Method and system for calculating fractional flow reserve based on real-time blood vessel image

Abstract

The invention discloses a fractional flow reserve calculation method and system based on a real-time blood vessel image. The method includes: acquiring a first image and a second image of a target blood vessel; the first image is a preoperative blood vessel image; the second image is a real-time angiography image of the intraoperative blood vessel; according to the first image or the second image, the blood vessel contour is recognized, the initial lumen area is calculated, and the first image and the second image are registered; calculating a predicted virtual fractional flow reserve before actual expansion of the stent and a real fractional flow reserve after expansion according to the lumen area of the registered first image, the input ideal expansion area and the selected implantation point; the application form can assist in judging whether the current stent foothold and model selection can effectively relieve ischemia caused by lesion or not, stent model selection and stent foothold selection of an operator during coronary intervention operation are facilitated, and operation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of medical image processing, and in particular to a method and system for calculating a blood flow reserve fraction based on real-time vascular images. Background Art

[0002] Fractional Flow Reserve (FFR) can accurately evaluate the severity of myocardial ischemia in patients. In clinical practice, it is used as a functional evaluation indicator to guide the need for coronary intervention and to conduct postoperative evaluation. However, due to certain limitations in the use of guidewires to measure FFR in clinical practice, relevant researchers have developed a method for calculating FFR based on images. However, the existing FFR calculation system cannot determine the real-time changes in FFR and has a certain lag. It is impossible to predict the safety of the implantation process in advance. Summary of the invention

[0003] Therefore, an object of the present invention is to provide a method and system for calculating blood flow reserve fraction based on real-time vascular images, and to calculate the blood flow reserve fraction during coronary stent implantation according to real-time visible images.

[0004] In order to achieve the above object, a method for calculating blood flow reserve fraction based on real-time vascular images of the present invention comprises the following steps: S1, acquiring a first image and a second image of a target blood vessel; the first image is a preoperative blood vessel image; the second image is a real-time angiography image of the target blood vessel during surgery, the real-time angiography image including stent information; S2, registering the first image and the second image; and displaying the stent outline in the first image according to the registration relationship; S3, calculating the lumen area corresponding to the stent outline of the first image, so as to calculate the predicted virtual blood flow reserve fraction before the stent is actually expanded and the real blood flow reserve fraction after the stent is expanded; Among them, the lumen area corresponding to the stent outline of the first image is calculated according to the input ideal expansion area of ​​the stent, so as to calculate the predicted virtual blood flow reserve fraction before the actual expansion of the stent; the lumen area corresponding to the stent outline of the first image is calculated according to the stent outline after expansion, so as to calculate the real blood flow reserve fraction after expansion.

[0005] Further preferably, when the first image is a blood vessel angiography image, the registration relationship between the first image and the second image is a corresponding relationship between coordinates of a specific position of the target blood vessel in the first image and the second image.

[0006] Further preferably, when the first image is an intravascular imaging sequence, the registration relationship between the first image and the second image is: a correspondence between the target blood vessel position captured in a specific frame in the intravascular imaging sequence and the corresponding target blood vessel position coordinates in the second image.

[0007] Further preferably, the method further includes generating a longitudinal section image according to the intravascular imaging sequence; and using the longitudinal section image to determine whether the implantation position of the stent can cover the lesion area.

[0008] Further preferably, in S3, the following formula is used to calculate the predicted virtual blood flow reserve fraction before the stent is actually expanded and the real blood flow reserve fraction after the stent is actually expanded: = in, Indicates blood flow, represents the lumen area of ​​the vessel segment of interest, including the lumen area corresponding to the stent outline, represents the blood density, is the friction term, Indicates proximal pressure.

[0009] Further preferably, in S3, when calculating the predicted virtual blood flow reserve fraction, the step further includes: When there is no plaque, the ideal expansion area of ​​the stent is the lumen area corresponding to the stent profile; When plaque is present, the lumen area corresponding to the stent profile after stent expansion is predicted based on the composition and size of the plaque, the pressure of the balloon and the ideal expansion area of ​​the stent.

[0010] Further preferably, when plaque exists, the lumen area corresponding to the stent outline is calculated according to the following formula: in, is the ideal expansion area of ​​the stent, is the arc occupied by the plaque, is the average plaque thickness, Inflation pressure of the stent balloon, is the plaque elastic modulus.

[0011] The present invention also provides a calculation system for blood flow reserve fraction based on real-time vascular images, which is used to implement the steps of the above-mentioned calculation method for blood flow reserve fraction based on real-time vascular images, including an image acquisition module, an image processing module and an image display module; The image acquisition module is used to acquire a first image and a second image of the target blood vessel; the first image is a preoperative blood vessel image; the second image is a real-time angiography image of the target blood vessel during the operation, and the real-time angiography image includes stent information; An image processing module registers the first image and the second image; and displays the stent outline in the first image according to the registration relationship; Calculating the lumen area corresponding to the stent outline of the first image to calculate the predicted virtual blood flow reserve fraction before the stent is actually expanded and the real blood flow reserve fraction after the stent is expanded; The image display module includes at least four graphical user interface components, wherein the first graphical user interface component is used to obtain the user's option for the virtual blood flow reserve fraction or the real blood flow reserve fraction; the second graphical user interface component is used to display the first image; the third graphical user interface component is used to display the second image; the fourth graphical user interface component displays the FFR change curve in response to the option selected in the first graphical user interface component and the vessel radius calculated from the corresponding vessel image and the virtual FFR or the real FFR; Further preferably, the first image displayed by the second graphical user interface component is a angiography image or an imaging sequence.

[0012] Further preferably, when the second graphical user interface component displays an intravascular imaging sequence, it also includes generating a longitudinal section view according to the intravascular imaging sequence; and using the longitudinal section view to determine whether the implantation position of the stent can cover the lesion area.

[0013] Compared with the prior art, the method and system for calculating the blood flow reserve fraction based on real-time vascular images disclosed in the present application have at least the following advantages: This technical solution can calculate the virtual FFR of the current target blood vessel after implantation of a specific model of stent, and assist in determining whether the current stent landing point and selection can effectively alleviate the ischemia caused by the lesion. It helps the surgeon to select the stent type and stent landing point during coronary intervention surgery, thereby improving the efficiency of the operation.

[0014] When the true blood flow reserve fraction is selected, the software automatically detects the balloon expansion size in real time while the doctor is expanding the balloon, displays the expanded stent outline at the corresponding stent balloon coverage position in the first image, and automatically measures the balloon expansion size at different positions to update the corresponding lumen area. The true blood flow reserve fraction is calculated based on the updated lumen area. This technical solution can display the current target vessel FFR in real time, evaluate the effect of interventional surgery in a timely manner, facilitate the operator to respond to adverse phenomena, effectively shorten the operation time, and improve the efficiency of the operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic flow chart of a method for calculating blood flow reserve fraction based on real-time vascular images according to the present invention.

[0016] Figure 2The figure is a schematic diagram of the interface layout of the system for calculating the blood flow reserve fraction based on real-time vascular images of the present invention.

[0017] Figure 3 It is a schematic diagram of the interface layout when the first image is a contrast image.

[0018] Figure 4 This is a schematic diagram of the interface layout when the first image is an intravascular imaging sequence.

[0019] Figure 5 Schematic diagram of the system interface when selecting the virtual blood flow reserve fraction.

[0020] Figure 6 Schematic diagram of the system interface when selecting the true blood flow reserve fraction. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below through the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, a method for calculating blood flow reserve fraction based on real-time vascular images provided by an embodiment of the present invention includes the following steps: S1, acquiring a first image and a second image of a target blood vessel; the first image is a preoperative blood vessel image; the second image is a real-time angiography image of the target blood vessel during surgery, the real-time angiography image including stent information; S2, registering the first image and the second image; and displaying the stent outline in the first image according to the registration relationship; Preferably, when the first image is a blood vessel angiography image, the registration relationship between the first image and the second image is the corresponding relationship between the coordinates of a specific position of the target blood vessel in the first image and the second image.

[0023] Further preferably, when the first image is an intravascular imaging sequence, the registration relationship between the first image and the second image is: a correspondence between the target blood vessel position captured in a specific frame in the imaging sequence and the corresponding target blood vessel position coordinates in the second image.

[0024] Further preferably, the method further includes generating a longitudinal section image according to the intravascular imaging sequence; and using the longitudinal section image to determine whether the stent can cover the diseased area.

[0025] It should be noted that the stent profile in the present application refers to the profile of the stent in the blood vessel, and does not limit whether the stent has been expanded or fully expanded.

[0026] During the operation, the surgeon can observe the position of the stent in real time in the second image. The system displays the stent outline in the first image based on the registration relationship between the first image and the second image, and estimates the virtual lumen area before the stent expands or calculates the actual lumen area after the stent expands (when no distinction is made, it is collectively referred to as the lumen area in the text) to facilitate subsequent calculations.

[0027] S3, calculating the lumen area corresponding to the stent outline of the first image, so as to calculate the predicted virtual blood flow reserve fraction before the stent is actually expanded and the real blood flow reserve fraction after the stent is expanded; Among them, the lumen area corresponding to the stent outline of the first image is calculated according to the input ideal expansion area of ​​the stent, so as to calculate the predicted virtual blood flow reserve fraction before the actual expansion of the stent; the lumen area corresponding to the stent outline of the first image is calculated according to the stent outline after expansion, so as to calculate the real blood flow reserve fraction after expansion.

[0028] It should be noted that the virtual blood flow reserve fraction refers to the predicted blood flow reserve fraction when the stent has entered the blood vessel and is not expanded; the real blood flow reserve fraction refers to the blood flow reserve fraction when the stent has entered the blood vessel and is fully expanded.

[0029] Specifically ,in represents the proximal pressure, which can be approximated by the patient's aortic pressure. It can be calculated by formula 1: in, Indicates that the position of the blood vessels changes. Indicates blood flow, represents the lumen area of ​​the vessel segment of interest, including the lumen area corresponding to the stent outline; represents the blood density, is the friction term.

[0030] In clinical practice, the length of the vascular segment of interest selected by the operator is larger than the length of the stent.

[0031] Therefore, the following formula is used for calculation: = It can be seen from the above formula that for the same first image of the same lesion site, the difference between the calculation of the virtual blood flow reserve fraction and the real blood flow reserve fraction lies in the calculation of the lumen area corresponding to the stent contour.

[0032] The calculation of virtual blood flow reserve fraction and real blood flow reserve fraction is explained below: S301, the operator inputs the virtual blood flow reserve score requirement, and the doctor inputs the ideal expansion area of ​​the stent through the interactive interface. The ideal expansion area is information that the doctor can obtain when selecting the stent. By moving the stent balloon in the blood vessel to adjust the stent footing point, the second image collects real-time data, and based on the registration relationship, the predicted stent contour after expansion is updated in real time at the corresponding stent balloon coverage position in the first image. The lumen area corresponding to the stent contour is calculated based on the ideal expansion area of ​​the stent, and the virtual blood flow reserve score is calculated using the lumen area corresponding to the stent contour. Furthermore, the lumen area of ​​the position can be determined based on the wall tissue at different positions. If there is no plaque, the lumen area corresponding to the stent contour is equal to the ideal expansion area of ​​the stent; if there is a plaque, the lumen area of ​​the stent after expansion is predicted based on the composition and size of the plaque, the pressure of the balloon and the ideal expansion area of ​​the stent. .

[0033] The lumen area Calculate according to the following formula: in, is the ideal expansion area of ​​the stent, is the arc occupied by the plaque, is the average plaque thickness, Inflation pressure of the stent balloon, is the plaque elastic modulus.

[0034] S302, the operator inputs the real blood flow reserve fraction requirement. During the balloon expansion process, the software automatically detects the stent expansion size in the second image in real time, displays the stent outline after expansion in the first image based on the aforementioned registration relationship, and automatically measures the stent expansion size at different positions as the lumen area corresponding to the stent outline. The real blood flow reserve fraction is calculated based on the lumen area corresponding to the stent outline.

[0035] This technical solution can display the true FFR of the current target blood vessel in real time, promptly evaluate the effect of interventional surgery, facilitate the operator to respond to adverse phenomena, effectively shorten the operation time and improve surgical efficiency.

[0036] like Figure 2 As shown, the present invention also provides a calculation system for blood flow reserve fraction based on real-time vascular images, which is used to implement the steps of the above-mentioned calculation method for blood flow reserve fraction based on real-time vascular images, including an image acquisition module, an image processing module and an image display module, wherein the real-time angiography image includes stent information; An image processing module registers the first image and the second image; and displays the stent outline in the first image according to the registration relationship; The lumen area corresponding to the stent outline of the first image is calculated to calculate the predicted virtual blood flow reserve fraction before the stent is actually expanded and the real blood flow reserve fraction after the expansion.

[0037] The image display module includes at least four graphical user interface components, wherein the first graphical user interface component is used to obtain the user's option for the virtual blood flow reserve fraction or the real blood flow reserve fraction; the second graphical user interface component is used to display the first image; the third graphical user interface component is used to display the second image; the fourth graphical user interface component displays the FFR change curve in response to the option selected in the first graphical user interface component and the vessel radius calculated from the corresponding vessel image and the virtual FFR or the real FFR. The first image displayed by the second graphical user interface component is a vascular angiography image or an intravascular imaging sequence.

[0038] When the second graphical user interface component displays an intravascular imaging sequence, it also includes generating a longitudinal section view according to the intravascular imaging sequence; and using the longitudinal section view to determine whether the stent can cover the lesion area.

[0039] During the implantation of the stent balloon, the surgeon tracks the position of the stent balloon in real time in the second image displayed by the third graphical user interface component, and displays the area covered by the stent balloon in real time in the first image according to the registration relationship between the first image and the second image. Figure 3 As shown, the second graphical user interface component displays the first image acquired before the operation, which is exemplarily an angiography image. The solid line segment AB shown in the figure is the area covered by the stent balloon displayed based on the registration relationship; when the first image is an intravascular imaging sequence, as shown in FIG. Figure 4 As shown, the second graphical user interface component displays the first image acquired before the operation, exemplarily an intravascular image and a longitudinal section view generated therefrom, and the solid line segment AB shown in the figure is the area covered by the stent balloon displayed based on the registration relationship, which helps the operator to observe whether the current stent landing point can cover the lesion area.

[0040] At this time, the virtual blood flow reserve fraction option or the real blood flow reserve fraction option can be selected through the first graphical user interface component.

[0041] Figure 5 The following is a schematic diagram of the system interface when the first image is an angiography image. This technical solution can calculate the virtual FFR of the current target vessel after implantation of a specific type of stent, and assist in determining whether the current stent landing point and stent selection can effectively alleviate the ischemia caused by the lesion, which helps the surgeon to select the stent type and stent landing point during coronary intervention surgery, thereby improving the efficiency of the operation.

[0042] Figure 6When selecting the true blood flow reserve fraction, during the balloon expansion process, the software automatically detects the stent expansion size in real time, displays the stent outline after expansion at the corresponding stent balloon coverage position in the first image, and automatically measures the balloon expansion size at different positions as the lumen area corresponding to the stent outline. The true blood flow reserve fraction is calculated based on the lumen area corresponding to the stent outline. This technical solution can display the current target vessel FFR in real time, timely evaluate the effect of interventional surgery, facilitate the operator to respond to adverse phenomena, effectively shorten the operation time, and improve the efficiency of the operation.

[0043] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A method for calculating blood flow reserve fraction based on real-time vascular images, characterized in that: The following steps are involved: S1, acquiring a first image and a second image of a target blood vessel; the first image is a preoperative blood vessel image; the second image is a real-time angiography image of the target blood vessel during surgery, the real-time angiography image including stent information; S2, registering the first image and the second image; and displaying the stent outline in the first image according to the registration relationship; S3, calculating the lumen area corresponding to the stent outline of the first image, so as to calculate the predicted virtual blood flow reserve fraction before the stent is actually expanded and the real blood flow reserve fraction after the stent is expanded; Among them, the lumen area corresponding to the stent outline of the first image is calculated according to the input ideal expansion area of ​​the stent, so as to calculate the predicted virtual blood flow reserve fraction before the actual expansion of the stent; the lumen area corresponding to the stent outline of the first image is calculated according to the stent outline after expansion, so as to calculate the real blood flow reserve fraction after expansion.

2. The method for calculating blood flow reserve fraction based on real-time vascular images according to claim 1, characterized in that: The first image is a blood vessel angiography image, and the registration relationship between the first image and the second image is the corresponding relationship between the coordinates of a specific position of the target blood vessel in the first image and the second image.

3. The method for calculating blood flow reserve fraction based on real-time vascular images according to claim 1, characterized in that: The first image is an intravascular imaging sequence, and the registration relationship between the first image and the second image is: the correspondence between the target blood vessel position captured in a specific frame in the intravascular imaging sequence and the corresponding target blood vessel position coordinates in the second image.

4. The method for calculating blood flow reserve fraction based on real-time vascular images according to claim 3, characterized in that: The method also includes generating a longitudinal section image according to an intravascular imaging sequence; and using the longitudinal section image to determine whether the implantation position of the stent can cover the diseased area.

5. The method for calculating blood flow reserve fraction based on real-time vascular images according to claim 1, characterized in that: In S3, the following formula is used to calculate the predicted virtual blood flow reserve fraction before the actual expansion of the stent and the real blood flow reserve fraction after the expansion: = in, Indicates blood flow, represents the lumen area of ​​the vessel segment of interest, including the lumen area corresponding to the stent outline, represents the blood density, is the friction term, Indicates proximal pressure.

6. The method for calculating blood flow reserve fraction based on real-time vascular images according to claim 5, characterized in that: In S3, the predicted virtual blood flow reserve fraction is calculated, which also includes: When there is no plaque, the ideal expansion area of ​​the stent is the lumen area corresponding to the stent profile; When plaque is present, the lumen area corresponding to the stent profile after stent expansion is predicted based on the composition and size of the plaque, the pressure of the balloon and the ideal expansion area of ​​the stent.

7. The method for calculating blood flow reserve fraction based on real-time vascular images according to claim 6, characterized in that: When plaque exists, the lumen area corresponding to the stent outline is calculated according to the following formula: in, is the ideal expansion area of ​​the stent, is the arc occupied by the plaque, is the average plaque thickness, Inflation pressure of the stent balloon, is the plaque elastic modulus.

8. A system for calculating blood flow reserve fraction based on real-time vascular images, characterized in that: The steps for implementing the method for calculating the blood flow reserve fraction based on real-time vascular images as described in any one of claims 1 to 7 above include an image acquisition module, an image processing module and an image display module; The image acquisition module is used to acquire a first image and a second image of the target blood vessel; the first image is a preoperative blood vessel image; the second image is a real-time angiography image of the target blood vessel during the operation, and the real-time angiography image includes stent information; An image processing module registers the first image and the second image; and displays the stent outline in the first image according to the registration relationship; Calculating the lumen area corresponding to the stent outline of the first image to calculate the predicted virtual blood flow reserve fraction before the stent is actually expanded and the real blood flow reserve fraction after the stent is expanded; The image display module includes at least 4 graphical user interface components, wherein the first graphical user interface component is used to obtain the user's option for the virtual blood flow reserve fraction or the real blood flow reserve fraction; the second graphical user interface component is used to display the first image; the third graphical user interface component is used to display the second image; and the fourth graphical user interface component displays the FFR change curve in response to the option selected in the first graphical user interface component and the vascular radius calculated from the corresponding vascular image and the virtual FFR or the real FFR.

9. The blood flow reserve fraction calculation system based on real-time vascular images according to claim 8, characterized in that: The first image displayed by the second graphical user interface component is an angiography image or an imaging sequence.

10. The blood flow reserve fraction calculation system based on real-time vascular images according to claim 9, characterized in that: When the second graphical user interface component displays an intravascular imaging sequence, it also includes generating a longitudinal section according to the intravascular imaging sequence; and using the longitudinal section to determine whether the implantation position of the stent can cover the lesion area.

Images