Thrombosis detection system and thrombus detection method

Abstract

To provide a thrombus detection system and a thrombus detection method which can enhance detection accuracy of a thrombus.SOLUTION: A thrombus detection system 10 comprises: an irradiation device (optical detector 12) which irradiates the blood including indocyanine green with near infrared light; a light-receiving device (optical detector 12) which receives fluorescence light obtained from the indocyanine green with the irradiation of the near infrared light; and a calculation device 14 which is connected to the light-receiving device (optical detector 12) and extracts as thrombus information image data having the luminance equal to or less than a threshold set according to the fluorescence of the indocyanine green of a thrombus portion in the image data of the received fluorescence light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thrombus detection system and a thrombus detection method. [Background technology]

[0002] In the treatment of patients with respiratory failure or circulatory failure, it is known to perform blood gas exchange using an extracorporeal circulation pathway equipped with, for example, an extracorporeal membrane oxygenation (ECMO) device. Specifically, in gas exchange using an extracorporeal circulation pathway, first, blood drawn from the patient is pumped into an oxygenator by a pump. The pumped blood is oxygenated in the oxygenator, and the oxygenated blood is then pumped back to the patient.

[0003] However, extracorporeal circulation pathways are composed of artificial components such as oxygenators, pumps, tubes, and connectors. Unlike living bodies, artificial components do not contain vascular endothelial cells with antithrombogenic properties. This poses the problem of susceptibility to thrombus formation in extracorporeal circulation pathways. This tendency is particularly pronounced in areas where blood flow stagnates. If thrombus flows into the patient's body, embolism is likely to occur.

[0004] Furthermore, if blood clots accumulate in the extracorporeal circulation pathway, it will cause problems with blood gas exchange. In particular, if blood clots accumulate in an oxygenator, the oxygenator's gas exchange capacity will decrease. As a method for solving the decrease in gas exchange capacity, for example, Non-Patent Document 1 discloses a method for detecting the state of blood clots in an oxygenator by measuring the pressure loss of blood flow in the extracorporeal circulation pathway. In Non-Patent Document 1, silicon is injected into the oxygenator to simulate the formation of blood clots, and the amount of blood clots in the blood is estimated by back-calculating the pressure loss when blood passes through the oxygenator. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] “Technical Indicators to Evaluate the Degree of Large Clot Formation inside the Membrane Fiber Bundle of an Oxygenator in an In Vitro Setup” Andreas Kaesler, “Artificial Organs” 2019 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the technology of Non-Patent Document 1, when a thrombus is relatively small, even if a thrombus is formed, it may not be reflected in the numerical value of the blood flow pressure loss. As a result, the thrombus that has actually formed may be overlooked, resulting in a problem of low accuracy in detecting the thrombus.

[0007] In view of the above problems, the present inventors have conducted extensive research and have found that indocyanine green (ICG) administered into the blood as a contrast agent is not taken up into thrombi formed in the blood. The present invention has been made based on this finding and provides a thrombus detection system and a thrombus detection method that can improve the accuracy of thrombus detection. [Means for solving the problem]

[0008] A thrombus detection system according to a first aspect of the present invention comprises an irradiation device that irradiates near-infrared light onto blood containing indocyanine green (ICG), a light-receiving device that receives fluorescence obtained from the indocyanine green (ICG) by irradiation with near-infrared light, and a calculation device connected to the light-receiving device that extracts, as thrombus information, image data from the image data of the received fluorescence that has a brightness below a threshold set according to the fluorescence of the indocyanine green (ICG) in the thrombus portion.

[0009] In the first aspect, a threshold is set according to the fluorescence of ICG in the thrombus portion of the fluorescence image data. Then, from the image data of the ICG fluorescence received by irradiating near-infrared light, image data having a brightness below the set threshold is extracted as thrombus information. That is, using ICG fluorescence imaging technology, a thrombus portion where ICG is not incorporated into the thrombus can be distinguished from a blood portion where ICG is present. Therefore, regardless of the size of the thrombus, any thrombus with a brightness below the threshold can be uniformly detected as a thrombus. Therefore, even small thrombi that do not appear in the numerical value of blood flow pressure loss can be prevented from being overlooked, thereby improving the accuracy of thrombus detection.

[0010] In the first aspect, the arithmetic device may further include an output device connected to the arithmetic device and configured to output the thrombus information to the outside.

[0011] In the above configuration, the output device that outputs thrombus information to the outside allows a person working in the detection work to quickly grasp that a thrombus has formed.

[0012] In the first aspect, the output device may be a display device that displays the position on the image data extracted as the thrombus information as the thrombus formation site.

[0013] In the above configuration, the position on the image data extracted as thrombus information is displayed on the display device as the thrombus formation site, making it easy for the person performing the detection work to visually recognize the thrombus formation site.

[0014] Another possible method for detecting thrombi using images is to observe the state of the blood using an iodine-based contrast agent. However, repeated administration of iodine-based contrast agents can easily cause kidney damage in subjects. For this reason, they may not always be appropriate for administration to living organisms. Furthermore, iodine-based contrast agents require radiation exposure to the subject in order to create contrast images. This raises concerns about radiation exposure for the patient as the subject and surrounding medical personnel. Another problem is that a relatively large installation space is required depending on the size of the radiation irradiating device.

[0015] In this regard, in the first embodiment in which ICG is used as the contrast agent, there is no need to use an iodine-based contrast agent, which improves safety when administered to a living body. In addition, since contrast images can be created without using radiation, there are no problems with radiation exposure or space required for installing the device.

[0016] In addition, in the first aspect, the computing device may perform a binarization process using a threshold value on the image data of the received fluorescence to create binary image data, and the display device may display the site of thrombus formation by displaying a binary image of colors divided into a first color representing a thrombus and a second color representing no thrombus, according to the created binary image data.

[0017] The above configuration allows for greater differences in shade and color tone between the first color representing a thrombus and the second color representing a non-thrombus in a binary image. In other words, the difference in shade between the thrombus portion where ICG is not incorporated and the blood portion where ICG is present can be increased, and the boundary between these two portions can be emphasized. This increases the objectivity of thrombus detection and makes it easier to visually detect thrombi by inspecting the binary image. In particular, by selecting two colors that are easily contrasted rather than the same color tone, detection workers are less likely to visually miss thrombi during detection. Furthermore, binarization of image data facilitates application to computer analysis and remote monitoring. Furthermore, the above configuration allows for visualization of thrombi using binary image data in almost real time with the timing of thrombus formation, thereby enabling rapid detection results.

[0018] In addition, the first aspect may further include an extracorporeal circulation path for circulating blood outside the subject's body.

[0019] In the above configuration, the thrombus detection system is connected to the extracorporeal circulation path, which is advantageous in that it can detect thrombi in the extracorporeal circulation path, where thrombi are more likely to form than in a circulation path within a living body. Furthermore, even when blood is circulating through the extracorporeal circulation path, thrombi can be detected without stopping blood circulation, and thrombi in the oxygenator can be visualized at the bedside, so there is no need to interrupt treatment.

[0020] In the first aspect, the extracorporeal circulation path may include an artificial lung, and thrombi may be detected using the brightness of fluorescence received from indocyanine green in the blood in the artificial lung.

[0021] In the above configuration, fluorescence is obtained from the blood inside the oxygenator, where thrombi are particularly likely to adhere, making it possible to effectively detect thrombi inside the oxygenator, thereby enabling treatment using the extracorporeal circulation route to be carried out more smoothly.

[0022] In the first aspect, the arithmetic device may perform a process of extracting image data as thrombus information over time.

[0023] With the above configuration, it is possible to more accurately grasp the change over time in the state of thrombus formation.

[0024] In addition, in the first aspect, the computing device may identify that a thrombus has actually formed in a location within the circulation path if the time at which the fluorescence that becomes image data containing thrombus information is received is within an analysis period set based on the ease of blood flow at the location within the circulation path corresponding to the position on the image data as thrombus information, and may identify that a thrombus has not actually formed in the location within the circulation path if the time at which the fluorescence that becomes image data containing thrombus information is received is not within the analysis period.

[0025] In the above configuration, even when image data is extracted as thrombus information, whether a thrombus has formed is identified depending on whether the time at which the fluorescence of the image data serving as thrombus information is received is included in the analysis period. This allows for increased accuracy in detecting thrombus, thereby reducing the risk of detecting false thrombus.

[0026] In the first aspect, the calculation device may calculate a rate of change over time in the area of ​​the thrombus formation site on the image data as the thrombus information.

[0027] In the above configuration, calculating the area expansion rate of the thrombus formation site as the area change rate makes it easier to predict the future size of the thrombus, making it possible to appropriately administer anticoagulant therapy, for example, by adjusting the dosage of an anticoagulant. Furthermore, when the thrombus detection system is applied to an extracorporeal circulation pathway, it makes it easier to predict future declines in gas exchange capacity, making it possible to appropriately estimate the timing of replacing components in the extracorporeal circulation pathway. Furthermore, when a thrombus is reduced by, for example, increasing the amount of anticoagulant administered into the blood, calculating the area reduction rate of the thrombus formation site as the area change rate makes it possible to assess the effectiveness of the administered anticoagulant.

[0028] A thrombus detection method according to a second aspect of the present invention includes irradiating near-infrared light onto blood containing indocyanine green, receiving fluorescence emitted from the indocyanine green by the near-infrared light irradiation, and detecting, as a thrombus formation site, a position on image data of the received fluorescence having a brightness equal to or less than a threshold set according to the fluorescence of the indocyanine green in the thrombus portion. According to the second aspect, thrombus can be detected with high accuracy, as in the first aspect. [Effects of the Invention]

[0029] According to the thrombus detection system and thrombus detection method of the present invention, it is possible to improve the accuracy of thrombus detection. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a diagram illustrating a thrombus detection system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view illustrating an oxygenator included in the extracorporeal circulation path. [Figure 3] FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2. [Figure 4] FIG. 4(A) is a diagram illustrating blood stored in a test container, and FIG. 4(B) is a diagram illustrating binary fluorescence image data obtained by irradiating near-infrared light onto the blood in the test container in FIG. 4(A). [Figure 5] 10 is a flowchart illustrating a thrombus detection method using the thrombus detection system according to the present embodiment. [Figure 6] FIG. 10 is a diagram illustrating binary image data of blood inside an oxygenator. [Figure 7] 1 is a graph illustrating changes in the brightness of blood fluorescence over time. [Figure 8] FIG. 10 is a diagram illustrating the state of blood inside the oxygenator in the first comparative example. [Figure 9] FIG. 10 is a diagram illustrating the state after blood has been washed away from the inside of the oxygenator in the second comparative example. [Figure 10]Figure 10(A) is a diagram illustrating binary image data of blood inside an artificial lung 4 hours after ICG administration, Figure 10(B) is a diagram illustrating binary image data of blood inside an artificial lung 6 hours after ICG administration, and Figure 10(C) is a diagram illustrating binary image data of blood inside an artificial lung 8 hours after ICG administration. DETAILED DESCRIPTION OF THE INVENTION

[0031] An embodiment of the present invention will be described below. In the following drawings, identical or similar parts are designated by the same or similar reference numerals. However, the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each device or component, etc., differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. Furthermore, the drawings also include parts with different dimensional relationships and ratios.

[0032] <Thrombosis detection system> First, a thrombus detection system 10 according to this embodiment will be described with reference to Figures 1 to 3. As shown in Figure 1, the thrombus detection system 10 according to this embodiment includes an optical detector 12 as an irradiation device and a light receiving device, a calculation device 14, and a display device 16.

[0033] The thrombus detection system 10 also includes an extracorporeal circulation path 30 for circulating blood outside the body of the subject 20. The optical detector 12 of the thrombus detection system 10 irradiates near-infrared light onto the ICG-containing blood of the subject 20 flowing inside an oxygenator 32 of the extracorporeal circulation path 30. The optical detector 12 also receives fluorescence obtained from the ICG in the blood by the irradiation of near-infrared light, and detects thrombus using the brightness of the received fluorescence.

[0034] (Extracorporeal circulation route) The extracorporeal circulation pathway 30 is mainly composed of an oxygenator 32, a pump 34, a tube 36, and a connector 38. The extracorporeal circulation pathway 30 extracts blood from the veins of the subject 20 (bleeding) using the pump 34, which is, for example, a centrifugal pump, and sends the extracted blood to the oxygenator 32. The blood that has undergone gas exchange in the oxygenator 32 is sent (blood sending) to the artery of the subject 20. The tube 36 and connector 38 that constitute the extracorporeal circulation pathway 30 may be provided with a flow meter 40 that measures the flow rate of blood, and a port 42 for administering ICG or an anticoagulant, or for obtaining a blood sample.

[0035] The circulatory pathway to which the thrombus detection system of the present invention is applied is not limited to an extracorporeal circulation pathway, but may also be an internal circulation pathway. For example, if the subject is a living organism such as a human, thrombi can be detected by administering ICG to a blood vessel within the living organism and receiving the fluorescence of the ICG at an appropriate site within the blood vessel without using components constituting an extracorporeal circulation pathway. Furthermore, the present invention is not limited to cases in which blood is flowing within the circulation pathway. For example, the present invention may be performed on stationary blood.

[0036] (artificial lung) As shown in Fig. 2, the oxygenator 32 of this embodiment has a main body 32A and a support part 32B that supports the main body 32A from below. Also, as shown in Fig. 3, the main body 32A has a hollow box-shaped casing 32A1 and, arranged inside the casing 32A1, a heat exchange part 32A2 where heat exchange with the inflowing blood is performed and a gas exchange part 32A3 where gas exchange with the blood after heat exchange is performed. In the oxygenator 32 of this embodiment, the gas exchange part 32A3 is a membrane type having a porous gas exchange membrane, but the present invention is not limited to this.

[0037] The casing 32A1 is provided with a plurality of cylindrical ports corresponding to the blood inlet 33A, blood outlet 33B, air vent 33C, air vent 33D, and dialysis circuit connection 33E. Each port connects the inside and outside of the casing 32A1. Although not shown, the casing 32A1 is also provided with a port for the gas inlet.

[0038] The wall surface of the casing 32A1 facing the heat exchanger 32A2 (the wall surface on the right side in FIG. 3), the wall surface of the casing 32A1 facing the gas exchanger 32A3 (the wall surface on the left side in FIG. 3), and the multiple ports provided in the casing 32A1 are all optically transparent. The wall surface and the multiple ports of the casing 32A1 can be made of, for example, a translucent resin.

[0039] This allows the person performing the detection work to observe from the outside the blood flowing inside the casing 32A1, including the surface of the gas-exchanging section 32A3, and also allows ICG fluorescence imaging to be performed using the optical detector 12. Note that if not only the oxygenator 32 but also the pump 34, the tube 36, and the connector 38 are made of optically transparent materials, ICG fluorescence imaging can also be performed.

[0040] As shown in FIG. 2, the casing 32A1 of the main body 32A of the oxygenator 32 is rhombic when the gas-exchanging section 32A3 is viewed from the front. In other words, the main body 32A is a regular square prism. However, in the present invention, the shape of the oxygenator is not limited to this. The oxygenator may have a wall surface that can be irradiated with near-infrared light from the outside and can receive the fluorescence of ICG. The shape of the oxygenator can be any shape, such as a cylindrical shape.

[0041] Inside the oxygenator 32, blood clots are more likely to form in locations where blood flow is more likely to stagnate (stagnate). In the case of a diamond-shaped oxygenator 32 such as that of this embodiment, as shown in Fig. 2, when viewing the gas-exchange section 32A3 from the front, blood flow is more likely to stagnate in areas such as the four corners at the top, bottom, left, and right ends of the diamond, the four sides of the diamond, and below the port of the dialysis circuit connection section 33E.

[0042] For this reason, thrombi are likely to form in region b below dialysis circuit connector 33E in Fig. 2, and region c where the flow direction changes at an angle of approximately 90 degrees along the inner wall surface of casing 32A1 in Fig. 3. On the other hand, for example, in region a on the left side of dialysis circuit connector 33E in Fig. 2, there are relatively few elements that interfere with the flow, so blood flows easily and thrombi are unlikely to form.

[0043] Furthermore, the thrombus detection system according to this embodiment is effective in detecting thrombi formed in the surface region of the gas-exchanging unit 32A3 and the surface region of the heat-exchanging unit 32A2, which are easily reached by ICG excitation light. The surface region of the heat-exchanging unit 32A2 includes the region on the inner wall surface of the casing 32A1 facing the heat-exchanging unit 32A2, the region on the membrane surface of the heat-exchanging unit 32A2, and the region between the opposing inner wall surface of the casing 32A1 and the membrane surface of the heat-exchanging unit 32A2. The surface region of the gas-exchanging unit 32A3 includes the region on the inner wall surface of the casing 32A1 facing the gas-exchanging unit 32A3, the region on the membrane surface of the gas-exchanging unit 32A3, and the region between the opposing inner wall surface of the casing 32A1 and the membrane surface of the gas-exchanging unit 32A3.

[0044] (Subject) The subject 20 of this embodiment illustrated in FIG. 1 is a human patient, but the subject is not limited to this in the present invention and may be any experimental animal other than a human. Furthermore, the subject itself is not essential in the present invention; it is sufficient to receive fluorescence from blood containing ICG. For example, fluorescence can be received from test blood. Circulating blood is also not essential; fluorescence can be received from stationary blood stored in a container or the like.

[0045] 1 also illustrates an example in which an extracorporeal membrane oxygenation (Veno-Arterial ECMO) circulation circuit is configured in which blood is withdrawn from the femoral vein at the base of the leg of the subject 20 and sent to the femoral artery. Although not shown, a blood withdrawal cannula is inserted into the femoral vein, and a blood transfer cannula is inserted into the femoral artery. However, the present invention is not limited to this. For example, an extracorporeal membrane oxygenation (Veno-Venous ECMO) system may be configured in which blood is withdrawn from the femoral vein at the base of the leg and sent to the jugular vein at the base of the neck. ECMO can be used both to assist cardiac function as a treatment for circulatory failure and to assist pulmonary function as a treatment for respiratory failure.

[0046] (indocyanine green) Indocyanine green (ICG) is excited by near-infrared light with a central wavelength of 760 nm and emits infrared fluorescence with a central wavelength of 840 nm. In this embodiment, the ICG is administered directly to the subject 20 through an intravenous drip line of the subject 20, but the present invention is not limited to this, and ICG can also be administered indirectly to the subject 20 through a port provided in the extracorporeal circulation path.

[0047] ICG administered into the blood is typically taken up by the liver of the subject 20 over time and excreted into the bile. In this embodiment, the administered dose of ICG is diluted to a level that allows fluorescence to be observed (monitored) in the blood circulating through the extracorporeal circulation path 30 for approximately 15 minutes after administration. A specific dilution procedure involves, for example, first dissolving ICG in a predetermined diluent such as distilled water, and then diluting it with physiological saline to a concentration of approximately 0.025 mg / ml. Next, approximately 10 ml of the diluted ICG solution can be administered to the subject 20, i.e., approximately 0.25 mg per observation. Note that in the present invention, the administered dose of ICG is not limited to 0.25 mg and can be changed as appropriate.

[0048] In this embodiment, by diluting and administering ICG, the amount administered to the subject 20 can be reduced compared to when it is not diluted, thereby reducing the burden on the living body and drug costs while still detecting thrombi. In this regard, for example, when ICG is administered by subcutaneous injection in other tests, about 0.5 mg / kg of ICG is often administered for liver function tests, and about 25 mg of ICG is often administered for specific tests of sentinel lymph nodes. Furthermore, when used in general blood flow evaluations other than thrombus detection, about 0.04 to 0.3 mg / kg of ICG is often administered.

[0049] For example, for an adult weighing 60 kg, 30 mg of ICG may be administered for liver function tests, 25 mg for specific tests of sentinel lymph nodes, and 2.4 mg to 18 mg for general blood flow evaluation. Compared to these other tests, in this embodiment, the amount administered can be reduced to approximately 0.25 mg per observation, which is one-tenth or less of the amount required.

[0050] (optical detector) The optical detector 12 of this embodiment functions as both an irradiating device and a light receiving device. However, the present invention is not limited to this, and the irradiating device and the light receiving device may be provided separately. The optical detector 12 outputs the brightness of the received fluorescence to the calculation device 14.

[0051] In this embodiment, two optical detectors 12 are arranged facing each other on the wall surface of the input side (right side in FIG. 1) and the wall surface of the output side (left side in FIG. 1) of the oxygenator 32. However, the present invention is not limited to this, and one optical detector 12 may be arranged only on the input side, or one optical detector 12 may be arranged only on the output side. However, because thrombi are likely to form on the output side of the oxygenator 32, it is preferable to arrange the optical detector 12 facing the output side of the oxygenator 32 in order to improve detection efficiency.

[0052] Furthermore, the optical detector 12 of this embodiment is portable and can be held by the operator of the detection work. This allows each part of the extracorporeal circulation pathway 30 to be observed at any angle and ICG fluorescence angiography to be performed. Note that the present invention is not limited to a portable optical detector, and a stationary optical detector, for example, may also be used.

[0053] An example of a commercially available optical detector 12 is an optical detector manufactured by Hamamatsu Photonics K.K. (product name: PDE-neo). This commercially available optical detector includes a light-emitting diode (LED) as an ICG excitation light source, an optical filter that blocks the excitation light and transmits only the fluorescence, a lens, and a two-dimensional charge-coupled device (CCD). The LED emits light in the near-infrared wavelength range with a center wavelength of 760 nm. The CCD has high sensitivity to wavelengths in the infrared region, and the lens transmits the received fluorescence to form an image on the CCD. Furthermore, the brightness of each pixel can be obtained as image data based on the charge generated in each CCD pixel.

[0054] (computing device) The arithmetic unit 14 is connected to the optical detector 12, which serves as a light-receiving device. From the image data of the received fluorescence, the arithmetic unit 14 extracts, as thrombus information, image data having a brightness equal to or lower than a threshold set according to the fluorescence of ICG in the thrombus portion. Specifically, the arithmetic unit 14 performs a binarization process using a threshold on the image data of the received fluorescence, and creates frames of binary image data at regular intervals over time. Within the frames, a coordinate space having a horizontal axis (X-axis) and a vertical axis (Y-axis) is defined (see FIG. 6).

[0055] In each of the generated time-series binary image data, image data representing thrombus information is extracted by associating one of the binary values ​​with image data portions having brightness below a threshold. The threshold can be set using experimental or simulation results.

[0056] The arithmetic device 14 can be configured as a computer equipped with, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), an internal storage device, an I / O port, etc. For convenience of explanation, the CPU, RAM, internal storage device, external storage device, and I / O port are not shown in the figures. The RAM, internal storage device, and I / O port are configured to be able to exchange data with the CPU via an internal bus.

[0057] An external storage device such as a flash memory or HDD (Hard Disk Drive) can be connected to the arithmetic unit 14. The internal storage device and the external storage device can store preset brightness thresholds and extracted image data to be used in the thrombus detection method of this embodiment. Although not shown, an input device such as a keyboard can be connected to the arithmetic unit 14. The input device can be used to input data for various tasks such as inputting threshold values, editing, and analyzing image data.

[0058] Here, the brightness acquired by the optical detector 12 varies over time depending on the ICG concentration in the blood from the time ICG is administered into the blood until it is excreted. In this embodiment, the period of variation is explained by dividing it into four periods, the first to fourth periods, for convenience. From the viewpoint of increasing accuracy, it is preferable to detect thrombus in the third period, in which the range of brightness variation is relatively small, out of the four periods.

[0059] Phase 1: Immediately after ICG administration, the brightness increases until it reaches a peak. Second stage: After reaching the peak, the brightness falls to a certain level. Third period: A period in which the fluctuation range of brightness is relatively small Stage 4: Gradual decrease in brightness

[0060] (display device) The display device 16 is connected to the computing device 14 and displays the coordinates of the position on the image data extracted as thrombus information as the thrombus formation site. The display device 16 corresponds to the "output device" of the present invention and outputs the thrombus information to the outside. The display device 16 in this embodiment is, for example, a liquid crystal display or the like capable of displaying image data, but in the present invention, any device capable of displaying image data can be used.

[0061] Furthermore, in the present invention, the calculation results output by the calculation device as thrombus information are not limited to image data displayed by a display device, but may be output by an output device other than a display device. The output device of the present invention may be, for example, an alarm device that can notify the outside of the formation of a thrombus by an acoustic signal such as an alarm sound, or may be text data displayed by a printing device such as a printer. Any output device can be connected to the thrombus detection system of the present invention. Furthermore, an output device is not required in the present invention.

[0062] In this embodiment, the display device 16 displays a binary image of colors divided into a first color representing a thrombus and a second color representing no thrombus, according to the binary image data created by the calculation device 14. The site of thrombus formation is displayed by the first color representing a thrombus.

[0063] 4(A) shows an example of static blood collected from the same experimental animal as subject 20 and accumulated in six test containers. Specifically, about 10 ml of an ICG solution diluted to about 0.025 mg / ml was administered to an experimental pig weighing about 80 kg.

[0064] None of the blood in the six test containers in Figure 4(A) was irradiated with near-infrared light. The photographs of the blood in the six test containers in Figure 4(A) were taken under ordinary indoor lighting. The blood in the six test containers differ from each other in that ICG was administered or not, and the time at which the blood was collected from the subject 20 after administration was approximately 5 minutes apart.

[0065] The blood sample 44A on the far left in Figure 4(A) was collected before ICG administration. The blood sample 44B second from the left in Figure 4(A) was collected immediately after ICG administration. The blood sample 44C third from the left in Figure 4(A) was collected 5 minutes after ICG administration. The blood sample 44D third from the right in Figure 4(A) was collected 10 minutes after ICG administration. The blood sample 44E second from the right in Figure 4(A) was collected 15 minutes after ICG administration. The blood sample 44F on the far right in Figure 4(A) was collected 20 minutes after ICG administration.

[0066] On the other hand, Figure 4(B) shows an example of binary image data obtained by irradiating near-infrared light onto the blood in the six test containers in Figure 4(A). Image data 54A on the left side of Figure 4(B) is binary image data corresponding to blood 44A in Figure 4(A) before ICG administration. Since no fluorescence is obtained from blood 44A that does not contain ICG, the color of the image data 54A is the same black as the background color. Therefore, it is difficult to identify the outline of the test container in which blood 44A has accumulated in Figure 4(B).

[0067] The second image data 54B from the left in Figure 4(B) corresponds to the blood 44B in Figure 4(A) collected immediately after ICG administration. The ICG concentration of blood 44B is the highest among the blood samples 44B to 44F in the five test containers to which ICG was administered, and therefore image data 54B is the brightest. Therefore, in Figure 4(B), the outline of the test container in which blood 44B has accumulated is easily identified.

[0068] Image data 54C, third from the left in Fig. 4(B), corresponds to blood 44C in Fig. 4(A) collected 5 minutes after ICG administration. Image data 54D, third from the right in Fig. 4(B), corresponds to blood 44D in Fig. 4(A) collected 10 minutes after ICG administration. Image data 54E, second from the right in Fig. 4(B), corresponds to blood 44E in Fig. 4(A) collected 15 minutes after ICG administration.

[0069] Image data 54F on the far right in Figure 4(B) corresponds to blood 44F in Figure 4(A) collected 20 minutes after ICG administration. The ICG concentration of blood 44F is the lowest among blood samples 44B to 44F in the five test containers to which ICG was administered, and therefore image data 54F has the lowest brightness. For this reason, it is difficult to identify the outline of the test container in which blood 44F has accumulated in Figure 4(B).

[0070] As shown in Figure 4(B), it is clear that fluorescence from ICG can be detected even from stationary blood. Figure 4(B) also illustrates the state in which the white fluorescence becomes lighter from the blood on the left to the blood on the right. This means that the ICG concentration decreases over time after administration, weakening the fluorescence obtained from ICG. It is particularly difficult to obtain fluorescence more than 15 minutes after administration.

[0071] <Thrombosis detection method> Next, a thrombus detection method using the thrombus detection system 10 according to this embodiment will be described with reference to Figures 5 to 9. First, the thrombus detection system 10 shown in Figure 1 is prepared. In addition, a laboratory pig weighing approximately 80 kg is prepared as the subject 20, and general anesthesia is induced in the prepared pig.

[0072] Next, a blood supply line is connected to the carotid artery of the subject 20, and a blood supply line is connected to the jugular vein. Then, the pump 34 of the extracorporeal circulation path 30 is driven to start blood circulation. Note that, in order to improve the ease of blood flow at the start of circulation, an anticoagulant such as heparin or nafamostat may be administered to the subject 20 in advance.

[0073] Next, approximately 10 ml of an ICG solution diluted to approximately 0.025 mg / ml is administered into the vein of the subject 20 (step S1 in FIG. 5). Next, the optical detector 12 irradiates the blood inside the oxygenator 32 with near-infrared light (step S2) and receives fluorescence from the ICG (step S3). Next, the arithmetic unit 14 acquires image data of the received fluorescence (step S4). Then, the arithmetic unit 14 creates binary image data from the acquired image data using a threshold value (step S5). By creating the binary image data, areas in the image data of the blood inside the oxygenator 32 that have brightness below the threshold value are extracted as thrombus information.

[0074] Next, as shown in FIG. 6, the display device 16 displays the position extracted as thrombus information as a thrombus formation site in black (step S6 in FIG. 5). Furthermore, a site having a brightness exceeding a threshold is displayed in white. That is, in this embodiment, the first color representing a thrombus is displayed in "black," and the second color representing blood not containing a thrombus is displayed in "white." Note that in the present invention, the two colors are not limited to black and white, and can be changed as appropriate, for example, to red and green.

[0075] In this embodiment, the processes of steps S2 to S6 are performed over time within 15 minutes after administration to create a series of frames of binary image data. Figure 6 shows, within a rectangular analysis region bounded by the x- and y-axes, image data 52A corresponding to main body 32A of casing 32A1, image data 53E corresponding to a port of dialysis circuit connector 33E, and three positions A to C.

[0076] Position A in FIG. 6 is included in the white area, which is a non-thrombus area, and corresponds to part a of the oxygenator 32 in FIG. 2. The (x, y) coordinates of position A are (x A ,y A ) Position B in FIG. 6 is included in the black part which is the thrombus part, and corresponds to part b of the oxygenator 32 in FIG. 2. The (x, y) coordinates of position B are (x B ,y B) In addition, position C in FIG. 6 is included in the black part which is the thrombus part, and corresponds to part c of the oxygenator 32 in FIG. 2. The (x, y) coordinates of position C are (x C ,y C )

[0077] Position B in Figure 6, which corresponds to position b in Figure 2, is black, indicating that blood flows relatively poorly in the region below dialysis circuit connector 33E inside casing 32A1 of oxygenator 32, resulting in the formation of a thrombus. Position C in Figure 6, which corresponds to position c in Figure 2, is black, indicating that blood flows relatively poorly in the region corresponding to the upper left edge of main body 32A of casing 32A1 of oxygenator 32 in Figure 2, resulting in the formation of a thrombus. Position A in Figure 6, which corresponds to position a in Figure 2, is white, indicating that blood flows relatively easily in the region below dialysis circuit connector 33E in Figure 2, resulting in the formation of a thrombus.

[0078] In addition, in the present invention, by continuously displaying a series of binary image data on the display device 16 according to this embodiment, it is also possible to observe the flow of blood around the thrombus as a moving image.

[0079] FIG. 7 shows a portion of the fluctuation in luminance over time at each of the three positions A to C in FIG. 6 within 15 minutes after ICG administration. At each of the three positions A to C, in the first period immediately after ICG administration, the luminance rises until it reaches a peak. In the second period, after reaching the peak, the luminance falls to a certain level. In the third period, the fluctuation range of the luminance is relatively small. Note that, for convenience of explanation, the graph in FIG. 7 only illustrates the region corresponding to the fluctuation period from the first period to part of the third period, but in reality, there are also fluctuation periods corresponding to the remainder of the third period and the fourth period.

[0080] In this embodiment, the set threshold is 80. Therefore, position B, where a brightness of approximately 60 to 70, which is below the threshold, is acquired in the third period, and position C, where a brightness of approximately 50 is acquired in the third period, are detected as thrombus formation sites. Furthermore, position A, where the brightness acquired in the third period fluctuates in the range of more than 80 to 100 or less, is detected as a non-thrombus formation site. Note that in the present invention, the brightness threshold is not limited to 80 and can be changed as appropriate.

[0081] Furthermore, in this embodiment, the value of the luminance itself is used as the threshold value, but the present invention is not limited to this, and for example, the rate of change in the luminance of the fluorescence may be used. Furthermore, a value such as the time lag from the administration of ICG until the luminance exceeds a predetermined value and begins to change may also be used. In other words, in the present invention, the criterion for determining whether or not there is a thrombus is not limited to the magnitude of the luminance.

[0082] <Comparative Example> On the other hand, as a first comparative example, a method was carried out in which a worker in the detection work visually observed the inside of the oxygenator 32 15 minutes after administration of ICG, at which point the binary image data shown in Fig. 6 was acquired, thereby observing thrombi with the naked eye. Although both thrombus-formed and non-thrombus-formed areas actually existed in the blood inside the casing 32A1 of the oxygenator 32, as shown in Fig. 8, it was difficult to clearly distinguish between them because they appeared in similar red tones.

[0083] Furthermore, the extracorporeal circulation path 30 was removed from the subject 20, and the circulating blood was replaced with saline to flush out the blood from the oxygenator 32 15 minutes after the administration of ICG. Then, as a second comparative example, a detection worker visually inspected the inside of the oxygenator 32 after the blood had been washed out, thereby observing thrombi with the naked eye. As shown in FIG. 9, three thrombus formation sites 60 were observed on the underside of the dialysis circuit connector 33E. Furthermore, thrombus formation sites 60 were also observed on the four sides and four corners of the casing 32A1 in FIG. 9.

[0084] (Action and effect) In this embodiment, a threshold is set according to the fluorescence of ICG in the thrombus portion of the fluorescence image data. Then, among the image data of the ICG fluorescence received by irradiating near-infrared light, image data having a brightness below the set threshold is extracted as thrombus information, and the location of the image data extracted as thrombus information is displayed as the thrombus formation site. That is, using ICG fluorescence imaging technology, thrombus portions where ICG is not incorporated into the thrombus can be distinguished from blood portions where ICG is present. Therefore, regardless of the size of the thrombus, any thrombus with a brightness below the threshold can be uniformly detected as a thrombus. This makes it possible to reduce detection omissions even for small thrombi that do not appear in the numerical value of blood flow pressure loss, thereby improving thrombus detection accuracy. Similarly, the thrombus detection method according to this embodiment enables thrombus detection with high accuracy.

[0085] In this embodiment, the display device 16, which serves as an output device for outputting thrombus information to the outside, allows the person performing the detection work to quickly grasp that a thrombus has formed. Furthermore, the position on the image data extracted as thrombus information is displayed as the thrombus formation site by the display device 16, making it easy for the person performing the detection work to visually recognize the thrombus formation site.

[0086] Furthermore, with regard to thrombi, it has been reported that, for example, thrombi are likely to form in the pump 34 and oxygenator 32 of the extracorporeal circulation pathway 30 in the blood of almost all patients infected with COVID-19, i.e., they exhibit a strong tendency for blood clotting. This strong tendency for blood clotting is thought to be influenced by cytokine storms in the blood and vascular endothelial damage in the immune response to COVID-19 that has invaded the body. For this reason, the thrombus detection system 10 and thrombus detection method according to the present embodiment are particularly advantageous when patients infected with COVID-19 undergo gas exchange treatment using an extracorporeal circulation pathway 30 such as ECMO.

[0087] Furthermore, when a method for detecting thrombi is used in which blood flowing inside the oxygenator 32 is visually inspected, as in the first comparative example, the color of thrombus and non-thrombus parts in the blood are the same red color, although they differ in shade, making it difficult to clearly distinguish them visually. This raises the concern that thrombi may be overlooked.

[0088] However, in this embodiment, it is possible to increase the difference in shading and color tone between the first color representing a thrombus and the second color representing a non-thrombus in a black-and-white binary image. That is, compared to obtaining a black-and-white (grayscale) binary image by simply photographing the oxygenator 32 with near-infrared light, it is possible to increase the difference in shading between the thrombus portion where ICG is not incorporated into the thrombus and the blood portion where ICG is present. Furthermore, the boundary between these two portions can be displayed in an emphasized manner. This increases the objectivity of thrombus detection and makes it easier to visually detect thrombus by inspecting the binary image.

[0089] In particular, by selecting two easily contrasting colors rather than the same color tone, the person performing the detection operation is less likely to visually miss a thrombus during detection. As a result, thrombus inside the oxygenator 32 can be detected early and evaluated in detail. Furthermore, in this embodiment, the image data is binarized, which facilitates application to computer analysis and remote monitoring. Furthermore, in this embodiment, thrombus visualization using binary image data is possible almost in real time with the timing of thrombus occurrence, so detection results can be obtained quickly.

[0090] Although it is possible to improve the visibility by washing away the blood inside the oxygenator 32, as in the second comparative example, this requires stopping the gas exchange procedure, making it difficult to perform detection during the gas exchange procedure.

[0091] However, in this embodiment, even during gas exchange treatment, the positions of image data having brightness below the threshold can be displayed as a binary image, eliminating the need to wash away blood from inside the oxygenator 32. Therefore, detection can be performed during gas exchange treatment.

[0092] In addition, in this embodiment, ICG is used as the contrast agent, and therefore there is no need to use an iodine-based contrast agent, which improves safety when administered to a living body. Furthermore, because contrast images can be created without using radiation, there are no problems with radiation exposure or space required for installing the device.

[0093] Furthermore, in this embodiment, the thrombus detection system 10 is connected to the extracorporeal circulation pathway 30, which is advantageous in that it can detect thrombus in the extracorporeal circulation pathway 30, where thrombus formation is more likely than in a circulation pathway within the body, for example.

[0094] Furthermore, conventional methods for detecting thrombi include measuring markers such as D-dimer, platelet count, and LDH in the blood. However, these markers do not necessarily reflect only the presence of thrombi. For example, D-dimer may be elevated in cases of pathologies or diseases other than thrombi, such as tumors. In other words, methods using markers have low specificity as tests for detecting thrombi. For this reason, even if a marker produces a reaction suggesting the presence of a thrombus, additional confirmation is required to rule out the possibility of other pathologies or diseases other than thrombi.

[0095] Another known conventional method for detecting thrombi is to perform CT scans of the oxygenator 32 in the extracorporeal circulation pathway 30 and visually check cross-sectional images of the interior of the oxygenator 32 to detect thrombi. However, when performing CT scans of the oxygenator 32, the patient, who is the subject 20 connected to the oxygenator 32, must be transported to the scan room when the oxygenator 32 is moved to the scan room. This not only places a burden on the patient, but also increases the burden on those around him or her who must assist in safely transporting the patient.

[0096] Furthermore, if CT scans are performed multiple times a day, the burden of moving the patient to the scan room increases, and there is also the risk of increased radiation exposure. While it is possible to visualize thrombi using CT scans of the oxygenator 32, it is difficult to perform CT scans at the bedside without moving the patient.

[0097] In this regard, in this embodiment, even if blood is circulating through the extracorporeal circulation path 30, thrombi can be detected without stopping the blood circulation, and thrombi in the artificial lung 32 can be visualized at the bedside, so there is no need to interrupt treatment.

[0098] Furthermore, within the extracorporeal circulation pathway 30, blood clots are particularly likely to adhere to the inside of the oxygenator 32. In this embodiment, fluorescence is obtained from the blood inside the oxygenator 32, so blood clots inside the oxygenator 32 can be effectively detected. This allows treatment using the extracorporeal circulation pathway 30 to be carried out more smoothly.

[0099] Furthermore, this embodiment enables early detection of thrombi in the oxygenator 32, thereby preventing the onset of embolism due to thrombi. Furthermore, it also enables appropriate adjustment of the timing and dosage of anticoagulant administration, thereby improving the therapeutic effect on the patient and preventing deterioration of the gas exchange capacity of the oxygenator 32.

[0100] Furthermore, this embodiment is particularly suitable for detecting thrombi that are likely to form between the inner wall surface of the oxygenator 32 and the surface of the gas-exchange section 32A3. That is, this embodiment is excellent for detecting thrombi that are likely to become a source of embolism on the surface of the gas exchange membrane of the oxygenator 32. For this reason, for example, by combining this embodiment with a method for detecting thrombi deep within the gas-exchange section 32A3 using the numerical value of pressure loss in the extracorporeal circulation path 30, the accuracy of thrombus detection can be further improved.

[0101] Furthermore, in this embodiment, the process of extracting image data as thrombus information is performed over time, so that the change in the state of thrombus formation over time can be grasped more accurately.

[0102] <First Modification> In the above embodiment, the case where thrombus detection is performed in the third period when the fluctuation range of brightness is relatively small when the fluctuation period is divided into periods taking into account fluctuations in ICG concentration in blood has been described. However, as a result of research by the present inventors, it has been found that because the fluidity of blood differs at each site in the circulatory pathway, the manner in which brightness decreases before reaching the third period is not strictly uniform but differs at each site.

[0103] For this reason, in this embodiment, when extracting image data as thrombus information, an "analysis period" based on the ease of blood flow is set in advance for each site in the circulation pathway. In other words, the start and end times of the period for identifying the authenticity of thrombus information are limited. The "analysis period" is set based on the ease of blood flow at the site in the circulation pathway corresponding to the position on the image data as thrombus information. Then, even if image data is extracted as thrombus information within the third period, it is determined whether the time when the fluorescence of this image data was received is included in the set analysis period. Depending on the determination result, it is determined whether a thrombus has actually formed, i.e., the authenticity of the thrombus information is confirmed.

[0104] Specifically, in "areas where blood flows easily" in the circulatory pathway, the third period is relatively short, and the fourth period described above arrives relatively early. In other words, the decrease in ICG concentration begins relatively early. For this reason, the time when the fluorescence in the image data is received may be in the fourth period, and the brightness may have fallen below the threshold.

[0105] As a result, even if a thrombus has not actually formed, the color of the thrombus is displayed by binarization, and the output indicates that a thrombus has formed. Therefore, if a medical professional who observes the color of the thrombus displayed as thrombus information judges it to be a thrombus (judges it to be a false thrombus), there is a concern that, for example, unnecessary administration of anticoagulants may be carried out.

[0106] For this reason, in the first modified example, the start time and end time of an "analysis period" included in the third period are set in advance for a region in the circulation pathway that is set as a "region through which blood flows easily." Then, if the time at which the fluorescence that becomes image data containing thrombus information is received is included in the set analysis period, the calculation device 14 determines that a thrombus has actually formed in the region in the circulation pathway. On the other hand, if the time at which the fluorescence that becomes image data containing thrombus information is received is not included in the analysis period, the calculation device 14 determines that a thrombus has not actually formed in the region in the circulation pathway.

[0107] For example, when a region in a binary image is determined to be a false thrombus, the identification result can be output by separating the region determined to be a false thrombus from other regions with a line of a specific color, or by color-coding the region with a predetermined color, etc. Furthermore, a group of coordinates included in the region determined to be a false thrombus or representative coordinates may be output.

[0108] The "parts through which blood flows easily" in the circulation path and the "analysis period" for each part through which blood flows easily can be set by experiment or simulation.

[0109] In the first modification, when extracting image data as thrombus information, an "analysis period" based on the ease of blood flow is set in advance for each site in the circulation path. Then, even when image data as thrombus information is extracted, whether a thrombus has formed is identified depending on whether the time when the fluorescence of the image data as thrombus information is received is included in the analysis period. This can further improve the accuracy of thrombus detection, thereby reducing the risk of detecting a false thrombus.

[0110] <Second Modification> Next, a second modified example in which the area change rate of a thrombus is calculated using a series of image data over time while a gas exchange procedure is being performed using the thrombus detection system 10 according to this embodiment will be described with reference to Fig. 10. In this embodiment, the "area change rate" includes both the area expansion rate and the area contraction rate of the thrombus formation site 60 on the binary image data.

[0111] First, we will explain the area change rate as the area expansion rate. For example, one hour after the start of circulation, a second ICG administration is performed, and as with the first administration, the same processes as in steps S2 to S6 are repeated over time for 15 minutes after the administration to create a series of binary image data. Similarly, two hours after the start of circulation, a third ICG administration is performed, and three hours after the start of circulation, a fourth ICG administration is performed, and so on, repeating the administration every hour and creating a series of binary image data following each administration.

[0112] Then, eight hours after the start of circulation, the final ninth administration of ICG is performed, and a series of binary image data covering 15 minutes after administration is created, thereby completing the gas exchange procedure. From the first administration of ICG to the final ninth administration of ICG, the oxygenator 32 is used continuously without being replaced or cleaned. Note that, although the present embodiment exemplifies a case in which ICG is administered nine times, the present invention is not limited to this, and the number of administrations can be set to one or more, any number, depending on the implementation policy of the thrombus detection method.

[0113] Figure 10(A) shows a binary image created 15 minutes after the fifth ICG administration, which was 4 hours after the start of circulation. Figure 10(B) shows a binary image created 15 minutes after the seventh ICG administration, which was 6 hours after the start of circulation. Figure 10(C) shows a binary image created 15 minutes after the ninth ICG administration, which was 8 hours after the start of circulation.

[0114] 10(A) to 10(C), a thrombus formation site 60 has occurred in a region below the port of the dialysis circuit connection portion 33E of the casing 32A1, and the area of ​​the black image data of the thrombus formation site 60 is expanding over time. In the second modified example, the calculation device 14 calculates the area of ​​the image data of the expanding thrombus formation site 60 over time, and the area expansion rate over time obtained from the calculated area can be calculated as the area change rate of the thrombus.

[0115] Conversely, the area of ​​the black image data of the thrombus formation site 60, which serves as thrombus information, may be reduced over time by, for example, increasing the amount of anticoagulant administered into the blood while performing gas exchange treatment using the thrombus detection system 10 according to this embodiment. The computing device 14 may then calculate the area of ​​the image data of the thrombus formation site 60 that is reducing over time, and calculate the rate of area reduction over time obtained from the calculated area as the rate of change in the area of ​​the thrombus.

[0116] In the second modification, calculating the area expansion rate of the thrombus formation site 60 as the area change rate makes it easier to predict the future size of the thrombus, which makes it possible to appropriately administer anticoagulant therapy, for example, by adjusting the dosage of an anticoagulant. Furthermore, since it becomes easier to predict future declines in the gas exchange capacity of the extracorporeal circulation pathway 30, it becomes possible to appropriately estimate the timing for replacing components. Furthermore, when a thrombus is reduced in size by, for example, increasing the amount of anticoagulant administered into the blood, calculating the area reduction rate of the thrombus formation site 60 as the area change rate makes it possible to assess the effectiveness of the administered anticoagulant.

[0117] <Other embodiments> Although the present invention has been described with reference to the above disclosed embodiments, the descriptions and drawings forming part of this disclosure should not be understood to limit the present invention. The present invention includes various embodiments not described above, and the technical scope of the present invention is defined only by the invention-specific matters in the scope of the claims that are appropriate from the above description. [Explanation of symbols]

[0118] 10. Thrombus Detection System 12 Optical detector 14 Arithmetic unit 16 Display device 20 Subject 30 Extracorporeal circulation pathway 32 Artificial lung 32A main body 32A1 casing 32A2 Heat exchange section 32A3 Gas exchange section 32B Support part 33A Blood inflow section 33B Blood outflow section 33C Air vent 33D Air vent 33E Dialysis circuit connection part 34 Pump 36 tubes 38 Connectors 40 Flow meter 42 ports 44A~44F Blood 54A~54F Image data corresponding to blood 52A Image data corresponding to the casing of the oxygenator body 53E Image data corresponding to the port of the dialysis circuit connection part 60 Thrombus formation site A-C: Position of the inside of the oxygenator on binary image data D Area on binary image data a~c Internal parts of the oxygenator

Claims

1. an irradiation device that irradiates near-infrared light onto blood containing indocyanine green; a light receiving device that receives fluorescence obtained from indocyanine green when irradiated with near-infrared light; a computing device connected to the light receiving device and configured to extract, as thrombus information, image data having a luminance equal to or less than a threshold set in accordance with the fluorescence of indocyanine green in the thrombus portion from image data of the received fluorescence; A thrombus detection system comprising:

2. Further, an output device is provided which is connected to the calculation device and outputs the thrombus information to the outside. The thrombus detection system of claim 1 .

3. the output device includes a display device that displays a position on the image data extracted as thrombus information as a thrombus formation site. The thrombus detection system according to claim 2 .

4. the calculation device performs binarization processing using the threshold value on the image data of the received fluorescence to create binary image data; the display device displays a binary image of two colors, a first color representing a thrombus and a second color representing no thrombus, in accordance with the generated binary image data, thereby displaying the thrombus formation site. The thrombus detection system according to claim 3 .

5. Further, an extracorporeal circulation path is provided for circulating the blood outside the subject's body. The thrombus detection system according to any one of claims 1 to 4.

6. the extracorporeal circulation pathway includes an oxygenator; detecting thrombi using the brightness of the fluorescence received from indocyanine green in the blood in the oxygenator; The thrombus detection system according to claim 5 .

7. the computing device performs a process of extracting image data as thrombus information over time; The thrombus detection system according to any one of claims 1 to 6.

8. The computing device If the time when the fluorescence that becomes the image data including the thrombus information is received is included in an analysis period that is set based on the ease of blood flow at a part in the circulation path that corresponds to the position on the image data as the thrombus information, it is determined that a thrombus has actually formed at the part in the circulation path, If the time when the fluorescence that becomes image data including thrombus information is received is not included in the analysis period, it is determined that a thrombus is not actually formed in the site within the circulatory pathway. The thrombus detection system according to claim 7 .

9. the calculation device calculates a rate of change in area of ​​the thrombus formation site over time on the image data as thrombus information; The thrombus detection system according to claim 7 or 8.

10. A method for detecting a thrombus in a thrombus detection system, comprising: The thrombus detection system Near-infrared light is irradiated onto blood containing indocyanine green, Fluorescence from indocyanine green is detected by irradiation with near-infrared light. Among the image data of the received fluorescence, a position on the image data having a brightness equal to or less than a threshold set in accordance with the fluorescence of indocyanine green in the thrombus portion is detected as a thrombus formation site. Clot detection methods.

Images