Method and system for electrical impedance imaging of blood perfusion

Abstract

The invention provides an electrical impedance imaging method and system for blood perfusion. The electrical impedance imaging method for blood perfusion comprises the following steps: acquiring a real-time photoelectric volume pulse wave signal at a fingertip of a target object; n groups of electrode pairs are arranged to form an array sensor, each group of electrode pair comprises two electrodes, and n is an integer not less than 4; array sensors are arranged in the circumferential direction of the thoracic cavity of the target object; in the adjacent excitation measurement mode, applying excitation current to the first electrode pair, sequentially measuring respective voltage difference data of other electrode pairs except the first electrode pair, and circularly applying the excitation current to the electrodes to obtain a plurality of impedance values; sampling each impedance value at equal time intervals to obtain an impedance signal corresponding to each impedance value, taking the photoelectric volume pulse wave signal as a reference signal, and performing matched filtering on each impedance signal to obtain a blood perfusion signal; and generating a blood perfusion image according to the blood perfusion signal, wherein the blood perfusion image represents the blood perfusion condition of the thoracic cavity.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electrical impedance imaging, and more specifically, to a method and system for electrical impedance imaging of blood perfusion. Background Art

[0002] Pulmonary gas exchange occurs in the alveoli. For effective gas exchange, the alveoli must be ventilated and perfused. Pulmonary ventilation refers to the process of air flowing into the lungs during inspiration (inhalation) and air flowing out of the lungs during exhalation (exhalation). Its imaging can reflect the conditions of pulmonary airways and alveolar ventilation. Blood perfusion is the result of the combined action of the heart and lungs. Its imaging can reflect the blood supply of the pulmonary artery.

[0003] Traditionally, radionuclide imaging is often used, which requires the human body to inhale radioactive particles or gases as imaging agents, and combined with single-photon emission computed tomography (SPECT) and computed tomography (CT) to obtain pulmonary ventilation or perfusion imaging. However, due to its susceptibility to respiratory system influence, the invasiveness of radioactive particles, and the possibility of biological cell damage caused by X-ray beams, it cannot be used frequently on patients as a long-term monitoring tool.

[0004] Contrast imaging is a traditional method for evaluating lung perfusion. During breath holding, a hypertonic saline solution (such as 10% NaCl solution) is injected into the human body in a "bolus" manner. The impedance change caused by the saline flowing through the blood circulation can indicate the perfusion amount. The disadvantage of this method is that breath holding affects the state of pulmonary blood flow, and it cannot be imaged simultaneously with the respiratory signal. Experiments on different individuals require recalibration.

[0005] Therefore, the current technical problem that needs to be solved urgently is how to separate the blood perfusion signal from the impedance signal. Summary of the invention

[0006] In order to solve at least one of the above-mentioned and other technical problems in the prior art, the embodiments of the present disclosure provide a method and system for electrical impedance imaging of blood perfusion, which can perform real-time imaging, avoid the influence of breath holding on blood flow status, and have fast filtering speed and strong noise suppression ability. The photoelectric volume accumulation pulse wave signal and the impedance signal are combined to increase the dimension and level of the data source, thereby improving the reliability of the blood perfusion signal.

[0007] The embodiment of the present disclosure provides a method for electrical impedance imaging of blood perfusion, comprising: acquiring a real-time photoelectric volumetric pulse wave signal at the fingertips of a target object; arranging n groups of electrode pairs to form an array sensor, wherein each group of the electrode pairs includes two electrodes, and the n is an integer not less than 4; arranging the array sensor along the circumferential direction of the chest cavity of the target object; in an adjacent excitation measurement mode, applying an excitation current to a first electrode pair, sequentially measuring the voltage difference data of each of the other electrode pairs except the first electrode pair, cyclically applying the excitation current to the electrodes to obtain a plurality of impedance values; sampling each of the impedance values ​​at equal time intervals to obtain an impedance signal corresponding to each of the impedance values, using the photoelectric volumetric pulse wave signal as a reference signal, and matching filtering each of the impedance signals to obtain a blood perfusion signal; generating a blood perfusion image according to the blood perfusion signal, wherein the blood perfusion image is used to characterize the blood perfusion condition of the chest cavity.

[0008] According to some embodiments of the present disclosure, the step of acquiring a real-time photoplethysmogram signal at a fingertip of a target object includes: conditioning the photoplethysmogram signal to filter out noise in the photoplethysmogram signal.

[0009] According to some embodiments of the present disclosure, in the adjacent excitation measurement mode, an excitation current is applied to the first electrode pair, and the voltage difference data of each of the other electrode pairs except the first electrode pair is measured in turn, and the excitation current is cyclically applied to the electrodes to obtain multiple impedance values, including: comparing the multiple voltage difference data with the excitation current respectively to obtain the multiple impedance values.

[0010] According to some embodiments of the present disclosure, the above-mentioned impedance values ​​are sampled at equal time intervals to obtain impedance signals corresponding to each of the above-mentioned impedance values, and the above-mentioned photoelectric volumetric pulse wave signal is used as a reference signal and matched filtered with each of the above-mentioned impedance signals to obtain a blood perfusion signal, which includes: using the above-mentioned photoelectric volumetric pulse wave signal as a reference signal and extracting the above-mentioned blood perfusion signal by frequency domain analysis.

[0011] According to some embodiments of the present disclosure, the blood perfusion image is generated according to the blood perfusion signal, wherein the blood perfusion image is used to characterize the blood perfusion condition of the thoracic cavity, including: generating the blood perfusion image according to the blood perfusion signal through an image reconstruction algorithm.

[0012] Another aspect of an embodiment of the present disclosure provides an electrical impedance imaging system for blood perfusion, comprising: an array sensor, arranged along a circumferential direction on the outside of the chest cavity of a target object; a photoplethysmogram acquisition unit, arranged at the fingertips of the target object, the photoplethysmogram acquisition unit being suitable for acquiring real-time photoplethysmogram signals; a multi-channel impedance measurement unit, configured to be connected to the array sensor, the multi-channel impedance measurement unit being suitable for applying an excitation current to the array sensor and obtaining an impedance value; a control unit, configured to be connected to the multi-channel impedance measurement unit, for controlling the multi-channel impedance measurement unit; a frequency domain analysis unit, configured to be connected to the multi-channel impedance measurement unit and the photoplethysmogram acquisition unit, respectively, the frequency domain analysis unit being suitable for separating blood perfusion signals; and an image reconstruction unit, configured to be connected to the frequency domain analysis unit, the image reconstruction unit being suitable for generating a blood perfusion image based on the blood perfusion signals.

[0013] According to some embodiments of the present disclosure, the array sensor is composed of a plurality of electrode arrangements.

[0014] According to some embodiments of the present disclosure, the electrical impedance imaging system of blood perfusion further includes: a signal conditioning unit, configured to be connected between the photoplethysmography acquisition unit and the frequency domain analysis unit, and the signal conditioning unit is suitable for filtering out noise in the photoplethysmography signal.

[0015] According to some embodiments of the present disclosure, the frequency domain analysis unit is composed of a matched filter.

[0016] According to an electrical impedance imaging method and system for blood perfusion of an embodiment of the present disclosure, a photoplethysmogram signal and an impedance signal are combined, the photoplethysmogram signal is used as a reference signal, and matched filtering is performed on the photoplethysmogram signal and multiple impedance signals respectively to obtain a blood perfusion signal, and a blood perfusion image is generated according to the blood perfusion signal. The blood perfusion image is used to characterize the blood perfusion of the thoracic cavity, and can be imaged in real time, avoiding the influence of breath holding on the blood flow state, and has a fast filtering speed and a strong noise suppression ability. The photoplethysmogram signal and the impedance signal are combined to increase the dimension and level of the data source, and improve the reliability of the blood perfusion signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of a method for electrical impedance imaging of blood perfusion according to an illustrative embodiment of the present disclosure;

[0018] Figure 2 is a structural diagram of an electrical impedance imaging system for blood perfusion according to an illustrative embodiment of the present disclosure; and

[0019] Figure 3is a working principle diagram of a frequency domain analysis unit according to an illustrative embodiment of the present disclosure.

[0020] In the drawings, the meanings of the reference numerals are as follows:

[0021] 1. Array sensor;

[0022] 2. Photoplethysmography acquisition unit;

[0023] 3. Multi-channel impedance measurement unit;

[0024] 4. Control unit;

[0025] 5. Signal conditioning unit;

[0026] 6. Frequency domain analysis unit;

[0027] 7. Image reconstruction unit. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0029] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0030] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0031] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0032] According to the inventive concept of one aspect of the present disclosure, electrical impedance tomography (EIT) is a non-invasive, radiation-free, real-time imaging method with low cost, easy to carry, and can be used as a long-term monitoring tool. By continuously rotating current injection and voltage measurement around the chest, electrical impedance tomography can obtain a tissue impedance distribution map on the cross section of the chest. Electrical impedance tomography can perform functional imaging of the lungs and obtain information on excessive expansion or collapse of the lungs that CT cannot display. In addition, regional lung ventilation or perfusion information can also be provided. However, when electrical impedance tomography is used for chest detection during respiration, ventilation is dominant for its impedance signal, accounting for most of the energy of the impedance signal, while the blood perfusion signal is much smaller than the ventilation signal. Therefore, in order to solve the problem of how to extract the blood perfusion signal from the impedance signal, the present invention combines the photoelectric volumetric pulse wave signal and the impedance signal, takes the photoelectric volumetric pulse wave signal as the reference signal, and performs matched filtering with multiple impedance signals respectively to obtain a blood perfusion signal, and generates a blood perfusion image according to the blood perfusion signal. The blood perfusion image is used to characterize the blood perfusion of the chest cavity, and can be imaged in real time, avoiding the influence of breath holding on the blood flow state, and has a fast filtering speed and strong noise suppression ability. The photoelectric volumetric pulse wave signal and the impedance signal are combined to increase the dimension and level of the data source, and improve the reliability of the blood perfusion signal.

[0033] Figure 1 is a flow chart of a method for electrical impedance imaging of blood perfusion according to an illustrative embodiment of the present disclosure.

[0034] According to the embodiments of the present disclosure, Figure 1 As shown, a method for electrical impedance imaging of blood perfusion includes the following steps S1-S6.

[0035] Step S1: Acquire a real-time photoplethysmogram signal at the fingertips of the target object.

[0036] Step S2: Arrange n groups of electrode pairs to form an array sensor 1, each group of electrode pairs includes two electrodes, and n is an integer not less than 4.

[0037] Step S3: Arrange the array sensor 1 along the circumferential direction of the chest cavity of the target object.

[0038] Step S4: in the adjacent excitation measurement mode, applying an excitation current to the first electrode pair, measuring the voltage difference data of each of the other electrode pairs except the first electrode pair in turn, applying the excitation current to the electrodes cyclically, and obtaining a plurality of impedance values.

[0039] Step S5: Sample each impedance value at equal time intervals to obtain an impedance signal corresponding to each impedance value, use the photoplethysmogram signal as a reference signal, and perform matched filtering with each impedance signal to obtain a blood perfusion signal.

[0040] Step S6: Generate a blood perfusion image according to the blood perfusion signal, and the blood perfusion image is used to represent the blood perfusion condition of the thoracic cavity.

[0041] According to an embodiment of the present disclosure, the target object may be a human body.

[0042] According to the embodiments of the present disclosure, during the cardiac fluctuation cycle, the blood flowing through the arterioles, capillaries and venules in the peripheral blood vessels changes pulsatilely accordingly. The blood volume is the largest when the heart contracts, and the volume is the smallest when the heart relaxes. This pulsating change of the photoelectric volumetric pulse wave signal is obtained through a photoelectric volumetric sensor, and the obtained waveform contains volumetric pulse blood flow information. Therefore, the systolic pressure and diastolic pressure can be obtained through the relationship between the volumetric pulse blood flow information and the blood pressure signal.

[0043] According to an embodiment of the present disclosure, n groups of electrode pairs can be taken as 8 groups of electrode pairs, each group of electrode pairs includes two electrodes, that is, 16 electrodes, each electrode is arranged to form an array sensor 1, and is numbered 1, 2, 3...16 respectively. The array sensor 1 can be composed of 4 or 8 or 16 electrodes.

[0044] According to an embodiment of the present disclosure, in an adjacent excitation measurement mode, an excitation current is applied to the first electrode pair (1, 2), and voltage difference data of each of the electrode pairs (2, 3), (3, 4), (4, 5) ... (15, 16), (16, 1) other than the first electrode pair (1, 2) are measured in turn, wherein the effective voltage difference data is the voltage difference data of each of the electrode pairs (3, 4), the electrode pair (4, 5) ... the electrode pair (15, 16).

[0045] According to an embodiment of the present disclosure, a photoplethysmogram signal and an impedance signal are combined, the photoplethysmogram signal is used as a reference signal, and matched filtering is performed on the multiple impedance signals to obtain a blood perfusion signal. A blood perfusion image is generated based on the blood perfusion signal. The blood perfusion image is used to characterize the blood perfusion of the chest cavity, and can be imaged in real time, avoiding the influence of breath holding on the blood flow state, and has a fast filtering speed and a strong noise suppression ability. The photoplethysmogram signal and the impedance signal are combined to increase the dimension and level of the data source, and improve the reliability of the blood perfusion signal.

[0046] According to an embodiment of the present disclosure, acquiring a real-time photoplethysmogram signal at a fingertip of a target object includes: conditioning the photoplethysmogram signal to filter out noise in the photoplethysmogram signal.

[0047] According to an embodiment of the present disclosure, filtering out noise in a photoplethysmography signal ensures signal quality when the photoplethysmography signal is used as a reference signal.

[0048] According to an embodiment of the present disclosure, in an adjacent excitation measurement mode, applying an excitation current to a first electrode pair, sequentially measuring the voltage difference data of each of the other electrode pairs except the first electrode pair, and cyclically applying the excitation current to the electrodes to obtain multiple impedance values ​​includes: comparing the multiple voltage difference data with the excitation current respectively to obtain multiple impedance values. Each impedance value is sampled at equal time intervals to obtain an impedance signal corresponding to each impedance value.

[0049] According to an embodiment of the present disclosure, the impedance signal can be expressed by the following formula (1):

[0050]

[0051] Wherein, Z represents the impedance signal, I represents the applied excitation current, and U represents the voltage difference data of the other electrode pairs.

[0052] According to the embodiments of the present disclosure, since different tissues in the target object have different electrical properties, the acquired impedance value can reflect the corresponding states and functional information of the electrical properties of different tissues in the body, with simple operation and low cost.

[0053] According to an embodiment of the present disclosure, taking 16 electrodes as an example, after applying an excitation current to the first electrode pair (1, 2) and measuring the voltage difference data of each of the other electrode pairs, an excitation current is applied to the electrode pair (2, 3), and the voltage difference data of each of the other electrode pairs (4, 5), (5, 6), (6, 7) ... (15, 16), (16, 1) other than the electrode pair (2, 3) are measured in turn. Then, an excitation current is applied to the electrode pair (3, 4), and the voltage difference data of each of the other electrode pairs (5, 6), (6, 7), (7, 8) ... (15, 16), (16, 1), (1, 2) other than the electrode pair (3, 4) are measured in turn. By analogy, the excitation current is applied to the 16 electrodes in a cycle to obtain 208 effective voltage difference data, half of which are repeated, that is, 104 effective voltage difference data are obtained, which are compared with the corresponding excitation currents to obtain 104 impedance values.

[0054] According to an embodiment of the present disclosure, if there are n groups of electrode pairs, the number N of effective voltage difference data can be expressed by the following formula (2):

[0055]

[0056] Wherein, N represents the number of valid voltage difference data.

[0057] According to the embodiments of the present disclosure, taking effective voltage difference data can reduce the error during matched filtering.

[0058] According to an embodiment of the present disclosure, each impedance value is sampled at equal time intervals to obtain an impedance signal corresponding to each impedance value, and the photoelectric volumetric pulse wave signal is used as a reference signal and matched filtered with multiple impedance signals to obtain a blood perfusion signal, which includes: using the photoelectric volumetric pulse wave signal as a reference signal and extracting the blood perfusion signal through frequency domain analysis.

[0059] According to an embodiment of the present disclosure, for a time series Z(i) consisting of impedance values, Z(i) is affected by both respiration and blood perfusion, and Z(i) can be expressed by the following formula (3):

[0060] Z(i)=aZ c (i)+bZ L (i)+σ (3)

[0061] Among them, Z c (i) represents the blood flow impedance value, a represents the coefficient of the blood flow impedance value, and Z L (i) represents the respiratory impedance value, b represents the coefficient of the respiratory impedance value, and σ represents other factors that affect the impedance value except blood flow and respiration.

[0062] According to the embodiment of the present disclosure, since the blood flow impedance value Zc (i) and respiratory impedance Z L (i) The frequency band range is different, and the blood perfusion signal can be extracted using frequency domain analysis.

[0063] According to an embodiment of the present disclosure, one channel of photoplethysmographic signal is used as a reference signal and matched filtered with a plurality of impedance signals to obtain a blood perfusion signal.

[0064] According to the embodiments of the present disclosure, the frequency domain analysis method can perform real-time imaging and is non-invasive to the target object. It does not require the target object to hold its breath, thus avoiding the impact of breath holding on the blood flow state. The photoelectric volumetric pulse wave signal is used as a reference signal, and the photoelectric volumetric pulse wave signal and the impedance signal are integrated, which increases the dimension and level of the data source and improves the reliability of the blood perfusion signal.

[0065] According to an embodiment of the present disclosure, a blood perfusion image is generated according to a blood perfusion signal, wherein the blood perfusion image is used to characterize the blood perfusion condition of the thoracic cavity, including: generating the blood perfusion image according to the blood perfusion signal by using an image reconstruction algorithm.

[0066] According to an embodiment of the present disclosure, a blood perfusion image is reconstructed in real time through an image reconstruction algorithm to reflect the blood perfusion or blood distribution of the thoracic cavity.

[0067] According to the embodiments of the present disclosure, since the impedance values ​​presented by the target object are different in different states, the state information of the target object can be reflected by the above method.

[0068] According to the embodiments of the present disclosure, the image reconstruction algorithm has high real-time performance, fast image reconstruction speed, high precision and high reliability.

[0069] According to an optional embodiment of the present disclosure, the photoplethysmogram signal can be replaced by a cardiac electrical signal acquired at the heart position, and the cardiac electrical signal is used as a reference signal to perform matched filtering with multiple impedance signals to obtain a blood perfusion signal, and then a blood perfusion image is generated based on the blood perfusion signal.

[0070] Figure 2 is a structural diagram of an electrical impedance imaging system for blood perfusion according to an illustrative embodiment of the present disclosure.

[0071] According to the embodiments of the present disclosure, Figure 2As shown, a blood perfusion electrical impedance imaging system includes an array sensor 1, a photoplethysmogram acquisition unit 2, a multi-channel impedance measurement unit 3, a control unit 4, a frequency domain analysis unit 6 and an image reconstruction unit 7. The array sensor 1 is arranged on the outside of the chest cavity of the target object along the circumferential direction. The photoplethysmogram acquisition unit 2 is arranged at the fingertips of the target object, and the photoplethysmogram acquisition unit 2 is suitable for collecting real-time photoplethysmogram signals. The multi-channel impedance measurement unit 3 is configured to be connected to the array sensor 1, and the multi-channel impedance measurement unit 3 is suitable for applying an excitation current to the array sensor 1 and obtaining an impedance value. The control unit 4 is configured to be connected to the multi-channel impedance measurement unit 3, and is used to control the multi-channel impedance measurement unit 3. The frequency domain analysis unit 6 is configured to be connected to the multi-channel impedance measurement unit 3 and the photoplethysmogram acquisition unit 2 respectively, and the frequency domain analysis unit 6 is suitable for separating blood perfusion signals. The image reconstruction unit 7 is configured to be connected to the frequency domain analysis unit 6, and the image reconstruction unit 7 is suitable for generating a blood perfusion image according to the blood perfusion signal.

[0072] According to an embodiment of the present disclosure, the control unit 4 controls the multi-channel impedance measurement unit 3 to apply an excitation current to the array sensor 1, thereby obtaining an impedance value.

[0073] According to the embodiments of the present disclosure, the electrical impedance imaging system of blood perfusion can perform real-time imaging, avoiding the influence of breath holding on the blood flow state, and has fast filtering speed and strong noise suppression ability. It combines the photoelectric volume accumulation pulse wave signal and the impedance signal, increases the dimension and level of the data source, and improves the reliability of the blood perfusion signal.

[0074] According to an embodiment of the present disclosure, the array sensor 1 is composed of a plurality of electrode arrangements.

[0075] According to an embodiment of the present disclosure, arranging a plurality of electrodes can avoid errors in voltage difference data caused by different intervals between electrodes.

[0076] According to an embodiment of the present disclosure, the electrical impedance imaging system of blood perfusion also includes a signal conditioning unit 5, which is configured to be connected between the photoplethysmography acquisition unit 2 and the frequency domain analysis unit 6, and the signal conditioning unit 5 is suitable for filtering out noise in the photoplethysmography signal.

[0077] According to an embodiment of the present disclosure, the control unit 4 simultaneously controls the signal conditioning unit 5 to acquire the photoplethysmogram signal through the photoplethysmogram acquisition unit 2 .

[0078] According to the embodiments of the present disclosure, the configuration of the signal conditioning unit ensures the signal quality of the photoplethysmography signal.

[0079] Figure 3is a working principle diagram of the frequency domain analysis unit 6 according to an illustrative embodiment of the present disclosure.

[0080] According to the embodiments of the present disclosure, Figure 3 As shown, the frequency domain analysis unit 6 is composed of a matched filter.

[0081] According to an embodiment of the present disclosure, the photoplethysmographic signal and the impedance signal are transmitted to the frequency domain analysis unit 6, the blood perfusion signal is separated by a matched filter, and the blood perfusion signal is transmitted to the image reconstruction unit 7 to generate a blood perfusion image.

[0082] According to an embodiment of the present disclosure, a matched filter is used to separate the blood perfusion signal. Taking 16 electrodes as an example, one photoelectric volumetric pulse wave signal after noise filtering is used as a reference signal, and matched filtering is performed with 104 impedance values ​​respectively to obtain 104 blood perfusion signals. The blood perfusion signal reaches a peak value at a specific moment when the matched filter outputs.

[0083] According to the embodiments of the present disclosure, the matched filter has a fast filtering speed and a strong noise suppression capability, and can meet the real-time requirements of lung perfusion imaging without adjusting the coefficients of the matched filter according to the heart rate and respiratory rate.

[0084] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure, and the shapes and sizes of the components in the drawings do not reflect the actual size and proportion, but only illustrate the contents of the embodiments of the present disclosure.

[0085] Unless otherwise indicated, the numerical parameters in this specification and the appended claims are approximate values ​​and can vary according to the desired properties obtained through the content of the present disclosure. Specifically, all numbers used in the specification and claims to express the content of the composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. In general, the meaning of the expression is to include a variation of ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments by a specific number.

[0086] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., to modify the corresponding elements, do not themselves mean that the elements have any ordinal numbers, nor do they represent the order of one element and another element, or the order in the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish a component with a certain name from another component with the same name.

[0087] In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to the above list, and can be changed or rearranged according to the required design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0088] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A method for electrical impedance imaging of blood perfusion, comprising: Acquire real-time photoplethysmographic signals at the fingertips of the target object; Arranging n groups of electrode pairs to form an array sensor, wherein each group of the electrode pairs includes two electrodes, and n is an integer not less than 4; Disposing the array sensor along the circumferential direction of the chest cavity of the target object; In the adjacent excitation measurement mode, an excitation current is applied to the first electrode pair, and the voltage difference data of each of the other electrode pairs except the first electrode pair is measured in sequence, and the excitation current is cyclically applied to the electrodes to obtain a plurality of impedance values; Sampling each of the impedance values ​​at equal time intervals to obtain impedance signals corresponding to each of the impedance values, using the photoplethysmogram signal as a reference signal, and performing matched filtering on each of the impedance signals to obtain a blood perfusion signal; A blood perfusion image is generated according to the blood perfusion signal, wherein the blood perfusion image is used to represent the blood perfusion condition of the thoracic cavity.

2. The electrical impedance imaging method of blood perfusion according to claim 1, wherein the step of obtaining a real-time photoplethysmographic signal at a fingertip of a target object comprises: The photoplethysmography signal is conditioned to filter out noise in the photoplethysmography signal.

3. The method for electrical impedance imaging of blood perfusion according to claim 1, wherein in the adjacent excitation measurement mode, an excitation current is applied to a first electrode pair, and voltage difference data of each of other electrode pairs except the first electrode pair is measured in sequence, and the excitation current is applied to the electrodes cyclically to obtain multiple impedance values, including: The plurality of voltage difference data are respectively compared with the excitation current to obtain a plurality of impedance values.

4. The electrical impedance imaging method of blood perfusion according to claim 1, wherein sampling each impedance value at equal time intervals to obtain an impedance signal corresponding to each impedance value, using the photoplethysmogram signal as a reference signal and matching filtering each impedance signal to obtain a blood perfusion signal comprises: The photoplethysmogram signal is used as a reference signal, and the blood perfusion signal is extracted by frequency domain analysis.

5. The electrical impedance imaging method of blood perfusion according to claim 1, wherein the blood perfusion image is generated according to the blood perfusion signal, wherein: The blood perfusion image is used to characterize the blood perfusion condition of the thoracic cavity and includes: A blood perfusion image is generated according to the blood perfusion signal by using an image reconstruction algorithm.

6. An electrical impedance imaging system for blood perfusion, comprising: An array sensor is disposed on the outside of the chest cavity of the target object along a circumferential direction; A photoplethysmography acquisition unit is disposed at the fingertips of the target object, and the photoplethysmography acquisition unit is suitable for acquiring real-time photoplethysmography signals; a multi-channel impedance measurement unit, configured to be connected to the array sensor, the multi-channel impedance measurement unit being adapted to apply an excitation current to the array sensor and obtain an impedance value; a control unit, configured to be connected to the multi-channel impedance measurement unit and used to control the multi-channel impedance measurement unit; A frequency domain analysis unit, configured to be connected to the multi-channel impedance measurement unit and the photoplethysmography acquisition unit, respectively, and the frequency domain analysis unit is suitable for separating a blood perfusion signal; An image reconstruction unit is configured to be connected to the frequency domain analysis unit, and the image reconstruction unit is suitable for generating a blood perfusion image according to the blood perfusion signal. 7 . The electrical impedance imaging system for blood perfusion according to claim 6 , wherein the array sensor is composed of a plurality of electrode arrangements.

8. The electrical impedance imaging system for blood perfusion according to claim 6, further comprising: The signal conditioning unit is configured to be connected between the photoplethysmography acquisition unit and the frequency domain analysis unit, and the signal conditioning unit is suitable for filtering out noise in the photoplethysmography signal. 9 . The electrical impedance imaging system for blood perfusion according to claim 6 , wherein the frequency domain analysis unit is composed of a matched filter.

Images