System and method for identifying blood vessels during fluorescence imaging

Abstract

This disclosure relates to a system and method for continuously identifying blood vessels in tissue during fluorescence imaging. In particular, this disclosure relates to continuously measuring and evaluating hemodynamics in tissue during medical procedures using fluorescence imaging, wherein the application of a fluorescent agent is controlled and automated, thereby identifying, mapping, and visualizing blood vessels in the tissue. One embodiment relates to a computer-implemented method for identifying blood vessels in a tissue, for example, during a medical procedure, the method comprising the steps of: continuously acquiring fluorescence images of the tissue, wherein fluorescence signals oscillate in a predetermined pattern, and analyzing the fluorescence images and the associated oscillation signals, thereby continuously identifying blood vessels in the tissue.

Description

[0001] This application is a divisional application of Chinese patent application number 2020800972346 (corresponding to PCT international application number PCT / EP2020 / 087507), filed on December 21, 2020, entitled "System and method for identifying blood vessels during fluorescence imaging". Technical Field

[0002] This disclosure relates to systems and methods for continuously identifying blood vessels in tissues using fluorescence imaging. In particular, this disclosure relates to the continuous measurement and assessment of hemodynamics in tissues during medical procedures using fluorescence imaging, wherein the application of a fluorescent agent is controlled and automated, thereby identifying, mapping, and visualizing blood vessels in the tissue. Background Technology

[0003] Today, tissue anatomy is a major part of surgery, often accounting for up to 50% of the surgical time. Before performing the actual surgical procedure, blood vessels and other central structures must be carefully isolated from the surrounding connective tissue. This is the case in surgical procedures such as bowel resection and anastomosis. However, despite this meticulous care, accidental tearing of blood vessels frequently occurs, leading to excessive bleeding and other complications, significantly prolonging the surgical time.

[0004] The challenge lies in the fact that blood vessels and central structures are not easily distinguishable from the surrounding connective tissue to the naked eye. This problem is further exacerbated by the increasing prevalence of obesity, as obese individuals have a large amount of connective tissue primarily composed of fat. Therefore, surgeons need tools that can easily distinguish and map blood vessels within connective tissue. This will allow for safer and faster tissue dissection and potentially significantly reduce surgical time. Shorter surgical times benefit both patients and the hospital as a whole; patients experience less surgical stress, and the hospital can perform more surgeries within the same timeframe.

[0005] Fluorescence imaging is a tool in which the injection of a fluorescent imaging agent (also known as a fluorescent contrast agent, fluorescent agent, such as indocyanine green (ICG)) is provided to visualize blood flow and perfusion in tissues of anatomical structures. A recent example is the Leica Microsystems GLOW800 augmented reality (AR) system, which simultaneously provides white light and real-time fluorescent blood flow views, allowing brain anatomy to be observed in natural colors, enhanced by real-time vascular flow. Summary of the Invention

[0006] One limitation of known fluorescence imaging procedures is that, for example, a typical dose of ICG used today requires at least 20-30 minutes of washout before a new measurement can be performed. That is, each dose of ICG can be considered a “single image exposure” as the bolus flows through the artery to provide a snapshot of the perfusion. The problem is that during intestinal surgery, the intestine undergoes peristaltic movement, and during tissue dissection, the surgeon is slowly working through connective tissue, so a single snapshot every 30 minutes is almost unusable. To overcome this limitation, the inventors have proposed a novel administration scheme for fluorescence imaging in PCT application entitled “System and method for automatic perfusion measurement” (PCT / EP2019 / 065648), which allows for “continuous” perfusion monitoring through the automated administration of microboluses based on time-separated administration of at least one fluorophore. The method generates a fluorescence signal from the perfused tissue that fluctuates over time in a predetermined pattern. PCT / EP2019 / 065648 is incorporated herein by reference in its entirety.

[0007] The inventors have now realized that the novel dosing scheme disclosed in PCT / EP2019 / 065648 can be used to identify blood vessels, for example, those hidden in connective tissue. Therefore, one aspect of this disclosure relates to a (computer-implemented) method for identifying blood vessels in a tissue, for example, during a medical procedure. The method includes the step of continuously generating and / or receiving fluorescent signals from the tissue (blood vessels in it), wherein the intensity and / or wavelength of the fluorescent signals vary and / or oscillates in a predetermined manner, for example, oscillating in a predetermined pattern, i.e., preferably, the oscillation pattern is externally applied in a predetermined and controllable manner. Preferably, the oscillation pattern is generated from a series of small injections of at least one fluorescent imaging agent, i.e., the oscillation pattern originates from repeated injections of the injection. The oscillation pattern can be considered to have a frequency (also called a period), such that the frequency of the pattern is determined by a series of injections administered with a predetermined and / or controlled duration between successive injections.

[0008] Due to object-specific hemodynamics, the inherent time difference in each fluorescence signal derived from each small bolus injection can be used to identify blood vessels. That is, the currently disclosed method may include the step of analyzing at least a portion of a fluorescence image and determining at least one time difference selected from the group consisting of: - The time difference between the injection of the bolus and the arterial or venous fluorescence signal. - The time difference between arterial fluorescence signals and venous fluorescence signals - The time difference between arterial or venous fluorescence signals and tissue fluorescence signals.

[0009] Alternatively, it can be described as continuously generating and / or receiving fluorescent signals from tissue (blood vessels), wherein the phase difference between the fluorescent signals from blood vessels and surrounding tissue is repeatedly and / or continuously applied.

[0010] As disclosed in PCT / EP2019 / 065648, one way to provide an oscillating fluorescence signal is to inject a micropump of ICG at regular intervals over a long period of time, such that the intensity of the fluorescence signal oscillates at a predetermined frequency, i.e., each injection of the injector is followed by the appearance of a fluorescence signal, and the oscillation frequency is determined by the injection time. As illustrated herein, micropumps enable continuous injection of ICG over a period of one hour or even several hours at controlled, predetermined and / or regular intervals (e.g., regular intervals of 1 to 10 minutes, such as 1-2 minutes, 2-3 minutes, 3-4 minutes, 4-5 minutes, 5-6 minutes, 6-8 minutes, or 8-10 minutes).

[0011] Because the fluorescence signal from the small injection continuously appears again and again, blood vessels can be identified repeatedly in the fluorescence image of the tissue, i.e., based on the time difference and oscillating fluorescence signal(s). That is, the disclosed method may also include the step of continuously acquiring fluorescence images of the tissue, and preferably, the step of analyzing the fluorescence images and associated changes and / or oscillation intensity, wavelength, and / or phase, thereby continuously identifying blood vessels in the tissue.

[0012] There are various known ways to analyze fluorescence signals and thus visualize blood vessels. A key aspect of the currently disclosed methods is about when to look for arteries, veins, tissues, etc. Repeated injections of small boluses ensure that fluorescence signals are repeatedly observed for analysis. Furthermore, the determination and / or knowledge of object-specific hemodynamic time constants ensures understanding when to look for or expect signals from arteries, veins, tissues, and / or other sources.

[0013] One or more object-specific hemodynamic parameters may be known in advance, such as one or more hemodynamic time constants, for example, from earlier procedures. Therefore, this disclosure also relates to a method for, for example, identifying blood vessels in an object's tissue during a medical procedure, the method comprising the following steps:

[0014] - Continuously acquire fluorescence images of the tissue, wherein the fluorescence signal oscillates in a predetermined pattern with a frequency, preferably, the pattern is generated from a series of injections of at least one fluorescent imaging agent, and wherein the series of injections is administered for a predetermined and / or controlled duration between successive injections, the predetermined and / or controlled duration determining the frequency of the pattern. - Analyze at least some or all of the fluorescence images, and - Based on the specific hemodynamic parameters of the one or more objects and the identification of fluorescence signals oscillating in a predetermined pattern, preferably, blood vessels in the fluorescence image of the tissue are identified continuously and / or repeatedly.

[0015] Another aspect of this disclosure relates to a system for identifying blood vessels in tissue during a medical procedure on a subject, wherein the system is configured to: continuously generate fluorescent signals from blood vessels in the tissue, wherein the intensity of the fluorescent signals oscillates in a predetermined pattern; continuously receive fluorescent images of the tissue; and analyze the fluorescent images and associated oscillation intensities to continuously identify blood vessels in the tissue. The system may include a controllable injection pump for containing at least one first fluorescent imaging agent, the injection pump being configured to inject a predetermined series of boluses of the first fluorescent imaging agent into a vein of the subject to generate a fluorescent signal oscillating in a predetermined pattern. Therefore, the system can be configured to perform the methods disclosed herein.

[0016] Therefore, for example, before and during tissue dissection, identified blood vessels can be visualized and mapped for medical personnel. A key advantage is that the currently disclosed methods (i.e., automated and continuous vessel identification and detection) can be performed in the background while the surgeon works with their normal white-light camera images. For example, a microbolus injection procedure can be initiated at the start of surgery and run in the background, monitored by a computer system that both measures and receives fluorescence signals and controls the intervals and dosage of the microbolus regimen. The surgeon can then turn to a computer-generated "vascular view" at any time during surgery, showing the vessels in the area of ​​interest. Advantageously, continuously identified vessels can be overlaid onto the white-light image in real time, allowing previously hidden vessels to appear as augmented reality objects in the white-light image in real time.

[0017] The currently disclosed method is extremely useful for surgeons during surgery, in any organ, and for any indication, especially when the structure and anatomy of blood vessels are of concern. It can also be used in plastic surgery to assess, for example, the vascular and anatomical structures of a flap to be transplanted, where it can provide information about where the flap should be dissected. Similarly, once the flap has been transplanted to the recipient, it can provide important information about the vascular structure and the success of vascular anastomosis.

[0018] The currently disclosed methods used in surgical procedures can be considered as surgical decision support. However, the use of the currently disclosed methods is not limited to use during surgical procedures. The currently disclosed methods can also be advantageously used to provide information about vascular structures and anatomy before or after surgery, or even to monitor wound healing and vascular anatomy in patients who have not undergone surgery at all. In these cases, the currently disclosed methods can be considered as medical examination tools much like CT scans.

[0019] This disclosure also relates to a computer program (product) having instructions that, when executed by a computing device or computing system, cause the computing device or computing system to perform the method of identifying blood vessels in a tissue as disclosed herein. Attached Figure Description

[0020] Figure 1A An example of an intensity profile is shown after the ICG bolus has been delivered to the object. Figure 1B The corresponding intensity curves are shown, in which the hemodynamic parameters perfusion slope, slope start, slope end, maximum intensity, elution slope, elution start, and elution slope end have been calculated and indicated in the figure.

[0021] Figure 2A The oscillation time-intensity fluorescence curves are shown, where the oscillations are disrupted due to ischemic attacks in human subjects.

[0022] Figure 2B This is a magnified view of the time interval around t=3800s in the previous figure, where an ischemic attack occurred.

[0023] Figure 2C Idealized data with and without ischemia are shown.

[0024] Figure 2D The data shown are idealized, in which only a portion of the oscillation time-intensity fluorescence curve can be detected.

[0025] Figure 3A Continuous measurements of human subjects injected with micropumps are shown.

[0026] Figure 3B It shows Figure 3A A magnified view of the area indicated in the middle.

[0027] Figure 4 Measurements are shown in a person who has suffered from venous obstruction, where blood flow is only partially restricted.

[0028] Figure 5AThis image shows a snapshot of an ICG analysis tool running on a humanoid subject (right forearm). The image was taken at a very early stage, with the micro-injection of ICG just being administered and beginning to enter the artery.

[0029] Figure 5B It shows a ratio Figure 5A A snapshot taken a few seconds later can identify multiple arteries.

[0030] Figure 6A It shows a ratio Figure 5B A snapshot taken a few seconds later shows the fluorescence intensity from a specific micro-injection agent, ICG, reaching its peak.

[0031] Figure 6B It shows a ratio Figure 6A A snapshot taken approximately one minute later shows the washout phase, where veins can be identified.

[0032] Figure 7 It shows Figure 6B The edge filtering version.

[0033] Figure 8 It shows in Figures 5A to 6B The images shown in the sequence have already identified the arteries.

[0034] Figure 9 It shows Figures 5A to 6B The images shown in the sequence already identify the veins.

[0035] Figure 10 The image is shown, in which Figures 8 to 9 The arteries and veins shown are visually enhanced in red (arteries) and blue (veins) and superimposed in the image, making them easily distinguishable. Detailed Implementation

[0036] One embodiment of this disclosure relates to a computer-implemented method for identifying blood vessels in a tissue, for example, during a medical procedure, the method comprising the steps of: continuously receiving fluorescence signals from blood vessels in the tissue, wherein the intensity of the fluorescence signals oscillates in a predetermined pattern; continuously acquiring fluorescence images of the tissue; and analyzing the fluorescence images and associated oscillation intensities to continuously identify blood vessels in the tissue.

[0037] The predetermined pattern may be characterized by having a predetermined frequency with a period between 30 seconds and 15 minutes (e.g., between 1 and 10 minutes, or between 1-2 minutes, 2-3 minutes, 3-4 minutes, 4-5 minutes, 5-6 minutes, 6-8 minutes, or 8-10 minutes within a time period of at least 10 minutes, or at least 15 minutes, or at least 30 minutes, or at least 1 hour, or at least 2 hours), and wherein the fluorescence signal oscillates in intensity according to the predetermined pattern. Also as explained herein, the predetermined pattern may originate from the controlled injection of a series of small boluses of at least one fluorophore (e.g., ICG).

[0038] In a preferred embodiment, the identified blood vessels are displayed and visualized continuously on a screen, for example. Furthermore, the identified blood vessels can be combined to identify one or more networks of interconnected blood vessels.

[0039] It can also continuously receive and acquire white light images of the tissue. Therefore, at least one white light image of the tissue can be generated, wherein, for example, the identified blood vessels are visually enhanced by superimposing them onto the white light image, preferably also by means of high-contrast colors, and the identified blood vessels are displayed on a screen, making the identified blood vessels appear as augmented reality objects.

[0040] A preferred embodiment of the currently disclosed method includes the step of distinguishing between arteries and veins within identified blood vessels, this distinction advantageously based on a predetermined pattern of oscillating fluorescence signals. The hemodynamics of bolus injections in arteries and veins are different, and when a bolus of, for example, ICG is administered through the patient, the fluorescence signal will initially appear in the artery, then in the microcirculation of the surrounding tissue, and after a period of time in the vein. Therefore, the time difference between bolus injection, arterial signal, tissue signal, and venous signal can be determined, for example, by analyzing a series of corresponding images and searching for signals in the following order: the first bolus or the first few boluses. That is, the novel microbolus dosing schemes currently in use provide a large amount of available temporal and / or wavelength dynamics. Because only one or a few microboluses of contrast agent are needed to determine the patient-specific / condition-specific time difference between bolus injection and arterial signal, and between arterial and venous signals, these time differences can be used in subsequent controlled microbolus administrations to continuously distinguish between arteries and veins. The time differences between arterial and tissue signals, and between tissue and venous signals, can also be utilized. Furthermore, the washout period of each micropump involves different hemodynamics of arteries, veins, and surrounding tissues, and these different hemodynamics can be used to identify blood vessels and distinguish between arteries and veins even during the washout period between injections.

[0041] One example of identifying blood vessels in a fluorescence image is by means of image filtering, preferably edge filtering, on the acquired fluorescence image. Due to oscillating fluorescence signals and hemodynamics in the tissue, there will almost always be regions in the acquired image where the image brightness changes drastically (i.e., the image is discontinuous). These regions are most commonly arteries or veins, so by continuously applying appropriate image filtering, blood vessels will appear substantially constant during successive administrations of the bolus.

[0042] Another, more accurate method identifies blood vessels based on the inherent phase difference between fluorescence signals associated with blood vessels and surrounding tissues, respectively. This is due to hemodynamics within the subject / patient. As disclosed herein, the overall oscillating fluorescence signal is applied through controlled and repeated injections of small boluses of a fluorophore (e.g., ICG). Due to the subject's hemodynamics, each bolus of the fluorophore will also produce a different fluorescence signal at a more localized level. The fluorophore from each small bolus will reach the artery, tissue, and vein at different time points, and thus the currently disclosed method utilizes these time differences to identify blood vessels, distinguish between blood vessels and tissues, and distinguish between arteries, veins, and tissues. The time difference between fluorescence signals originating from arteries, tissues, and veins, respectively, can be viewed as a phase difference within a continuously evolving fluorescence signal. That is, at any time during the oscillating fluorescence signal, a phase difference exists at different locations in the corresponding acquired fluorescence image due to the different hemodynamics in the arteries, veins, and surrounding tissues (i.e., due to the inherent time difference derived from the subject's hemodynamics). The object-specific time difference is known, or the first of several bolus injections can be used to determine the object-specific time difference; that is, determining at least one time difference selected from the group consisting of: the time difference between bolus injection and arterial or venous fluorescence signals, the time difference between arterial and venous fluorescence signals, and the time difference between arterial or venous fluorescence signals and tissue fluorescence signals. One or more of these time differences can be “converted” into a corresponding phase / phase difference or one or more of blood vessels, arteries, veins, surrounding tissues, and / or other things. Therefore, knowing the expected phase of arteries, veins, and surrounding tissues allows each pixel or ROI in the fluorescence image to be associated with the classification of arteries, veins, surrounding tissues, or other things.

[0043] The expected phase of arteries, veins, and surrounding tissues at a given time point can be directly correlated with a predetermined oscillation pattern that determines the period and frequency of the oscillating fluorescence signal. The expected phase can be approximated, calculated, and / or determined during a medical procedure, for example, as an initial learning period, where the oscillating fluorescence signal is observed for one or more micropumps to measure hemodynamics associated with a specific condition. Therefore, the expected phase of arteries, veins, and surrounding tissues can be directly correlated with the time point of injection of the bolus. Thus, in subsequent medical procedures, the time point of each bolus injection provides information on the expected phase of arteries, veins, and surrounding tissues.

[0044] Therefore, a preferred embodiment of the currently disclosed method includes the steps of: determining the phase difference between a fluorescence signal originating from an artery in the tissue and a fluorescence signal originating from a vein in the tissue and optionally a fluorescence signal originating from tissue surrounding the blood vessels, and correlating the phase difference with a predetermined oscillation mode.

[0045] Therefore, analyzing the phase and / or phase difference in a sequence of fluorescence images is one way to identify blood vessels in fluorescence images. That is, by knowing the phase of the fluorescence signal, blood vessels in a sequence of fluorescence images can be identified / detected at the pixel-by-pixel level—this can be done at any time during a micro-injection dosing regimen. This phase information, combined with knowledge of the predetermined injection administration (i.e., the fluorescence signal oscillating in a predetermined pattern), provides the necessary information as to whether a pixel or region of interest in the image is a blood vessel, or even whether a pixel or region of interest in the image is an artery, vein, tissue, or something else. Thus, the actual drawing of blood vessels (including arteries and veins) in essentially every fluorescence image can be provided, for example, pixel-by-pixel, by pixel group, or by ROI, in the form of each pixel or ROI classified as a blood vessel (preferably including arteries or veins), surrounding tissue, or optionally something else.

[0046] In summary, the currently disclosed method can provide medical personnel with a continuously updated map of blood vessels, including arteries and veins, within the anatomical region of the surgeon's field of vision / focus. Specifically, the identified arteries and veins can be overlaid onto a white light image for visual enhancement, making them visually distinguishable, for example, each with a separate high-contrast color, and displayed on the screen.

[0047] Once blood vessels are identified and possibly mapped (preferably including identified arteries and veins) in a fluorescence image or its sequence, they can be tracked in subsequent fluorescence images, even if movement (e.g., peristaltic movement) is involved. For example, tracking of identified blood vessels can be provided using tracking methods available in the prior art and known to those skilled in the art. An example of tracking in a fluorescence image is disclosed in WO2018 / 104552.

[0048] In another embodiment, the currently disclosed method further includes the step of administering a series of boluses of at least one fluorescent imaging agent into the (venous) vein of a subject, thereby generating a predetermined pattern of oscillating fluorescence intensity and / or wavelength. Preferably, the series of boluses is administered for a predetermined duration between successive boluses.

[0049] The preferred fluorescent imaging agent used is ICG, and preferably, each injection of ICG corresponds to less than 0.01 mg ICG / kg body weight, more preferably less than 0.005 mg ICG / kg body weight, even more preferably less than 0.004 mg ICG / kg body weight, even more preferably less than 0.003 mg ICG / kg body weight, even more preferably less than 0.002 mg ICG / kg body weight, and most preferably less than 0.001 mg ICG / kg body weight. This series of injections can be automatically administered by a controlled (e.g., computer-controlled) infusion pump.

[0050] The tissue being imaged can be part of the internal organs of the object. The tissue being imaged can also be part of the anatomical structures in the gastrointestinal tract (preferably selected from: the oral cavity; the pharynx; the small intestine including the duodenum, jejunum, and ileum; the stomach including the esophagus, cardia, and pylorus; and the large intestine including the cecum, colon, rectum, and anal canal). That is, the imaged tissue may undergo peristaltic movement during medical procedures.

[0051] Alternatively, the tissue being imaged can be part of the object's skin. For example, the tissue being imaged is part of the object's wound.

[0052] system

[0053] As previously stated, this disclosure also relates to a system for identifying blood vessels in tissue during a medical procedure on an object, the system being configured to...

[0054] - Continuous generation of fluorescent signals from blood vessels in the tissue, wherein the intensity of the fluorescent signal oscillates in a predetermined pattern. - Continuously receive fluorescence images of tissues, and - Analyze fluorescence images and associated oscillation intensities to continuously identify blood vessels in tissues.

[0055] In a preferred embodiment, the system further includes a controllable injection pump for containing at least one first fluorescent imaging agent, the injection pump being configured to inject a predetermined series of boluses of the first fluorescent imaging agent into a vein of the subject, thereby generating a fluorescent signal oscillating in a predetermined pattern.

[0056] Fluorescence images can be received by a suitable imaging unit that may be part of the currently disclosed system, such as a camera, for example, a surgical laparoscope or microscope camera, such as a video camera. Analysis can be provided locally by the processing unit or as part of a cloud service.

[0057] The currently disclosed system can be configured to execute all steps of the currently disclosed method.

[0058] Preferably, the predetermined injection agent corresponds to a first fluorescent imaging agent of less than 0.01 mg ICG / kg body weight. The predetermined injection agent may also correspond to a first fluorescent imaging agent of less than 0.5 mg ICG. Preferably, the fluorescent agent is ICG, and preferably, the amount of ICG in the predetermined injection agent is less than 0.01 mg / kg of the subject's body weight. Therefore, preferably, the amount of ICG in the predetermined injection agent is less than 1 mg ICG or less than 0.5 mg ICG.

[0059] The system can be configured to inject the propellant at intervals between 5 and 600 seconds, for example, between 15 and 300 seconds, for example, between 45 and 210 seconds, for example, between 90 and 120 seconds.

[0060] Another advantage of the currently disclosed method is the opportunity to identify local vascular networks. By briefly clamping a freely visible vessel, the associated perfusion area is defined, and the associated network becomes clearly visible by subsequently observing fluctuating ICG signals, as the perfusion in that area changes rapidly.

[0061] Intraoperative fluorescence imaging

[0062] Intraoperative imaging and real-time assessment of perfusion (e.g., blood flow) can be performed using near-infrared light from a surgical microscope or camera and by acquiring video of fluorescence excited in the near-infrared region by a fluorescent contrast agent that has been administered intravenously as a tracer. This allows for real-time confirmation of the perfusion status during surgery. In this disclosure, perfusion in the vessel is used to identify the vessel using fluorescence imaging, but is not necessarily limited to the intraoperative use of a surgical camera.

[0063] The currently disclosed systems and methods can provide enhanced tissue characteristic information, including the location of superficial and deep vessels, especially when using different fluorophores, as careful selection of different fluorophores provides options with perfusion information from different depths within the tissue.

[0064] During medical procedures, such as diagnostic, screening, examination, and / or surgical procedures involving fluorescence imaging, a solvent comprising a fluorescent contrast agent (e.g., ICG) is injected intravenously, and the molecules are excited by an infrared light source, such as a laser with a wavelength in the infrared wavelength range (e.g., about 780 nm). Fluorescence at a wavelength of about 830 nm is then emitted from the excited contrast agent molecules and can be recorded using an imaging device, such as a camera. Filters can be provided to block the excitation light, as the excitation intensity is typically much greater than the fluorescence intensity. The excitation intensity per emission angle can be about 1 W, while the fluorescence power per pixel can be about 0.15 pW. Despite these size differences of several orders of magnitude, a good signal-to-noise ratio (SNR) can still be achieved. The recorded fluorescence provides an image of perfusion in the imaged tissue, and because ICG has a penetration depth of 5–10 mm, it allows visualization of blood vessels located deeper within the tissue. Because ICG molecules bind to proteins in the blood, the video images contain information about the perfusion level—information that surgeons may find difficult to quantify during surgery if they only see the acquired video images.

[0065] In the systems and methods disclosed herein, the fluorescent contrast agent is selected from the group consisting of indocyanine green (ICG) and fluorescein isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, phthalaldehyde, fluorescein, rose red, trypan blue, fluorescein, green fluorescent protein, flavin, methylene blue, porphyrin, anthocyanin dye, IRDDye800CW, CLR1502 bound to a target ligand, OTL38 bound to a target ligand, or combinations thereof.

[0066] Indocyanine green (ICG) is an anthocyanin dye used in medical diagnostics and is by far the most commonly used dye for perfusion assessment. It has a peak spectral absorption at approximately 800 nm. These infrared frequencies penetrate the retinal layer, allowing ICG angiography to image deeper circulatory patterns than fluorescence angiography. ICG binds tightly to plasma proteins and becomes localized to the vascular system. It is administered intravenously and, depending on liver function, is excreted from the body through the liver into the bile, with a half-life of approximately 3–4 minutes. Sodium ICG is usually supplied in powder form and is soluble in a variety of solvents; typically, 5% (<5%, depending on the batch) of sodium iodide is added to ensure better solubility. Sterile lyophilized water-ICG solutions are approved in many European countries and the United States under the names ICG-Pulsion, IC-Green, and VERDYE as diagnostic agents for intravenous use.

[0067] The absorption and fluorescence spectra of ICG are in the near-infrared region. Typically, a laser with a wavelength of approximately 780 nm is used for excitation. At this wavelength, the fluorescence of ICG can be detected by filtering out the scattered light from the excitation beam.

[0068] ICG toxicity is classified as low, but administration is not without risk, for example, during pregnancy. It is known that ICG decomposes into toxic waste under UV light, producing many substances that remain unknown. Therefore, as demonstrated in this paper, minimizing the dose of ICG used during fluorescence imaging is in the patient's best interest.

[0069] Fluorescein is another dye widely used as a fluorescent tracer in many applications. Fluorescein has maximum absorption at 494 nm and maximum emission at 512 nm (in water). Therefore, it is suitable for use in combination with ICG, as the absorption and emission wavelengths of the two dyes are separated by hundreds of nanometers.

[0070] Dosage regimen

[0071] This disclosure also relates to a method for automated perfusion assessment of an object's anatomical structure, the method comprising administering approximately 1 / 10 of the normal dose of a bolus for perfusion assessment into a vein. For indocyanine green (ICG), the normal bolus dose is 0.1-0.3 mg / kg body weight. According to this disclosure, a bolus of a first fluorescent imaging agent (e.g., ICG) at a dose less than 0.01 mg / kg body weight, preferably less than 0.005 mg / kg body weight, more preferably less than 0.0049 mg / kg body weight, and even more preferably less than 0.0048 mg / kg body weight, even more preferably less than 0.0047 mg / kg body weight, most preferably less than 0.0046 mg / kg body weight, and even more preferably less than 0.004 mg / kg body weight can be used. For other fluorescent imaging agents described herein, the bolus dose is similarly reduced according to this disclosure. As described above, the reagent can be injected by a controlled infusion pump, for example, as a series of boluses with predetermined time intervals between subsequent boluses. After each injection of the bolus, fluorescence emission from the anatomical structure can be measured. This method for automated perfusion assessment of the subject's anatomical structures can also be combined with currently disclosed methods for continuously identifying blood vessels in tissues, particularly regarding bolus administration protocols.

[0072] The minimum bolus dose that provides quantifiable fluorescence emission representing anatomical structures and / or identifiable vessels can be determined after administering a series of increasing boluses. The boluses may include reagents with incremental or decremental amounts, for example, the amount may be increased or decreased in 10% increments from one bolus dose to the next.

[0073] Preferably, the injectable is provided as a regular series of injections, each with a predetermined and regular time interval. The interval between injections can be between 5 and 600 seconds, for example, between 5 and 300 seconds, for example, between 10 and 180 seconds, for example, between 10 and 140 seconds, for example, between 10 and 90 seconds, for example, between 15 and 80 seconds, for example, between 20 and 70 seconds, for example, between 30 and 60 seconds. In another embodiment, the interval between injections can be between 5 and 600 seconds, for example, between 10 and 600 seconds, for example, between 15 and 600 seconds, for example, between 15 and 300 seconds, for example, between 30 and 240 seconds, for example, between 45 and 240 seconds, for example, between 90 and 240 seconds, for example, between 90 and 120 seconds. Preferably, it is between 60 and 600 seconds, or between 120 and 600 seconds. Preferably, the intervals between injections are long enough to allow for measurement of the perfusion slope in the anatomical structure for each injection, preferably wherein the perfusion slope includes a slope initiation point and an elution slope.

[0074] For ICG, the amount of fluorescent imaging agent is preferably between 0.0001 and 0.001 mg / kg body weight per injection, for example, between 0.001 and 0.01 mg / kg body weight per injection, preferably between 0.0005 and 0.005 mg / kg body weight per injection, and more preferably between 0.001 and 0.004 mg / kg body weight per injection. Advantageously, the initial amount of fluorescent imaging agent is at least 0.001 mg / kg body weight, preferably less than 0.005 mg / kg body weight. Subsequent injections can then increase by at least 0.001 mg / kg body weight per injection from one injection to the next, preferably less than 0.005 mg / kg body weight. For other types of fluorescent imaging agents, the dosage is preferably selected based on their fluorescence relative to ICG. Thus, fluorescent imaging agents with higher emissivity are preferably administered at correspondingly lower doses. For example, the dose can be substantially inversely linearly proportional to the quantum yield of the fluorescent imaging agent. Dosage can also be based on the absorption and emission spectra relative to ICG.

[0075] Preferably, the injection agent has a liquid volume between 0.5 μL and 10 mL, for example, 0.5 to 5 mL. That is, this amount of the first fluorescent imaging agent is preferably dissolved in the liquid. In a preferred embodiment of this disclosure, an isotonic solution (e.g., saline) is injected immediately after the injection of the fluorescent imaging agent injection agent, for example, wherein the volume of the isotonic solution is 1-20 mL, for example, 2.5-15 mL, for example, 5-10 mL.

[0076] In another embodiment of this disclosure, a second fluorescent imaging agent is applied, the second fluorescent imaging agent having an emission maximum value that differs from the emission maximum value of the first fluorescent imaging agent by at least 50 nm or at least 100 nm. Preferably, the first and second fluorescent imaging agents are applied alternately. Advantageously, the interval between the application of different fluorescent imaging agents is half the interval between subsequent applications of the same fluorescent imaging agent.

[0077] In another embodiment of the currently disclosed method, a series of fluorescence images of the anatomical structure and / or tissue are formed for assessment of perfusion and / or identification of blood vessels. Fluorescence can be automatically detected by irradiating the anatomical structure / tissue with a light source capable of exciting a fluorescent imaging agent, and emission can be quantified and / or analyzed using a series of fluorescence images of the anatomical structure / tissue.

[0078] The time interval between injections can be determined by a computer configured to detect the perfusion slope caused by each injection. Furthermore, the amount of fluorescent imaging agent in the injection can be controlled by a computer configured to determine the minimum injection amount corresponding to the minimum fluorescence emission representing the perfusion of the anatomical structure. This computer may be part of a currently disclosed system.

[0079] In another embodiment, perfusion assessment includes determining the location of perfusion complications within anatomical structures. Therefore, perfusion assessment can be used in conjunction with diagnostic or surgical procedures, such as diagnostic laparoscopy, exploratory laparoscopy, surgical laparoscopy with conventional laparoscopy, robotic surgery, and open surgery. Alternatively, the procedure may include creating anastomoses, such as intestinal anastomoses, wound repairs, plastic surgery, cardiac surgery, or cancer surgery.

[0080] Another embodiment of this disclosure relates to a fluorescent imaging agent used in the methods disclosed herein. Yet another embodiment relates to the use of the fluorescent imaging agent in the preparation of a medicament for use in automated perfusion assessment and / or continuous identification of blood vessels as disclosed herein.

[0081] In another embodiment of this disclosure, the fluorescent developer is re-injectable. In some cases, a longer phase may be required, such as at least 2 minutes, preferably at least 3 minutes, even more preferably at least 4 minutes, even more preferably at least 5 minutes, almost most preferably at least 8 minutes, and most preferably at least 10 minutes, during which the fluorescent developer is not injected to allow it to be washed away, thereby reducing the background level. Once the background level has decreased to an acceptable level, such as below a certain percentage of the maximum fluorescence intensity or until fluorescence is substantially unmeasurable, the injection of the fluorescent developer can continue.

[0082] The currently disclosed system can be configured to execute the currently disclosed method. This can be provided by a system having at least one processor and a memory thereon storing instructions that, when executed by one or more processors, cause the system to execute the currently disclosed method for automated perfusion assessment of anatomical structures.

[0083] Oscillation Dynamics

[0084] The inventors have also recognized that the measurement and analysis of repeatable bolus injections can be additionally extended from the interpretation and quantification of single inflow and / or single effluent phases to the analysis of oscillatory fluorescence dynamics. These oscillatory fluorescence dynamics can reveal physical perfusion characteristics that have been impossible to achieve without invasive procedures until now.

[0085] The currently disclosed systems and methods can be configured to repeatedly inject small boluses, such as minimum boluses, at regular intervals. Depending on, for example, the injection time interval, these boluses may cause cyclic variations that, when measured, exhibit an approximate sinusoidal form. In such a curve, the expected measured intensity signal increases with the inflow of a fluorescent imaging agent from a given bolus, then decreases during the elution phase of the bolus, until it increases again in subsequent boluses, and so on, thus producing a periodic (sinusoidal) pattern.

[0086] Preferably, the currently disclosed system can be configured to identify parameters of the oscillation intensity curve, such as frequency and / or amplitude. The trained system can then predict the direction and regularity of upcoming signal dynamics. Preferably, the system uses measurements to identify oscillation patterns, enabling the system to subsequently detect differences between the measurements and expected values. The measurements can also be continuously used to improve pattern recognition, i.e., the expected values. Alternatively or additionally, injection parameters such as injection frequency, dosage, and flow rate can be used to determine the expected values, i.e., the oscillation patterns.

[0087] By predicting expected values ​​through the system, the onset of ischemic conditions can be detected and alerted at an early point in time (ideally instantaneously). Detection of ischemic conditions can be a function of one or more expected values ​​and one or more detection values, such as a threshold. However, with currently available methods of continuously identifying blood vessels, relevant medical personnel can visually observe ischemic conditions or any type of damage or rupture in blood vessels or vascular networks almost immediately.

[0088] The difference from the expected sinusoidal pattern may be caused by, for example, the onset of ischemic conditions in at least a portion of the anatomical structure / tissue visible in a video image, or by regional changes in perfusion to a given area. Figure 2A The text provides an explanatory diagram illustrating this change in dynamics caused by the onset of ischemia in human subjects. Figure 2B A narrower scaling is provided. As can be seen, a transition from regular oscillating fluorescence signals to ischemic flat lines can be detected. However, it should be noted that perfusion changes in the anatomical structures of interest may result in other measurement patterns besides ischemic flat lines. An example is venous occlusion, where blood outflow from the anatomical region is blocked or reduced, leading to changes in oscillatory dynamics due to blockage or accumulation of fluorescein in a given area. Figure 4 As seen in the diagram, when the periodic oscillations stop, the result is not a flat line.

[0089] As described in this paper, this system can observe and detect changes in perfusion levels in a given region of a video image within seconds. This can be detected in regions that have been observed for extended periods (e.g., many minutes), where dynamics have been continuously visualized and therefore the phase is known. Interpretive diagrams are provided in... Figure 2C As shown in the figure, this highlights the differences in signals that can be expected between ischemic / healthy tissue regions. However, it can also be determined in anatomical regions visualized only over short time intervals (e.g., 10–20 seconds), because the described system is trained to anticipate and detect a phase of the described oscillatory dynamics signal in the tissue at a given time, a phase consisting of regular rises and falls in the time-intensity signal. See also Figure 2D It shows how the phase might look when the recorded image drifts into and out of focus on the anatomical region of interest.

[0090] Preferably, the system includes a tracking device and can operate independently in the background, while the surgeon is only exposed to a visible white light signal and is therefore only interrupted / notified by a warning signal. For example, during the detection of an ischemic attack.

[0091] Another aspect of this disclosure relates to continuous perfusion assessment associated with repeated injections of a fluorescent active agent and the resulting oscillation curves. In addition to detecting unpredictable changes in perfusion, the system can also be used to assess perfusion areas of arteries. As an example, a surgeon may consider incising an artery as part of a surgical procedure. Before incising the artery, the surgeon may temporarily restrict perfusion through said artery, and the currently disclosed method allows visualization of the perfusion area of ​​said artery for a short period of time (e.g., less than 1 minute). This can be valuable information for the surgeon during ongoing surgical procedures. In a similar manner, the system can be used to assess drainage areas of veins or groups of veins, lymphatic vessels, lymph nodes, or other parts of the circulatory and / or lymphatic pathways. By temporarily restricting blood flow through a vessel, blood will pool in the anatomical area normally drained by that vessel or group of vessels. This allows visualization of the anatomical area drained by the vessel for a relatively short period of time (e.g., less than 2 minutes). This can provide important information to the surgeon, for example, during ongoing surgical procedures in fields such as general surgery and plastic surgery, including wound and reconstructive surgery.

[0092] Gastrointestinal tract

[0093] Gastrointestinal complications are often associated with local hemodynamics. That is, changes in normal hemodynamic conditions may be an indicator of an increased risk of complications. Therefore, when examining the gastrointestinal tract, for example, to diagnose or locate complications, such as during diagnostic laparoscopy, exploratory laparoscopy, or surgical laparoscopy with conventional laparoscopy, or robotic surgery, and in open surgery, perfusion assessment of the gastrointestinal tract, particularly in and near the surface of the gastrointestinal tract, such as the tissue of the gastrointestinal wall, can be an important diagnostic tool. Perfusion assessment is also important during surgical procedures that create anastomoses, which can be provided to establish communication between two formerly distant portions of the gastrointestinal tract. As an example, intestinal anastomoses establish communication between two formerly distant portions of the intestine and typically restore intestinal continuity after removal of pathological conditions affecting the intestinal tract. For example, intestinal anastomoses can be provided to 1) restore the continuity of the intestine (e.g., the intestinal tract) after resection of a diseased portion of the intestine, and 2) bypass an unresectable diseased portion of the intestine (e.g., the intestinal tract). Intestinal anastomoses may also be required in certain pediatric conditions [6].

[0094] Resection of the diseased bowel segment can be performed in the following situations: Gangrene of the intestinal tract caused by vascular damage due to mesenteric vascular disease, long-term intestinal obstruction, intussusception, or volvulus. Malignant tumors Benign conditions (such as intestinal polyps, intussusception, ascariasis with intestinal obstruction) Infection (e.g., tuberculosis complicated by stenosis or perforation) Traumatic perforation Large perforations that cannot be repaired with primary suture (traumatic) Radiation enteritis complicated by bleeding, stricture or perforation Inflammatory bowel disease, ulcerative colitis, or Crohn's disease that is unresponsive to medication or associated with complications (such as bleeding, perforation, toxic megacolon, dysplasia / cancer). Chronic constipation, idiopathic slow transit constipation, or congenital megacolon: When the disease is difficult to treat with medication, subtotal colectomy may be performed.

[0095] Unresectable diseased bowel segments can be bypassed in the following situations: Locally advanced tumors causing luminal obstruction Metastatic diseases leading to intestinal obstruction Poor overall condition or inability to undergo major resection Pediatric conditions that may require intestinal anastomosis include the following: Congenital abnormalities (e.g., Meckel's diverticulum, intestinal atresia, intestinal malrotation with volvulus leading to gangrene, meconium ileus, duplicated cysts, congenital megacolon) Inflammatory conditions (e.g., necrotizing enterocolitis, pulmonary tuberculosis, intestinal perforation) Other conditions (e.g., intussusception, vascular dysplasia, polyposis, ascariasis). As part of other surgical procedures (e.g., Kasai portosystemic anastomosis, choledochal cyst, urinary diversion, pancreatic tumors). Unfortunately, postoperative complications associated with gastrointestinal anastomosis are common, often due to insufficient perfusion (capillary blood supply) at the anastomosis site (the junction of the two parts of the intestine). Insufficient perfusion can lead to anastomotic leakage, a serious and common complication, for example, associated with colorectal surgery, where it occurs in over 10% of procedures. In colon cancer surgery, over 30% of patients with anastomotic leakage die from postoperative complications, and of the remaining patients, 25% suffer from the stoma for the rest of their lives. Risk factors associated with leakage include anastomotic tension, tissue damage, and particularly reduced blood perfusion.

[0096] Therefore, in one embodiment, this disclosure relates to image analysis of one or more video sequences representing at least a portion of the gastrointestinal tract, acquired, for example, before, during, and / or after surgery (particularly surgery involving the gastrointestinal tract). This can be particularly applicable to gastrointestinal surgery—the video sequences can therefore be included in the external portion of at least a portion of the gastrointestinal tract, preferably making it possible to measure and assess perfusion in at least a portion of the gastrointestinal wall.

[0097] The gastrointestinal tract is an organ system in humans and other animals that ingests food, digests it to extract and absorb energy and nutrients, and excretes waste products as feces and urine. The gastrointestinal tract can be viewed as a tube that transfers food to the digestive organs. Therefore, the term "gastrointestinal tract" as used herein includes the oral cavity; the pharynx; the small intestine, comprising the duodenum, jejunum, and ileum; the stomach, comprising the esophagus, cardia, and pylorus; and the large intestine, comprising the cecum, colon, rectum, and anal canal.

[0098] Clinical application

[0099] The visualization of vascular anatomy as disclosed herein is crucial during virtually any type of surgery, as continuous monitoring of blood vessels reduces the risk of accidental vascular rupture. In particular, the currently disclosed systems and methods can also be used in the following clinical applications: Abdominal / General Surgery Resection surgery is used to quickly locate the correct blood vessel to be cut / ligated. Ischemic bowel surgery is used to quickly identify which and where blood vessels are blocked and anatomical structures are under-perfused.

[0100] Acute abdomen is used to help identify underlying pathology, such as ruling out ischemia.

[0101] Repeat surgery is performed on patients with numerous surgical adhesions who have previously undergone surgery.

[0102] Cancer surgery performed by a general surgeon to detect blood vessels, such as during resection.

[0103] A routine surgery basically involves any organ in the abdomen, such as when performing an anastomosis or surgery on the stomach (ventricle).

[0104] A routine surgical procedure, whether involving infection, superficial or deep, to examine blood vessels and create a vascular map.

[0105] Thyroid surgery Thyroid surgery involves the removal of thyroid tissue. Continuous monitoring of blood vessels is a major advantage because thyroid surgery carries the risk of excessive bleeding. Thyroid surgery also carries the risk of dissecting or removing a portion of one or more parathyroid glands, and currently available methods can be used to identify and map blood vessels in the relevant area, making it easier for surgeons to visualize the parathyroid glands.

[0106] pelvic surgery Gynecological / urological surgery to quickly locate the correct blood vessel to be cut / ligated, and to identify and differentiate blood vessels during the procedure.

[0107] Cancer surgery to examine blood vessels.

[0108] Plastic Surgery Skin grafts are used to quickly locate the correct blood vessel in the donor to be cut / ligated and to monitor perfusion of the same blood vessel in the recipient; whether in an emergency during surgery or in the days that follow, to monitor healing and angiogenesis.

[0109] In all the skin near surgical sites, additional information is required from the surgeon to detect and map vascular structures in the anatomical region before and during surgery, as deemed necessary. Specifically, the currently disclosed method can be used as a clinical tool to identify and map a patient's blood vessels and associated vascular anatomy several days or weeks before surgery, allowing medical personnel time for careful surgical planning. This mapping can be performed according to the currently disclosed method, which measures fluorescence signals through the skin in the area of ​​interest for, for example, 30-45 minutes, and creates 2D or 3D maps for use by medical personnel in planning. The maps of identified vessels can be combined with other examinations, such as CT scans, MR scans, or ultrasound scans. A key advantage of the currently disclosed method is that it allows the identification and mapping of vessels that are too small to be accurately mapped in, for example, CT scans.

[0110] Eating throat and neck surgery

[0111] Various surgeries include: facial plastic surgery, tracheostomy, cancer treatment, etc.

[0112] Orthopedic surgery Amputation is performed to quickly identify and map blood vessels before amputation is carried out in lame or anatomical areas, in order to select the correct amputation site and the best location for re-closing the skin to ensure optimal healing.

[0113] Infections, etc., so as to detect and map blood vessels where debridement or similar procedures are required.

[0114] Heart surgery

[0115] CABG is used to quickly identify and locate peripheral vessels of the heart during bypass surgery.

[0116] Vascular surgery

[0117] Amputation surgery, in order to quickly identify and locate the correct blood vessel to be cut / ligated, as described above, To collect blood vessels for bypass surgery in order to quickly identify and locate the correct blood vessel to be cut / ligated.

[0118] Example

[0119] Figures 1A to 1B The intensity curves shown are the results of injecting a normal amount of fluorophore (ICG in these cases) into the bolus. The amount of ICG in each bolus is chosen such that the fluorescence emission is visible to the human eye. These examples are provided to illustrate various perfusion parameters that can be calculated after fluorescence imaging. These same parameters can also be largely determined after injecting much smaller doses, i.e., the microdose method disclosed herein, utilizing potentially repeatable and continuous measurements, along with associated perfusion assessments and vascular identification.

[0120] Figure 1A An example of an intensity curve obtained from tissue after ICG bolus is presented, for example, from a region of interest in a video sequence. The same type of data can be obtained if another contrast agent is used. The intensity is essentially zero until a sharp increase indicates that ICG molecules have passed through the imaged tissue and have been excited to fluoresce. This is followed by a gradual elution of the ICG molecules. Intensities are expressed in arbitrary units.

[0121] Figure 1BThe corresponding intensity curves are shown, in which the hemodynamic parameters of perfusion slope, slope start, slope end, maximum intensity, elution slope, elution start, and elution slope end are calculated and illustrated in the figure. The evaluation of the perfusion parameters is further disclosed in pending application WO2018 / 104552, which is incorporated herein by reference in its entirety.

[0122] Figure 2A Actual measurement data from human subjects are shown. Micropumps of ICG were repeatedly administered to human subjects at regular intervals (approximately 2 minutes in this example). The initial micropump of ICG consisted of an amount of 0.00456 mg ICG / kg human subject body weight, and each subsequent micropump of ICG consisted of the same amount of 0.00456 mg ICG / kg human subject body weight. The time-intensity curve shows a substantially sinusoidal pattern of linear increase with time. The increase in intensity over time is related to the ratio between the fluorophore dose and the elution time, during which the fluorescence intensity decreases. At a certain time point, in Figure 2B At approximately t=3800s, perfusion is restricted, leading to ischemic episodes, which can be seen from the lack of oscillations after this time point, forming a line that can be described as an ischemic flat line.

[0123] Figure 2C Idealized data showing a sinusoidal time-intensity curve are presented. The measured ROI intensity increases after injection of the fluorescent developer and decreases during the elution phase. At approximately t=3750s, due to the onset of ischemic conditions, the measured data show a fixed measured ROI intensity value. Alternatively, in the absence of ischemic conditions, the measurements are expected to follow the dashed line, such that the measured ROI values ​​continuously follow a sinusoidal pattern.

[0124] Figure 2DIdealized data showing a sinusoidal time-intensity curve without ischemic conditions is illustrated, where the anatomical region of interest drifts in and out of focus. If the ROI will be continuously observable, the dashed line indicates the expected measurement. If this is not possible, for example, due to the anatomical region of interest drifting in and out of focus of the recorded image, the measured data may be incomplete, or gaps may exist—time intervals where no measurement data for the anatomical region of interest is acquired. Therefore, even in the case of incomplete recorded data, the system is preferably able to identify the sinusoidal pattern because the phase of the dynamics is known. If the system can correctly identify the sinusoidal pattern, it provides the expected intensity value of the ROI at each time point, which can then be used for comparison with the measured value. If one or more measured values ​​differ from one or more expected values, the system can be configured to provide an alert to the surgeon. Thus, the system can be configured to identify the phase of the oscillation / sinusoidal pattern at the time point or interval of measurement and then compare it with the expected phase at that time point or interval, wherein the expected phase is preferably based on the identified oscillation pattern and / or the known frequency of repeated bolus injections. Therefore, the system does not necessarily require continuous measurements. Instead, it can combine the expected phase of the oscillation mode with the time information of the measured time points or intervals, so that a specific phase of the expected oscillation mode will appear in the measured intervals.

[0125] Figure 3A Fluorescence intensity measurements of human subjects were shown over extended time intervals of approximately 40 minutes, during which the subjects were repeatedly injected with micropumps of ICG. The initial micropump of ICG comprised an amount of 0.006 mg ICG / kg human subject body weight, and each subsequent micropump of ICG comprised the same amount of 0.006 mg ICG / kg human subject body weight. The intensities of seven independent regions of interest (ROIs) were measured and have been assigned individual colors in the graph. The measured fluorescence intensities exhibit a periodic sinusoidal pattern, with a frequency consistent with the injection frequency (approximately 120 seconds). Due to the relatively short injection duration compared to the dose size, the pattern increases substantially linearly due to the accumulation of the fluorescent imaging agent. At approximately t = 2000 s, the repeated injection of the fluorescent imaging agent was stopped, resulting in an approximately exponential decay of the fluorescence intensity.

[0126] Figure 3B It shows Figure 3A A magnified view of the marked area. Here, smaller fluctuations can be seen within the same ROI and between different ROIs. Furthermore, while the patterns within each ROI have the same period, the intensity of the periodicity varies.

[0127] Figure 4A time-intensity plot of measurements taken on human subjects via repeated micro-injections of a fluorescent imaging agent is shown. The initial micro-injection of ICG consisted of an amount of 0.00456 mg ICG / kg body weight of the human subject, and each subsequent micro-injection of ICG consisted of the same amount of 0.00456 mg ICG / kg body weight of the human subject. The plot illustrates the result of venous occlusion, where perfusion was restricted, but not completely blocked, between approximately t = 62–78 minutes. In this case, the oscillatory dynamics of the measured fluorescence intensity ceased, and the measurements showed an irregular increase during venous occlusion. Therefore, it should be noted that reduced perfusion does not necessarily result in a flat line, which is typically a result of ischemic conditions.

[0128] Figure 5A A snapshot of the ICG analysis tool running on a humanoid object is shown. Figure 5 to Figure 10 The image obtained shows a segment of the right forearm, where fluorescent signals are visible through the skin of the arm. Figure 5A The images in the image were taken at a very early stage of ICG injection, where the micro-pump of ICG has just been administered and begun to enter the arteries, i.e., some arteries can be identified. The four boxes in the image indicate the measurement areas, i.e., regions of interest (ROIs), and four ICG intensity curves are shown on the right, one for each ROI. One ROI is located on an artery, and the corresponding intensity curve is the highest. One ROI is located on a tissue area, and the associated intensity curve shows that some ICG has diffused into the tissue. Two ROIs are located on veins and are almost flat, indicating that the ICG has not yet left the tissue area to be delivered back through the vein. The intensity curves of the two venous ROIs overlap and are indistinguishable from each other. The phase difference of the four ICG intensity curves is clearly visible. Therefore, if the expected phases of the arteries, veins, and tissues are known, then... Figure 5A The four ROIs can be classified as arteries, veins, and surrounding tissues, respectively.

[0129] Figure 5B It shows a ratio Figure 5AA snapshot taken a few seconds later, in which multiple arteries can be visually identified. Several dark areas remain where ICG has not yet diffused, meaning the ICG is still entering the object. All four ICG intensity curves for the four ROIs are steadily increasing. However, as can be seen from the curves, there are significant phase differences in the three groups of curves: 1) arteries, 2) tissue, and 3) veins. The artery ROI leads the other two groups. The tissue ROI is "behind" the artery curve. The tissue ROI "leads" the vein ROI. Note that the phase differences in the two directions are more or less equal, meaning the tissue is approximately halfway through the ICG molecular journey from artery to tissue to vein. Similarly, if the expected phase is known, the ROI can be classified as artery, vein, surrounding tissue, or others. This can be provided for all pixels or groups of pixels in the image; that is, if the expected phase is known, all pixels can be classified as artery, vein, surrounding tissue, or others. In other words, image filtering can provide visual identification of blood vessels, but if the phase of the individual signals relative to a predetermined oscillation pattern is known, all or most pixels in the image can be classified, i.e., more detailed information can be obtained. For example, this can be used when overlaying blood vessels onto a white light image, or when tracking objects in an image sequence is required in cases where movement (e.g., peristaltic movement) occurs.

[0130] Figure 6A It shows a ratio Figure 5B A snapshot taken a few seconds later shows the fluorescence intensity of a specific microinjection agent, ICG, reaching its peak. After this point, more ICG will begin to leave the tissue area compared to the amount that has entered. Compare this image with... Figures 5A to 5B Comparing the earlier snapshots shown, it's clear that almost the entire area is now visible. The darkest area is now the vein, which hasn't yet begun delivering ICG from the tissue. This is also reflected in the corresponding ICG intensity curve on the right. The ICG curve is still increasing, indicating it's still in the arterial-dominated phase, but the concave shape of the curve suggests that the peak intensity is approaching. However, a phase difference is still visible between the ICG intensity curves. In this snapshot, vessels are not clearly identified because too much ICG is entering the tissue area from the arteries, while not enough is entering the veins. However, veins can actually be identified as dark areas.

[0131] Figure 6B It shows a ratio Figure 6A A snapshot taken approximately one minute later shows the washout phase, where veins are clearly identified. Corresponding perfusion analysis from the associated ICG curves shows that the venous ROI has significantly the highest intensity; however, it also shows that the timescale differs during the washout phase, meaning that longer timescales may be needed to assess the phase difference between arteries, tissue, and veins during the washout phase. The phase difference is still visible in the ICG curves.

[0132] Figure 7 It shows Figure 6B An edge-filtering version of this algorithm demonstrates an example of visual enhancements that can be provided to healthcare professionals during medical procedures using currently disclosed methods. Once the phase difference for a specific situation is known, it becomes clear when arteries and veins are optimally identified separately. Figure 7 In this procedure, veins are visually enhanced, which will allow surgeons to avoid accidentally cutting any veins. Figure 7 It uses a pixel-by-pixel method and combines it with the understanding of... Figure 6B Edge filtering is applied, followed by a smoothing filter. The result is a noticeable darkening of the entire image, excluding the main veins. This information can be overlaid / superimposed on any screen the surgeon can see during surgery, including a white-light image screen, to improve the surgeon's decision-making basis.

[0133] Figure 8 It shows in Figures 5A to 6B The images shown in the sequence have already identified the arteries. Arteries are visually enhanced with black, thus making them visible in grayscale images.

[0134] Figure 9 It shows in Figures 5A to 6B The images shown in the sequence have already identified the veins. Veins are visually enhanced with black, so they are visible in grayscale images.

[0135] Figure 10 The image is shown, in which Figures 8 to 9 The arteries and veins shown are visually enhanced in red (arteries) and blue (veins) and superimposed in the image, making them clearly visible and easily distinguishable. This is an example of an augmented reality (AR) view that can be provided to surgeons during medical procedures employing the currently disclosed methods. Red pixels have been plotted to the artery group, and blue pixels to the vein group. These plots can be continuously updated as the micro-injection protocol can run in the background. In practice, a given group (e.g., the artery group) has a known phase that can be identified during the initial learning phase of the micro-injection protocol, where the arterial phase can be associated with the time point of each injection. Once the arterial phase is known, a segment of the fluorescence signal (e.g., a few seconds) is sufficient to evaluate the associated perfusion curve of one or more pixels or ROIs in the image series and calculate a phase-matching score. If the phase in a pixel / ROI matches the arterial phase, the phase-matching score is high, so the pixel can be identified as an artery and, in this case, colored in red. A similar calculation can be performed for veins. This phase-matching evaluation can be provided during both the ICG inflow and washout periods. Therefore, currently available methods for continuously identifying blood vessels in tissues can run continuously in the background.

[0136] project

[0137] 1. A computer-implemented method for identifying blood vessels in tissue (during a medical procedure) of an object, the method comprising the following steps: - Continuously acquire fluorescence images of the tissue, wherein the fluorescence signal oscillates in a predetermined pattern, and - Analyze the fluorescence images and associated oscillation signals to continuously identify blood vessels in the tissue.

[0138] 2. The method according to Project 1, wherein the identified blood vessel groups are combined to identify a network of one or more interconnected blood vessels.

[0139] 3. The method according to any one of the preceding items, wherein the predetermined pattern is characterized by having a predetermined frequency with a period between 30 seconds and 15 minutes, for example, between 1 and 10 minutes, or between 1-2, 2-3, 3-4, 4-5, 5-6, 6-8, or 8-10 minutes within a time period of at least 10 minutes, or at least 15 minutes, or at least 30 minutes, or at least 1 hour, or at least 2 hours, and wherein the fluorescence signal oscillates in intensity according to the predetermined pattern.

[0140] 4. The method according to any one of the preceding items, wherein the identified blood vessels are continuously displayed and visualized on the screen.

[0141] 5. The method according to any one of the preceding items, wherein blood vessels are identified based on the phase difference between fluorescence signals associated with blood vessels and surrounding tissues, respectively.

[0142] 6. The method according to any one of the preceding items, comprising the step of generating at least one white light image of the tissue, wherein the identified blood vessels are visually enhanced.

[0143] 7. The method according to any one of the preceding items, wherein white light images of the tissue are also continuously acquired.

[0144] 8. The method according to item 7, wherein the identified blood vessels are superimposed on the white light image, which is visually enhanced and displayed on the screen.

[0145] 9. The method according to any one of the preceding items further includes the step of: determining a phase difference between a fluorescence signal originating from an artery in the tissue and a fluorescence signal originating from a vein in the tissue and optionally a fluorescence signal originating from tissue surrounding the blood vessel, and correlating the phase difference with a predetermined oscillation mode.

[0146] 10. The method according to any one of the preceding items, wherein the sequence of acquired fluorescence images is analyzed and the pixels in the fluorescence images are classified as: 1) artery, 2) vein, 3) surrounding tissue or 4) other based on the phase of the fluorescence signal in the corresponding pixel relative to the predetermined oscillation mode.

[0147] 11. The method according to any one of the preceding items, comprising the step of: distinguishing arteries and veins in the identified blood vessels based on the predetermined pattern of the oscillating fluorescence signal.

[0148] 12. The method according to item 11, wherein arteries and veins are distinguished based on the phase difference in the associated fluorescence signals.

[0149] 13. The method according to any one of items 11-12 above, wherein the identified arteries and veins are superimposed on a white light image and visually enhanced such that the arteries and veins are visually distinguishable and displayed on the screen.

[0150] 14. The method according to any one of the preceding items, wherein blood vessels are identified and / or visualized by image filtering such as edge filtering.

[0151] 15. The method according to any one of the preceding items, wherein during the medical procedure, a series of boluses of at least one fluorescent imaging agent are provided to a vein of the subject to generate the predetermined pattern of oscillating fluorescence intensity.

[0152] 16. The method according to item 15, wherein the series of injection agents are applied, with a predetermined duration between successive injection agents.

[0153] 17. The method according to any one of the preceding items, wherein the fluorescent imaging agent is ICG and each injection of ICG corresponds to less than 0.01 mg ICG / kg body weight, preferably less than 0.005 mg ICG / kg body weight.

[0154] 18. The method according to any one of the preceding items, wherein the series of injection agents is automatically injected by a controllable injection pump.

[0155] 19. The method according to any one of the preceding items, wherein the imaged tissue is part of an anatomical structure in the gastrointestinal tract, preferably selected from: the oral cavity; the pharynx; the small intestine including the duodenum, jejunum and ileum; the stomach including the esophagus, cardia and pylorus; and the large intestine including the cecum, colon, rectum and anal canal.

[0156] 20. The method according to any one of the preceding items, wherein the imaged tissue undergoes peristaltic movement during the medical procedure.

[0157] 21. The method according to any one of the preceding items, wherein the imaged tissue is part of the internal organs of the object.

[0158] 22. The method according to any one of the preceding items, wherein the imaged tissue is a part of the skin of the object.

[0159] 23. The method according to any one of the preceding items, wherein the imaged tissue is part of a wound on the object.

[0160] 24. The method according to any one of the preceding items, wherein the image is acquired during thyroid surgery, and wherein blood vessels in one or more parathyroid glands are identified and visualized to medical personnel participating in the surgery.

[0161] 25. The method according to any one of the preceding items, wherein the at least one fluorescent imaging agent comprises indocyanine green (ICG), fluorescein isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, phthalaldehyde, fluorescein, rose red, trypan blue, fluorescein, green fluorescent protein, flavin, methylene blue, porphyrin, anthocyanin dye, IRDDye800CW, CLR1502 bound to a target ligand, OTL38 bound to a target ligand, or combinations thereof.

[0162] 26. A system for identifying blood vessels in tissue during a medical procedure on an object, the system being configured to...

[0163] - Fluorescent signals are continuously generated from blood vessels in the tissue, wherein the intensity of the fluorescent signals oscillates in a predetermined pattern. - Continuously receive fluorescence images of the tissue, and - Analyze the fluorescence images and associated oscillation intensities to continuously identify blood vessels in the tissue.

[0164] 27. The system according to item 26 includes a controllable injection pump for containing at least one first fluorescent imaging agent, the injection pump being configured to inject a predetermined series of boluses of the first fluorescent imaging agent into a vein of the subject, thereby generating the fluorescent signal oscillating in the predetermined pattern.

[0165] 28. The system according to item 27, wherein the predetermined injection agent corresponds to a first fluorescent imaging agent of less than 0.01 mg ICG / kg body weight.

[0166] 29. The system according to any one of items 27-28, wherein the predetermined injection agent corresponds to a first fluorescent imaging agent of less than 0.5 mg ICG.

[0167] 30. The system according to any one of items 27-29, wherein the fluorescent agent is ICG and wherein the amount of ICG in the predetermined injection is less than 0.01 mg / kg body weight.

[0168] 31. The system according to any one of items 27-30, wherein the fluorescent agent is ICG, and wherein the amount of ICG in the predetermined injection is less than 1 mg ICG or less than 0.5 mg ICG.

[0169] 32. The system according to any one of items 27-31, wherein the system is configured to inject the propellant at intervals between 5 and 600 seconds, for example between 15 and 300 seconds, for example between 45 and 210 seconds, for example between 90 and 120 seconds.

[0170] 33. A method for automated perfusion assessment of an anatomical structure of an object, the method comprising: administering a bolus of a first fluorescent imaging agent corresponding to less than 0.01 mg ICG / kg body weight into a vein; acquiring and analyzing time series of fluorescence images of tissues of the anatomical structure after injection of the first fluorescent imaging agent; and determining at least one perfusion parameter of the anatomical structure based on the analysis.

[0171] 34. The method according to any one of the preceding items, wherein fluorescence emission from the anatomical structure is measured after each injection of the bolus.

[0172] 35. A system for automatically assessing the perfusion of an anatomical structure during a medical procedure on a subject, the system comprising a controllable injection pump for containing at least one first fluorescent imaging agent, the injection pump being configured to inject a predetermined amount of the first fluorescent imaging agent into the bloodstream of the subject, wherein the system is configured to receive and analyze time-series fluorescence images of tissues of the anatomical structure after injection of the first fluorescent imaging agent, and to determine at least one perfusion parameter of the anatomical structure based on the analysis.

Claims

1. A computer-implemented method for identifying blood vessels in a tissue of an object, for example, during a medical procedure, the method comprising the steps of: - Continuously acquire fluorescence images of the tissue, wherein the fluorescence signal oscillates in a predetermined pattern with a frequency, the pattern being generated from a series of injections of at least one fluorescent imaging agent, and wherein the series of injections is administered for a predetermined and / or controlled duration between successive injections, the duration determining the frequency of the pattern. - Analyze at least a portion of the fluorescence images and determine at least one time difference selected from the group consisting of: The time difference between the injection of the bolus and the arterial or venous fluorescence signal. The time difference between arterial fluorescence signals and venous fluorescence signals The time difference between arterial or venous fluorescence signals and tissue fluorescence signals, and - Based on one or more of the time differences and fluorescence signals oscillating in the predetermined pattern, blood vessels in the fluorescence image of the tissue are continuously identified.

2. The method according to claim 1, wherein, The frequency of the pattern includes a period of 1 to 5 minutes within a time period of at least 15 minutes, and wherein the fluorescence signal oscillates in intensity according to the predetermined pattern.

3. The method according to any one of the preceding claims, wherein, The identified blood vessels are combined to identify one or more networks of interconnected blood vessels.

4. The method according to any one of the preceding claims, wherein, The identified blood vessels are continuously displayed and visualized on the screen.

5. The method according to any one of the preceding claims, comprising the following steps: The time difference between arterial and venous fluorescence signals is determined, and arteries and veins in the identified blood vessels are distinguished based on the time difference and the predetermined pattern of the oscillating fluorescence signal.

6. The method according to claim 5, wherein, The identified arteries and veins are superimposed onto the white light image, which enhances their visual appearance, making them visually distinguishable and displayed on the screen.

7. The method according to any one of the preceding claims, wherein, The sequence of acquired fluorescence images is analyzed, and the corresponding pixels are classified into: 1) artery, 2) vein, 3) peripheral tissue, or 4) other based on the phase of the fluorescence signal in the pixels of the fluorescence images relative to the predetermined oscillation mode.

8. The method according to any one of the preceding claims, wherein, Blood vessels are identified and visualized through image filtering, such as edge filtering.

9. The method according to any one of the preceding claims, wherein, During image acquisition, a series of boluses of at least one fluorescent imaging agent are administered into a vein of the subject to generate the predetermined pattern of oscillating fluorescence intensity, wherein the series of boluses is administered for a predetermined duration between successive boluses.

10. The method according to claim 9, wherein, The fluorescent imaging agent is ICG, and each injection of ICG corresponds to less than 0.01 mg ICG / kg body weight.

11. The method according to claim 9, wherein, The fluorescent imaging agent is ICG, and each injection of ICG corresponds to less than 0.005 mg ICG / kg body weight.

12. The method according to claim 9, wherein, The fluorescent imaging agent is ICG, and wherein each injection of ICG corresponds to less than 0.004 mg ICG / kg body weight, more preferably less than 0.003 mg ICG / kg body weight, even more preferably less than 0.002 mg ICG / kg body weight, and most preferably less than 0.001 mg ICG / kg body weight.

13. The method according to any one of the preceding claims, wherein, The series of injection agents are automatically injected by a controllable injection pump.

14. The method according to any one of the preceding claims, wherein, The tissue being imaged is a portion of the anatomical structures in the gastrointestinal tract, preferably selected from: the oral cavity; the pharynx; the small intestine including the duodenum, jejunum, and ileum; the stomach including the esophagus, cardia, and pylorus; and the large intestine including the cecum, colon, rectum, and anal canal.

15. The method according to any one of the preceding claims, wherein, The imaged tissue undergoes peristaltic movement during the medical procedure.

16. The method according to any one of the preceding claims, wherein, The tissue being imaged is a portion of the object's internal organs, or a portion of the object's skin, or a portion of the object's wound.

17. The method according to any one of the preceding claims, wherein, The images were acquired during thyroid surgery, and in which blood vessels in one or more parathyroid glands were identified and visualized to medical personnel involved in the surgery.

18. The method according to any one of the preceding claims, wherein, The at least one fluorescent imaging agent is selected from the group consisting of: indocyanine green (ICG), fluorescein isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, phthalaldehyde, fluorescein, rose red, trypan blue, fluorescein, green fluorescent protein, flavin, methylene blue, porphyrin, anthocyanin dye, IRDDye800CW, CLR1502 bound to a target ligand, OTL38 bound to a target ligand, or combinations thereof.

19. A computer program having instructions that, when executed by a computing device or computing system, cause the computing device or computing system to perform a method for identifying blood vessels in tissue of an object according to any one of the preceding claims.

20. A system for identifying blood vessels in a tissue of an object, the system being configured for - A fluorescent signal is continuously generated from the blood vessels in the tissue, wherein, The fluorescence signal oscillates in a predetermined pattern with a frequency, the pattern being generated from a series of injections of at least one fluorescent imaging agent, wherein the series of injections is administered for a predetermined and / or controlled duration between successive injections, the duration determining the frequency of the pattern. - Continuously receive fluorescence images of the tissue. - Analyze at least a portion of the fluorescence images and determine at least one time difference selected from the group consisting of: The time difference between the injection of the bolus and the arterial or venous fluorescence signal. The time difference between arterial fluorescence signals and venous fluorescence signals The time difference between arterial or venous fluorescence signals and tissue fluorescence signals, and - Based on one or more of the time differences and fluorescence signals oscillating in the predetermined pattern, blood vessels in the fluorescence image of the tissue are continuously identified.

21. The system of claim 20, comprising a controllable injection pump for containing at least one first fluorescent imaging agent, the injection pump being configured to inject a predetermined series of boluses of the first fluorescent imaging agent into a vein of the subject, thereby generating the fluorescent signal oscillating in the predetermined pattern.

22. The system according to any one of claims 20-21, wherein, The fluorescent agent is ICG, and the amount of ICG in the predetermined bolus is less than 0.005 mg / kg body weight, and the system is configured to inject the bolus at intervals between 1 and 5 minutes.

23. The system according to any one of claims 20-22, wherein, The system is configured to perform the steps of any one of claims 1-18.

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