodiment, the real-time coordinates of the plurality of electrodes measured by the plurality of inertial measurement units comprise: select one of the plurality of inertial measurement units as a reference inertial measurement unit, and establish a reference coordinate system with the reference inertial measurement unit as the origin, wherein the reference inertial measurement unit is located directly above a body part protrusion point of the patient; convert the relative coordinates of the plurality of electrodes measured by the plurality of inertial measurement units through the reference coordinate system to obtain absolute coordinates of the plurality of electrodes, and take the absolute coordinates of the plurality of electrodes as real-time coordinates of the plurality of electrodes measured.

[0043] In this embodiment, the implementation method of measuring the real-time coordinates of the plurality of electrodes by the plurality of inertial measurement units is: selecting the IMU at the xiphoid process from the 16 IMUs as the reference inertial measurement unit, and establishing a reference coordinate system with the reference inertial measurement unit as the origin. The Z axis of the reference coordinate system is perpendicular to the body surface outward (determined by the fusion of the gravity direction perceived by the accelerometer and the gyroscope data), the X axis is parallel to the body surface and points to the right side of the patient (determined by the fusion of the north-south pole direction perceived by the magnetometer and the gyroscope data), and the Y axis is determined by the right-hand rule (X axis cross product Z axis) and points to the front of the patient. The reference IMU is located directly above the body protrusion point (such as the xiphoid process), which ensures that the attitude change can accurately reflect the movement of the entire thoracic cage. The relative coordinates measured by other IMUs are converted through the reference coordinate system to calculate the absolute coordinates of each electrode. The coordinate conversion can be realized through the calibrated relative position vector and the IMU attitude matrix, and the formula is, for example: P abs = R ref * P rel + T ref , wherein P abs is the absolute coordinates of the IMU, R ref is the attitude rotation matrix of the reference IMU, P rel is the relative coordinates of the IMU, and T ref is the absolute position vector of the reference IMU.

[0044] The establishment of the reference coordinate system is the key to realizing high-precision measurement of the system. Placing the reference IMU directly above the body protrusion point (such as the xiphoid process) can minimize the error in establishing the coordinate system, as this point is relatively stable during respiratory movement. Coordinate conversion through the reference coordinate system ensures that all electrode coordinates are in the same reference system, avoiding inconsistencies between different IMU coordinate systems. The theoretical basis of this method is rigid body kinematics, that is, through the known reference point and relative position relationship, the absolute position of other points can be accurately calculated.

[0045] Further, in an embodiment, the measuring the real-time coordinates of the plurality of electrodes by the plurality of inertial measurement units comprises: When the number of inertial measurement units is less than the number of electrodes, the real-time coordinates of the plurality of electrodes are obtained by spatial interpolation or deformation model method based on the real-time rotation measured by the plurality of inertial measurement units.

[0046] In this embodiment, in an ideal case, one-to-one correspondence between the IMU and the EIT electrode (one IMU is arranged close to one EIT electrode) is the optimal solution, which can most directly and accurately obtain the spatial coordinates of each electrode, and the theoretical error is the smallest. However, for cost, power consumption or integration complexity, when the number of inertial measurement units is less than the number of electrodes, the real-time coordinates of the plurality of electrodes can be obtained by spatial interpolation or deformation model method based on the real-time rotation measured by the plurality of inertial measurement units. The spatial interpolation method, for example, in a 16-electrode ring array, only 8 IMUs are arranged, and one IMU is arranged every other electrode. The system estimates the coordinates of the other 8 electrodes without IMUs by using a spatial interpolation algorithm (such as linear interpolation, cubic spline interpolation, or deformation interpolation based on a patch mechanics model) based on the coordinates of the 8 known IMUs. This requires that the deformation model and the interpolation function of the patch be established during system initialization calibration. The deformation model method, for example, uses fewer IMUs (such as 4) distributed at several key positions (such as the four corners) of the patch. The flexible patch is regarded as a continuous elastic body. According to the displacement and attitude change of the several key points, the displacement of any point (i.e. each electrode) on the patch is calculated by a pre-trained mechanical deformation model (such as the Cauchy-Green strain tensor model). This model can be obtained by preliminary finite element simulation or calibration experiment.

[0047] When the number of IMUs is limited, the spatial interpolation or deformation model method can effectively solve the coordinate measurement problem while maintaining the balance of system cost and complexity. This makes the system capable of realizing high-precision monitoring at a lower hardware cost, which is particularly suitable for large-scale clinical applications, while maintaining the core advantages of dynamic topology self-mapping, so that the motion artifact elimination effect is not significantly affected.

[0048] In a second aspect, the embodiments of the present application also provide a resistive impedance tomography device.

[0049] In an embodiment, with reference to Figure 4 , Figure 4 The functional module schematic diagram of an embodiment of the resistive impedance tomography device of the present application is shown in Figure 4 The resistive impedance tomography device comprises: The measurement module 10 is configured to measure the real-time coordinates of the plurality of electrodes by the plurality of inertial measurement units, and simultaneously acquire the real-time voltages of the plurality of electrodes, wherein the plurality of inertial measurement units and the plurality of electrodes are conformally integrated on a flexible patch, and the flexible patch is attached to a body part of a patient. The obtaining module 20 is configured to obtain, based on the real-time coordinates of the plurality of electrodes, a transient finite element mesh of the body part of the patient by using a mesh deformation method or a mesh selection method. The generating module 30 is configured to use the real-time voltages of the plurality of electrodes to solve the inverse problem equation with the transient finite element mesh as a forward model, to generate an electrical impedance tomography image of the body part of the patient.

[0050] Further, in an embodiment, the obtaining module 20 is configured to: obtain a preset standard mesh corresponding to the body part of the patient, the preset standard mesh comprising first preset coordinates corresponding to positions of the plurality of electrodes; construct a transformation function based on the real-time coordinates of the plurality of electrodes and the corresponding first preset coordinates; convert initial preset coordinates of each mesh element of the preset standard mesh to new coordinates using the transformation function, and use the preset standard mesh after the coordinate conversion as the transient finite element mesh of the body part of the patient.

[0051] Further, in an embodiment, the obtaining module 20 is configured to: obtain a plurality of pre-selected meshes, wherein each pre-selected mesh comprises second preset coordinates corresponding to positions of the plurality of electrodes; calculate, for each pre-selected mesh, a root mean square error between the real-time coordinates of the plurality of electrodes and the corresponding second preset coordinates; use the pre-selected mesh corresponding to the minimum root mean square error as the transient finite element mesh of the body part of the patient.

[0052] Further, in an embodiment, the generating module 30 is configured to: calculate a Jacobian matrix based on the transient finite element mesh; use the real-time voltages of the plurality of electrodes and the Jacobian matrix to solve the inverse problem equation to obtain an electrical conductivity variation of each mesh element of the transient finite element mesh; generate the electrical impedance tomography image of the body part of the patient using the transient finite element mesh and a color corresponding to the electrical conductivity variation of each mesh element.

[0053] Further, in an embodiment, the inverse problem equation is: (J T *J+λ*R)*Δσ=J T *(Vm-V0); wherein J is the Jacobian matrix, each element J ij in the Jacobian matrix J represents a sensitivity of a real-time voltage of an i-th mesh element to an electrical conductivity variation of a j-th mesh element, J Tis the transpose of the Jacobian matrix, λ is a regularization parameter, R is a regularization matrix, Δσ is the conductivity change to be solved, Vm is the real-time voltage, and V0 is the reference voltage.

[0054] Further, in an embodiment, the measurement module 10 is configured to: select one of the plurality of inertial measurement units as a reference inertial measurement unit, and establish a reference coordinate system with the reference inertial measurement unit as the origin, wherein the reference inertial measurement unit is located directly above the protruding point on the patient's body part; perform coordinate conversion on the relative coordinates of the plurality of electrodes measured by the plurality of inertial measurement units through the reference coordinate system to obtain absolute coordinates of the plurality of electrodes, and use the absolute coordinates of the plurality of electrodes as the real-time coordinates of the plurality of electrodes measured.

[0055] Further, in an embodiment, the measurement module 10 is configured to: when the number of inertial measurement units is less than the number of electrodes, obtain the real-time coordinates of the plurality of electrodes based on the real-time coordinates measured by the plurality of inertial measurement units through spatial interpolation or a deformation model method.

[0056] The functions of each module in the above electrical impedance tomography device correspond to the steps in the above electrical impedance tomography method embodiments, and the functions and implementation processes will not be described here.

[0057] In a third aspect, the embodiments of the present application provide an electrical impedance tomography device.

[0058] Reference Figure 5 , Figure 5 FIG. 1 is a schematic diagram of a hardware structure of an electrical impedance tomography device according to an embodiment of the present application. In the embodiments of the present application, the electrical impedance tomography device can include a processor, a memory, a communication interface, and a communication bus.

[0059] The communication bus can be of any type and is used to interconnect the processor, the memory, and the communication interface.

[0060] The communication interface includes an input / output (I / O) interface, a physical interface, and a logical interface, and is used to interconnect devices within the electrical impedance tomography device, and is also used to interconnect the electrical impedance tomography device with other devices (such as other computing devices or user devices). The physical interface can be an Ethernet interface, a fiber interface, an ATM interface, etc.; the user device can be a display (Display), a keyboard (Keyboard), etc.

[0061] The memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), and the like.

[0062] The processor can be a general-purpose processor, which can invoke the electrical impedance tomography program stored in the memory and execute the electrical impedance tomography method provided by the embodiments of the present application. For example, the general-purpose processor can be a central processing unit (CPU). The method executed when the electrical impedance tomography program is invoked can refer to the embodiments of the electrical impedance tomography method of the present application, which will not be described herein.

[0063] Those skilled in the art can understand that the hardware structure shown in the above-mentioned embodiments is not a limitation of the present application, and can include more or less components, or combine certain components, or different component arrangements. Figure 5 The hardware structure shown in the above-mentioned embodiments is not a limitation of the present application, and can include more or less components, or combine certain components, or different component arrangements.

[0064] In a fourth aspect, the embodiments of the present application further provide a readable storage medium.

[0065] The readable storage medium of the present application stores the electrical impedance tomography program, wherein when the electrical impedance tomography program is executed by the processor, the steps of the electrical impedance tomography method as described above are implemented.

[0066] The method implemented when the electrical impedance tomography program is executed can refer to the embodiments of the electrical impedance tomography method of the present application, which will not be described herein.

[0067] It should be noted that the above-mentioned serial numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0068] The terms “include,” “comprise,” “have,” and any variations thereof, in the specification and in the claims of the present application, and the above-described drawings, are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or device that includes a list of steps or units is not limited to the listed steps or units, but can optionally further include steps or units not listed, or can optionally further include other steps or units inherent to such processes, methods, products, or devices. The terms “first”, “second”, and “third” and the like descriptions are used to distinguish different objects, and do not represent the order or limit the types of “first”, “second”, and “third”.

[0069] In the description of the embodiments of the present application, “exemplary”, “for example”, or “for instance” is used to represent an example, illustration, or description. Any embodiment or design scheme described as “exemplary”, “for example”, or “for instance” in the embodiments of the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the words “exemplary”, “for example”, or “for instance” are intended to present the relevant concept in a specific manner.

[0070] In the description of the embodiments of the present application, unless otherwise specified, “ / ” represents the meaning of or, for example, A / B can represent A or B; “and / or” in the text only represents a description of the relationship between the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, in the description of the embodiments of the present application, “multiple” means two or more than two.

[0071] In some of the processes described in the embodiments of the present application, a plurality of operations or steps are included in a specific order, but it should be understood that these operations or steps can be executed or performed in parallel or in an order different from that in which they appear in the embodiments of the present application. The serial number of the operation is only used to distinguish different operations, and the serial number itself does not represent any execution order. In addition, these processes can include more or fewer operations, and these operations or steps can be executed in sequence or in parallel, and these operations or steps can be combined.

[0072] From the above description of the embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment method can be realized by means of software and a general hardware platform as required, of course, it can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which is stored in a storage medium (such as a ROM / RAM, a magnetic disk, an optical disk) as described above, and includes a plurality of instructions for causing a terminal device to execute the methods described in the embodiments of the present application.

[0073] The preferred embodiments of the present application have been described above with the illustrated embodiments, and are not intended to limit the scope of patent protection for the present application. Any equivalent structure or equivalent process variations, which directly or indirectly incorporate the contents of the specification and drawings of the present application, are also intended to be included within the scope of patent protection for the present application.

Claims

1. An electrical impedance tomography method, characterized by, The electrical impedance tomography method comprises: Real-time coordinates of the plurality of electrodes are measured by a plurality of inertial measurement units, and real-time voltages of the plurality of electrodes are obtained simultaneously, wherein the plurality of inertial measurement units are conformally integrated with the plurality of electrodes on a flexible patch, and the flexible patch is attached to a body part of a patient; Based on the real-time coordinates of the plurality of electrodes, an instantaneous finite element grid of the body part of the patient is obtained by using a mesh deformation method or a mesh selection method; The instantaneous finite element grid is used as a forward model, and the real-time voltages of the plurality of electrodes are used to solve a reverse problem equation, so as to generate an electrical impedance tomography image of the body part of the patient.

2. The electrical impedance tomography method of claim 1, wherein, Based on the real-time coordinates of the plurality of electrodes, the instantaneous finite element grid of the body part of the patient is obtained by using the mesh deformation method, which comprises: A preset standard grid corresponding to the body part of the patient is obtained, and the preset standard grid comprises first preset coordinates corresponding to positions of the plurality of electrodes; Based on the real-time coordinates of the plurality of electrodes and the corresponding first preset coordinates, a transformation function is constructed; The initial preset coordinates of each grid element of the preset standard grid are converted into new coordinates by using the transformation function, and the preset standard grid after the coordinate conversion is taken as the instantaneous finite element grid of the body part of the patient.

3. The electrical impedance tomography method of claim 1, wherein, Based on the real-time coordinates of the plurality of electrodes, the instantaneous finite element grid of the body part of the patient is obtained by using the mesh selection method, which comprises: A plurality of pre-selected grids are obtained, wherein each pre-selected grid comprises second preset coordinates corresponding to positions of the plurality of electrodes; For each pre-selected grid, a root mean square error between the real-time coordinates of the plurality of electrodes and the corresponding second preset coordinates is calculated; The pre-selected grid corresponding to the minimum root mean square error is taken as the instantaneous finite element grid of the body part of the patient.

4. The electrical impedance tomography method of claim 1, wherein, The instantaneous finite element grid is used as a forward model, and the real-time voltages of the plurality of electrodes are used to solve a reverse problem equation, so as to generate an electrical impedance tomography image of the body part of the patient, which comprises: Based on the instantaneous finite element grid, a Jacobian matrix is calculated; The real-time voltages of the plurality of electrodes and the Jacobian matrix are used to solve the reverse problem equation, so as to obtain an electrical conductivity variation of each grid element of the instantaneous finite element grid; The instantaneous finite element grid and the color corresponding to the electrical conductivity variation of each grid element are used to generate the electrical impedance tomography image of the body part of the patient.

5. The electrical impedance tomography method of claim 4, wherein, The reverse problem equation is: (J T *J+λ*R)*Δσ=J T *(Vm-V0); where J is the Jacobian matrix, each element J ij represents the sensitivity of the real-time voltage of the i-th grid cell to the conductivity change of the j-th grid cell, J T is the transpose of the Jacobian matrix, λ is the regularization parameter, R is the regularization matrix, Δσ is the conductivity change to be solved, Vm is the real-time voltage, and V0 is the reference voltage.

6. The electrical impedance tomography method of claim 1, wherein, The real-time coordinates of the plurality of electrodes are measured by the plurality of inertial measurement units, which comprises: One of the plurality of inertial measurement units is selected as a reference inertial measurement unit, and a reference coordinate system is established with the reference inertial measurement unit as an origin, wherein the reference inertial measurement unit is located directly above a salient point of the body part of the patient; The relative coordinates of the plurality of electrodes measured by the plurality of inertial measurement units are converted into absolute coordinates of the plurality of electrodes by the reference coordinate system, and the absolute coordinates of the plurality of electrodes are taken as the real-time coordinates of the plurality of electrodes measured.

7. The electrical impedance tomography method of claim 1, wherein, The real-time coordinates of the plurality of electrodes are measured by the plurality of inertial measurement units, which comprises: When the number of the inertial measurement units is less than the number of the electrodes, the real-time coordinates of the plurality of electrodes are obtained by a spatial interpolation method or a deformation model method based on the real-time coordinates measured by the plurality of inertial measurement units.

8. An electrical impedance tomography apparatus, characterized in that The electrical impedance tomography device comprises: a measurement module, configured to measure real-time coordinates of a plurality of electrodes by a plurality of inertial measurement units, and to obtain real-time voltages of the plurality of electrodes, wherein the plurality of inertial measurement units are conformally integrated with the plurality of electrodes on a flexible patch, and the flexible patch is attached to a body part of a patient; an obtaining module, configured to obtain an instantaneous finite element mesh of the body part of the patient by using a mesh deformation method or a mesh selection method based on the real-time coordinates of the plurality of electrodes; a generating module, configured to use the real-time voltages of the plurality of electrodes to solve a reverse problem equation by taking the instantaneous finite element mesh as a forward model, and to generate an electrical impedance tomography image of the body part of the patient.

9. An electrical impedance tomography device, characterized by The electrical impedance tomography device comprises a processor, a memory, and an electrical impedance tomography program stored in the memory and executable by the processor, wherein the electrical impedance tomography program, when executed by the processor, implements the steps of the electrical impedance tomography method according to any one of claims 1 to 7.

10. A readable storage medium, characterized by, The readable storage medium stores an electrical impedance tomography program, wherein the electrical impedance tomography program, when executed by a processor, implements the steps of the electrical impedance tomography method according to any one of claims 1 to 7.

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