Eit-based regional exhalation washout assessment method, system, storage medium

Abstract

The application provides an EIT-based regional exhalation emptying evaluation method and system and a storage medium, and belongs to the technical field of medical information software, and the technical points are as follows: synchronous data in a forced vital capacity action process of a subject is acquired, including a time-exhalation cumulative volume curve and a time-impedance value curve of each pixel point of a lung; impedance change values of each pixel point are mapped from a time domain to a normalized exhalation process domain; a normalized residual gas proportion and an average residual gas proportion of each pixel point are calculated, and then a dynamic emptying residual error is solved. Accordingly, a delayed emptying area proportion is determined. Finally, FV-RETI and Pdelay are solved. By using the technical scheme, regional lung emptying heterogeneity in a forced exhalation process can be quantified.

Description

Technical Field

[0001] This invention belongs to the technical field of intelligent medical care, specifically relating to a regional expiratory airway assessment method, system, and storage medium based on EIT. Background Technology

[0002] EIT (Extracorporeal Immunotherapy) has been extensively studied for obtaining parameters for lung function assessment. For example: Reference 1, “Liu Wu, Sun Lulu, Li Jiayun, et al. Evaluation of the effect of thoracic electrical impedance tomography derived parameters on atelectasis in hospitalized patients [J]. Journal of Naval Medical University, 2025, 46(11):1439-1446”, proposed the Center of Ventilation (CoV), which is used to quantify the spatial distribution characteristics of lung ventilation.

[0003] Reference 2, CN118697320B, proposes Global Inhomogeneity (GI) to assess the spatial dispersion of lung function.

[0004] Reference 3, "Muders T, Henze B, Simon P, et al. A Modified Method to AssessTidal Recruitment by Electrical Impedance Tomography[J] Journal of Clinical Medicine, 2019, 8(8)", proposes regional ventilation delay inhomogeneity (RVDI) to quantify the temporal heterogeneity of lung ventilation.

[0005] However, EIT is still insufficient in detecting many small airway lesions (such as early COPD), mainly due to the following problems: First, there is a lack of standardized expiratory process coordinates, making cross-individual comparisons impossible.

[0006] Existing EIT analyses all use absolute time as the horizontal axis, but the duration of exhalation varies greatly among individuals (2-3 seconds for healthy individuals, and more than 6-10 seconds for COPD patients), so the "delay" indicator based on absolute time is not comparable.

[0007] Second, the evaluation dimensions are too narrow, ignoring the spatial characteristics of the empty space.

[0008] Current EIT (Extended Inhalation Test) breath analyses mostly focus on single numerical indicators, severely missing structural information about abnormally emptied regions. For the same proportion of delayed regions, continuous distribution and highly fragmented distribution have drastically different pathological significance, but current techniques cannot quantify this difference.

[0009] Third, it cannot distinguish the persistence characteristics of the delay.

[0010] Current methods can only determine the presence of airway emptying delay, but cannot describe the dynamic evolution of the delay during the expiratory process. Some lung areas experience delay only in the early stages, while others experience delay throughout the entire process and with increasing severity. This "persistent" characteristic is a key indicator for differentiating between central airway obstruction, peripheral small airway disease, and dynamic hyperinflation.

[0011] In summary, existing technologies are unable to achieve standardized spatiotemporal dynamic quantitative assessment of regional expiratory heterogeneity. Summary of the Invention

[0012] The purpose of this invention is to solve the problems existing in the prior art and to provide a coupled detection method, detection system, and storage medium based on breath detection and electrical impedance imaging.

[0013] A regional expiratory emptying assessment method based on EIT (Expiratory Intake Test), which is not a diagnostic method for disease, includes the following steps: Step a: Acquire synchronous data during the subject's forced vital capacity exercise. The synchronous data includes: the time t-cumulative expiratory volume V(t) curve, and the time t-impedance transformation value ΔZ of any pixel p in the lung. p (t) curve; Where △Zp(t) represents the change in impedance value of pixel point p at any time t relative to the impedance value at the start of exhalation tstart; Step b, solve for the time t-normalized expiratory process coordinate s(t) curve; s(t) = [V(t) - V(tstart)] / [V(tend) - V(tstart)]; tend represents the end of exhalation; Step c, through the ts(t) curve, t-ΔZ p (t) curve, obtain the s-ΔZ corresponding to any pixel p in the lung. p (s) curve; Step d: Obtain the s-normalized residual gas ratio φ corresponding to any pixel p in the lung. p (s) curve; φ p (s) = [△Z p (s)-△Z p (s=1)] / [△Z p (s=0)-△Z p [(s=1)+ε];ε is a small constant; Step e, based on the s-φ corresponding to any pixel p in the lung p (s) curve, solve for s - the average residual gas ratio φ of the entire lung region pixels. global(s) curve: φ global (s) represents the arithmetic mean of the proportion of remaining gas in all pixels of the whole lung at any normalized expiratory process coordinate s; Step f: Solve for the s-dynamic emptying residual r corresponding to any pixel p in the lung. p (s) curve; r p (s) = φ p (s)-φ global (s); Step g: Solve for the s-Adelay(s) curve; Adelay(s) represents the proportion of pixels marked as delayed to the total number of pixels in the lungs under any normalized expiratory process coordinate s; Each pixel in the lungs is analyzed individually to determine whether it is marked as delayed. When r p (s)>τ delay At that time, pixel p is marked as delayed; τ delay This is the relative threshold for delay; or, When s is greater than 0.85 and φ p (s) is greater than θ abs At that time, pixel p is marked as delayed; θ abs A fixed threshold for normalizing the proportion of residual gas; Step h, set the minimum abnormal area threshold α min Solve for the regional expiratory air volume index (FV-RETI); ; in, .

[0014] Furthermore, it also includes step i, solving for the delay-induced emptying persistence ratio Pdelay: .

[0015] Furthermore, step g also includes: obtaining a set of lung region pixels that are determined to be delayed emptying during the exhalation process s.

[0016] Furthermore, ε=10 -6 .

[0017] Furthermore, τ delay The value is 0.03.

[0018] Furthermore, θ abs The value is 0.15.

[0019] Furthermore, α min The value is 0.10.

[0020] A regional expiratory airway assessment system based on EIT includes: The data acquisition module is used to acquire synchronous data during a subject's forced vital capacity exercise. This synchronous data includes: a time t-cumulative expiratory volume V(t) curve, and a time t-impedance transformation value ΔZ for any lung pixel p. p (t) curve The normalized exhalation process coordinate solution module is used to solve the time t-normalized exhalation process coordinate s(t) curve; s(t) = [V(t) - V(tstart)] / [V(tend) - V(tstart)]; tstart and tend represent the start time and end time of exhalation, respectively; The domain mapping module, based on the ts(t) curve and t-ΔZ... p (t) curve establishes the relationship between s and ΔZ for any pixel p in the lung. p The mapping relationship between them forms s-△Z p (s) curve; The signal normalization module is used to obtain the s-normalized residual gas ratio φ corresponding to any pixel p in the lung. p (s) curve, φ p (s) = [△Z p (s)-△Z p (s=1)] / [△Z p (s=0)-△Z p [(s=1)+ε];ε is a small constant; The global averaging module is used to calculate the average residual gas ratio φ of pixels across the entire lung region (s-). global (s) curve; φ global (s) represents the arithmetic mean of the proportion of remaining gas in all pixels of the whole lung at any normalized expiratory process coordinate s; The residual calculation module is used to solve for the s-dynamic emptying residual r corresponding to any pixel p in the lung. p (s) curve; r p (s) = φ p (s)-φ global (s); The delay recognition module is used to solve the s-Adelay(s) curve; Adelay(s) represents the proportion of pixels marked as delayed to the total number of pixels in the lungs under any normalized expiratory process coordinate s, i.e., the proportion of delayed emptying area. When r p (s)>τ delay At that time, pixel p is marked as delayed; τ delay This is the relative threshold for delay; or, When s is greater than 0.85 and φ p (s) is greater than θ abs At that time, pixel p is marked as delayed; θ abs A fixed threshold for normalizing the proportion of residual gas; The exponent calculation module is used to solve for FV-RETI; α min This is the minimum abnormal area threshold.

[0021] Furthermore, it also includes: a persistence calculation module, used to calculate the persistence ratio Pdelay of the delay drain; .

[0022] A storage medium characterized in that it stores a program capable of executing the aforementioned EIT-based regional expiratory clearance assessment method.

[0023] The advantages of the technical solution of this invention are mainly reflected in: First, the first fundamental concept of this application is: This application proposes a method for calculating the Flow-Volume–Mapped Regional Expiratory Time-delay Index (FV-RETI) based on flow-volume state mapping. By introducing flow-volume data to guide the spatiotemporal remapping of EIT image sequences, it achieves accurate quantitative assessment of regional expiratory time-delay anomalies.

[0024] Second, compared with the scheme that calculates a single coupled index based on expiratory flow rate and changes in the average impedance of the whole lung, this application uses the cumulative expiratory volume to construct normalized expiratory process coordinates and maps the EIT dynamic image from the time domain to a unified expiratory process domain. While preserving the pixel-level spatial information of the lung area, it further calculates the local residual gas ratio, dynamic emptying residual, delayed emptying area ratio Adelay, delayed emptying persistence ratio Pdelay, and regional expiratory emptying index FV-RETI.

[0025] This technical solution not only reflects the overall degree of regional expiratory emptying abnormalities, but also determines the location, extent, duration, and dynamic changes of abnormal areas during the early, middle, and late stages of expiration, reducing the impact of differences in expiratory duration, expiratory rate, and expiratory effort among different subjects on the comparability of results. Compared to single-parameter evaluation methods that compress EIT images into the average impedance value of the whole lungs, this application retains the spatiotemporal characteristics of regional ventilation heterogeneity, providing a clearer physiological interpretation and richer evaluation dimensions. It can be used for auxiliary screening of obstructive ventilatory dysfunction, disease follow-up, comparison before and after bronchiectasis, and evaluation of rehabilitation treatment effects, thus possessing stronger practical application significance and clinical feasibility.

[0026] Third, the method of this application can be used to evaluate the therapeutic effect of bronchodilators. By comparing the change in FV-RETI before and after medication, it can be determined whether the drug effectively improves the local airway emptying function. When FV-RETI decreases significantly, it indicates that the drug effectively opens the local airway and improves regional airway synchronicity.

[0027] Fourth, when solving for Adelay, this application simultaneously locates the specific location of the delayed emptying area in the lungs (such as the upper lung, lower lung, left lung, and lower lung), which can provide an objective basis for specifying personalized respiratory rehabilitation training programs, and evaluate the rehabilitation effect through FV-RETI.

[0028] Fifth, this application employs two methods in determining the delay: (1) Detection of relative threshold of exhalation: when r p (s)>τ delay When the delay of pixel p relative to the overall average level exceeds a threshold, it is judged as a delay. (2) Fixed threshold detection of normalized residual gas ratio at end-expiratory phase: At end-expiratory phase (s>0.85), to prevent relative delay detection failure (at which point both overall and local signals approach 0), a fixed threshold detection condition for normalized residual gas ratio is added: φ p (s) is greater than the fixed threshold θ of the normalized residual gas proportion. abs At that time, pixel p is also marked as delayed.

[0029] The location, extent, and shape of the delayed emptying zone differ depending on the expiratory process. Attached Figure Description

[0030] The present invention will be further described in detail below with reference to the embodiments shown in the accompanying drawings, but this does not constitute any limitation on the present invention.

[0031] Figure 1 The flowchart illustrating the calculation process of FV-RETI in this application is shown.

[0032] Figure 2 This diagram illustrates the comparison between healthy individuals and COPD patients (rows 1 and 2 represent EIT image sequence results mapped to normalized expiratory process coordinates for healthy individuals and COPD patients, respectively; rows 3 and 4 represent the normalized residual gas ratio φ for healthy individuals and COPD patients, respectively). p result).

[0033] Figure 3 The typical s-Adelay curves for the healthy group and the COPD group are shown.

[0034] Figure 4 The distribution of FV-RETI and Pdelay parameters is shown in the diagram, comparing the healthy group and the COPD group.

[0035] Figure 5 The graph illustrates the change in the proportion of delayed emptying area in healthy subjects and COPD patients as the exhalation process.

[0036] Figure 6 It illustrates four core indicators for comparing lung emptying function between healthy subjects and COPD patients.

[0037] Figure 7 This illustrates the comparison of average emptying progress between healthy subjects and COPD patients.

[0038] Figure 8 The diagram illustrates the comparison of emptying residuals between healthy subjects and COPD patients.

[0039] Figure 9 The diagram illustrates the comparison of early and late expiratory load in healthy subjects and COPD patients.

[0040] Figure 10 The diagram illustrates the proportions of delayed airway area in healthy subjects and COPD patients at s=25%, 50%, and 75% expiratory points. Detailed Implementation

[0041] The objectives, advantages, and features of this invention will be explained through the following non-limiting description of preferred embodiments. These embodiments are merely typical examples of applying the technical solutions of this invention, and all technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by this invention.

[0042] like Figure 1 As shown, a regional expiratory emptying assessment method based on EIT includes the following steps: S100, acquire synchronization data under FVC action; The synchronized data includes: the time-to-cumulative expiratory volume (V(t)) curve within a single expiratory cycle obtained from a pulmonary flowmeter, and the t-impedance change value ΔZ of any lung pixel p obtained from an EIT device. p (t) curve; Among them, △Z p (t) represents the change in impedance value of pixel p at any time t relative to the impedance value at the start of exhalation tstart; For pulmonary flow meters, the typical approach is to obtain the time-expiratory flow rate Q(t) curve within a single expiratory cycle. By integration, the cumulative expiratory volume V(t) at any time t can be obtained. tstart indicates the start time of exhalation.

[0043] S200, solve for the time t-normalized expiratory process coordinate s(t) curve; To eliminate the influence of differences in expiratory duration, expiratory speed, and expiratory effort among different subjects on the comparison of EIT time series, this method constructs a normalized expiratory process coordinate based on cumulative expiratory volume, rather than directly using physical time t as the analysis coordinate; s(t)=[V(t)-V(tstart)] / [V(tend)-V(tstart)]; tend indicates the end of exhalation; s(t)∈[0,1]; when s=0, it represents the beginning of exhalation; when s=1, it represents the end of exhalation.

[0044] S300, through the ts(t) curve, t-ΔZ p (t) curve, to obtain the s-ΔZ corresponding to any pixel p in the lung. p (s) curve, that is, using t as an intermediate quantity, directly obtains s-ΔZ p The mapping relationship between them; S400, for any pixel p in the lung, via s-△Z p (s) Curve solution for s-normalized residual gas ratio φ p (s) curve; In order to compare the emptying speed of different pixels, the impedance signal needs to be standardized. φ p (s) = [△Z p (s)-△Z p (s=1)] / [△Z p (s=0)-△Z p [(s=1)+ε];ε is a small constant, typically taking the value 10. -6 To prevent division by zero; At the beginning of exhalation, φp ≈1 (maximum gas); expiratory endpoint φ p ≈0 (gas venting).

[0045] S500, based on the s-φ corresponding to any pixel p in the lung p (s) curve, solve for s - the average residual gas ratio φ of the entire lung region pixels. global (s) curve; ; Where N represents the total number of pixels in the entire lung pixel set L, φ global (s) represents the arithmetic mean of the proportion of remaining gas in all pixels of the whole lung at any normalized expiratory process coordinate s; S600, calculate the s-dynamic emptying residual r corresponding to any pixel p in the lung. p (s) curve; r p (s) = φ p (s)-φ global (s); S700, solve for the s-Adelay(s) curve; Adelay(s) represents the proportion of pixels marked as delayed to the total number of pixels in the lungs under any normalized expiratory process coordinate s, i.e., the proportion of delayed emptying area: When r p (s)>τ delay At that time, pixel p is marked as delayed; τ delay This is the relative threshold for delay, typically set to 0.03. or, When s is greater than 0.85 and φ p (s) is greater than θ abs At that time, pixel p is marked as delayed; θ abs This is a fixed threshold for normalizing the proportion of residual gas, typically set to 0.15. S800, solve for FV-RETI and Pdelay; ; α min The minimum abnormal area threshold is generally set to 0.10; that is, when Adelay(s) ≤ 0.10, the delay area of ​​the process point is considered to be too small and has no clinical significance.

[0046] Define the characteristic function: FV-RETI refers to: on the s-Adelay(s) curve graph, the curve is higher than α. minThe total area enclosed by the part and the horizontal axis.

[0047] The FV-RETI value ranges from [0, 1] and is used to quantify the cumulative load of regional expiratory delay in the test subjects.

[0048] It should be noted that the overall lung pixel set L is the effective lung tissue pixel set retained within the anatomical lung contour after removing the heart region, the major blood vessel region, and the chest wall interference region.

[0049] A regional expiratory emptying assessment system based on EIT, comprising: The data acquisition module is used to acquire synchronous data during a subject's forced vital capacity exercise. This synchronous data includes: a time t-cumulative expiratory volume V(t) curve, and a time t-impedance transformation value ΔZ for any lung pixel p. p (t) curve The normalized exhalation process coordinate solution module is used to solve the time t-normalized exhalation process coordinate s(t) curve; s(t) = [V(t) - V(tstart)] / [V(tend) - V(tstart)]; tstart and tend represent the start time and end time of exhalation, respectively; The domain mapping module, based on the ts(t) curve and t-ΔZ... p (t) curve establishes the relationship between s and ΔZ for any pixel p in the lung. p The mapping relationship between them forms s-△Z p (s) curve; The signal normalization module is used to obtain the s-normalized residual gas ratio φ corresponding to any pixel p in the lung. p (s) curve, φ p (s) = [△Z p (s)-△Z p (s=1)] / [△Z p (s=0)-△Z p [(s=1)+ε];ε is a small constant; The global averaging module is used to calculate the average residual gas ratio φ of pixels across the entire lung region (s-). global (s) curve; φ global (s) represents the arithmetic mean of the proportion of remaining gas in all pixels of the whole lung at any normalized expiratory process coordinate s; The residual calculation module is used to solve for the s-dynamic emptying residual r corresponding to any pixel p in the lung. p (s) curve; r p (s) = φ p (s)-φ global(s); The delay recognition module is used to solve the s-Adelay(s) curve; Adelay(s) represents the proportion of pixels marked as delayed to the total number of pixels in the lungs under any normalized expiratory process coordinate s, i.e., the proportion of delayed emptying area. When r p (s)>τ delay At that time, pixel p is marked as delayed; τ delay This is the relative threshold for delay, typically set to 0.03. or, When s is greater than 0.85 and φ p (s) is greater than θ abs At that time, pixel p is marked as delayed; θ abs This is a fixed threshold for normalizing the proportion of residual gas, typically set to 0.15. The exponent calculation module is used to solve for FV-RETI; α min This is the minimum abnormal area threshold.

[0050] Furthermore, it also includes: a persistence calculation module, used to calculate the persistence ratio Pdelay of the delay drain; .

[0051] like Figure 3 As shown, the solid line represents the group mean, the shading represents the standard error (SEM) of the mean, and the dashed line represents the minimum abnormal area threshold of 10%. In the healthy group, the Adelay was close to 0 in the first 30% of exhalation, then rose to about 10%–14%, and was only slightly higher than the threshold in the mid-to-late stages. In the COPD group, the Adelay rapidly rose to about 45%–46% when the exhalation process was 10%–20%, and then gradually decreased, but remained above about 27% before 90% of the exhalation process, which was always significantly higher than the healthy group and the threshold. This indicates that the delayed emptying area appeared earlier and covered a wider area in the COPD group, and continued to exist throughout most of the exhalation process.

[0052] This method can classify the cumulative load of regional expiratory delay in subjects based on FV-RETI. When FV-RETI < 0.2, it is a low-load regional expiratory delay; when 0.2 ≤ FV-RETI < 0.3, it is a medium-load regional expiratory delay; and when FV-RETI ≥ 0.3, it is a high-load regional expiratory delay.

[0053] The persistence of delayed emptying is further classified based on Pdelay: when Pdelay < 0.75, it is low persistence; when 0.75 ≤ Pdelay < 0.9, it is medium persistence; when Pdelay ≥ 0.9, it is high persistence.

[0054] The FV-RETI grading is used to characterize the cumulative load of regional expiratory emptying abnormalities, and the Pdelay grading is used to characterize the persistence of abnormal emptying in the normalized expiratory process. The above thresholds are exemplary and can be adjusted based on training samples with known lung function status, device parameters, and clinical validation results.

[0055] The FV-RETI is used to characterize the cumulative area load of regional expiratory delay in a subject throughout the normalized expiratory process. A larger FV-RETI indicates a larger range of delayed expiratory regions and / or more stages of them existing in the expiratory process, and more pronounced regional expiratory heterogeneity.

[0056] The FV-RETI parameter can be used to grade the degree of regional expiratory emptying abnormalities, and to assist in the assessment of small airway dysfunction and obstructive ventilatory dysfunction. Furthermore, by comparing FV-RETI changes before and after intervention or at different follow-up time points for the same subject, the trend of regional emptying synchronicity can be evaluated. Further combining Adelay, Pdelay, and the delayed emptying pixel set Mdelay can obtain information on the area, persistence, and spatial distribution of abnormal regions. These parameters are used to assist in screening, follow-up monitoring, and evaluation of intervention effects, and do not constitute a disease diagnosis conclusion on their own.

[0057] from Figure 4 It can be seen that when FV-RETI is less than 0.18, it indicates that the person is healthy, while a value greater than 0.18 indicates that there is lung damage.

[0058] Figure 5 This demonstrates that the proportion of delayed emptying regions in the whole lung (Adelay) in healthy subjects and COPD patients is a dynamic process that changes with the exhalation process.

[0059] Figure 6 The graphs show the changes in key indicators for healthy subjects and COPD patients: mean Adelay (the average proportion of lung areas in a delayed state during the entire exhalation process), maximum Adelay (the peak value of the delayed proportion during the entire exhalation process), FV-RETI (delay area composite index, the higher the score, the worse the overall emptying function), and Pdelay (proportion of delay. What percentage of the time period during the entire exhalation process is delayed (greater than the threshold)).

[0060] Figure 7This demonstrates the rate at which the average percentage of residual gas in the whole lungs of healthy subjects and COPD patients decreases during the exhalation process.

[0061] Figure 8 This demonstrates the average performance of each lung pixel's emptying velocity during the entire exhalation process in healthy subjects and COPD patients, and the magnitude of the deviation relative to the average emptying velocity of the whole lung. From Figure 8 It can be seen that the heat map of a healthy person is usually relatively uniform, while the heat map of a COPD patient shows a dark red band that runs through the entire mid-to-late expiration period, reflecting severe regional asynchronous emptying of the lungs.

[0062] Figure 9 This study illustrates the airway emptying during the first and second halves of expiration in healthy subjects and COPD patients. The average delay for all frames in the first half of expiration was calculated as the early load. The average delay for the second half of expiration was calculated as the late load.

[0063] Figure 10 The diagram illustrates the proportions of delayed airway area in healthy subjects and COPD patients at s=25%, 50%, and 75% expiratory points.

[0064] One healthy subject and one COPD patient were selected. During forced vital capacity (FVC) exhalation, spirometry flow-volume signals and EIT dynamic image sequences were simultaneously acquired. Normalized expiratory process coordinates with values ​​ranging from 0 to 1 were constructed based on the cumulative expiratory volume, and the EIT image sequences were remapped to these coordinates. Subsequently, within the effective lung area, the normalized residual gas ratio, dynamic emptying residual, and delayed emptying area ratio (Adelay) for each pixel were calculated. Furthermore, the delayed emptying persistence ratio (Pdelay), the regional expiratory emptying delay index (FV-RETI), and the delayed load at different expiratory stages were obtained.

[0065] The calculation results showed that the mean delay (Adelay) of healthy subjects was 17.1%, the maximum delay was 32.8%, the pre-delay (Pdelay) was 64.4%, and the FV-RETI was 16.6%. The Adelay was close to 0 in the first 25% of the expiratory process, then gradually increased, reaching about 30% in the mid-expiratory phase; it generally decreased in the late expiratory phase, but experienced brief fluctuations at approximately 85%–90% of the expiratory process. The delayed load in the early and late expiratory phases of healthy subjects was 9.7% and 23.4%, respectively; at 25%, 50%, and 75% of the normalized expiratory process, the Adelay was approximately 0%, 30.0%, and 26.7%, respectively. The dynamic emptying residuals mainly exhibited a relatively limited banded distribution, suggesting that the emptying process in most lung areas was relatively coordinated.

[0066] The mean delay (Adelay) for COPD patients was 33.8%, the maximum delay was 54.1%, the pre-delay (Pdelay) was 91.1%, and the free-volume repetition (FV-RETI) was 33.8%. After the start of expiration, the Adelay rapidly increased to over 40%, reaching a maximum of approximately 54% in the early expiratory phase; although it gradually decreased thereafter, it remained above the minimum abnormal area threshold for most of the expiratory process. The delayed load in the early and late expiratory phases of COPD patients was 40.7% and 26.7%, respectively; at 25%, 50%, and 75% of the normalized expiratory process, the Adelay was approximately 54.0%, 39.5%, and 26.8%, respectively. The dynamic emptying residual plot showed a wider range and longer duration of positive and negative residual bands, and the mean emptying progress curve also exhibited more obvious staged and non-linear changes, reflecting a more significant difference in emptying progress between different lung regions.

[0067] Compared with healthy subjects, COPD patients showed increases in mean delay, maximum delay, FV-RETI, and P-delay of approximately 16.7, 21.3, 17.2, and 26.7 percentage points, respectively. Specifically, FV-RETI was approximately 2.0 times that of healthy subjects, and the early expiratory delay load was approximately 4.2 times that of healthy subjects. The delay at 75% of the expiratory process was relatively similar for both groups, while the differences were most significant in the early and mid-expiratory stages, indicating that the early expiratory delay characteristic has high application value in distinguishing between the two groups of subjects.

[0068] This embodiment demonstrates that the method can quantify regional expiratory clearance differences among different subjects in terms of the stage of delayed expiratory clearance, regional range, duration, and cumulative abnormal load.

[0069] The physical symbols used in this application are explained below: t: Physical time, representing the time for simultaneous sampling by the spirometer and EIT.

[0070] tstart: The start time of exhalation, indicating the time when FVC begins exhalation.

[0071] tend: the time at which exhalation ends, indicating the time when FVC (Frequency Control Flow) ends.

[0072] Q(t): Flow velocity, in L / s.

[0073] V(t): The cumulative exhaled volume at time t, which can be obtained directly from the pulmonary flow meter or by integrating the flow rate Q(t) over time.

[0074] P: Any pixel in the lung area.

[0075] △Z p (t): Z p (t)-Z p(tstart) represents the change in impedance value of any pixel p relative to the impedance value at the start of exhalation tstart.

[0076] s(t): Normalized expiratory process coordinates at time t, with values ​​ranging from [0,1] to [0%,100%]. V(tstart): The cumulative exhaled volume of tstart.

[0077] V(tend): The cumulative exhaled volume of tend. L: The entire set of pixels for the lung.

[0078] N: The total number of pixels in the entire lung, satisfying N=|L|.

[0079] Z p (s m ): The change in EIT impedance mapped to the normalized expiratory process, representing the change in pixel p during the expiratory process s. m The signal value below.

[0080] φ p (s): Local residual gas ratio, representing the normalized residual gas amount of pixel p relative to the starting point of exhalation at coordinate s during the exhalation process.

[0081] φ global (s): Overall residual gas ratio, representing the arithmetic mean of the overall residual gas ratio of all pixels in the whole lung at any normalized exhalation process coordinate s.

[0082] r p (s): Dynamic emptying residual, representing the difference between the local residual gas ratio of pixel p and the average residual gas ratio of the whole lung area.

[0083] τ delay Relative delay threshold: Used to determine whether a pixel belongs to a delay-empty region.

[0084] θ abs Absolute delay threshold.

[0085] Mdelay(s): Dynamic delayed emptying region, representing the number of lung region pixels that are determined to be delayed emptying during the exhalation process s.

[0086] Adelay ( s): Delayed emptying area ratio, which represents the proportion of pixels marked as delayed to the total number of pixels in the whole lung under any normalized expiratory process coordinate s, i.e., Mdelay(s) / N.

[0087] α min Minimum abnormal area threshold, used to determine whether there is a meaningful delayed emptying during a certain exhalation process.

[0088] Pdelay: Proportion of delayed emptying duration, representing the proportion of delayed emptying area in the entire normalized expiratory process. Adelay(s): The proportion of the process interval length exceeding the minimum abnormal area threshold αmin to the total expiratory process.

[0089] FV-RETI: Flow-volume guided regional expiratory airflow index, representing the cumulative load of delayed airflow area along the normalized expiratory process.

[0090] The above-described embodiments are preferred embodiments of the present invention and are only used to facilitate the illustration of the present invention. They are not intended to limit the present invention in any way. Any person skilled in the art who makes local modifications or alterations to the technical content disclosed in the present invention without departing from the scope of the technical features of the present invention shall still fall within the scope of the technical features of the present invention.

Claims

1. A regional expiratory emptying assessment method based on EIT, which is not a diagnostic method for diseases, characterized in that... Includes the following steps: Step a: Acquire synchronous data during the subject's forced vital capacity exercise. The synchronous data includes: the time t-cumulative expiratory volume V(t) curve, and the time t-impedance transformation value ΔZ of any pixel p in the lung. p (t) curve; Where △Zp(t) represents the change in impedance value of pixel point p at any time t relative to the impedance value at the start of exhalation tstart; Step b, solve for the time t-normalized expiratory process coordinate s(t) curve; s(t) = [V(t) - V(tstart)] / [V(tend) - V(tstart)]; tend represents the end of exhalation; Step c, through the ts(t) curve, t-ΔZ p (t) curve, obtain the s-ΔZ corresponding to any pixel p in the lung. p (s) curve; Step d: Obtain the s-normalized residual gas ratio φ corresponding to any pixel p in the lung. p (s) curve; φ p (s) = [△Z p (s)-△Z p (s=1)] / [△Z p (s=0)-△Z p [(s=1)+ε];ε is a small constant; Step e, based on the s-φ corresponding to any pixel p in the lung p (s) curve, solve for s - the average residual gas ratio φ of the entire lung region pixels. global (s) curve: φ global (s) represents the arithmetic mean of the proportion of remaining gas in all pixels of the whole lung at any normalized expiratory process coordinate s; Step f: Solve for the s-dynamic emptying residual r corresponding to any pixel p in the lung. p (s) curve; r p (s)=φ p (s)-φ global (s); Step g: Solve for the s-Adelay(s) curve; Adelay(s) represents the proportion of pixels marked as delayed to the total number of pixels in the lungs under any normalized expiratory process coordinate s; Each pixel in the lungs is analyzed individually to determine whether it is marked as delayed. When r p (s)>τ delay At that time, pixel p is marked as delayed; τ delay This is the relative threshold for delay; or, When s is greater than 0.85 and φ p (s) is greater than θ abs At that time, pixel p is marked as delayed; θ abs This is a fixed threshold for normalizing the proportion of residual gas; Step h, set the minimum abnormal area threshold α min Solve for the regional expiratory air volume index (FV-RETI); ； in, 。 2. The regional expiratory emptying assessment method based on EIT according to claim 1, characterized in that, It also includes step i, solving for the delay-out duration ratio Pdelay: 。 3. The regional expiratory emptying assessment method based on EIT according to claim 1, characterized in that, ε=10 -6 。 4. The regional expiratory emptying assessment method based on EIT according to claim 1, characterized in that, τ delay The value is 0.

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5. The regional expiratory emptying assessment method based on EIT according to claim 1, characterized in that, θ abs The value is 0.

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6. The regional expiratory emptying assessment method based on EIT according to claim 1, characterized in that, α min The value is 0.

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7. The regional expiratory emptying assessment method based on EIT according to claim 1, characterized in that, Step g also includes: obtaining the set of lung region pixels that are determined to be delayed emptying during the exhalation process s.

8. A regional expiratory airway assessment system based on EIT, characterized in that, include: The data acquisition module is used to acquire synchronous data during a subject's forced vital capacity exercise. This synchronous data includes: a time t-cumulative expiratory volume V(t) curve, and a time t-impedance transformation value ΔZ for any lung pixel p. p (t) curve The normalized exhalation process coordinate solution module is used to solve the time t-normalized exhalation process coordinate s(t) curve; s(t) = [V(t) - V(tstart)] / [V(tend) - V(tstart)]; tstart and tend represent the start time and end time of exhalation, respectively; The domain mapping module, based on the ts(t) curve and t-ΔZ... p (t) curve establishes the relationship between s and ΔZ for any pixel p in the lung. p The mapping relationship between them forms s-△Z p (s) curve; The signal normalization module is used to obtain the s-normalized residual gas ratio φ corresponding to any pixel p in the lung. p (s) curve, φ p (s) = [△Z p (s)-△Z p (s=1)] / [△Z p (s=0)-△Z p [(s=1)+ε];ε is a small constant; The global averaging module is used to calculate the average residual gas ratio φ of pixels across the entire lung region (s-). global (s) curve; φ global (s) represents the arithmetic mean of the proportion of remaining gas in all pixels of the whole lung at any normalized expiratory process coordinate s; The residual calculation module is used to solve for the s-dynamic emptying residual r corresponding to any pixel p in the lung. p (s) curve; r p (s) = φ p (s)-φ global (s); The delay recognition module is used to solve the s-Adelay(s) curve; Adelay(s) represents the proportion of pixels marked as delayed to the total number of pixels in the lungs under any normalized expiratory process coordinate s, i.e., the proportion of delayed emptying area. When r p (s)>τ delay At that time, pixel p is marked as delayed; τ delay This is the relative threshold for delay; or, When s is greater than 0.85 and φ p (s) is greater than θ abs At that time, pixel p is marked as delayed; θ abs A fixed threshold for normalizing the proportion of residual gas; The exponent calculation module is used to solve for FV-RETI; α min This is the minimum abnormal area threshold.

9. A regional expiratory airway assessment system based on EIT according to claim 8, characterized in that, Also includes: The continuous calculation module is used to calculate the delay emptying duration ratio Pdelay; 。 10. A storage medium, characterized in that, It stores a program capable of performing the EIT-based regional expiratory clearance assessment method as described in any one of claims 1 to 7.

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