System and method for automated perfusion measurement

Abstract

The present disclosure relates to a system and method for automatically measuring and assessing hemodynamics in tissue of an anatomical structure of a subject. In particular, the present disclosure relates to continuously measuring and assessing hemodynamics during a medical procedure using fluorescence imaging, and wherein the administration of a fluorescent agent is controlled and automatic. One aspect relates to a method for automatically assessing perfusion of an anatomical structure of a subject, 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. Another aspect relates to a system for automatically assessing perfusion of an anatomical structure during a medical procedure of a subject, the system comprising a controllable injection pump for accommodating at least one first fluorescent imaging agent, the injection pump being configured to inject a predefined amount of the first fluorescent imaging agent into the subject's blood, wherein the system is configured to receive and analyze a time series of fluorescent images of the tissue of the anatomical structure after injection of the first fluorescent imaging agent, and determine at least one perfusion parameter of the anatomical structure based on the analysis.

Description

[0001] The present disclosure relates to a system and method for automatically measuring and evaluating blood dynamics in tissue of an anatomical structure of a subject. In particular, the present disclosure relates to continuously measuring and evaluating blood dynamics in medical procedures using fluorescence imaging, and wherein the administration of a fluorescent agent is controlled and automated. Background of the Invention

[0003] The injection of fluorescent imaging agents (also called fluorescent contrast agents, also called fluorescers, such as indocyanine green (ICG)) to visualize blood flow and perfusion in anatomical structures was introduced many years ago, but there are few clinical applications of this technology. Currently, the dose of the fluorescent agent must be large enough to ensure that the visual signal is strong enough to be easily detected by the surgeon. Therefore, the assessment of, for example, perfusion in tissue based on fluorescent agents is based on the surgeon's visual observation, i.e. it is largely subjective and may therefore vary from surgeon to surgeon. An improved quantitative analysis method for perfusion assessment in the gastrointestinal tract is disclosed in the pending application PCT / EP2017 / 082204 entitled "System and method for assessing perfusion in an anatomical structure" by the same inventors and published as WO 2018 / 104552. This application is incorporated by reference in its entirety.

[0004] Existing fluorescence imaging methods are typically based on very few perfusion measurements, perhaps only once, taken at critical points during a medical procedure, such as before a bowel resection and after forming a bowel anastomosis. In order to create a fluorescence signal visible to the surgeon (or other medical professional), a large dose of the fluorescent agent is required. Such a large dose results in a visible burst of fluorescence emission, but the washout period may be 20-30 minutes, during which the fluorescent agent is still in the patient's blood, producing a visible background fluorescence emission signal. During the washout period when the fluorescent agent is removed from the blood, this visible fluorescence emission signal will generally prevent medical personnel from starting new fluorescence measurements during the washout period.

[0005] Today, measurements with fluorescence imaging involve many manual steps, where the entire operating room is "on hold" for several minutes. It is usually the surgeon who decides to perform a measurement involving fluorescence imaging, such as evaluating perfusion in the tissue of an anatomical structure. Initially, the surgeon correctly places the anatomical area of ​​interest in the video image received from a white light camera, such as an endoscopic camera. The surgeon then switches the normal white light to another camera, which can capture the fluorescence emitted from the area of ​​interest, and the surgeon then prompts an assistant to inject a fluorescent agent into a surrounding vein. After waiting for about 30 seconds, the first fluorescence emission signal will appear, and the surgeon waits for several minutes until it is determined that the visible fluorescence signal has been adequately evaluated. Summary of the invention

[0006] The manual implementation and evaluation of fluorescence imaging, combined with only discrete measurements and a long washout period, constitutes a significant practical limitation to the use of fluorescence image perfusion analysis in both elective and emergency procedures. During emergency procedures, it is critical not to perform more extensive surgical interventions than necessary, as this increases operative time and postoperative morbidity. At the same time, surgeons cannot afford to leave behind poorly perfused bowel organs or sections, which can lead to tissue ischemia, necrosis, infection, anastomotic leaks, and even death [Lioit et al. 2018]. Therefore, it is an object of the present invention to make fluorescence imaging easier to integrate during emergency procedures.

[0007] Thus, in a first embodiment, the present disclosure relates to a system for automatically assessing the perfusion of an anatomical structure of a subject, for example during a medical procedure such as surgery. The system can be configured to control the injection of a predefined amount of a fluorescent imaging agent into the subject's blood. The injection can be provided by a controllable injection pump, which can be under the control of the system. The injection pump can be part of a system comprising at least one controllable injection pump for accommodating at least one fluorescent imaging agent. That is, the injection pump can be configured to inject a predefined amount of the fluorescent imaging agent into the subject's blood. Preferably, the system is configured so that the predefined amount of the fluorescent imaging agent can be repeatedly injected at regular and / or predefined intervals. The system can be further configured to receive and analyze time-series fluorescent images (also referred to as video images) of the tissue of the anatomical structure after the injection of the fluorescent imaging agent. Based on the analysis, at least one perfusion parameter of the anatomical structure can be determined.

[0008] By automating the fluorescence perfusion assessment, we reduce the time that the surgeon and the rest of the operating room staff must idle. Automation of the administration of fluorescent agents could further increase the use of fluorescence imaging, making perfusion assessment even easier. This could lead to modifications in surgical strategy, for example, creating a larger resection, or performing a resection where no resection was planned, or not resecting all together even if a resection was planned.

[0009] In emergency situations, surgical time is a limiting factor. The surgical plan will often be more unplanned than in elective surgeries. During such emergency procedures, multiple perfusion assessments of the same or different tissues may need to be performed in a short period of time. While a single perfusion measurement can be performed in a reasonable amount of time, multiple measurements will quickly extend the surgical time and become unfeasible. This is a barrier and why these measurements are not routinely used today.

[0010] Therefore, the system disclosed in the present application can be further configured to control the injection pump to inject an initial bolus of the fluorescent imaging agent, and then analyze the fluorescent emission generated by the initial bolus. The initial bolus, preferably combined with a saline solution flush, should be selected depending on the circumstances, i.e., which type of fluorescent agent is used and the patient's configuration, such as age, weight, height, etc. However, an amount of less than 0.01 mg / kg of subject body weight (i.e., less than 0.5 mg for a 50 kg patient and less than 1 mg for a 100 kg patient) is generally a good starting point, especially when using ICG.

[0011] The inventors have recognized, for example, by using computer image analysis, that the quantifiable fluorescence emission from tissue of anatomical structures is much less than that visible to the human eye. That is, much smaller doses, such as microdoses, are possible, because the fluorescence signal intensity only needs to be large enough to be measurable by computer vision and image analysis, rather than by visual inspection by a surgeon. That is, a microdose of a fluorescent agent can be administered to a subject, and, for example, perfusion parameters can be determined therefrom.

[0012] The minimum bolus that provides quantifiable fluorescence emission can be estimated according to the situation. However, in order to find a more accurate minimum effective bolus, the system disclosed in the present application can be further configured to determine the subject-specific minimum effective bolus of the fluorescent imaging agent by the following steps: controlling the injection pump to inject a series of boluses with varying amounts of the fluorescent imaging agent according to a predefined standard (e.g., increasing or decreasing), with a predefined time period between each bolus, analyzing the fluorescence emission of the anatomical structure after the injection of each bolus, and determining the size of the minimum effective bolus that provides quantifiable fluorescence emission from the anatomical structure.

[0013] By applying microdoses of the fluorescent agent, the minimum time between consecutive measurements can be significantly reduced. Moreover, by determining the actual subject-specific minimum bolus that provides quantifiable fluorescence emission, it is also ensured that a minimum washout period is provided, which can minimize the duration between consecutive fluorescence measurements. This is because smaller doses can be removed from the blood more quickly.

[0014] Once a suitable bolus size is found that provides a quantifiable fluorescence signal and a short washout period that allows repeated injections of the fluorescent imaging agent and fluorescence measurements, the system can be configured to perform automatic measurements of perfusion parameters, for example, with a predefined frequency determined by the washout period. Thus, the system disclosed in the present application can be further configured to automatically: 1) control the syringe pump to inject a series of predefined boluses of the fluorescent imaging agent, a predefined bolus such as a minimum effective bolus, with a predefined time period between each bolus, and 2) determine at least one perfusion parameter of the anatomical structure after injection of each bolus.

[0015] Now, continuous perfusion assessment of anatomical structures is provided to surgeons and other medical professionals in the operating room. Therefore, the systems and methods disclosed in the present application open up the possibility of providing continuous fluorescence imaging measurements, which can provide a series of perfusion parameters as a kind of background information during medical procedures. That is, even if the surgeon has changed back to white light imaging during the actual surgical procedure, the fluorescence measurement can still be performed automatically in the background without manual intervention. Therefore, valuable information about perfusion can be provided to medical personnel continuously and in a temporal perspective, because repeated perfusion measurements provide the possibility of tracking the development of perfusion parameters over time. Therefore, the use of automation and microdosing in fluorescence perfusion measurements will open up a whole new range of applications, including regular use in emergency and elective procedures to continuously assess the vitality of tissues and organs (such as thyroid and parathyroid glands, hepatobiliary ducts, reproductive organs and bladder); tumors and their localization, including lymph nodes and possible metastases; and assessment of skin / tissue / vascular perfusion in various medical procedures, such as assessment of wounds and wound healing.

[0016] When fluorescence perfusion is measured in the traditional way, i.e., when a single measurement is taken at one or more different points in the surgery, the measurement will always be sensitive to measurement "noise". Automation of fluorescence perfusion measurements and the reduction of the minimum interval between consecutive measurements makes it more feasible to take multiple measurements of the same region of interest during a medical procedure. Providing multiple measurements is a great advantage because it reduces the effects of random noise caused by random diffusion of the fluorescent agent, physiological variations in blood flow, and distribution in the microcirculation of any anatomical region. Overall multiple measurements of the same region of interest result in a better and physiologically correct perfusion assessment.

[0017] If the surgeon wishes, the surgeon can still perform and save "normal" / full dose fluorescence perfusion measurements, providing a visual signal at critical points in the surgical procedure. These can, for example, be used as documentation of the quality of the procedure in the electronic medical record. After planning the first measurement, the surgeon can continue the medical procedure with minimal interruption to understand the entered perfusion values ​​or to change areas under continuous assessment.

[0018] The inventors have further recognized that the measurement and analysis of reproducible bolus injections can be extended from the interpretation and quantification of single inflow and / or single outflow phases to the analysis of oscillatory fluorescence dynamics. These oscillatory fluorescence dynamics can reveal hitherto unavailable physical perfusion features without invasive measures.

[0019] The systems and methods disclosed in the present application can be configured to repeatedly inject small boluses at regular intervals, such as the minimum boluses disclosed herein. These boluses can cause periodic changes depending on, for example, the injection time interval, which, when measured, is in the approximate form of an oscillating curve, such as a regular oscillating curve, such as a sine curve. In such a curve, the intensity signal measured is expected to increase as the fluorescent imaging agent flows from a given bolus, then decreases during the washout period of the bolus, until it increases again at a subsequent bolus, and so on, resulting in a periodic (sinusoidal) pattern.

[0020] Therefore, the present disclosure also relates to a (computer-implemented) method for detecting perfusion changes in an anatomical region of interest of a subject by image processing of the hemodynamics in at least a portion of the anatomical region of interest in a video image acquired from the subject. In one embodiment, the method comprises the following steps: image analysis of at least one video sequence obtained during and / or after the supply of multiple boluses containing a fluorescent imaging agent to the subject. In that case, it is advantageous if multiple boluses are provided according to a predefined pattern, for example in terms of frequency and / or dose, which is also further elaborated in the present disclosure. Subsequent perfusion parameters in one or more regions of interest can now be calculated based on image analysis, i.e., when multiple doses are administered to the subject, perfusion parameters can be continuously calculated as boluses are provided. Using the changes in the multiple perfusion parameters provided over time (and bolus administration), it is possible to monitor subsequent perfusion parameters to determine perfusion changes in the region of interest. Such changes in perfusion may indicate a problem.

[0021] Preferably, the system disclosed in the present application is configured so that it can identify parameters of the oscillation intensity curve, such as frequency, phase and / or amplitude. The trained system can then turn to predict the direction and regularity of the upcoming signal dynamics. The system preferably uses measured values ​​to identify oscillation patterns so that the system can then detect the difference between the measured values ​​and the expected values. The system does not necessarily have to continuously measure the anatomical region of interest, on the contrary, it may only be able to measure at scattered time intervals, such as when the anatomical region of interest drifts in and out of the focus of the recorded image. In these cases, the expected phase of the oscillation pattern at the measured time interval can be compared with the measured phase. The measured values ​​can be further continuously used to update the detected pattern, i.e., the expected value. Alternatively or additionally, injection parameters such as push frequency, dose and flow rate can be used to determine the expected value, i.e., the oscillation pattern.

[0022] Deviations from an expected sinusoidal pattern may be due to, for example, the onset of an ischemic condition in at least a portion of the anatomy visible in the video image, or regional changes in perfusion to a given region. Fig. 12AAn illustrative figure is given in which this kinetic change is demonstrated in human subjects due to an ischemic episode. Fig. 12B A narrower zoom is given in . As can be seen, a transition from a regular oscillating fluorescence signal to an ischemic plateau can be detected. However, it should be noted that changes in perfusion of the anatomical structure of interest can result in other measured patterns besides the ischemic plateau. An example is venous occlusion, where blood flow out of an anatomical region is blocked or reduced due to congestion or accumulation of fluorescent agent in a given area, resulting in a change in the oscillatory dynamics. Fig. 13C It can be seen that although the periodic oscillations have stopped, the result is not a flat line.

[0023] Preferably, the system disclosed in the present application includes a tracking device and is able to run independently in the background, while the surgeon is only exposed to the visible white light signal and is therefore only interrupted / notified by a warning signal during, for example, detecting an ischemic attack, which can be defined by the amount of time prolonged in the ischemic condition.

[0024] Following the above disclosure, the present disclosure also relates to a method for automated perfusion assessment of an anatomical structure of a subject, the method comprising administering a bolus of about 1 / 10 of the normal dose for perfusion assessment into an intravenous cavity. For indocyanine green (ICG), a normal bolus is 0.1-0.3 mg / kg body weight. According to the present disclosure, a bolus of less than 0.01 mg / kg body weight of a first fluorescent imaging agent can be used. For other fluorescent imaging agents described herein, the bolus is similarly reduced according to the present disclosure.

[0025] For example, the systems and methods disclosed in the present application can be used, where quantification of the circulation through the tissue can play a decisive role during surgical operations, i.e., in the field of visceral surgery such as left-sided colon and rectal resection, gastric slice displacement after esophagectomy, free small bowel transplantation for insertion, anastomosis, etc. The methods disclosed in the present application can also be applied to detect secondary perfusion abnormalities in the case of strangulated hernia or bridenileus. In cardiac surgery, the systems and methods disclosed in the present application can be used to check the efficiency of coronary artery bypass grafting and measure perfusion during surgery. In the field of plastic surgery, the perfusion of transplanted flaps can be monitored (e.g., continuously), and tissue damage can be evaluated in the case of trauma, as well as wound healing (e.g., chronic wounds).

[0026] Another aspect of the present disclosure relates to continuous perfusion assessment related to repeated injections of fluorescent active agents and monitoring of the resulting oscillation curve. In addition to detecting unforeseen perfusion changes, the system can also be used to assess the perfusion area of ​​an artery. For example, a surgeon may consider cutting an artery as part of a surgical procedure. Before cutting an artery, the surgeon may temporarily limit the perfusion through the artery, and the method disclosed in the present application may enable visualization of the perfusion area of ​​the artery in a short period of time (e.g., less than 1 minute). This may be valuable information for surgeons during continuous surgical operations. In a similar manner, the system can be used to assess the drainage area of ​​a vein or a group of veins, lymphatic vessels, lymph nodes, or other parts of a circulation and / or lymphatic pathway. By temporarily limiting the flow of blood through a vessel, blood will gather in an anatomical region that is normally drained by the vessel or the group of vessels. This enables visualization of an anatomical region drained by the vessel in a relatively short period of time (e.g., less than 2 minutes). This can provide important information to surgeons in fields such as general surgery and plastic surgery (including wound and reconstructive surgery), such as during continuous surgical operations.

[0027] Yet another aspect of the present disclosure relates to a computer program, such as a computer program recorded on a storage medium, which is to be loaded into the memory of a computer or the system disclosed herein, and which enables the computer / system to perform the steps of any method disclosed herein.

[0028] Yet another aspect of the present disclosure relates to an imaging system, namely an endoscopic imaging system, comprising a processing unit configured to perform the steps of any of the methods disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1A , 1C and 1E show an example of an intensity curve after providing an ICG bolus to a subject, Figure 1B , 1D and 1F show the corresponding intensity curves, wherein the hemodynamic parameters perfusion slope, slope start, slope end maximum intensity, washout slope, washout start and washout slope end have been calculated and shown in the figure.

[0030] Figures 2A-2F Three embodiments are shown that illustrate the method disclosed herein for determining the point in time at which the perfusion slope begins (ie, the slope start point). Figure 2B , 2D and 2F are Figure 2A , 2C And a close-up of 2E, where the slope begins.

[0031] Figures 3A-3FThree embodiments are shown that illustrate the method disclosed herein for determining perfusion slope based on histogram data.

[0032] Figures 4A-4F Three embodiments are shown that illustrate the methods disclosed herein for defining and determining maximum slope strength. Figure 4B , 4D and 4F are Figure 4A , 4C and a close-up of 4E, where the curve has its maximum intensity.

[0033] Figures 5A-5F Three examples are shown illustrating the methods disclosed herein for analyzing the elution of fluorescent contrast agents. Figure 5B , 5D and 5F respectively Figure 5A , 5C and a close-up of 5E, where ICG is washed away.

[0034] Figures 6A-6D Two additional fluorescence measurements using ICG analysis are shown, illustrating the robustness of the analysis methods disclosed herein.

[0035] Figure 7 Output video frames acquired during bowel surgery, four different regions of interest and their analysis are shown.

[0036] Fig. 8A A still image from a normal video sequence acquired before resection of a patient's colon is shown. The image shows the small intestine (lower part) and the colon (upper part).

[0037] Figure 8B Shown with Fig. 8A Fluorescent images of essentially the same subsection of the gastrointestinal tract in FIG. 1 but acquired later, ie, after a bolus of fluorescent contrast agent (ICQ) has been injected into the patient.

[0038] Fig. 9A Shown in Figure 8B The intensity curve obtained in the ROI and the perfusion slope calculated according to the method disclosed in this article, that is, the perfusion slope of the colon and small intestine before resection.

[0039] Fig. 9B Shows Fig. 9A Perfusion slopes in the small intestine (left) and colon (right), but Fig. 9B The slopes have been normalized to the perfusion slope of the small intestine.

[0040] Fig. 10A Shown with Fig. 8A Normal image of essentially the same GI tract subsection but acquired after resection of the colon and before anastomosis.

[0041] Fig. 10B After the ICG bolus has been injected, the Fig. 10A Fluorescence image of the image in. Five ROIs are shown in the image.

[0042] Fig.11A Shown by Fig. 10A and 10B The measured intensity curves are shown.

[0043] Fig. 11B Shows Fig.11A Perfusion slopes in the small intestine (left) and colon (right, blue, green, and yellow), but here Fig. 11B The slopes have been normalized to the perfusion slope of the small intestine.

[0044] Fig. 12A Shown are oscillating time-intensity fluorescence curves where the oscillations are disrupted due to an ischemic episode in a human subject.

[0045] Fig. 12B A zoomed-in view of the time interval around t=3800 s in the previous figure is shown, where the ischemic episode occurred.

[0046] Fig. 12C Idealized data with and without ischemic conditions are shown.

[0047] Fig.12D Idealized data are shown, where only a portion of the oscillating time intensity fluorescence curve can be detected.

[0048] Fig.13A Serial measurements of a human subject injected with a microbolus are shown.

[0049] Fig. 13B Shows Fig.13A Magnified view of the interval shown.

[0050] Fig. 13C Measurements are shown for a person experiencing a venous obstruction, where blood flow is only partially restricted. DETAILED DESCRIPTION OF THE INVENTION

[0052] In order to determine the subject-specific minimum effective bolus, the background level of the setup can be advantageously determined, so that the minimum quantifiable fluorescent signal can be determined. Therefore, the system disclosed in the present application is advantageously configured to: 1) receive a time series image of the tissue of the anatomical structure before injecting the fluorescent agent, and 2) determine the background noise level therefrom. Before or after this, one or more regions of interest (ROIs) can be selected. This selection of ROI can be provided manually by the user, automatically or semi-automatically by the system, wherein the system suggests multiple ROIs, and the user can edit and / or move the suggested ROIs accordingly. The background noise level can be determined for each ROI.

[0053] As previously mentioned, the minimum effective bolus can be determined, in particular the specific minimum effective bolus of the subject can be determined. The size of the minimum effective bolus can be determined, for example, based on the background noise level, in particular according to the standard deviation of the background noise level. For example, the minimum effective bolus can be determined as the bolus providing the maximum intensity, which is a predefined coefficient multiplied by the standard deviation of the background noise level. We note that the intensity of the background noise level may be close to zero or may not be close to zero. Background noise may also change (for example, due to a long series of microbolus). However, the change in background noise is preferably on a much larger time scale, for example, at least 2 times larger than the intensity change observed for a single injection, more preferably at least 4 times larger, even more preferably at least 6 times larger, most preferably at least 10 times larger.

[0054] Values ​​from multiple ROIs may be provided, and the intensities between different ROIs may vary significantly, especially the maximum intensity. The minimum effective bolus may be determined as the bolus that provides the maximum intensity, which is a predefined coefficient multiplied by the standard deviation of the background noise level. In one embodiment, this must apply to all ROIs. However, in some cases, for example, the selected ROI does not provide a viable signal, such as when there is no perfusion in the section. In this case, one or more ROIs may be abandoned in the evaluation of the minimum effective bolus.

[0055] The above-mentioned predefined coefficient may be at least 5, more preferably at least 10, even more preferably at least 25, most preferably at least 50.

[0056] Once the minimum effective bolus is determined, such as the subject-specific minimum effective bolus, the actual bolus used in the continuous and repeated measurement program that continues can be the minimum effective bolus. However, in order to ensure that a usable signal is provided, it can be determined that the actual bolus to be used is a certain percentage of the minimum effective bolus. The actual bolus used can be less than the feasible bolus determined, but in particular, the actual bolus used can be greater than the minimum effective bolus, such as at least 125% of the minimum effective bolus, more preferably at least 150%, even more preferably at least 200%, most preferably at least 300%. However, it is important to note that the actual bolus can vary over time and does not have to be set to a constant percentage value of the minimum effective bolus. On the contrary, the actual bolus can vary over time. For example, when an initial large actual bolus is injected and then a smaller actual bolus is injected, this is the case. In this way, the intensity signal may be saturated with an initial large actual bolus that may be between 125% and 375% of the minimum effective bolus, more preferably between 150% and 350% of the minimum effective bolus, even more preferably between 175% and 325% of the minimum effective bolus, and most preferably between 200% and 300% of the minimum effective bolus. Thereafter, after the initial large actual bolus, smaller actual boluses may be repeatedly injected at a constant percentage value of the minimum effective bolus, such as approximately 100% of the minimum effective bolus.

[0057] When the subject-specific minimum effective bolus is determined, the bolus is injected with a period of time between each bolus, preferably a predefined time period, but may be a time period that can be adjusted based on the measured fluorescence measurement. The time period can also be customized for a specific situation (e.g., a subject). At least initially, the time period between injections is typically about 20-60 seconds, and may even be 20-40 seconds or 20-30 seconds. In other cases, at least when using ICG, the time period between injections is typically about 5-600 seconds, and may even be 30-300 seconds or 90-120 seconds, because this is the normal duration from the slope rising until the intensity drops sufficiently again.

[0058] The time period from injection of the fluorescent agent to when fluorescent emission can be detected varies from case to case and can generally depend on, for example, tissue perfusion characteristics and blood flow characteristics, but can also depend on other individual factors of the patient, such as anatomical structure, tissue composition and interaction dynamics, or other possible factors, such as the fluorescent agent, etc. This time period can be estimated, but it is advantageous if the specific time period is known. Therefore, the system disclosed in the present application can be further configured to determine a subject-specific conversion period, which is defined as the time period from the injection of the bolus of the fluorescent imaging agent to the rise in the fluorescence slope in the fluorescent emission of the anatomical structure.

[0059] The system disclosed in the present application can be further configured to determine a subject-specific interruption interval, which is defined as the following time period: from the time the fluorescence slope rises to the time when the fluorescence emission is equal to the background noise, or until the fluorescence emission drops below multiple standard deviations of the background noise, such as 20, 10 or 5 times SD, that is, the subject-specific time period during which there is detectable fluorescence emission.

[0060] The system disclosed in the present application can be further configured to determine a subject-specific rise+fall interval, which is defined as the time period from the rise of the fluorescence slope, through the maximum intensity until the fluorescence emission falls to less than 50% of the maximum intensity or more preferably 25% of the maximum intensity, even more preferably less than 10%, still more preferably less than 5%, and most preferably less than 1%.

[0061] The system disclosed in the present application can be further configured to determine a subject-specific injection interval, which is defined as the time period from the injection of the fluorescent agent, the rise of the fluorescence slope, passing the maximum intensity until the fluorescence emission drops to less than 50% of the maximum intensity, or more preferably less than 25% of the maximum intensity, even more preferably less than 10%, still more preferably less than 5%, and most preferably less than 1%. Once the fluorescence emission drops below a certain intensity, a new bolus can be detected to quantify the fluorescence emission. That is, the subject-specific injection interval can be regarded as the time required to wait between subsequent micro-doses of fluorescent agent injections. However, since a certain amount of time is required from the injection of the subsequent bolus until it reaches the anatomical structure, the subject-specific rise / fall interval defined above can also be regarded as the time required to wait between subsequent injections of micro-doses of fluorescent agent.

[0062] The properties of existing fluorescent agents (e.g., ICG) are well known, and the waiting time between subsequent injections can also be predefined. The rise / fall interval defined above is generally about 20-60 seconds, and can even be 20-40 seconds or 20-30 seconds. In another embodiment, the rise+fall interval defined above is generally about 5-600 seconds, and can even be 30-300 seconds or 90-120 seconds.

[0063] Instead of waiting for the fluorescent agent to be washed out of the blood, the perfusion parameters can be determined after the new bolus of fluorescent agent is injected, before the previous bolus is removed / eluted. In particular, this is possible if the subsequent bolus is larger than the previous bolus, thereby also ensuring that an increased amount of fluorescent agent is administered. Therefore, the system disclosed in the present application can be configured to automatically: 1) control the syringe pump to inject a series of boluses of fluorescent imaging agent in increasing or decreasing amounts (e.g., increasing or decreasing amounts), with a predefined time period between each bolus; and 2) determine at least one perfusion parameter of the anatomical structure after the injection of each bolus. The incremental amount can, for example, start from 100% and increase linearly by 10%, such as 110%, 120%, 130%, 140%, etc. Or increase by 25%, i.e. 100%, 125%, 150%, 175%, etc. Or increase by 50%, i.e. 100%, 150%, 200%, 250%, etc. Or increase by 100%, i.e. 100%, 200%, 300%, 400%, etc. Or increase exponentially, such as 100%, 200%, 400%, 800%, etc.

[0064] The decrement may, for example, start at 200% and decrease linearly by 10%, such as 190%, 180%, 170%, 160%, etc. Or decrease by 25%, such as 200%, 175%, 150%, 125%, etc. Or decrease by 50%, such as 250%, 200%, 150%, 100%, etc. Or decrease by 100%, such as 400%, 300%, 200%, 100%, etc. Or decrease exponentially, such as 800%, 400%, 200%, 100%, etc.

[0065] Automatic system

[0066] The system disclosed herein may be configured to determine the at least one perfusion parameter in one or more regions of interest located in the anatomical structure and optionally in adjacent anatomical structures.The system may be configured such that these regions of interest may be selected by a user of the system.

[0067] The system disclosed in the present application may be further configured to send the at least one perfusion parameter for presentation on a display, that is, so that medical personnel can track the progress of perfusion assessment during a medical procedure, and the display may be a white light picture superimposed with the parameter.

[0068] The system disclosed in the present application may further include at least one processor and a memory having instructions stored thereon, and when the instructions are executed by one or more processors, the system performs the contents disclosed in this document.

[0069] A syringe pump (also referred to as a drug pump) can be a part of the automatic perfusion assessment system disclosed in the present application. A syringe pump can be configured to deliver a time-controlled periodic infusion of a fluorescent agent to a target, such as a subject. The control of a syringe pump can be provided by a programmable and / or controllable control unit. Therefore, a control unit can be configured to automatically operate the syringe pump to periodically infuse the fluorescent agent with a controllable and / or predefined amount of a bolus dose according to the present invention and a bolus agent of a controllable and / or predefined duration between infusions. That is, the system can only be configured to control a syringe pump, for example, by configuring a control unit for controlling a syringe pump. Controllable syringe pumps are commercially available, such as KDS single syringe pumps (series 100) purchased from Sigma-Aldrich or Legato 212 dual syringe pumps purchased from World Precision Instruments, or Fusion controllable syringe pumps purchased from Chemyx.

[0070] The automatic system disclosed in the present application can be external to an existing fluorescence imaging system, that is, only configured to control the syringe pump and receive time series fluorescence images from the existing system for analysis, such as an external system, such as an endoscopic and / or laparoscopic device, such as the Novadaq Pinpoint endoscopic fluorescence imaging system or the Novadaq Spy-Phi portable handheld imaging system, wherein the imaging unit and the optional light source are included in the system. Existing laparoscopic systems from Olympus, Stryker, KarlStorz or surgical robots from Intuitive can also be selected.

[0071] However, the system disclosed in the present application can also be a more complete fluorescence imaging system, for example, an endoscope and / or laparoscopic system, which may include one or more light sources for fluorescence excitation and control thereof. That is, in a further embodiment, the system also includes at least one light source, which is configured to provide excitation light to induce the fluorescence emission of the first and / or second fluorescent agent in the anatomical structure. For example, a near-infrared light source (e.g., for ICG) that can be directly connected to a camera. Similarly for the imaging unit, that is, the system may include an imaging unit that is configured to record at least one time series of fluorescence emission from the anatomical structure. For example, a digital video camera can record the emission of the fluorescent agent in real time, which means that perfusion can be evaluated and recorded in real time. The imaging unit can be further configured for white light imaging, so that normal images of the anatomical structure can be received and / or viewed, that is, while recording the fluorescence signal with a separate camera. This can be provided by another camera in the imaging unit.

[0072] Accordingly, one embodiment of the present disclosure is directed to a system for automated perfusion assessment of an anatomical structure during a medical procedure in a subject, the system comprising:

[0073] - a controllable syringe pump for containing at least one fluorescent imaging agent,

[0074] - at least one light source configured to provide excitation light to induce fluorescence emission of said fluorescent agent in said anatomical structure,

[0075] - an imaging unit configured to record at least one video sequence of fluorescence emissions from the anatomical structure,

[0076] The system is configured to automatically control the injection pump, light source and imaging unit for

[0077] - injecting a predefined amount of said fluorescent imaging agent into the blood of a subject,

[0078] - after injection of a fluorescent imaging agent, inducing and analyzing fluorescent emission from said anatomical structure,

[0079] - determining at least one perfusion parameter of the anatomical structure based on the analysis.

[0080] Intraoperative fluorescence imaging

[0081] Perfusion (e.g., blood flow) can be imaged intraoperatively and assessed in real time using near-infrared light from a surgical microscope and acquiring video of fluorescence in the near-infrared region stimulated by a fluorescent angiographic contrast agent that has been administered intravenously as a tracer. This allows real-time confirmation of perfusion status during surgery.

[0082] The systems and methods disclosed herein can provide enhanced tissue characterization information, including the location of superficial and deeper vessels, particularly when different fluorescent agents are used, because careful selection of different fluorescent agents provides the option of obtaining perfusion information from different depths in the tissue.

[0083] During medical procedures such as diagnosis, screening, examination and / or surgical procedures involving fluorescence imaging, a solvent containing a fluorescent contrast agent (e.g., ICG) is injected intravenously, and the molecule is excited by an infrared light source (e.g., a laser with a wavelength in the infrared wavelength range, e.g., about 780 nm). Fluorescence with a wavelength of about 830 nm is then emitted from the excited contrast agent molecules and can be recorded with an imaging device (e.g., in the form of a camera). A filter can be provided to block the excitation light because the excitation intensity is usually much greater than the fluorescence intensity. The excitation intensity can be about 1 W per emission angle, while the fluorescence power pr. pixel can be about 0.15 pW. Despite the difference of several orders of magnitude, a good signal-to-noise ratio (SNR) can be achieved. The recorded fluorescence provides an image of perfusion in the imaging tissue, and because the penetration depth of ICG is 5-10 mm, deeper blood vessels can be seen. Since the ICG molecules bind to proteins in the blood, the video images contain information about the perfusion level-but it is difficult for surgeons to quantify this information during surgery if only the acquired video images are seen.

[0084] In the systems and methods of the present disclosure, the fluorescent contrast agent is selected from: indocyanine green (ICG) and fluorescein isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, o-phthalaldehyde, fluorescamine, rose Bengal, trypan blue, fluorescein gold, green fluorescent protein, flavin, methylene blue, porphysomes, cyanine dyes, IRDDye800CW, CLR 1502 bound to a targeting ligand, OTL38 bound to a targeting ligand, or a combination thereof.

[0085] Indocyanine green (ICG) is a cyanine dye used in medical diagnostics, and it is currently the most common dye used for perfusion assessment. It has a peak spectral absorption at about 800 nm. These infrared frequencies penetrate the retinal layers, allowing ICG angiography to image deeper circulation patterns than fluorescein angiography. ICG is tightly bound to plasma proteins and is confined to the vascular system. It is administered intravenously and is eliminated from the body by the liver into the bile with a half-life of about 3-4 minutes, depending on liver performance. ICG sodium salt is usually provided in powder form that can be dissolved in a variety of solvents; 5% (<5%, depending on the batch) of sodium iodide is usually added to ensure better solubility. Sterile lyophilizates of aqueous ICG solutions have been approved as diagnostic agents for intravenous use in many European countries and the United States under the names ICG-Pulsion, IC-Green and VERDYE.

[0086] The absorption and fluorescence spectra of ICG are in the near-infrared region. Typically, a laser with a wavelength of about 780 nm is used for excitation. At this wavelength, the fluorescence of ICG can be detected by filtering out scattered light from the excitation beam.

[0087] The toxicity of ICG is classified as low, but administration is not without risk, for example during pregnancy. It is known that ICG decomposes into toxic waste products under the influence of UV light, producing many still unknown substances. That is, as demonstrated herein, minimizing the dose of ICG used during fluorescence imaging is within the patient's interest.

[0088] Fluorescein is another dye that is widely used as a fluorescent tracer for many applications. Fluorescein has an absorption maximum at 494 nm and an emission maximum (in water) at 512 nm. It is therefore suitable for use in combination with ICG, as the absorption and emission wavelengths of the two dyes are separated by hundreds of nanometers.

[0089] Automated perfusion assessment method

[0090] As previously described, the present disclosure also relates to a method for automatically assessing the perfusion of an anatomical structure of a subject, the method comprising administering a bolus into a vein having about 1 / 10 of the normal dose for perfusion assessment. For indocyanine green (ICG), a normal bolus is 0.1-0.3 mg / kg body weight. According to the present disclosure, a bolus of less than 0.01 mg / kg body weight of a first fluorescent imaging agent can be used. For other fluorescent imaging agents described herein, the bolus is similarly reduced according to the present disclosure. As described above, the agent can be injected by a controllable injection pump, for example, in a series of boluses, with a predefined time interval between subsequent boluses. After each bolus injection, the fluorescence emission from the anatomical structure can be measured.

[0091] A minimum bolus that provides a quantifiable bolus of fluorescence emission representative of anatomical perfusion may be determined after a series of increasing boluses are administered. Boluses may include increasing or decreasing amounts of the agent, for example the amount may increase or decrease in 10% increments from one bolus to a subsequent bolus.

[0092] The interval between the bolus can be 5 to 600 seconds, for example 5 to 300 seconds, for example 10 to 180 seconds, for example 10 to 140 seconds, for example 10 to 90 seconds, for example 15 to 80 seconds, for example 20 to 70 seconds, for example 30 to 60 seconds. In another embodiment, the interval between the bolus can be 5 to 600 seconds, for example 10 to 600 seconds, for example 15 to 600 seconds, for example 15 to 300 seconds, for example 30 to 240 seconds, for example 45 to 240 seconds, for example 90 to 240 seconds, for example 90 to 120 seconds. The interval between the bolus is preferably long enough to allow the perfusion slope in the anatomical structure to be measured for each bolus, preferably, wherein the perfusion slope includes a slope starting point and an elution slope.

[0093] For ICG, the amount of the fluorescent imaging agent is preferably 0.0001 to 0.01 mg / kg body weight per bolus, for example 0.001 to 0.01 mg / kg body weight per bolus. The initial amount of the fluorescent imaging agent is advantageously at least 0.001 mg / kg body weight. Subsequent boluses increase by at least 0.001 mg / kg body weight from one bolus to a subsequent bolus. For other types of fluorescent imaging agents, the dose is preferably selected based on its fluorescence relative to ICG. Therefore, it is preferred to administer a fluorescent imaging agent with a higher emissivity at a correspondingly lower dose. The dose can, for example, be substantially inversely linear with the quantum yield of the fluorescent imaging agent. The dose can further be based on the absorption and emission spectra relative to ICG.

[0094] The bolus is preferably a liquid volume of 0.5 μL to 10 mL, such as 0.5-5 mL. In a preferred embodiment of the present disclosure, a certain volume of isotonic solution (e.g., saline) is injected immediately after the injection of the fluorescent imaging agent of the bolus, for example, wherein the volume of the isotonic solution is 1-20 mL, such as 2.5-15 mL, such as 5-10 mL.

[0095] In a further embodiment of the present disclosure, a second fluorescent imaging agent is administered, the emission maximum of the second fluorescent imaging agent differing from the emission maximum of the first fluorescent imaging agent by at least 50 nm or at least 100 nm. The first and second fluorescent imaging agents are preferably administered alternately. Advantageously, the interval between administrations of different fluorescent imaging agents is half the interval between subsequent administrations of the same fluorescent imaging agent.

[0096] In a further embodiment of the method disclosed in the present application, a series of fluorescence images of the anatomical structure are formed for assessing perfusion. Fluorescence can be automatically detected by illuminating the anatomical structure with a light source capable of exciting the fluorescent imaging agent, and the emission is quantified by a series of fluorescence images of the anatomical structure.

[0097] The intervals between boluses are determined by a computer configured to detect the perfusion slope caused by each bolus. In addition, the amount of fluorescent imaging agent in the bolus can be controlled by a computer configured to determine a minimum bolus corresponding to a minimum fluorescence emission representative of perfusion of the anatomical structure. The computer can be part of the system disclosed in the present application.

[0098] In a further embodiment, the perfusion assessment includes locating a perfusion complication in the anatomy. Thus, the perfusion assessment can be used in conjunction with a diagnostic or surgical procedure, for example, including diagnostic laparoscopy, exploratory laparoscopy, surgical laparoscopy with conventional laparoscopy, robotic surgery, and open surgery. The procedure can optionally include anastomosis, such as intestinal anastomosis; wound; plastic surgery; cardiac surgery or cancer.

[0099] A further embodiment of the present disclosure relates to a fluorescent imaging agent for use in the methods disclosed herein.Another further embodiment relates to the use of a fluorescent imaging agent in the preparation of a medicament for use in the automated perfusion assessment methods disclosed herein.

[0100] In a further embodiment of the present disclosure, the fluorescent imaging agent can be injected repeatedly. In some cases, a longer period of time 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, in which the fluorescent imaging agent is not injected, so as to allow the fluorescent imaging agent to be washed away, thereby reducing the background level. Once the background level is reduced to an acceptable level, such as a certain percentage below the maximum fluorescence intensity, or until substantially no fluorescence is measured, the injection of the fluorescent imaging agent can be continued.

[0101] The system disclosed in the present application can be configured to perform the method for automatically assessing the perfusion of an anatomical structure disclosed above. This can be provided by a system having at least one processor and a memory having instructions stored thereon, which, when executed by one or more processors, causes the system to perform the method for automatically assessing the perfusion of an anatomical structure disclosed in the present application.

[0102] Perfusion parameters

[0103] Various parameters can be determined based on image analysis of the fluorescence emission. Extracted from the image analysis are typically intensity values ​​relative to time, and these values ​​can be used to generate a number of time series variation curves, and the shapes of the time series variation curves can be analyzed. Based on this analysis, i.e., based on the results of the image analysis of time series fluorescence images (also called video series fluorescence images), relative and / or quantitative data of perfusion, blood volume and / or blood flow can be determined. In particular, the perfusion slope of the flow of fluorescent contrast agent through at least one region of interest can be determined. The perfusion slope is a key parameter because it is a direct indication of perfusion in the imaged tissue.

[0104] The perfusion parameters may be determined from fluorescence intensity values ​​extracted from one or more regions of interest (typically including tissue). The configuration of the regions of interest, such as the size of the regions, the number of regions, the location in the image, etc., may be provided automatically, semi-automatically or manually by a user (e.g., a doctor / surgeon). By at least some manual intervention, the user is able to select additional regions of interest or remove existing regions of interest. Preferably, one or more regions are also moved around in the image so that the regions of interest are located in relevant areas of the image, preferably prior to the capture of the video sequence.

[0105] The perfusion slope can be determined from the fluorescence intensity values ​​integrated over the entire region of interest including the tissue. Initially, before contrast agent injection, the curve will be a substantially flat line. After contrast agent injection, once the bolus of contrast agent molecules are excited and reach the region of interest, the region of interest will begin to fluoresce - the result is a substantially linearly increasing line. When the bolus of contrast agent molecules levels off, the fluorescence intensity in the region of interest will also level off, and washout will begin when the amount of contrast agent molecules decreases (substantially linearly) to zero.

[0106] However, this is an idealized scenario and the curves may vary over time and from patient to patient, so it is important to have a robust definition of the perfusion parameters so that they can be automatically determined to be reproducible and comparable across runs.

[0107] The perfusion slope can be defined by the slope of the extracted intensity values ​​from the slope start point to the slope end point. The perfusion slope can be determined only as a linear fit to the curve. The challenge is to determine the starting point (slope start point) and the end point (slope end point) of the fit, especially in real time. The slope start point is the most important of the two and can be defined as the time point at which the slope exceeds a predefined first threshold. The first threshold can be determined, for example, by three parameters: a predefined coefficient k, and the mean and standard deviation (std) of the intensity values ​​before the slope start point or before the supply of the fluorescent contrast agent. The slope start point can then be defined as the time point at which the slope exceeds the mean value k*std. The slope end point can be correspondingly defined as the time point at which the slope decreases beyond a predefined second threshold after the slope start point. The constant k can be determined according to the settings, but typically k is in the range of 3-10.

[0108] Advantageously, however, the perfusion slope may be determined based on a histogram of the parameter space binning all slopes after the slope start, and wherein the perfusion slope is determined as the most frequent value of the histogram. That is, after the slope start, slope values ​​are calculated for all subsequent intensity points based on the slope start. The slope end point may then be derived therefrom. The slope values ​​calculated immediately after the slope start may be assigned a greater weight in the histogram than later slope values, since it is certain that the perfusion slope has started after the slope start. For example, the first 100 calculated slope values ​​may be assigned a weight of 100, 99, 98, etc., respectively, in the histogram. If a higher constant k is chosen, even more weight may be assigned to the initial value of the perfusion slope. The histogram-centric approach is very accurate and may advantageously be used in real-time or near real-time situations.

[0109] Another parameter that can be determined is the elution slope, which represents the evanescent flow of contrast agent, for example, through at least one of the regions of interest. However, due to the increase in the flow of contrast agent, the perfusion slope is usually positive, while the elution slope is opposite to the perfusion slope (indicated by the sign), that is, usually negative. The elution slope can add information about perfusion in the tissue. However, the elution slope can also be related to an indication of the function of an organ (such as the liver). Similar to the perfusion slope, the elution slope can be defined by the slope of the intensity value from the elution start point to the elution end point. The elution start point appears after the slope end point. The elution slope can be determined by a histogram of the parameter space of all slope bins after the elution start point, and the elution slope is determined as the most frequent value of the histogram. As described above for the perfusion slope, certain calculated elution slope values ​​can be assigned a greater weight than other values ​​in the histogram, particularly the initial value of the elution slope after the elution slope start point.

[0110] The maximum intensity reached can be easily determined, e.g. for each ROI. However, a more relevant parameter may be the maximum slope intensity, which is the intensity at which the intensity values ​​begin to level off. The maximum slope intensity may be defined as the intensity value at the end of the slope. A more precise definition may be the intensity value at the time point at which the distance from the straight line (which has a gradient perfusion slope and intersects the curve point determined by the start of the slope) exceeds a predefined limit (e.g. based on, e.g., the standard deviation of the perfusion slope). For example, the maximum slope intensity may be at a position where the intensity level differs from the perfusion slope by a predefined factor multiplied by the standard deviation of the perfusion slope.

[0111] Slope rise time may also be relevant and may be defined as the difference between the time points of maximum slope intensity and the start of the slope, ie the time it takes for the contrast agent to flow through or accumulate in the tissue, which may be an indication of blood flow velocity.

[0112] The relative perfusion slope can then be defined as the inverse of the slope rise time. The subject-specific relative perfusion slope can then be defined as the relative perfusion slope multiplied by the maximum intensity of the region of interest where perfusion is at a local (or global) extreme. That is, a perfusion parameter that is normalized to become a patient-specific perfusion slope parameter.

[0113] track

[0114] In a further embodiment, tracking of the motion of an anatomical structure (e.g., the gastrointestinal tract) in a time series of images (e.g., video images) is provided. Thus, the systems and methods disclosed herein may employ tracking, as exemplified below, so that perfusion parameters may be extracted from the same anatomical structure and the same portion of the anatomical structure in repeated / continuous measurements. The tracked motion of the anatomical structure or at least a portion thereof may be used so that at least one region of interest corresponds to the same portion of the anatomical structure in the video images.

[0115] Especially in open surgery, the camera may be moved around during surgery. Therefore, during surgery and during continuous perfusion measurements, a selected ROI may completely disappear from the image. Tracking as disclosed herein is also about identifying when the relevant region and / or anatomical structure is within the image - and when it is not, so as not to mistakenly compare perfusion parameters measured from completely different regions.

[0116] The purpose of tracking is primarily to ensure that data (e.g., pixel intensity values) are sampled from the same tissue region. Thus, if the anatomical structure moves in the image, tracking should ensure that any region of interest as defined herein will move accordingly to ensure that the sampled data for the region of interest is understandable. In this regard, it is not important whether the anatomical structure physically moves, such as due to breathing and / or peristalsis of the subject, or whether the imaging device acquiring the image moves relative to the anatomical structure. What is important is whether the imaged object moves within the acquired image.

[0117] Thus, yet another aspect of the present disclosure more generally relates to a computer-implemented method of image processing motion / dynamics of at least a portion of an anatomical structure (e.g., during a medical procedure) from a video image representing at least an external portion of the anatomical structure, the method comprising the steps of:

[0118] - selecting one or more regions of interest in at least one of said video images, at least a first said region of interest corresponding to a part / sub-part of an anatomical structure,

[0119] - tracking the movement of anatomical structures in said video images, and

[0120] - correlating said movement of the anatomical structure such that at least said first region of interest corresponds to a same portion of the anatomical structure in said video image.

[0121] Tracking of an object in an image sequence (e.g., a video sequence) can be provided in different ways. Roughly speaking, there are at least two different approaches: free image tracking (FIT), which is based only on an input video source, and object-based tracking (OBT), in which a predefined and / or identifiable object is associated with the object being tracked in the image.

[0122] Free image tracking can be provided, for example, by a classifier: based on the input image, the classifier algorithm calculates a classifier of the most recognizable features in the area surrounding a given ROI (for more ROIs, each ROI will be assigned a sensitive area within which tracking is applicable to the given ROI). In one embodiment of the present disclosure, motion tracking of anatomical structures is provided by free image tracking, for example in the form of classifier-based tracking, which includes the following steps: determining a classifier of a more recognizable feature in a video image (preferably in an area adjacent to or surrounding at least one region of interest).

[0123] Free image tracking can also rely on color-based tracking: before a medical procedure such as surgery, at least one ROI of the object (e.g., an anatomical structure, such as the intestine) has been marked with a color and / or pattern (preferably, a predefined color or pattern). The marking can be provided by, for example, a surgeon. If the actual ROI has been marked, the color-based algorithm can obtain the form of the marking and use it as a specific region of interest. The color-based algorithm can be configured to first perform color filtering and then perform object confirmation. Based on the nature of the marking (mainly color), a target RGB or HSV index can be provided for filtering. Then filtering, such as in the form of HSV thresholding, can be provided to obtain a Boolean map of the input image pixels, and the Boolean map will only contain pixels covering the marking. Object confirmation can then be provided by, for example, noise filtering, such as by opening or closing based on erosion / dilation to remove noise from the Boolean map. Using these noise filters, an improved Boolean map with a "filled" ROI can be obtained. That is, the resulting Boolean map is full of zeros (or vice versa) in addition to patches filled with 1, and each patch will correspond to a ROI.

[0124] Another example of free image tracking is based on cross-correlation: after selecting ROI images (usually "normal" white light images), the area within each ROI is stored as an initial reference for each ROI. These initial ROI references are then subsequently used as templates in cross-correlation functions, for example, applied continuously and / or in real time, as a tracking function for each ROI. The cross-correlation function can be a form of pattern recognition and can be seen as a measure of similarity as a function of the displacement of two images relative to each other, i.e. it is very suitable for use as a tracking function. For example, at least initially, the actual tracking function can be limited to the area adjacent to each ROI, because in most cases the actual movement will be periodic. During the medical procedure, additional ROI images can be acquired and stored, and if these additional ROI image acquisitions are used as the basis for an average, the initial template can be improved (possibly continuously improved) to become the new (and possibly final) ROI template used in tracking. Such an improved template, which includes information from several ROI images, therefore includes a temporal aspect. This can make tracking better and / or more efficient. For example, if bowel movement is tracked, the bowel rolls back and forth during the procedure. While it may be more difficult to track the ROI at each position of the scrolling motion when only the initial template ROI is used in tracking, it is much easier to track the ROI at each position of the scrolling motion if an average template averaged from multiple templates of the scrolling motion is used.

[0125] In object-based tracking, one or more objects are physically attached to the target that must be tracked, such as the intestines. Since the object(s) are usually predefined, for example, by size, shape, and color, a classifier can be trained before tracking, i.e., the tracking system used can be configured to automatically recognize (and thus track) the predefined objects. In one embodiment of the present disclosure, anatomical structure motion tracking is provided by object-based tracking, for example, by tracking the motion of one or more predefined objects attached to the anatomical structure.

[0126] As an example of object-based tracking, two (or more) spheres (or another geometrically well-defined object) can be attached to the "top" part of the anatomical structure, and one (or more) spheres can be attached to the lower / bottom part of the anatomical structure (as seen from the imaging device). If the objects attached to the top are different from the objects attached to the bottom, it is easy to distinguish the top from the bottom. If the spheres emit trackers, they are more recognizable and therefore easier to track. They can, for example, contain a fluorescent agent so that the spheres are visible when excited. They can then be confirmed in the image by, for example, Hough circle recognition (or another feature extraction). They can also be colored and confirmed by the color recognition method described above. Since the "top" / "bottom" objects are pre-defined and therefore known in advance, it is easy to train classifiers for these two types of objects. In order to train a classifier for an object, a large database of pictures of the objects can be used to train the classifier. By using the classifier, the location of the "top" and "bottom" objects in the image can be determined very accurately.

[0127] Since the objects are fixed to the target, such as the tissue of the intestine, the ROI can be defined based on these objects (e.g. "top" and "bottom"). For example, in the case of using four objects, the ROI corners can simply correspond to the four tracked object positions. In the case of two objects, the ROI can be defined between the two object positions: for example, a parallelogram, extending from the middle to half height - this determines the angle.

[0128] It should also be noted that tracking is not limited to determining the two-dimensional position / coordinates of the region of interest. Instead, tracking can be achieved by determining the position / coordinates of the region of interest with respect to all three dimensions of Euclidean space. For three-dimensional reconstruction of objects, a variety of imaging methods are known. For example, these methods include methods based on oblique illumination (in which the object is illuminated from the side), microscopy techniques (such as confocal microscopy, light sheet fluorescence microscopy, 3D deconvolution microscopy), and other methods in which the properties of known objects are used to obtain depth information. Other methods for obtaining depth information are known to those skilled in the art and can be used in conjunction with the system disclosed in the present application to accurately track the region of interest in three dimensions. The depth information obtained is preferably used by the system to evaluate the measured perfusion metrics, for example by normalizing the measured fluorescence intensity based on the distance to the region of interest.

[0129] Perfusion assessment

[0130] A lot of valuable information can be obtained from the above perfusion parameters. However, in order to define the perfusion parameters, some kind of reference may be needed.

[0131] In one embodiment, video sequences acquired from different parts of the anatomical structure can be used to calculate perfusion parameters related to each part, and these perfusion parameters can be compared so that the perfusion in different parts of the anatomical structure can be compared, that is, the perfusion parameters obtained from one video sequence can be used as a reference so that a quantitative assessment of perfusion can be provided between video sequences related to different parts of the anatomical structure.

[0132] In another embodiment, different regions of interest from the same video sequence can be selected so that perfusion parameters associated with one region of interest are used as a reference for other regions of interest, thereby providing a quantitative assessment of perfusion between different regions of interest in the same video sequence. These different regions of interest can be selected so that they represent different parts of the anatomical structure or different but adjacent anatomical structures, for example, if the anatomical structure is the gastrointestinal tract, the different parts of the gastrointestinal tract can be the colon and the small intestine. For example, surgery may be performed on the colon, but by comparing with the small intestine, which is typically located near the colon in the body and can thus be imaged during video acquisition, a reference that is not affected by the surgery can be provided. Another example is a prospective skin flap compared to healthy skin that is well perfused in plastic surgery.

[0133] That is, determining at least a first perfusion parameter, such as a flow of fluorescent contrast agent through at least a first said region of interest, wherein the first perfusion parameter is selected from the group consisting of: perfusion slope, washout slope, maximum slope intensity, relative perfusion slope, and subject-specific relative perfusion slope, and determining at least a second perfusion parameter, such as a flow of fluorescent contrast agent through at least a second region of interest, wherein the second perfusion parameter is selected from the group consisting of: perfusion slope, washout slope, maximum slope intensity, relative perfusion slope, and subject-specific relative perfusion, wherein the first and second regions of interest represent different parts of an anatomical structure or different anatomical structures. Then, the perfusion of one of the different parts of the anatomical structure can be evaluated by comparing the perfusion of at least another of the different parts.

[0134] Therefore, a further embodiment comprises the following steps:

[0135] - Performing image analysis on at least two of the following video sequences, each acquired after administration of a fluorescent contrast agent to the subject:

[0136] o a first video image representing at least a first portion of an anatomical structure or at least a first anatomical structure, and

[0137] o a second video image representing at least a second and different portion of the anatomical structure or at least a second and different anatomical structure,

[0138] - calculating intensity values ​​in one or more regions of interest based on an image analysis of the first video image and the second video image, and

[0139] - determining a perfusion slope of a fluorescent contrast agent flow through at least a first region of interest selected in the first video sequence and through at least a second region of interest selected in the second video sequence.

[0140] Another embodiment relates more specifically to anastomosis procedures, where perfusion assessment can be an important indicator of where to provide resection and whether the final anastomosis has adequate perfusion. Therefore, a further embodiment further comprises the following steps:

[0141] - Performing image analysis on two or more of the following video sequences, each acquired after administration of a fluorescent contrast agent to a subject:

[0142] a) video images acquired before an intestinal resection (e.g. bowel resection),

[0143] b) video images acquired after resection but before anastomosis, and

[0144] c) Video image acquired after anastomosis.

[0145] - calculating intensity values ​​in one or more regions of interest based on image analysis, wherein at least a first of said regions of interest is the same region in said two or more video sequences, and

[0146] - Based on the two or more video sequences, determining a perfusion slope of a fluorescent contrast agent flow through at least a first region of interest.

[0147] Based on the two or more video sequences, one or more of the following parameters may be determined based on the two or more video sequences: washout slope, maximum slope intensity, relative perfusion slope, and subject-specific relative perfusion slope.

[0148] Having parameters from two (or more) video sequences acquired at different times during a medical procedure makes it possible to use parameters extracted from one video sequence as reference parameters. Thus, quantitative data of perfusion in at least one of the regions of interest based on slope parameters can be determined from the at least two video sequences. As a result, quantitative and qualitative evaluation parameters can be provided to surgeons during and after a medical procedure such as gastric surgery, for example, to assist in evaluating whether an intestinal (e.g., bowel) resection looks promising. During and after surgery, the results can be evaluated almost immediately, for example, to evaluate whether an anastomosis has adequate perfusion. For example, this can be done by comparing perfusion parameters obtained continuously before, during and / or after surgery or during a medical procedure in order to quantify perfusion changes. Tracking of motion may be key to accurately quantifying perfusion changes, as this is a way to ensure that it is the same region of interest that is being evaluated continuously for perfusion before, during and / or after surgery or during a medical procedure.

[0149] Thresholds specific to perfusion parameters may be provided. Likewise, an uncertainty may be associated with a given threshold. Threshold comparisons may, for example, indicate whether an operation is proceeding well or whether perfusion according to the parameter in question has fallen below a critical level. For several perfusion parameters, a "weighted average answer" may also be provided.

[0150] In one embodiment of the present disclosure, a perfusion slope (and / or other perfusion parameters as described) is calculated from a video sequence acquired before resection and a video sequence acquired after resection but before anastomosis. The relationship between the two perfusion slopes is a measure of the difference in perfusion before and after resection. If perfusion drops below a predefined threshold after resection, a warning may be given. More information may be extracted if perfusion slopes are calculated before and after resection for two, three or more regions of interest - these regions of interest are the same tissue regions imaged before and after resection.

[0151] Oscillatory dynamics

[0152] The inventors have further recognized that the measurement and analysis of reproducible bolus injections can be extended from the interpretation and quantification of single inflow and / or single outflow phases to the analysis of oscillatory fluorescence dynamics. These oscillatory fluorescence dynamics can reveal physical perfusion features that have heretofore been unavailable without invasive measures.

[0153] The systems and methods disclosed in the present application 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 can result in periodic changes that are approximately sinusoidal when measured. In such a curve, the intensity signal measured is expected to increase with the influx of the fluorescent imaging agent from a given bolus, then decrease during the washout phase of the bolus until it increases again under a subsequent bolus, and so on, resulting in a periodic (sinusoidal) pattern.

[0154] Preferably, the system is configured such that it can identify parameters of the oscillation intensity curve, such as frequency and / or amplitude. The trained system can then in turn predict the direction and regularity of the upcoming signal dynamics. The system preferably uses the measured values ​​in order to identify the oscillation pattern, so that the system can thereafter detect differences between the measured values ​​and the expected values. The measured values ​​can further be used continuously to improve the pattern recognition, i.e. the expected values. Alternatively or additionally, injection parameters such as bolus frequency, dose and flow rate can be used to determine the expected values, i.e. the vibration pattern.

[0155] With the system predicting the expected value, it can detect and indicate the onset of an ischemic condition at an early point in time, ideally instantaneously. The detection of an ischemic condition can be a function of expected value(s) and detected value(s), such as a threshold.

[0156] Deviations from an expected sinusoidal pattern may be due to, for example, the onset of an ischemic condition in at least a portion of the anatomy visible in the video image, or regional variations in perfusion to a given region. Fig. 12A An illustrative figure is given in which this kinetic change is demonstrated in human subjects due to an ischemic episode. Fig. 12B A zoomed view of a narrower range is given in . As can be seen, a transition from a regular oscillating fluorescence signal to an ischemic plateau can be detected. However, it should be noted that changes in perfusion of the anatomical structure of interest can lead to other measurement patterns besides the ischemic plateau. An example is venous occlusion, where blood flow out of an anatomical region is blocked or reduced due to congestion or accumulation of fluorescent agent in a given area, resulting in a change in the oscillatory dynamics. From Fig. 13C It can be seen that although the cyclic oscillations have stopped, the result is not a flat line.

[0157] As described herein, such a system can observe and detect changes in the perfusion level of a given area in a video image within a few seconds. This can be detected in an area that has been observed for a long time (e.g., many minutes) where the dynamics have been continuously visualized and the phase is therefore well known. Fig. 12CAn illustrative diagram is shown in , which highlights the difference between the signals that one can expect to observe for ischemic / healthy tissue regions. However, it can also be determined in anatomical regions that are only visualized during short time intervals (e.g., 10-20 seconds), because the system is trained to expect and detect a certain phase of the described oscillatory dynamic signal at a given time in the tissue, consisting of regular rises and falls of the temporal intensity signal. See Fig.12D , which shows how the anatomical region of interest would look if it drifted in and out of focus of the recorded images.

[0158] Preferably, the system includes tracking means and can run independently in the background, while the surgeon is only exposed to the visible white light signal and is therefore only interrupted / notified by the warning signal. During detection of the onset of an ischemic condition, for example.

[0159] Another aspect of the present disclosure relates to continuous perfusion assessment related to repeated injections of fluorescent active agents and monitoring of the resulting oscillation curve. In addition to detecting unforeseen perfusion changes, the system can also be used to assess the perfusion area of ​​an artery. For example, a surgeon may consider cutting an artery as part of a surgical procedure. Before cutting an artery, the surgeon may temporarily limit the perfusion through the artery, and the method disclosed in the present application may enable visualization of the perfusion area of ​​the artery in a short period of time (e.g., less than 1 minute). This may be valuable information for surgeons during continuous surgical procedures. In a similar manner, the system can be used to assess the drainage area of ​​a vein or a group of veins, lymphatic vessels, lymph nodes, or other parts of a circulation and / or lymphatic pathway. By temporarily limiting the flow of blood through a vessel, blood will gather in an anatomical region that is normally drained by the vessel or the group of vessels. This enables visualization of an anatomical region drained by the vessel in a relatively short period of time (e.g., less than 2 minutes). This can provide important information to surgeons in fields such as general surgery and plastic surgery (including wound and reconstructive surgery), such as during continuous surgical procedures.

[0160] Anatomy

[0161] The anatomical structure of the systems and methods disclosed herein can be an internal organ of a subject. Perfusion will then typically be assessed in tissue external to the organ. Alternatively, the anatomical structure can be (a portion of) the skin of a subject. Perfusion will then typically be assessed in skin tissue.

[0162] Perfusion assessment of wounds is also highly relevant. Thus, the anatomical structure may include at least one wound, which would be the subject of perfusion assessment.

[0163] The anatomical structure may be the gastrointestinal tract, preferably including the buccal cavity; pharynx; small intestine, including the duodenum, jejunum, and ileum; stomach, including the esophagus, cardia, and pylorus; large intestine, including the cecum, colon, rectum, and anal canal.

[0164] Gastrointestinal

[0165] Complications related to the gastrointestinal tract are usually related to local hemodynamics. That is, changes in normal hemodynamic conditions can indicate an increased risk of complications. Therefore, when examining the gastrointestinal tract, for example, for diagnosing complications or determining the location of complications, such as during diagnostic laparoscopy, exploratory laparoscopy or surgical laparoscopy or robotic surgery using traditional laparoscopy and in open surgery, perfusion assessment of the gastrointestinal tract (particularly on and near the surface of the gastrointestinal tract, such as tissue of the gastrointestinal wall) can be an important diagnostic tool. During the formation of a surgical procedure that can provide anastomosis for establishing communication between two previously distant parts of the gastrointestinal tract, perfusion assessment is also important. As an example, an intestinal anastomosis establishes communication between two previously distant parts of the intestine, and usually restores the continuity of the intestine after removing the pathological conditions affecting the intestine. Providing an intestinal anastomosis can be, for example, used in the following aspects: 1) restore the continuity of the intestine (intestinal) (such as bowel) after resection of the diseased intestine, and 2) bypass the diseased intestine (intestine) that cannot be removed, such as bowel (bowel). Certain pediatric conditions may also require intestinal anastomosis[6].

[0166] Diseased bowel may be removed in the following settings:

[0167] Intestinal gangrene, which is caused by damage to blood vessels due to mesenteric vascular disease, long-standing intestinal obstruction, intussusception, or volvulus

[0168] Malignant tumors

[0169] Benign diseases (e.g., intestinal polyps, intussusception, ascariasis with intestinal obstruction)

[0170] Infection (eg, tuberculosis complicated by stricture or perforation)

[0171] Traumatic perforation

[0172] Large perforations that cannot be repaired by primary suture (traumatic)

[0173] Radiation enteritis complicated by bleeding, stricture or perforation

[0174] Inflammatory bowel disease, ulcerative colitis, or Crohn's disease that is refractory to medical therapy or is associated with complications (e.g., bleeding, perforation, toxic megacolon, dysplasia / cancer)

[0175] Chronic constipation, idiopathic slow-transit constipation, or Hirschsprung's disease: If the disease is refractory to medical therapy, a subtotal colectomy may be done.

[0176] Unresectable diseased bowel may be bypassed in the following settings:

[0177] Locally advanced tumors causing luminal obstruction

[0178] Metastatic disease causing intestinal obstruction

[0179] Poor overall condition or condition that cannot be extensively excised

[0180] Pediatric conditions that may require an intestinal anastomosis include the following:

[0181] Congenital anomalies (eg, Meckel's diverticulum, intestinal atresia, malrotation with volvulus leading to gangrene, meconium ileus, duplication cysts, Hirschsprung disease)

[0182] Inflammatory conditions (eg, necrotizing enterocolitis, enterocolitis, tuberculosis, intestinal perforation)

[0183] Other conditions (eg, intussusception, angiodysplasia, polyposis, ascariasis)

[0184] As part of other surgical procedures (e.g. Kasai anorectal anastomosis, choledochal cyst, urinary diversion, pancreatic tumor)

[0185] Unfortunately, postoperative complications associated with gastrointestinal anastomoses are common, often due to inadequate perfusion (capillary blood supply) at the anastomosis, the connection of two parts of the intestine. Inadequate perfusion can lead to anastomotic leaks, a serious and frequent complication associated with, for example, colorectal surgery, where more than 10% of surgeries result in complications. In colon cancer surgery, more than 30% of patients with anastomotic leaks die due to postoperative complications, and of the remaining patients, approximately 25% are affected by the stoma for the rest of their lives. Risk factors associated with fistulas include anastomotic tension, tissue damage, and especially reduced blood perfusion.

[0186] Thus, in one embodiment, the present disclosure relates to performing image analysis on one or more video sequences representing at least a portion of the gastrointestinal tract, e.g., acquired before, during and / or after surgery (particularly surgery involving the gastrointestinal tract). This may be particularly applicable to gastrointestinal surgery - thus, the video sequence may include the exterior of at least a portion of the gastrointestinal tract, preferably such that perfusion in at least a portion of the gastrointestinal wall can be measured and assessed.

[0187] The gastrointestinal tract is the organ system in humans and other animals that takes in food, digests it to extract and absorb energy and nutrients, and excretes the remaining waste as feces and urine. The gastrointestinal tract can be thought of as a tube that moves food to the digestive organs. Therefore, the term gastrointestinal tract as used herein includes the buccal cavity; pharynx; small intestine, including the duodenum, jejunum, and ileum; stomach, including the esophagus, cardia, and pylorus; and large intestine, including the cecum, colon, rectum, and anal canal. Example

[0188] The intensity curves shown in the examples are the result of bolus injections using normal amounts of fluorescent agents (ICG in these cases). The amount of ICG in each bolus was selected so that the fluorescence emission is visible to the human eye. The examples are provided to illustrate various perfusion parameters that can be calculated after fluorescence imaging. These same parameters can also be determined to a large extent after injection of much smaller doses, i.e., the microdosage method disclosed herein with possible repeated and continuous measurements and related perfusion assessments.

[0189] Figure 1A , 1C 1E and 1E show examples of intensity curves obtained from tissue after providing an ICG bolus to a subject, 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 rise in intensity indicates that ICG molecules pass through the imaged tissue and are excited to fluoresce. After the intensity peak, the ICG molecules are gradually washed away. The intensity is expressed in arbitrary units. Figure 1B , 1D and 1F show the corresponding intensity curves, wherein the hemodynamic parameters perfusion slope, slope start, slope end maximum intensity, washout slope, washout start and washout slope end have been calculated and are shown in the figure.

[0190] Figures 2A-2F Three embodiments are shown that illustrate the method disclosed herein for determining the point in time at which the perfusion slope begins (ie, the slope start point). Figure 2B , 2D and 2F are Figure 2A , 2C and a close-up of 2E, where the slope starts, i.e. the right graph shows a close-up of the left curve, where the slope start is in more detail. It can be seen that the slope start is defined as the time point at which the slope exceeds the mean value k*std, where k is a predefined constant and std is the standard deviation of the intensity values ​​before the slope start. The slope starts at Figure 2B Indicated by a circle.

[0191] Figures 3A-3F Three embodiments are shown, which illustrate the method disclosed herein for determining the perfusion slope based on histogram data. The left figure shows an intensity curve, where Figure 3A Corresponds to Figure 2A , Figure 3E Corresponds to Figure 2E The slope starts at Figure 3A Indicated by arrows in Figure 3C and 3E Indicated by a circle in the figure. All possible slopes of the intensity curve have been calculated from the slope start point to the end point of the intensity curve. All calculated slopes are collected and binned in the histogram shown on the right. The perfusion slope is defined as the most frequent value of the histogram, i.e. the highest histogram bin. Figure 3A , 3C and the calculated perfusion slope of each intensity curve in 3E, i.e., Figure 3B , 3D and the highest histogram bar in 3F, in Figure 3A , 3C and 3E are marked with straight lines.

[0192] Figures 4A-4F Three embodiments are shown that illustrate the methods disclosed herein for defining and determining maximum slope strength. Figure 4B , 4D and 4F are Figure 4A , 4C and a close-up of 4E, where the curves have their maximum intensity. The maximum intensity of the curves is at Figure 4B Indicated by an asterisk in Figure 4D and 4F The maximum slope intensity is represented by a square in the figure, and the maximum slope intensity is represented by a diamond in the figure. The maximum slope intensity is defined as the intensity value at the time point where the distance to the perfusion slope exceeds a predefined limit, such as a limit based on a constant (k2) multiplied by the standard deviation of the perfusion slope. As shown in Figure 4, there may be a significant difference in time and intensity between the maximum intensity and the maximum slope intensity of the curve. The slope rise time can be defined as the difference between the peak (maximum) intensity of the curve and the beginning of the slope. However, as shown here, the slope rise time defined as the difference between the maximum slope intensity and the beginning of the slope gives a more relevant definition of the slope rise time.

[0193] Figures 5A-5F Three examples are shown illustrating the method disclosed herein for analyzing the elution of fluorescent contrast agents. The intensity curves are the same as in FIG. 4 . Figure 5B , 5D and 5F respectively Figure 5A , 5C and a close-up of 5E, where ICG is washed away. In the left image, the maximum intensity is at Figure 5A Indicated by an asterisk in Figure 5C and 5Edenoted by squares in the figure. A close-up of the elution portion is shown in the figure on the right. The elution data has been analyzed in the same manner as the perfusion slope, and all possible elution slopes have been calculated. Similar to the determination of the perfusion slope in the above example, the elution slopes can be binned and classified in a histogram (not shown) to select the elution slope with the highest frequency. The elution start point is usually after the maximum intensity of the curve. In this embodiment, the elution start point is defined as symmetrical around the maximum curve intensity and the maximum slope intensity. In this embodiment, the elution end point is determined in the same manner as the determination of the maximum slope intensity in the above example, i.e. when the intensity differs from the elution slope by a predefined constant multiplied by the standard deviation of the elution slope.

[0194] Figures 6A-6D Two additional fluorescence measurements using ICG analysis are shown, illustrating the robustness of the analysis method disclosed in this application. Fig. 6A The first figure shown shows intensity data, slope starting point, calculated perfusion slope (dashed line), maximum slope intensity and maximum curve intensity. The right figure shows a histogram of perfusion slope data with binning. It can be seen that the intensity data is not as stable as other intensity curves disclosed herein, with many local changes and no obvious intensity reduction after the perfusion slope. There will be elution of the ICG molecule, but the data shown here do not include this part. Fig. 6A and 6B It is shown that the exemplary method disclosed herein is a very robust procedure that can be used to automatically and in real time determine the perfusion slope and other perfusion parameters derived therefrom. Fig. 6A A large difference between the maximum slope intensity and the time point of maximum curve intensity is also shown. The slope rise time derived from the maximum slope intensity is considered to be a more relevant parameter to characterize the passage of the ICG bolus.

[0195] by Figure 6C The second figure shown also shows that the intensity data is not stable, and all the calculated perfusion slopes are distributed in a larger interval, such as Fig.6D However, by selecting the histogram bins with the highest frequencies, relevant and accurate perfusion slope parameters can still be extracted from the data, thus providing another example of the robustness of the method disclosed in the present application.

[0196] Figure 7Output video frames of the video sequence obtained during intestinal surgery are shown. The upper right corner shows the original video (i.e., one frame) of the operation obtained during the ICG bolus. The upper left corner shows the same video frame after image processing, and tissue perfusion can now be seen more clearly. As indicated in the figure, four regions of interest (1, 2, 3, 4) are indicated in the video frame. The figure below shows the mean pixel intensity of the four regions of interest, as a function plot of time (seconds) relative to normalized intensity. The perfusion slopes of four ROIs (1, 2, 3, 4) are calculated and shown with straight lines in the figure.

[0197] When observing only the two video frames above, it is impossible for the surgeon to determine whether all ROIs 1, 2, and 3 are equally and adequately perfused, e.g., whether regions 1, 2, and 3 are equally suitable for anastomosis. This can also be seen in the figure below, after about 70 seconds, where the pixel intensities of ROIs 1, 2, and 3 are similar. However, by applying the methods disclosed herein to determine the perfusion slopes of different ROIs, an objective perfusion measurement can be immediately provided to the surgeon. Figure 7 In the embodiment of FIG. 4 , it can be seen from the calculated perfusion slope that ROI 3 has reduced perfusion compared to ROI 1 and ROI 2. This information provides the surgeon with an objective perfusion parameter on which to base his or her surgical decision, thereby ultimately increasing the chances of a successful surgical outcome.

[0198] Fig. 8A A still image from a normal video sequence acquired prior to resection of a patient's bowel is shown. The image shows the small intestine (lower portion) and the colon (upper portion). It is the colon that is about to be resected, but by including the small intestine in the image analysis, an additional, potentially unbiased, high perfusion reference measurement of the patient's perfusion can be provided for comparison with later perfusion measurements.

[0199] Figure 8B Shown with Fig. 8A Figure 2 is a fluorescence image of essentially the same gastrointestinal tract subsection in Figure 2 but acquired later (i.e., after a bolus of fluorescent contrast agent (ICQ) has been injected into the patient). Three ROIs are indicated in the image used for image analysis: the upper left blue box located at the colon, the lower red box located at the small intestine (high perfusion reference), and the upper right box located at a reference location in the image with essentially no blood perfusion (no / low perfusion reference).

[0200] Fig. 9A Shown in Figure 8BThe intensity curves obtained in the ROI and the perfusion slopes calculated according to the method disclosed in this article, that is, the perfusion slopes of the colon and small intestine before resection. Although the intensity curves look very different, the calculated perfusion slopes of the colon and small intestine are comparable, however, the perfusion slope of the small intestine is steeper (higher perfusion level) than the perfusion slope of the colon. This is also Fig. 9B , where the perfusion slopes of the small intestine (left) and colon (right) have been normalized to the perfusion slope of the small intestine.

[0201] Fig. 10A Shown with Fig. 8A A normal image of essentially the same subsection of the gastrointestinal tract in FIG, but acquired after resection of the intestine and before anastomosis. This is a critical part of the surgery where the surgeon must assess whether the perfusion of both ends of the intestine left after resection is adequate for the anastomosis, or whether more intestine must be resected to ensure that the anastomosis is formed in an area of ​​optimal perfusion, ultimately increasing the chances of a successful outcome. Therefore, the surgeon is interested in obtaining measurements of perfusion of various areas surrounding the resected intestine. The small intestine is marked at the bottom of the image and the resected intestine (colon) is marked at the top of the image.

[0202] Fig. 10B After the ICG bolus has been injected, the Fig. 10A Five ROIs are shown: one on the small intestine (red) as a high perfusion reference, one located at a reference position in the image (black) with essentially no blood perfusion (no / low perfusion reference), and three (blue, green, and yellow) on the resected intestine (colon).

[0203] Fig.11A Shown by Fig. 10A and 10B The intensity curves obtained from the measurements are shown. The red ROI corresponds to the small intestine and gives the steepest perfusion slope, and the black reference ROI naturally gives the lowest perfusion slope. The blue, green, and yellow ROIs corresponding to the three ROIs located on the intestine provide comparable perfusion slopes, also in Fig. 11B Figure 2 summarizes the perfusion slopes of the small intestine (left, red) and the intestinal tract (right, blue, green, and yellow) normalized to the perfusion slope of the small intestine. Fig. 9B There is a clear difference. Fig. 9B (Before resection), the perfusion in the intestinal segment was comparable to that in the small intestine, whereas after resection, the perfusion in the resected intestinal segment was much lower than that in the small intestine. Fig. 9A (before resection) and Fig.11A (after resection), the absolute value of the perfusion slope was much larger after resection, and this was also true for the small intestine. This suggests that the absolute value of the perfusion slope (and other perfusion parameters) is not as important as the relative value, as Fig. 9B and 11BThat is, it is important to have one or more reference ROIs in the image analysis so that the calculated perfusion parameters can be compared with comparable perfusion parameters obtained from the same video clip. In this example, the method of determining perfusion disclosed herein detected a significant decrease in perfusion of the intestine (colon) relative to that of the small intestine. This important information can guide the surgeon in selecting the optimal location for the anastomosis.

[0204] Fig. 12A Actual measurement data from human subjects are shown. The human subjects were repeatedly injected with microboluses of ICG at regular intervals (about 2 minutes in this example). The time intensity curve shows a substantially sinusoidal pattern that increases linearly with time. The increase in intensity over time is related to the ratio between the fluorescer dose and the washout time, during which the fluorescence intensity decreases. At a certain time point, approximately t=3800 s, Fig. 12B , perfusion becomes restricted, leading to the onset of ischemia, which can be seen by the lack of oscillations after this time point, forming a pattern that can be described as an ischemic plateau.

[0205] Fig. 12C Idealized data showing a time-intensity sinusoidal curve is shown. After injection of the fluorescent imaging agent, the measured ROI intensity increases, while it decreases during the washout phase. At approximately t=3750s, due to the onset of an ischemic condition, the measured data shows a fixed measured ROI intensity value. Alternatively, if there were no ischemic condition, the measured values ​​would be expected to follow the dotted line so that the measured ROI values ​​continuously follow a sinusoidal pattern.

[0206] Fig.12DIdealized data showing a time-intensity sinusoidal curve in the absence of an ischemic condition is shown, where the anatomical region of interest drifts in and out of focus. If the ROI is continuously observable, the dashed line shows the expected measured value. If this is not possible, for example because the anatomical region of interest drifts in and out of focus of the recorded image, the measured data may be incomplete, but there may be gaps - time intervals in which the measured data of the anatomical region of interest is not obtained. Therefore, even if the recorded data is incomplete, the system is preferably able to identify the sinusoidal pattern. If the system is able to correctly identify the sinusoidal pattern, it can be provided with the expected intensity value of the ROI at each time point, which is then used to compare with the measured value. If (one or more) measured values ​​are different from (one or more) expected values, the system can be configured to provide an alarm to the surgeon. Therefore, the system can be configured so that it identifies the phase of the oscillation / sinusoidal pattern of the measured time point or interval, and then compares it with the expected phase of the time point or interval, where the expected phase is preferably based on the identified oscillation pattern and / or known frequency of repeated bolus injections. As a result, the system does not necessarily require continuous measurements, but can be based on the expected phase of the oscillation pattern combined with time information of the measured time points or intervals so that a specific phase of the oscillation pattern is expected to occur in the measured interval.

[0207] Fig.13A Fluorescence intensity measurements of a human subject performed over a longer time interval (about 40 minutes) are shown, into which the human subject has been repeatedly injected with ICG microbolus. The intensities of seven separate ROIs were measured and assigned separate colors in the figure. The measured fluorescence intensity exhibits a periodic sinusoidal pattern with a frequency consistent with the injection frequency (about 120 s). Due to the relatively short injection time compared to the dose size, the pattern is a substantially linear increase 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.

[0208] Fig. 13B Shows Fig.13A Here, we can see that the fluctuations within the same ROI and between different ROIs are small. At the same time, the cyclic intensity patterns are different, and the patterns of each ROI have the same period.

[0209] Fig. 13CA time intensity graph of measurements made on a human subject with reproducible injections of microboluses of a fluorescent imaging agent is shown. The graph shows the result of a venous occlusion, where between approximately t=62-78 minutes, perfusion is limited, although not completely impeded. In this case, the oscillatory dynamics of the measured fluorescence intensity ceases, and the measurements show an irregular increase during the venous occlusion. It should therefore be noted that reduced perfusion does not necessarily result in a flat line, as is otherwise commonly obtained during ischemic conditions.

[0210] References

[0211] References

[0212] [1] C. Toens et al.: Validation of IC-VIEW fluorescence videography in arabbit model of mesentereic ischaemia and reperfusion. Int J ColorectalDis2006; 21:332-338.

[0213] [2] N.Nerup et al.: Quantification of fluorescence angiography in aporcine model. Langenbecks Arch Surg, published online 15 November 2016.

[0214] [3] L. Boni et al.: Indocyanine green-enhanced fluorescence to assess bowelperfusion during laparoscopic colorectal resection. Surg Endosc (2016) 30:2736–2742

[0215] [4] R.Uitert et al.: A stable optic-flow based method for trackingcolonoscopy images.Conference Paper, July 2008

[0216] [5] US 2016 / 262638

[0217] [6] D.Stein et al.: Colon Resection. http: / / emedicine.medscape.com / article / 1891505-overview, September 2015

[0218] project

[0219] 1. A method for automated perfusion assessment of an anatomical structure of a subject, the method comprising administering a bolus of a first fluorescent imaging agent into a vein corresponding to less than 0.01 mg ICG / kg body weight, acquiring and analyzing time-series fluorescent images of tissue 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.

[0220] 2. The method according to item 1, wherein the drug is injected via a controllable injection pump.

[0221] 3. A method according to any of the preceding items, wherein the medicament is injected in the form of a series of boluses with a predefined time between subsequent boluses.

[0222] 4. A method according to any of the preceding items, wherein the fluorescence emission of the anatomical structure is measured after each bolus injection.

[0223] 5. A method according to any of the preceding clauses, wherein the bolus comprises increasing or decreasing amounts of the agent.

[0224] 6. A method according to item 5, wherein the amount is increased or decreased from one bolus to a subsequent bolus in increments of 10%.

[0225] 7. A method according to any of the preceding items, wherein a minimum bolus is determined after administering a series of increasing or decreasing boluses, said minimum bolus providing quantifiable fluorescence emission representative of perfusion of the anatomical structure.

[0226] 8. A method according to any of the preceding items, wherein the interval between boluses is between 5 and 600 seconds, such as between 15 and 300 seconds, such as between 45 and 210 seconds, such as between 90 and 120 seconds.

[0227] 9. A method according to any of the preceding items, wherein the interval between boluses is long enough to allow measurement of the perfusion slope of each bolus in the anatomical structure, preferably wherein the perfusion slope comprises a slope onset and a washout slope.

[0228] 10. A method according to any of the preceding items, wherein a volume of isotonic solution (e.g., saline) is injected immediately after the injection of the bolus of fluorescent imaging agent, e.g., wherein the volume is 1-20 mL, e.g., 2.5-15 mL, e.g., 5-10 mL.

[0229] 11. The method according to any of the preceding items, wherein the amount of fluorescent imaging agent corresponds to 0.0001 to 0.01 mg ICG / kg body weight per bolus, such as 0.0001 to 0.01 mg ICG / kg body weight per bolus.

[0230] 12. The method according to any of the preceding items, wherein the initial amount of the fluorescent imaging agent corresponds to at least 0.001 mg ICG / kg body weight.

[0231] 13. The method of claim 12, wherein subsequent boluses are increased or decreased from one bolus to a subsequent bolus by an amount corresponding to at least 0.001 mg ICG / kg body weight.

[0232] 14. The method according to any of the preceding items, wherein the bolus has a liquid volume of 0.5 μL to 10 mL, such as 0.5-5 mL.

[0233] 15. The method according to any of the preceding items, wherein a second fluorescent imaging agent is administered, the emission maximum of the second fluorescent imaging agent differing by at least 50 nm from the emission maximum of the first fluorescent imaging agent.

[0234] 16. The method according to any of the preceding items, wherein a third, fourth, fifth or more fluorescent imaging agents are administered.

[0235] 17. The method according to item 15 or 16, wherein the first fluorescent imaging agent and the subsequent fluorescent imaging agents are administered alternately.

[0236] 18. A method according to item 15, 16 or 17, wherein the interval between administrations of different fluorescent imaging agents is half the interval between subsequent administrations of the same fluorescent imaging agent.

[0237] 19. A method according to any of the preceding items, wherein fluorescence is automatically detected by illuminating the anatomical structure with a light source capable of exciting the fluorescent imaging agent, and the emission is quantified by a series of fluorescent images of the anatomical structure.

[0238] 20. A method according to any of the preceding clauses, wherein the time period between boluses is determined by a computer configured to detect a perfusion slope caused by each bolus.

[0239] 21. A method according to any of the preceding items, wherein the doses of the fluorescent imaging agent and / or the time periods between boluses are selected such that an oscillatory pattern of a time series of the mean intensity of the ROI is received.

[0240] 22. A method according to any of the preceding items, wherein longer breaks, such as at least 1 minute, are maintained at regular intervals, such as every 20 boluses, more preferably every 40 boluses, most preferably every 60 boluses, so that the background fluorescence level can be reduced.

[0241] 23. A method according to any of the preceding items, wherein the amount of fluorescent imaging agent in the bolus is controlled by a computer configured to determine a minimum bolus that is capable of determining a minimum fluorescent emission representative of perfusion of the anatomical structure.

[0242] 24. A method according to any of the preceding items, wherein the anatomical structure is the gastrointestinal tract, preferably including the buccal cavity; pharynx; small intestine, including the duodenum, jejunum and ileum; stomach, including the esophagus, cardia and pylorus; large intestine, including the cecum, colon, rectum and anal canal.

[0243] 25. The method according to any of the preceding items, wherein the anatomical structure is an internal organ of a subject.

[0244] 26. The method of any of the preceding items, wherein the anatomical structure is the skin of a subject.

[0245] 27. The method according to any of the preceding items, wherein the anatomical structure comprises a wound which is the subject of perfusion assessment.

[0246] 28. A method according to any one of the preceding items, wherein the fluorescent imaging agent comprises indocyanine green (ICG), fluorescein isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, o-phthalaldehyde, fluorescamine, rose bengal, trypan blue, fluorescein gold, green fluorescent protein, flavin, methylene blue, porphysome, cyanine dye, IRDDye800CW, CLR 1502 bound to a targeting ligand, OTL38 bound to a targeting ligand, or a combination thereof.

[0247] 29. A method according to any of the preceding items, further comprising the step of tracking the movement of anatomical structures in the video image.

[0248] 30. A method according to any one of the preceding items, further comprising the following steps: tracking the movement of at least a portion of the anatomical structure in the video image, and associating the movement so that at least the first region of interest corresponds to the same sub-portion of the anatomical structure in the video image.

[0249] 31. A method according to any of the preceding items, wherein motion tracking is provided by free image tracking.

[0250] 32. A method according to any of the preceding items, wherein motion tracking is provided in the form of classifier-based tracking by free image tracking, and the free image tracking comprises the following steps: in the video image, preferably in at least one area adjacent to or surrounding an area, a classifier of multiple identifiable features is determined.

[0251] 33. A method according to any of the preceding items, wherein motion tracking is provided in the form of color based tracking by free image tracking.

[0252] 34. A method according to any of the preceding items, wherein the movement tracking is based on color tracking of one or more color markings that have been applied to the gastrointestinal tract.

[0253] 35. A method according to any of the preceding items, wherein motion tracking comprises the steps of: colour filtering and thresholding to obtain a Boolean map of pixels in the video image.

[0254] 36. The method according to any of the preceding items, further comprising the step of: noise filtering to improve the Boolean graph.

[0255] 37. A method according to any of the preceding items, wherein motion tracking is provided by object based tracking.

[0256] 38. A method according to any of the preceding items, wherein motion tracking is provided by tracking the motion of one or more predefined objects attached to the anatomical structure.

[0257] 39. A method according to any of the preceding items, comprising the steps of creating ROI templates by initially storing an image of each ROI, and wherein motion tracking is provided by applying cross-correlation to each ROI template.

[0258] 40. The method according to any of the preceding items, wherein tracking is performed such that three-dimensional information of at least a portion of the anatomical structure is acquired.

[0259] 41. The method according to any of the preceding items, wherein the perfusion assessment comprises determining the location of a perfusion complication in the anatomical structure.

[0260] 42. The method of any of the preceding items, wherein the perfusion assessment is used in conjunction with a diagnostic or surgical procedure.

[0261] 43. The method of claim 42, wherein the procedure comprises diagnostic laparoscopy, exploratory laparoscopy, surgical laparoscopy and conventional laparoscopy, robotic surgery, and open surgery.

[0262] 44. The method according to item 42, wherein the procedure comprises anastomosis, such as an intestinal anastomosis.

[0263] 45. A fluorescent imaging agent for use in a method according to any one of the preceding items.

[0264] 46. ​​Use of a fluorescent imaging agent in the preparation of a medicament for use in the automated perfusion assessment method according to any one of the preceding items 1 to 44.

[0265] 47. A system for automatic perfusion assessment of an anatomical structure during a medical procedure on a subject, comprising a controllable injection pump for containing at least one first fluorescent imaging agent, the injection pump being configured to inject a predefined amount of the first fluorescent imaging agent into the blood of the subject, wherein the system is configured to receive and analyze time-series fluorescent images of tissue of the anatomical structure after injection of the first fluorescent imaging agent, and determine at least one perfusion parameter of the anatomical structure based on the analysis.

[0266] 48. A system according to any of the preceding items, wherein the system is configured to control the injection pump to inject an initial small bolus of fluorescent imaging agent, preferably in an amount corresponding to less than 0.01 mg ICG / kg body weight, and then analyze the fluorescent emission generated by the initial bolus.

[0267] 49. A system according to any of the preceding items, wherein the system is configured to control the injection pump to inject an initial small bolus of fluorescent imaging agent, preferably in an amount corresponding to less than 1 mg ICG or less than 0.8 mg ICG or less than 0.6 mg ICG or less than 0.4 mg ICG or less than 0.2 mg ICG, and then analyze the fluorescent emission generated by the initial bolus.

[0268] 50. The system according to any of the preceding clauses, wherein the system is configured to determine a subject-specific minimum effective bolus of the fluorescent imaging agent by:

[0269] - controlling the syringe pump to inject a series of boluses of the fluorescent imaging agent in predefined increasing or decreasing amounts with a predefined period of time between each bolus,

[0270] - Analysis of fluorescence emission of anatomical structures after injection of each bolus, and

[0271] -Determine the minimum bolus size that provides quantifiable fluorescence emission from the anatomical structure.

[0272] 51. A system according to any of the preceding items, wherein the system is configured to: 1) receive time series images of tissue of the anatomical structure before injection of a fluorescent agent; and 2) determine background noise levels therefrom.

[0273] 52. A system according to any of the preceding items, wherein the system is configured to determine a subject-specific conversion period, wherein the subject-specific conversion period is defined as the time period from injection of a bolus of fluorescent imaging agent to an increase in fluorescence slope in fluorescence emission.

[0274] 53. A system according to any of the preceding items, wherein the system is configured to determine a subject-specific interruption interval, wherein the subject-specific interruption interval is defined as a time period from when the fluorescence slope rises to when the fluorescence emission is equal to the background noise.

[0275] 54. A system according to any of the preceding items, wherein the system is configured to automatically: 1) control an injection pump to inject a series of boluses of a predefined fluorescent imaging agent, a predefined bolus such as a minimum effective bolus, and a predefined duration between each bolus, and 2) determine at least one perfusion parameter of the anatomical structure after injection of each bolus.

[0276] 55. The system according to any of the preceding items, wherein the system is configured for determining the at least one perfusion parameter in one or more regions of interest located in the anatomical structure and optionally in adjacent anatomical structures.

[0277] 56. A system according to any of the preceding items, wherein the system is configured to automatically: 1) control an injection pump to inject a series of boluses of the fluorescent imaging agent in increasing or decreasing amounts, with a predefined time period between each bolus; and 2) determine at least one perfusion parameter of the anatomical structure after injection of each bolus.

[0278] 57. A system according to any of the preceding items, comprising at least a second controllable injection pump for containing at least a second fluorescent agent, the second fluorescent agent being different from the first fluorescent agent, the second injection pump being configured to inject a predefined amount of the second fluorescent imaging agent into the blood of the subject.

[0279] 58. A system according to any of the preceding items, wherein the system is configured for determining the at least one perfusion parameter in one or more regions of interest located in the anatomical structure and optionally in adjacent anatomical structures.

[0280] 59. A system according to any of the preceding item 58, configured such that the region of interest can be selected by a user of the system.

[0281] 60. A system according to any of the preceding items, further comprising at least one light source configured to provide excitation light to induce fluorescent emission from the first and / or second fluorescent agent in the anatomical structure.

[0282] 61. The system according to any of the preceding items, further comprising: an imaging unit configured to record at least one time series of fluorescence emissions from the anatomical structure.

[0283] 62. A system according to any of the preceding items, wherein the imaging unit is configured for white light imaging.

[0284] 63. The system according to any of the preceding items, configured to send the at least one perfusion parameter for presentation on a display.

[0285] 64. A system according to any of the preceding items, wherein the anatomical structure is the gastrointestinal tract, preferably including the buccal cavity; pharynx; small intestine, including the duodenum, jejunum and ileum; stomach, including the esophagus, cardia and pylorus; large intestine including the cecum, colon, rectum and anal canal.

[0286] 65. A system according to any of the preceding items, wherein the anatomical structure is an internal organ of a subject.

[0287] 66. A system according to any of the preceding items, wherein the anatomical structure is the skin of a subject.

[0288] 67. A system according to any of the preceding items, wherein the anatomical structure includes a wound, and the wound is the subject of perfusion assessment.

[0289] 68. The system according to any of the preceding items, wherein the system is part of a laparoscopic setup, wherein the imaging unit and the light source are incorporated into the laparoscopic unit.

[0290] 69. A system according to any of the preceding items, wherein the system is part of an open surgical setting, wherein the imaging unit and the light source are incorporated into the open surgical unit.

[0291] 70. A system according to any of the preceding items, wherein the fluorescent imaging agent comprises indocyanine green (ICG), fluorescein isothiocyanate, rhodamine, phycoerythrin, phycocyanin, allophycocyanin, o-phthalaldehyde, fluorescamine, rose bengal, trypan blue, fluorescein gold, green fluorescent protein, flavin, methylene blue, porphyrin liposomes, cyanine dyes, IRDDye800CW, CLR 1502 bound to a targeting ligand, OTL38 bound to a targeting ligand, or a combination thereof.

[0292] 71. A system according to any of the preceding items, wherein the system is configured to assess the drainage area of ​​a vein or a group of veins, a lymphatic vessel, a lymph node, or other portion of a circulatory and / or lymphatic pathway.

[0293] 72. A system according to any of the preceding items, configured to perform the method of any of items 1-44.

[0294] 73. A computer-implemented method for detecting changes in perfusion of at least a portion of an anatomical structure, wherein a repeatable bolus comprising a fluorescent imaging agent is continuously injected into a subject; the method comprising the steps of:

[0295] i. measuring a time series of fluorescence intensity in a region of interest of at least a portion of an anatomical structure;

[0296] ii. Identify the measurement pattern of the time series of measurements,

[0297] iii. creating an expected pattern based on the measured pattern, the fluorescence intensity of at least a portion of the anatomical structure of interest being expected to follow the expected pattern;

[0298] iv. measuring the fluorescence intensity of the anatomical region of interest;

[0299] v. Analyze the discrepancies between expected patterns and measured values; and

[0300] vi. Repeating steps iv. and v. to continuously assess perfusion of at least a portion of the anatomical region of interest.

[0301] 74. The computer-implemented method of item 73, wherein an alert is issued to the user based on the difference between the expected pattern and the measured value according to a predetermined function, such as a predetermined threshold.

[0302] 75. A computer-implemented method according to any of items 73-74, wherein the identified oscillation pattern is continuously updated between steps iv. and v.

[0303] 76. A computer-implemented method according to any of items 73-75, wherein the oscillation pattern is identified based on frequency, amplitude, phase and / or background intensity.

[0304] 77. A computer-implemented method according to any of items 73-76, wherein the bolus is substantially a minimum effective bolus.

[0305] 78. A computer-implemented method according to any of items 73-77, wherein an injection parameter such as injection frequency is additionally or alternatively used to identify the oscillation pattern.

[0306] 79. A computer-implemented method according to any one of items 73-78, wherein the method is used to predict the onset of an ischemic condition.

[0307] 80. A computer-implemented method according to any of items 73-79, wherein the anatomical region of interest is detected by tracking.

[0308] 81. A computer-implemented method according to any of items 73-80, wherein the tracking of the anatomical region of interest is performed in three dimensions.

[0309] 82. A computer-implemented method according to any one of items 73-81, wherein the bolus is injected over a longer period of time, such as between 1 and 5 minutes, more preferably between 1 and 4 minutes, even more preferably between 1 and 3 minutes, and most preferably between 1.5 and 2.5 minutes.

[0310] 83. A computer-implemented method according to any of items 73-82, wherein periodically, for example after every 10-300 boluses, more preferably after every 30-300 boluses, more preferably after every 90-300 boluses, and most preferably after every 200-300 boluses, a longer pause, for example between 1-10 minutes, is taken during the pause during which no fluorescent imaging agent is injected into the subject.

[0311] 84. A computer-implemented method according to any of items 73-83, wherein an alert is issued to the user based on the difference between the measured value and the expected value of the phase, frequency and / or amplitude.

[0312] 85. A computer-implemented method according to any one of items 73-84, wherein the method is capable of detecting ischemia and / or venous occlusion and / or assessing the perfusion area of ​​an artery.

[0313] 86. A computer-implemented method according to any of items 73-85, wherein the method is configured to compensate for measurements at non-continuous intervals, such as when a region of interest drifts in and out of focus, and compare these to an expected pattern.

[0314] 87. A computer-implemented method for detecting changes in perfusion of an anatomical region of interest of a subject by image processing hemodynamics in at least a portion of the anatomical region of interest in a video image acquired from the subject, the method comprising the steps of:

[0315] - performing image analysis on at least one video sequence acquired during and / or after application of a plurality of boluses comprising a fluorescent imaging agent to a subject, wherein the plurality of boluses are supplied according to a predefined pattern, e.g. in terms of frequency and / or dosage,

[0316] - calculating subsequent perfusion parameters of one or more regions of interest based on the image analysis, and

[0317] - Monitoring subsequent perfusion parameters to determine changes in perfusion in said region of interest.

[0318] 88. The method according to item 87 comprises the steps of any one of items 1-46 or items 73-86.

Claims

1. A system for automated perfusion assessment of an anatomical structure during a medical procedure on a subject, the system comprising a processing unit and a controllable syringe pump for containing at least one first fluorescent imaging agent, wherein the system is configured to: - controlling the syringe pump to automatically inject a series of predefined boluses of the first fluorescent imaging agent in the form of indocyanine green (ICG) into a vein of the subject with a predefined time period between each bolus of the series of boluses, each bolus having a predefined amount of ICG less than 0.01 mg ICG / kg body weight, - receiving and analyzing time series fluorescence images of tissue of the anatomical structure after each ICG bolus injection, and - determining by said processing unit at least one perfusion parameter of said anatomical structure based on said analysis after each ICG bolus injection.

2. The system of claim 1, wherein each bolus corresponds to less than 0.5 mg ICG.

3. The system according to claim 1 or 2, wherein: The system is configured to inject boluses with a time period between 5 and 600 seconds between each bolus.

4. The system according to claim 1 or 2, wherein: The system is configured to inject boluses with a time period between 15 and 300 seconds between each bolus.

5. The system according to claim 1 or 2, wherein: The system is configured to inject boluses with a time period between 45 and 210 seconds between each bolus.

6. The system according to claim 1 or 2, wherein: The system is configured to inject boluses with a time period of between 90 and 120 seconds between each bolus.

7. The system of claim 1 or 2, wherein the system is configured to determine a subject-specific minimum effective bolus of ICG by: - controlling the syringe pump to inject a series of boluses with varying amounts of ICG with a predefined period of time between each bolus, - Analysis of fluorescence emission of anatomical structures after injection of each bolus, and -Determine the minimum bolus size that provides quantifiable fluorescence emission from the anatomical structure.

8. The system according to claim 7, wherein: The quantifiable fluorescence emission of the anatomical structure corresponds to the fluorescence emission from which the perfusion slope can be determined.

9. A system according to claim 1 or 2, wherein the system is configured to determine a subject-specific interruption interval, wherein the subject-specific interruption interval is defined as the time period from when the fluorescence slope rises to when the fluorescence emission drops to a multiple standard deviation below the background noise.

10. The system of claim 9, wherein the plurality of standard deviations is 20, 10, or 5 standard deviations.

11. A system according to claim 1 or 2, which is configured to contain at least a second fluorescent imaging agent, which is different from the first fluorescent imaging agent, and wherein the system is configured to inject one or more boluses having a predefined amount of the second fluorescent imaging agent into the blood of the subject.

12. A system according to claim 1 or 2, wherein the system is configured to determine the at least one perfusion parameter in one or more regions of interest located in the anatomical structure and optionally in adjacent anatomical structures, and wherein the regions of interest are optionally selectable by a user of the system.

13. A system according to claim 1 or 2, further comprising at least one light source configured to provide excitation light to induce fluorescence emission from the first fluorescent imaging agent in the anatomical structure; and an imaging unit configured to record the time series of fluorescence emissions from the anatomical structure.

14. The system according to claim 11 further comprises at least one light source configured to provide excitation light to induce fluorescence emission from the first fluorescent imaging agent and / or the second fluorescent imaging agent in the anatomical structure; and an imaging unit configured to record the time series of fluorescence emissions from the anatomical structure.

15. A system according to claim 12, which is also configured to track the movement of at least a sub-portion of the anatomical structure in the time series images, and to be related to the movement so that at least one of the regions of interest corresponds to the same sub-portion of the anatomical structure in the images, and wherein the motion tracking is provided by free image tracking and / or by object-based tracking.

16. Use of a controllable injection pump containing a first fluorescent imaging agent in the production of a system for automatic perfusion assessment of an anatomical structure during a medical procedure in a subject, wherein the injection pump is configured to administer a bolus of the first fluorescent imaging agent in the form of indocyanine green corresponding to less than 0.01 mg ICG / kg body weight into the subject's vein, wherein the system is configured to acquire and analyze time-series fluorescent images of tissue of the anatomical structure after injection of the first fluorescent imaging agent, and determine at least one perfusion parameter of the anatomical structure based on the analysis.

17. The use according to claim 16, wherein the first fluorescent imaging agent is injected via a controllable injection pump.

18. Use according to claim 16, wherein the first fluorescent imaging agent ICG is injected in a series of boluses with a predefined time period between subsequent boluses.

19. Use according to claim 18, wherein the fluorescence emission of the anatomical structure is measured after injection of each bolus.

20. The use according to claim 18, wherein the bolus comprises increasing or decreasing amounts of the first fluorescent imaging agent.

21. The use according to claim 20, wherein the amount is increased or decreased from one bolus to a subsequent bolus in increments of 10%.

22. The use according to claim 21, wherein a minimum bolus is determined after administration of a series of increasing or decreasing boluses, said minimum bolus providing a quantifiable fluorescence emission representative of perfusion of the anatomical structure.

23. The use according to claim 18, wherein the time period between boluses is between 5 and 600 seconds.

24. The use according to claim 18, wherein the time period between boluses is between 15 and 300 seconds.

25. The use according to claim 18, wherein the time period between boluses is between 45 and 210 seconds.

26. The use according to claim 18, wherein the time period between boluses is between 90 and 120 seconds.

27. The use of claim 18, wherein the time period between boluses is long enough to allow measurement of the perfusion slope of each bolus in the anatomical structure.

28. The use according to claim 27, wherein the perfusion slope comprises a slope onset and an elution slope.

29. The use according to claim 18, wherein a volume of isotonic solution is injected immediately after the injection of a bolus of the first fluorescent imaging agent ICG.

30. The use according to claim 29, wherein the isotonic solution is saline.

31. The use according to claim 29, wherein the volume is 1-20 mL.

32. The use according to claim 29, wherein the volume is 2.5-15 mL.

33. The use according to claim 29, wherein the volume is 5-10 mL.

34. Use according to claim 18, wherein the amount of the first fluorescent imaging agent corresponds to 0.001 to 0.01 mg ICG / kg body weight per bolus.

35. The use according to claim 18, wherein the initial amount of the first fluorescent imaging agent corresponds to at least 0.001 mg ICG / kg body weight.

36. Use according to claim 35, wherein subsequent boluses are increased or decreased from one bolus to a subsequent bolus by an amount corresponding to at least 0.001 mg ICG / kg body weight.

37. The use according to claim 16, wherein the bolus has a liquid volume of 0.5 μL to 10 mL.

38. Use according to claim 37, wherein the bolus has a liquid volume of 0.5-5 mL.

39. The use according to any one of claims 16 to 38, wherein A second fluorescent imaging agent is administered, the emission maximum of the second fluorescent imaging agent differing by at least 50 nm from the emission maximum of the first fluorescent imaging agent.

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