JP7202595B2 - Blood vessel image processing system and blood vessel image processing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a blood vessel image processing system and a blood vessel image processing method, and more particularly to a blood vessel image processing system and a blood vessel image processing method that can more accurately grasp the presence or absence of stenosis of blood vessels.

Conventionally, there has been a demand for techniques for noninvasively or minimally invasively preventing and diagnosing coronary artery stenosis and ischemic conditions that cause heart disease. Stenosis of the coronary arteries is a critical lesion leading to ischemic heart disease. As a method for diagnosing this stenosis, for example, coronary angiography (CAG) using a catheter is known. This coronary angiography involves injecting a contrast agent through a catheter, and is a fluoroscopic imaging method for observing the state of the coronary arteries under X-ray fluoroscopy, which is useful for discovering coronary artery stenosis and occlusion.

As a diagnostic index for organic lesions of coronary arteries, an index called myocardial flow reserve ratio (FFR: Fractional Flow Reserve) is also known. FFR is defined as the ratio of maximum coronary blood flow with stenosis to maximum coronary blood flow without stenosis, and approximately corresponds to the ratio of intracoronary pressure distal to stenosis to intracoronary pressure proximal to stenosis. Since FFR measurement utilizes a pressure sensor provided at the tip of a catheter, cardiac catheterization is also required. A method of measuring intravascular pressure and the like by cardiac catheterization and obtaining FFR based on the data is also conventionally known.

On the other hand, for example, Patent Document 1 discloses a system configured to inject a contrast agent from a vein, image a coronary artery with contrast enhancement, and display a curve representing changes in the CT value of the coronary artery on a graph.

JP 2016-016096

In Patent Document 1, basically, the CT value in the blood vessel gradually decreases toward the peripheral side of the blood vessel. In this way, in the case of the method of analyzing the CT value data that decreases toward the peripheral side of the blood vessel, even if there is stenosis at a position relatively close to the peripheral side of the blood vessel, the decrease in the CT value due to the presence of the stenosis is unlikely to appear conspicuously, and it is assumed that stenosis may be relatively difficult to grasp.

On the other hand, it is considered preferable, for example, to image the inside of the blood vessel relatively uniformly by devising the injection conditions of the contrast medium, in that the stenosis evaluation of the blood vessel can be performed more accurately. Based on such an imaging method, the present inventors not only plot CT value data in blood vessels, but also provide more multifaceted imaging result information so that doctors can We focused on the fact that it is possible to more accurately grasp the presence or absence of stenosis, etc.

The present invention has been made in view of the problems described above, and an object of the present invention is to relate to a blood vessel image processing system and a blood vessel image processing method, and to make it possible to more accurately grasp the presence or absence of stenosis or the like in blood vessels. It is to provide technology.

One aspect of the present invention for solving the above problems is as follows:
A blood vessel image processing system comprising an image processing unit,
The image processing unit is
a: a process of identifying pixel value data at a plurality of locations of a contrast-enhanced blood vessel;
b: a process of obtaining an index value by dividing the pixel value by the cross-sectional area, using cross-sectional area data of the blood vessel at each position and pixel value data at each position with respect to a plurality of positions of the blood vessel;
c: a process of plotting and displaying the index values;
is configured to do
Blood vessel imaging system.

(Explanation of terms)
A “medicine” refers to, for example, a contrast agent, physiological saline, or a mixture thereof.
Specific examples of the "contrast agent" include a contrast agent with an iodine concentration of 240 mg/ml (for example, a viscosity of 3.3 Pa s at 37°C and a specific gravity of 1.268 to 1.296), a contrast agent with an iodine concentration of 300 mg/ml ( For example, a contrast medium with a viscosity of 6.1 mPa·s and a specific gravity of 1.335 to 1.371 at 37°C and an iodine concentration of 350 mg/ml (for example, a viscosity of 10.6 mPa·s and a specific gravity of 1.392 to 1.392 to 1.37°C at 37°C). 433), etc.

Advantageous Effects of Invention According to the present invention, it is possible to provide a blood vessel image processing system and a blood vessel image processing method that enable a more accurate grasp of the presence or absence of stenosis or the like in a blood vessel.

1 is a diagram schematically showing the configuration of an entire system including a blood vessel image processing system according to one embodiment of the present invention; FIG. It is a perspective view which shows the structural example of a chemical injection device. 1 is a schematic diagram for explaining an aorta and a coronary artery; FIG. Fig. 3 is a flow chart showing a procedure of one form of the invention; FIG. 4 is a diagram showing an example of injection conditions for analysis of coronary artery vascular conditions. The coronary artery is linearly displayed by image processing, and is a schematic diagram for explaining the relationship between the distance from the origin and the CT value (no stenosis). It is an example of data showing the relationship between the distance from the origin of the blood vessel and the CT value or the like. The coronary artery is linearly displayed by image processing, and is a schematic diagram for explaining the relationship between the distance from the origin and the CT value (with stenosis). Fig. 9(a) is a normal state without stenosis, and Fig. 9(b) is an abnormal state with stenosis. . It is an example of a mode in which a blood vessel is divided into a plurality of segments along the length direction.

FIG. 1 is a diagram schematically showing the configuration of an entire system including a blood vessel image processing system according to one embodiment of the present invention. This system, for example, includes an imaging device 300, a medical record management device HIS 360, an imaging management device RIS 370, a data storage device PACS 380, a liquid injection device 100 for injecting a contrast medium or the like into a subject, and a blood vessel image processing device. It includes a system 400 and a network 350 connecting each device. A conventionally known configuration may be used for the configuration other than the blood vessel image processing system 400 . The system may omit one or more of the above devices.

A HIS (Hospital Information System) 360 is a computer in which a dedicated computer program is installed, and has a chart management system. The electronic medical record managed by the medical record management system includes, for example, a medical record ID that is unique identification information, a subject ID for each subject, personal data such as the subject's name, and medical chart data related to the subject's disease. , etc., may be included. In addition, the body weight, sex, age, etc. of the subject may be registered in the chart data as personal condition data related to treatment in general.

A RIS (Radiology Information System) 370 manages imaging order data for imaging fluoroscopic image data of a subject with unique identification information. This imaging order data may be created based on an electronic medical record obtained from the HIS. The imaging order data includes, for example, an imaging job ID that is unique identification information, a job type such as CT imaging or MR imaging, the subject ID and medical chart data of the electronic medical record described above, the identification information of the CT scanner, the start and end of imaging, and the like. date and time, body division or imaging part, proper type consisting of the type of liquid medicine such as a contrast agent corresponding to the imaging work, proper ID consisting of the liquid medicine ID suitable for the imaging work, etc. may be included.

A PACS (Picture Archiving and Communication Systems) 380 receives fluoroscopic image data with imaging order data from the imaging device and stores it in a storage device.

The imaging apparatus 300 is, for example, an X-ray CT apparatus, and includes an imaging unit that captures a fluoroscopic image of the subject, a bed on which the subject is placed, and a control unit that controls their operations. good too. The imaging unit includes an X-ray irradiation unit that has an X-ray tube, a collimator, and the like and that irradiates the subject with X-rays, and an X-ray that detects the X-rays that have passed through the subject. It may have a detection unit having a detector. The X-ray irradiation unit and the detection unit are configured to perform scanning while rotating around the subject's body axis while maintaining their positional relationship.

The liquid injector 100 will be described with reference to FIG. 2 as well. The liquid injector 100 includes, for example, an injection head 110 held by a movable stand 111 and a console 150 connected to the injection head 110 via a cable 102 . In this example, two syringes are detachably attached to the injection head 110 in parallel. Note that the injection head 110 and the console 150 may be connected wirelessly.

A contrast medium, a physiological saline solution, and the like are exemplified as the drug solution filled in the syringe. For example, one syringe may be filled with contrast medium and the other syringe may be filled with physiological saline. The syringe has a hollow cylindrical cylinder member and a piston member slidably inserted into the cylinder member. The cylinder member may have a cylinder flange formed at its proximal end and a conduit portion formed at its distal end. By pushing the piston member into the cylinder member, the drug solution in the syringe is pushed out through the conduit portion. The syringe may be of a pre-filled type in which a chemical solution is filled in advance, or may be of a suction type in which an empty syringe is used by sucking the chemical solution.

An extension tube is connected to the conduit portion of each syringe. The extension tube may be a so-called T-shaped tube or Y-shaped tube, for example, a tube connecting the conduit part and the branch part of one syringe, a tube connecting the conduit part and the branch part of the other syringe, It may have a tube connecting the branch and the subject. For example, an injection needle is connected to the tip side (not shown) of the tube. The drug solution is injected into the blood vessel by piercing the subject's blood vessel with the injection needle and pushing out the drug solution in the syringe. As the extension tube, a mixing device (for example, a device that generates a swirling flow inside to mix the chemicals) at the confluence point of the first chemical and the second chemical can be used. good.

Although the detailed illustration of the injection head is omitted, the injection head may be as follows. That is, the injection head has, for example, a housing that extends long in the front-rear direction, and two recesses on which syringes are placed are formed on the front end side of the upper surface of the housing. The concave portion is a portion that functions as a syringe holding portion. A syringe may be directly attached to the recess, or may be attached via a predetermined syringe adapter. The injection head also has a piston drive mechanism that has at least the function of pushing the piston member of the syringe. Two systems are provided for the piston drive mechanism, and each mechanism operates independently. The piston drive mechanism may have the function of retracting the piston member, for example, for drawing the liquid medicine into the syringe. The two piston drive mechanisms may be driven simultaneously or at separate timings. Although not shown in detail, the piston drive mechanism includes a drive motor, a motion conversion mechanism that converts the rotational output of the drive motor into linear motion, and is connected to the motion conversion mechanism to move the piston member forward and/or backward. It may also have a syringe presser (ram member) that allows the pressure to flow. As such a piston driving mechanism, a well-known mechanism generally used in chemical injectors can be used. An actuator other than the motor may be used as the drive source. Instead of the "piston drive mechanism", a drive mechanism may be provided for delivering the drug solution from a prescribed drug solution container (for example, bottle, bag, etc.) other than the syringe to the subject. An example of the drive mechanism may be a roller pump or the like that pushes the tube to deliver the chemical solution.

If an IC tag (identification tag) is attached to the syringe, the injection head may have a reader/writer for reading information on the IC tag and/or writing information on the IC tag. This reader/writer may be provided in a recess in which the syringe is mounted. Note that the reader/writer may have only the function of reading the information on the IC tag.

The console 150 may be placed and used in an operating room adjacent to an examination room in one example. The console 150 has a display 151 that displays a predetermined image, an operation panel 159 provided on the front surface of the housing, a control circuit arranged inside the housing, and the like. The operation panel 159 is a portion on which one or more physical buttons are arranged and is operated by an operator. The display 151 may be a touch panel display device or a simple display device. The console 150 may have speakers or the like (not shown) for outputting sound and/or voice.

A storage unit (not shown) of the console 150 may store various data related to creation of an injection protocol, execution of injection, and the like. For example, it is data of a graphical user interface, data of injection conditions (injection pattern), and the like.

(blood vessel image display system)
The blood vessel image processing system 400 includes an input device 461, an image processing unit 450, an interface 463, a storage unit 460, etc., as an example. Examples of the input device 461 include general devices such as a keyboard and mouse. If necessary, a microphone or the like for voice input may be used. Although not limited, the blood vessel image processing system 400 may be configured with a workstation, laptop computer, tablet terminal, or the like.

The interface 463 is for connection with various external devices and the like, and although only one interface is shown in the drawing, a plurality of interfaces may be provided as a matter of course. The connection method (communication method) may be wired or wireless. In the example of FIG. 1, the imaging device 300 or the like is connected to the interface 463 via a network, whereby data from the imaging device 300, PACS 380, or the like is read into the blood vessel image processing system 400 (or by the system 400 identified).

The storage unit 460 may be configured by a hard disk drive (HDD), a solid state drive (SSD), and/or a memory, etc., and stores OS (Operating System) programs and , a blood vessel image processing program according to one embodiment of the present invention may be stored.

Other computer programs used for various processes, data tables, image data, and the like may be stored in the storage unit 460 as necessary. Computer programs are executed by being loaded into the memory of the processor. The computer program may be downloaded in whole or in part from an external device via any network when necessary. A computer program may be stored in a computer-readable recording medium.

Blood vessel image processing system 400 is configured to display predetermined information on display 430 . The display 430 is not particularly limited, but an LCD (Liquid Crystal Display) display, an organic EL (Organic Electro-Luminescence) display, or the like can be used. When the blood vessel image processing system 400 is configured as one housing, the display 430 may be provided integrally with a part thereof. Alternatively, it may be configured separately from the main body (not shown) and used in connection therewith.

(Configuration of image processing unit)
The image processing unit 450 is a processor including a CPU, a memory, and the like. In order to implement the blood vessel image processing method according to one embodiment of the present invention, for example, the image processing unit 450 reads (identifies) imaging data captured by an imaging device. ) function, a function to recognize the shape and running state of blood vessels, a function to deform and display blood vessels linearly, a blood vessel cross-sectional area calculation function, a CT value data identification function, a regression analysis function, etc. good.

[motion]
Next, the operation of the blood vessel image processing system and the image processing method of this embodiment will be described with specific examples. In the following, an example in which a coronary artery is imaged with contrast and the result is evaluated will be described.

As shown in FIG. 3, "coronary arteries" are blood vessels that branch left and right from the vicinity of the root of the aorta and extend along the surface of the myocardium, supplying oxygen-rich blood to the heart. There are two main coronary arteries, the left coronary artery (LCA) and the right coronary artery (RCA), and the left coronary artery is further divided into two, the left anterior descending artery (LAD) and the left circumflex artery (LCX). These large arteries branch out like the branches of a tree, gradually forming smaller arteries that run outside the heart, and then become smaller vessels that extend inward, thereby supplying blood to the entire myocardium. Diseases in these coronary arteries include arteriosclerosis. That is, when fat such as cholesterol is deposited on the inner wall of the blood vessel, a swelling (plaque or the like) is formed inside the blood vessel, which causes the blood vessel to become constricted. The diameter (internal diameter) of the main blood vessels of normal coronary arteries is usually about 3 to 4 mm, but when the plaque becomes large and the lumen of the blood vessel narrows, sufficient blood cannot be delivered to the heart muscle, resulting in angina pectoris and myocardial infarction. It will lead to

(Step S1)
As shown in the flowchart of FIG. 4, in step S1, a contrast medium is injected into a blood vessel to perform contrast-enhanced imaging. Although not limited, in this embodiment, as an example, injection of the contrast agent is performed in the following injection pattern. That is, in order to achieve uniform delivery of the contrast medium to blood vessels such as coronary arteries, injection conditions including injection patterns called variable patterns are used. FIG. 5 shows the relationship between the injection speed (vertical axis) and the injection time (horizontal axis) of the liquid medicine. As shown in FIG. 5, this injection condition includes three phases.

(i) first phase (from time t0 to time t1)
Inject contrast only. The injection rate monotonically decreases linearly or non-linearly from rate Vc ₀ to rate Vc ₁ . Velocity Vc ₀ may be, for example, 5.0±1.0 ml/sec for a subject weighing approximately 60 kg (an example of 370 mg/ml contrast agent iodine dose). Velocity Vc ₁ may be, for example, 4.0±0.5 ml/sec. As a preferable example, the speed _Vc0 is _5.1 ml/sec and the speed Vc1 is 4.0 ml/sec.

The term "monotonically decreasing" includes not only a linear increase/decrease of the injection rate, but also a substantially linear increase/decrease in a curved or step-like manner. The duration of the first phase depends on the amount of the contrast medium to be injected and the like. As an example, the amount of the contrast medium may be set to about 20 to 30 ml, and the length may be set so that the amount can be injected. In the above, an example of a subject weighing about 60 kg was given, but the injection rate (in other words, the amount of iodine injected per unit time) may be varied according to the weight of the subject. good. For example, if the weight of the subject is about 40-50 kg or thereabouts, a contrast agent with an iodine content of 300 mg/ml is used, and the speed _Vc0 is set in the range of 3.5-5.0 ml/sec. Vc1 may be in the range of 3.0 to 4.5 ml _/ sec (but lower than the initial speed). In addition, if the weight of the subject is about 70 to 80 kg or thereabouts, a contrast agent with an iodine content of 370 mg/ml is used as an example, and the speed Vc ₀ is set in the range of 4.0 to 6.0 ml/sec. Vc1 may be in the range of 4.0 to 5.5 ml _/ sec (but lower than the initial speed).

(ii) Second phase (time t1 to time t2)
Continuing to inject only contrast medium. _The injection rate monotonically decreases linearly or non _- linearly from rate Vc1' to Vc2. Velocity Vc1' may be between velocity _Vc0 and velocity Vc1, and more specifically, it is preferred in _one form that velocity _Vc1 ' is at _least lower than velocity _Vc0 . As an example, the velocity Vc ₁ ′ may be in the range of 4.0-5.0 ml/sec for a subject weighing approximately 60 kg. Velocity Vc2 may be, for example, in the range of _2.0-3.0 ml/sec. The injection volume of contrast medium in the second phase may be 20 ml or more. The duration of the second phase also depends on the amount of the contrast medium to be injected, but as an example, it may be about 15 to 30 ml, preferably 20 ml±5 ml, so that the amount can be injected.

As in the first phase, the injection rate in the second phase (in other words, the amount of iodine injected per unit time) can be changed as appropriate according to the body weight of the subject. For example, if the weight of the subject is about 40-50 kg or thereabouts, a contrast agent with an iodine content of 300 mg/ml is used, and the velocity Vc ₁ ′ is in the range of 3.5-4.5 ml/sec. Velocity Vc2 may be in the range of about 3.0 to 4.5 ml/sec (but _{lower than} velocity Vc1'). In addition, if the weight of the subject is about 70 to 80 kg or thereabouts, a contrast agent with an iodine content of 370 mg/ml is used as an example, and the velocity Vc ₁ ′ is set in the range of 4.0 to 5.5 ml/sec. Velocity Vc2 may be in the range of 3.5 to 5.0 ml/sec (but slower _than velocity _Vc1 '). A subject weighing about 70 kg or more may be injected with 30 ml or more of the contrast agent.

(iii) Third phase (time t2 to time t3)
Inject saline only. The infusion rate may be a constant rate of, for example, about _2.0-3.0 ml/sec, and in particular may be the same as the rate Vc2. The amount of saline to be injected may be in the range of 10-40 ml, for example.

By injecting a contrast agent from a vein under such conditions and performing imaging after the contrast agent has reached the coronary artery, the coronary artery can be dyed substantially uniformly over its entire length. FIG. 6 is a diagram schematically showing a state in which the inside of a coronary artery is dyed substantially uniformly with a contrast medium. In this figure, the function of the blood vessel image processing system 400 is used to transform the coronary artery into a straight line for display. The left side of the figure is the origin side and the right side is the distal side. P ₁ , P ₂ . . . _{P n} indicate the position of the vessel and S ₁ , S ₂ . _In the drawings, for convenience of illustration, P1 is shown as "P1" or the like.

(Steps S2, S3)
Next, in step S2, the blood vessel image processing system 400 acquires image data obtained by imaging and performs the following processing. Regarding acquisition of image data, as a specific example, data may be read into the image processing system from the PACS 380 or the like in which the data is stored.

Using the read data, the blood vessel _{cross -sectional areas S 1 , S 2 .} The blood vessel cross- _sectional areas S ₁ , S ₂ , . The CT value is an example, and the CT value near the center of the blood vessel cross section may be used. The plurality of blood vessel positions P ₁ , P ₂ . . . P _n may be equally spaced, or may at least partially include non-equally spaced portions. In obtaining the CT value, plot values obtained by MIP (Maximum Intensity Projection) may be used in addition to the above. MIP is a method of creating a projection image by adopting the highest CT value of the projected portion as a projection image from a certain direction. The linearization of blood vessels may also be displayed in MIP.

FIG. 7 is an example of data showing the relationship between the distance from the origin of the blood vessel and the CT value, etc. The CT value data obtained in this step is plotted. When the contrast agent is injected under conditions of a constant injection rate, rather than injection conditions including a variable pattern as in the present embodiment, the CT value generally decreases gradually as the inner diameter of the blood vessel becomes narrower toward the distal side. go. On the other hand, in the present embodiment, since the injection is performed under the injection conditions shown in FIG. 5, as illustrated in FIG. The values are almost uniform on the lateral and peripheral sides. A straight line La is an approximate straight line obtained by regression analysis of CT value data. In the flowchart of FIG. 4, the process of regression analysis and display is shown as step S3 as an example.

(Steps S4, S5)
Next, in step S4, the CT values (CT value ₁ , CT value ₂ , ... CT value _n ) are _calculated as blood vessel cross _- sectional areas S1, S2, ..., _Sn for _each of _a plurality of blood vessel positions P1, P2, ..., _Pn . Find the index values H ₁ , H2 . . . H _n divided by:
_Hn =(CT value) _n / _Sn
In FIG. 7, in addition to the CT value data, the “index value H” data obtained by dividing the CT value by the cross-sectional area of the blood vessel is also plotted (see plotted triangles).

In this embodiment, the approximate straight line Lb obtained by performing regression analysis on these plot data is also displayed (step S5).

The advantages of using the index value H as described above include the following points. For example, as shown in FIG. 8, there is stenosis at position P ₃ of the blood vessel, but the CT values in the blood vessel are substantially uniform at positions P ₁ to P ₄ (and beyond). Assuming that the blood vessel cross _- sectional area at the position P3 is smaller than others, the index value H at this position is locally high. This can also be understood from the fact that the peak of the plot appears at the position indicated by "P3" in FIG. Note that a predetermined attention mark may be displayed at or near the peak of the plot so that the location of such a peak can be easily recognized visually. Examples of attention marks include, but are not limited to, circular marks and arrow-shaped marks.

On the other hand, looking only at the plot of the CT value (or the approximate straight line La), there is a slight decrease in the CT value near P3 _, but the degree of change is relatively small, and the presence of stenosis may not be understood. There is also On the other hand, in the index value H _, a remarkable change was observed near P3, and even in the case where it is difficult to grasp the stenosis only by plotting the CT value, the presence of the stenosis can be grasped more reliably. Become.

The present invention is not necessarily limited to the display mode as shown in FIG. 7 regarding what display is performed in the blood vessel image processing system. An aspect may be adopted in which only the plot of the index value H of the CT value/vessel cross-sectional area (and its approximate straight line Lb) is displayed, and the CT value plot (and its approximate straight line La) is not displayed. However, it is preferable to display both plots in that more detailed information about the blood vessel or the inside of the blood vessel can be provided.

For example _, when looking only at the change in the index value H in FIG. Looking at it, the CT value did not decrease so much even _on the peripheral side of P3, suggesting that there was blood flow. In other words, based on these multiple pieces of information, it can be determined that there is stenosis at the position of P3 _, but the stenosis does not impede blood flow.

According to the display mode as shown in FIG. 7 of the present embodiment, detailed diagnosis by a doctor based on composite data is thus possible. Therefore, in this case, it is preferable to have a configuration in which both the plot of the CT value and the plot of the index value H are displayed. A device (for example, an image processing unit) compares the plot data and/or the shape and inclination of the approximate straight line with a predetermined standard, and as a result, determines whether it is normal and/or abnormal. In that case, it may be configured to issue a predetermined alert (visual information such as text and diagrams and/or auditory information).

Subsequently, changes in the slope of the index value H (slope of the approximated curve Lb) will be described. 9A and 9B are graphs schematically showing simplified approximate curves La, Lb, etc. FIG. Indicates a normal state. In addition, in FIG. 9, only approximated curves are shown for the sake of simplification of explanation, but plot data may be displayed as a matter of course.

As shown in FIG. 9(a), when the CT value is substantially constant throughout the blood vessel (see the approximate straight line La), the thickness of the blood vessel basically gradually becomes thinner toward the peripheral part. , CT value/vessel cross-sectional area S becomes higher toward the peripheral side, forming an approximate straight line Lb rising to the right.

On the other hand, FIG. 9B shows an example in which there is a stenosis (not shown) at a predetermined position in the blood vessel, and little blood flows beyond the stenosis. In this case, the CT value becomes lower toward the obliteration side, and the approximation curve La' slopes down to the right. On the other hand, the cross-sectional area of the blood vessel is basically smaller toward the peripheral side as in FIG. or flat).

The above suggests that the presence or absence of stenosis can be estimated from changes in the slope of the approximation line Lb' of the index value H. It should be noted that the specific threshold (inclination of the approximate straight line Lb') for determining the presence or absence of stenosis does not need to be specified as a specific numerical value. The threshold may be appropriately set according to the environment of the work station or the like, the condition of the subject, or the like.

As described above, in the blood vessel image processing system 400 of the present embodiment, the image processing unit 450 performs a: processing to identify CT value data at a plurality of positions of a blood vessel that has been contrast-enhanced; With respect to the position of the blood vessel, using the data of the cross-sectional area of the blood vessel at each position and the data of the CT value at each position, a process of obtaining an index value by dividing the pixel value by the cross-sectional area, and c: Plotting and displaying the index value It performs a process to cause Therefore, it is possible to determine, based on the plot of the index values, even the stenosis of the blood vessel, which is difficult to determine based on the plot data of the CT values alone. Furthermore, according to the configuration in which the plot of the CT value and the plot of the index value are displayed, it is possible to make a more complex judgment based on both data.

In addition, as shown in FIG. 9, focusing on the correlation between the slope of the index value obtained by dividing the CT value by the cross-sectional area of the blood vessel and the presence of stenosis in the blood vessel, the slope of the index value can be used to determine stenosis. It may be used as a judgment material.

Although one embodiment of the present invention has been described above with specific examples, the present invention can be modified in various ways without departing from the gist of the invention:
(a) For example, the coronary arteries have been described above, but the present invention can also be applied to other blood vessels. This is because even in blood vessels other than coronary arteries, the same effect as the above embodiment can be expected by dyeing the inside of the blood vessel substantially uniformly and using the plot of the index value of CT value/vessel cross-sectional area. .
(b) As an injection condition for dyeing the inside of the blood vessel substantially uniformly, the one shown in FIG. 5 is preferable as an example, but it is not necessarily limited to this. Depending on the type, shape, running state, etc. of the target blood vessel, it is possible to uniformly dye the entire blood vessel with a single-phase or multi-phase injection of contrast medium at a constant velocity (assisted with physiological saline if necessary). sometimes. Alternatively, conditions may be preferable in which the second phase of the injection conditions of FIG. 5 is changed to isokinetic injection of the contrast agent.
(c) In the above embodiment, the "CT value" was used as an example. Blood vessel image processing as described above may be performed. In FIG. 7, the vertical axis represents the CT value (unit: HU), but instead of the CT value, the image processing may be performed using the pixel value, for example, the gradation data of the image. Not only the graph display of FIG. 7, but also other data processing may be performed using the gradation data of the image instead of the CT value.
(d) In the above embodiment, an example was shown in which linear models (approximate straight lines La, Lb, etc.) were displayed as a result of regression analysis. may

Additionally, it may be constructed as follows:
(e) Linearly deformed blood vessel image In FIG. 6, a linearly deformed blood vessel is depicted. Specifically, it may be created by the following method: (i) Only blood vessels are extracted from the original medical image, and (ii) data that includes blood vessels and their surrounding anatomical structures (e.g., parenchymal systems such as organs), etc., instead of extracting only blood vessels; deformed and straightened, or (iii) a combination of the above. Here, extraction of blood vessels may be performed automatically by equipment, may be performed by human work, or may be a combination thereof.

(f) Other aspects of "index value" In the above embodiment, the index value is obtained by dividing the CT value by the cross-sectional area of the blood vessel. Although it is written as "CT value", it may be a predetermined pixel value instead of the CT value):
Index value Ha = (CT value/vessel cross-sectional area)/(reference CT value of the blood vessel)
The “reference CT value” refers to a value that is a reference value for the CT value of the blood vessel, and may be, for example, a CT value at an arbitrary point near the origin of the blood vessel. As a specific example, if the reference CT value is 400 HU, the CT value of the target point is 360 HU, and the blood vessel cross-sectional area is 10 mm ² , the index value H′=(360/10)/400, which is 0.09.

Regarding the reference CT value of the blood vessel, the point near the blood vessel origin may be more specifically as follows. Here, as a specific example, the case where the three major branches of the coronary artery are numbered from 1 to 15 (according to the example of the American Heart Association) will be given. Regarding numbers, the right coronary artery (RCA) is divided into 1: right coronary artery (proximal), 2: right coronary artery (central), 3: right coronary artery (distal), 4AV: atrioventricular branch. Ascending blood vessel, 4PD: Posterior descending branch: A blood vessel that divides into two and goes downward. For the left coronary artery (LCA): 5: left main coronary artery (LMT), left anterior descending artery (LAD) and left circumflex artery (LCX). For the left anterior descending artery (LAD), 6: left anterior descending (proximal), 7: left anterior descending (central), 8: left anterior descending (distal), 9: first diagonal (D1) , 10: the second diagonal branch (D2). For the left circumflex branch (LCX), 11: left circumflex branch (proximal), 12: pure marginal branch (OM), 13: left circumflex branch (distal), 14: posterior lateral branch (PL), 15: Posterior descending branch (PD). Here, the "reference CT value" may be obtained based on CT values of 1, 5, 6, or 11, for example. In this case, a value obtained by averaging the CT values of a plurality of subjects may be used as the reference CT value.

(g) Segmentation along the blood vessel length direction As shown in FIG. (Sec1 to sec4 in the example of the figure) may be analyzed. The method of division may be based on the tendency of the plotted data. Alternatively, regardless of the tendency of the data, it may be divided into sections for each predetermined distance. According to the method of performing analysis by dividing into a plurality of sections in this way (in other words, performing analysis by dividing areas), for example, detailed trends can be grasped for each section, and as a result, blood vessel A more detailed analysis of stenosis and the like can be performed.

Furthermore, for each individual segment as shown in FIG. 10, create an approximate straight line or approximate curve for the CT value and / or index value (further, other predetermined data may be added), It may be displayed accordingly. According to this, as an example, it is possible to determine vascular stenosis based on the slope of the approximate straight line for each segment.

(h) Tendency of Index Value to Increase on Blood Vessel Peripheral Side By the way, it is assumed that the index value obtained by dividing the blood vessel CT value by the blood vessel cross-sectional area increases toward the blood vessel peripheral side. Considering these peripheral effects, the following index values may be used:
Index value Hb = (CT value/cross-sectional area of blood vessel)/distance from predetermined reference point of blood vessel An example of the "distance from a predetermined reference point of blood vessel" is the distance (mm) from the origin of the blood vessel. may

(i) Utilization of machine learning The basic idea of one aspect of the present invention is to use data such as the CT value of blood vessels and predetermined index values obtained by dividing the CT value by the cross-sectional area, and use them for predetermined judgments. is. Therefore, a machine learning technique may be used in which predetermined regularity is found based on data of a plurality of subjects and inference is made for unknown data. Machine learning can be usefully used, for example, for evaluation of vascular stenosis, evaluation of blood flow state, and the like. As the blood flow evaluation, for example, the coronary flow reserve ratio (FFR) or the like, which is an index showing how much the blood flow is inhibited by the stenotic lesion, may be used.

Machine learning methods include, but are not limited to, neural networks, CNN (Convolution Neural Network), RNN (Recurrent Neural Network), LSTM (Long Short-Term Memory), logistic regression, support vector machine, decision tree It may use one or a combination of such as learning.

It should be noted that the various constituent elements (devices, apparatuses, units, modules, etc.) referred to in this specification do not need to exist independently of each other. that one component is made up of more than one member, that one component is part of another component, or that part of one component overlaps part of another component , etc. The various components need only be configured to implement their functions, and may be implemented by hardware or computer programs. For example, a certain component can be realized as dedicated hardware that exhibits a predetermined function, a setting device in which a predetermined function is realized by a computer program, a combination of these, or the like.

(Appendix)
This application discloses the following inventions. It should be noted that the symbols in parentheses are attached for reference and do not limit the present invention in any way:
1. A blood vessel imaging system (400) comprising an image processing unit (450), comprising:
The image processing unit (450) comprises:
a: a process of identifying pixel value data at a plurality of locations of a contrast-enhanced blood vessel;
b: With respect to the plurality of positions (P ₁ -P _n ) of the blood vessel, using the data of the cross-sectional area (S ₁ -S _n ) of the blood vessel at each position and the data of the pixel value at each position, the pixel value is calculated. a process of obtaining an index value (H ₁ -H _n ) divided by the cross-sectional area (S ₁ -S _n );
c: a process of plotting and displaying the index value (H ₁ −H _n );
A blood vessel imaging system configured to perform:

Instead of plotting index values, only an approximate straight line (or approximate curve) described below may be displayed. Alternatively, only predetermined judgment results obtained by using such data (such as suggesting the possibility of stenosis in a certain part of the blood vessel) without visual display such as plotting of index values or approximate straight lines may be output.

2. The blood vessel image processing system as described above, wherein the image processing unit further performs d: a process of plotting and displaying the pixel value data at a plurality of positions (P ₁ -P _n ) of the blood vessel.

3. The blood vessel image processing system described above, wherein the image processing unit further performs c1: a process of performing regression analysis on the index value (H ₁ −H _n ) and displaying an approximate straight line or an approximate curve.

4. The blood vessel image processing system as described above, wherein the pixel value data of the blood vessel is data in which the pixel values are substantially uniform on the side of the origin of the blood vessel and on the peripheral side of the blood vessel. Note that "substantially uniform" means that the rate of decrease is within 20% (or 15%) when comparing the pixel value on the peripheral side and the pixel value on the origin side, for example.

5. The contrast-enhanced imaging is performed by injecting a contrast medium under injection conditions including a variable pattern, where the variable pattern includes a phase in which the injection rate of the contrast medium monotonously decreases with the lapse of injection time. , a blood vessel imaging system as described above.

6. The blood vessel image processing system described above, wherein the blood vessel is a coronary artery and the pixel value is a CT value.

7. The blood vessel image processing system as described above, wherein the image processing unit further performs a process of linearly deforming and displaying the target blood vessel.

8. A blood vessel imaging system as described above, further comprising a display.

A1. A method for image processing contrast-enhanced blood vessel image data, comprising:
a: identifying pixel value data at a plurality of positions of a contrast-enhanced blood vessel;
b: obtaining an index value obtained by dividing the pixel value by the cross-sectional area, using cross-sectional area data of the blood vessel at each position and pixel value data at each position with respect to a plurality of positions of the blood vessel;
c: plotting and displaying the index values;
A blood vessel image processing method that performs

B1. A blood vessel image processing program containing instructions for executing each step of the blood vessel image processing method.

It should be noted that the present application relates to the above-mentioned 2. as an invention relating to a system. ~8. (further including specific features disclosed as embodiments) expressed as inventions of methods and computer programs. Regarding the blood vessel image processing method, this method includes not only a mode in which each step included in the method is performed by one subject (computer, processor), but also a mode in which a plurality of separately configured subjects perform the steps. .

100 chemical injection device 102 cable 110 injection head 150 console 151 display 300 imaging device 360 HIS
370 RIS
380 PACS
400 blood vessel image processing system 430 display 450 image processing unit

Claims (8)

A blood vessel image processing system comprising an image processing unit,
The image processing unit is
a: a process of identifying pixel value data at a plurality of locations of a contrast-enhanced blood vessel;
b: a process of obtaining an index value by dividing the pixel value by the cross-sectional area, using cross-sectional area data of the blood vessel at each position and pixel value data at each position with respect to a plurality of positions of the blood vessel;
c: a process of plotting and displaying the index values;
is configured to do
The pixel value data of the blood vessel is data obtained by injecting a contrast agent under injection conditions such that the pixel values are substantially uniform on the side of the origin of the blood vessel and on the peripheral side of the blood vessel.
Blood vessel imaging system. The image processing unit further comprises:
d: performing a process of plotting and displaying the pixel value data at a plurality of positions of the blood vessel;
The blood vessel image processing system according to claim 1. The image processing unit further comprises:
c1: performing a process of performing regression analysis on the index values and displaying an approximate straight line or an approximate curve;
The blood vessel image processing system according to claim 1 or 2. The contrast-enhanced imaging is performed by injecting a contrast agent under injection conditions including a single phase or a plurality of phases in which the first phase is an injection pattern in which the injection rate of the contrast agent monotonically decreases with the lapse of injection time . ,
The blood vessel image processing system according to any one of claims 1 to 3 . The injection condition includes a plurality of phases, wherein the first phase and the second phase of the plurality of phases are injections according to an injection pattern in which the injection rate of the contrast agent monotonously decreases with the passage of injection time.
The blood vessel image processing system according to claim 4. the blood vessel is a coronary artery;
the pixel values are CT values;
The blood vessel image processing system according to any one of claims 1 to 5. The image processing unit further comprises:
performing a process of linearly deforming and displaying the target blood vessel;
The blood vessel image processing system according to any one of claims 1 to 6. The blood vessel imaging system of any one of claims 1-7, further comprising a display.

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