JP7677843B2 - Medical image processing device, system and method - Google Patents

Description

The embodiments disclosed in this specification and drawings relate to medical image processing devices, systems, and methods.

Conventionally, a technique for presenting various information about blood flow in blood vessels based on medical images of the blood vessels of a subject's heart has been known as a technique for supporting the diagnosis and formulation of treatment plans for cardiac diseases. For example, a technique for calculating and displaying wall shear stress (WSS) at each position in a blood vessel as one piece of information about blood flow is known.

Special Publication No. 2020-518362 JP 2011-62358 A Special Publication No. 2016-533815

One of the problems that the embodiments disclosed in this specification and the drawings attempt to solve is to display wall shear stress in an easily observable manner. However, the problems that the embodiments disclosed in this specification and the drawings attempt to solve are not limited to the above problem. Problems that correspond to the effects of each configuration shown in the embodiments described below can also be considered as other problems.

The medical image processing device according to the embodiment includes an acquisition unit, an extraction unit, and a display control unit. The acquisition unit acquires the distribution of wall shear stress in blood vessels. The extraction unit extracts a representative value or a characteristic vascular region from the distribution of wall shear stress in the blood vessels based on extraction criteria defined for each region according to the shape or properties of the blood vessels. The display control unit changes the display form of the wall shear stress in the blood vessels based on the extraction result of the representative value of wall shear stress or the characteristic vascular region.

FIG. 1 is a diagram showing an example of the configuration of a medical image processing system and a medical image processing apparatus according to the first embodiment. FIG. 2 is a diagram for explaining a display example of the WSS according to the first embodiment. FIG. 3 is a diagram for explaining an example of the extraction process and the display control process according to the first embodiment. FIG. 4 is a diagram for explaining an example of the extraction process and the display control process according to the first embodiment. FIG. 5 is a diagram for explaining an example of the extraction process and the display control process according to the first embodiment. FIG. 6 is a diagram for explaining an example of the extraction process and the display control process according to the first embodiment. FIG. 7 is a diagram for explaining an example of the extraction process and the display control process according to the first embodiment. FIG. 8 is a diagram illustrating an example of a display of the extraction criteria according to the first embodiment. FIG. 9 is a flowchart showing the processing procedure of the processing performed by each processing function of the processing circuitry of the medical image processing apparatus according to the first embodiment. FIG. 10 is a diagram for explaining an example of the extraction process and the display control process according to the first embodiment. FIG. 11 is a diagram illustrating an example of a display control process according to the second embodiment. FIG. 12 is a diagram illustrating an example of a display control process according to the second embodiment. FIG. 13 is a diagram illustrating an example of a display control process according to the second embodiment. FIG. 14 is a diagram for explaining an example of a blood vessel deformation process according to the second embodiment. FIG. 15 is a diagram illustrating an example of a display control process according to the second embodiment. FIG. 16 is a diagram illustrating an example of a display control process according to the second embodiment. FIG. 17 is a diagram illustrating an example of a display control process according to the second embodiment. FIG. 18 is a diagram showing a display example of a schematic diagram of a blood vessel cross section according to the second embodiment. FIG. 19 is a diagram showing an example of a graph display according to the third embodiment. FIG. 20 is a diagram illustrating an example of a display control process according to the fourth embodiment. FIG. 21 is a diagram illustrating an example of a display control process according to the fourth embodiment.

Below, embodiments of a medical image processing device, system, and method are described in detail with reference to the drawings. Note that the medical information processing device and medical information processing method according to the present application are not limited to the embodiments shown below. In addition, the embodiments can be combined with other embodiments or conventional technologies to the extent that no inconsistencies arise in the processing content.

(First embodiment)
FIG. 1 is a diagram showing an example of the configuration of a medical image processing system and a medical image processing apparatus according to the first embodiment.

For example, as shown in FIG. 1, the medical image processing system 100 according to this embodiment includes an X-ray CT (Computed Tomography) device 110, a medical image storage device 120, a medical information display device 130, and a medical image processing device 140. Here, each device and system is connected to be able to communicate with each other via a network 150.

In addition to the X-ray CT device 110, the medical image processing system 100 may further include other medical image diagnostic devices such as a Magnetic Resonance Imaging (MRI) device, an ultrasound diagnostic device, a Positron Emission Tomography (PET) device, and a Single Photon Emission Computed Tomography (SPECT) device. The medical image processing system 100 may further include other systems such as an electronic medical record system, a Hospital Information System (HIS), and a Radiology Information System (RIS).

The X-ray CT device 110 generates a CT image of the subject. Specifically, the X-ray CT device 110 collects projection data representing the distribution of X-rays that have passed through the subject by rotating the X-ray tube and the X-ray detector on a circular orbit that surrounds the subject. The X-ray CT device 110 then generates a CT image based on the collected projection data.

The medical image storage device 120 stores various medical images related to subjects. Specifically, the medical image storage device 120 acquires CT images from the X-ray CT device 110 via the network 160, and stores the CT images in a memory circuit within the device. For example, the medical image storage device 120 is realized by a computer device such as a server or a workstation. Also, for example, the medical image storage device 120 is realized by a PACS (Picture Archiving and Communication System) or the like, and stores CT images in a format that complies with DICOM (Digital Imaging and Communications in Medicine).

The medical information display device 130 displays various medical information related to the subject. Specifically, the medical information display device 130 acquires medical information such as CT images and image processing results from the medical image storage device 120 via the network 150, and displays the medical information on a display within the device itself. For example, the medical information display device 130 is realized by computer equipment such as a workstation, personal computer, or tablet terminal.

The medical image processing device 140 performs various image processing related to the subject. Specifically, the medical image processing device 140 acquires CT images from the X-ray CT device 110 or the medical image storage device 120 via the network 150, and performs various image processing using the CT images. For example, the medical image processing device 140 is realized by computer equipment such as a server or a workstation.

For example, the medical image processing device 140 includes a network (NetWork: NW) interface 141, a memory circuit 142, an input interface 143, a display 144, and a processing circuit 145.

The NW interface 141 controls the transmission and communication of various data sent and received between the medical image processing device 140 and other devices connected via the network 150. Specifically, the NW interface 141 is connected to the processing circuitry 145, and transmits data received from other devices to the processing circuitry 145, or transmits data received from the processing circuitry 145 to other devices. For example, the NW interface 141 is realized by a network card, a network adapter, a NIC (Network Interface Controller), etc.

The memory circuitry 142 stores various data and programs. Specifically, the memory circuitry 142 is connected to the processing circuitry 145, and stores data received from the processing circuitry 145, or reads out stored data and transmits it to the processing circuitry 145. For example, the memory circuitry 142 is realized by a semiconductor memory element such as a random access memory (RAM) or a flash memory, a hard disk, an optical disk, etc.

The input interface 143 accepts input operations of various instructions and various information from the user. Specifically, the input interface 143 is connected to the processing circuit 145, converts the input operations received from the user into electrical signals, and transmits them to the processing circuit 145. For example, the input interface 143 is realized by a trackball, a switch button, a mouse, a keyboard, a touchpad that performs input operations by touching the operation surface, a touch screen in which a display screen and a touchpad are integrated, a non-contact input interface using an optical sensor, and a voice input interface. Note that in this specification, the input interface 143 is not limited to only those that have physical operation parts such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and transmits this electrical signal to a control circuit is also included as an example of the input interface 143.

The display 144 displays various information and data. Specifically, the display 144 is connected to the processing circuit 145, and displays various information and data received from the processing circuit 145. For example, the display 144 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, a touch panel, etc.

The processing circuitry 145 controls the entire medical image processing device 140. For example, the processing circuitry 145 performs various processes in response to input operations received from a user via the input interface 143. For example, the processing circuitry 145 receives data transmitted by another device from the NW interface 141 and stores the received data in the memory circuitry 142. Also, for example, the processing circuitry 145 transmits data received from the memory circuitry 142 to the NW interface 141, thereby transmitting the data to another device. Also, for example, the processing circuitry 145 displays the data received from the memory circuitry 142 on the display 144.

A configuration example of the medical image processing system 100 and medical image processing device 140 according to this embodiment has been described above. For example, the medical image processing system 100 and medical image processing device 140 according to this embodiment are installed in medical facilities such as hospitals and clinics, and support users such as doctors in making diagnoses and formulating treatment plans for heart diseases.

Specifically, the medical image processing device 140 calculates and displays the wall shear stress (WSS) at each position of the blood vessel based on medical images of the blood vessels in the subject's heart. Here, the medical image processing device 140 displays the wall shear stress in an easy-to-observe manner. In other words, the medical image processing device 140 displays the WSS in an easy-to-understand manner, thereby reducing the effort required for users such as doctors to interpret the WSS.

WSS is calculated at each position on the inner wall of a blood vessel. In other words, WSS is an index value that is distributed three-dimensionally throughout the entire blood vessel. On the other hand, the display screen of an image display device such as a monitor is two-dimensional, so when blood vessels are displayed as images, a two-dimensional image viewed from a specific direction or a two-dimensional image of a specific cross section is displayed. In such a display screen, the three-dimensional structure of the blood vessel is expressed by continuously changing the specific direction in the two-dimensional image viewed from the specific direction described above.

For example, the coronary arteries are displayed as a three-dimensional structure using VR (Volume Rendering) or SR (Surface Rendering) displays, but at any one time, a two-dimensional image of the coronary arteries observed from a specific direction is displayed on the screen. Therefore, when mapping the WSS calculated at each position of the blood vessel onto a VR-displayed coronary artery image, observable WSS (WSS in the observable area) and unobservable WSS (WSS in the unobservable area) will be generated.

Figure 2 is a diagram for explaining an example of the display of the WSS according to the first embodiment. Here, Figure 2 shows observable and unobservable areas when observing a VR image of a coronary artery. For example, as shown in Figure 2, if the WSS is calculated for the entire area of the coronary artery V1 and the calculated WSS is mapped and displayed on the coronary artery V1, the WSS in the direction displayed on the screen (the WSS on the front side of the screen) can be observed, but the WSS in the direction not displayed on the screen (the WSS on the back side of the screen) cannot be observed.

Therefore, in such a display, if a WSS with important characteristics is present at the back of the screen, the user may miss the characteristic WSS. Furthermore, when rotating and observing a VR image, the user must observe in a 360-degree direction in order to risk missing the characteristic WSS, which is time-consuming.

The medical image processing device 140 according to this embodiment is configured to extract a representative value or display area of the WSS to be displayed based on extraction criteria determined according to the area, thereby displaying the WSS in a more easily understandable manner and reducing the effort required for users such as doctors to interpret the WSS.

Specifically, the medical image processing device 140 extracts characteristic WSS or characteristic regions from each position of the blood vessel and changes the display format of the WSS to display the WSS in a more easily understandable manner.

The medical image processing device 140 having such a configuration will be described in detail below. Note that the following describes an example in which a coronary artery CT image is used as a medical image related to blood vessels.

For example, as shown in FIG. 1, in this embodiment, the processing circuitry 145 of the medical image processing device 140 executes an acquisition function 145a, a calculation function 145b, an extraction function 145c, an image generation function 145d, and a display control function 145e. Here, the calculation function 145b is an example of an acquisition unit. Also, the extraction function 145c is an example of an extraction unit. Also, the display control function 145e is an example of a display control unit.

The acquisition function 145a acquires coronary artery CT images of the subject from the X-ray CT device 110 or the medical image storage device 120 via the NW interface 141. Specifically, the acquisition function 145a acquires three-dimensional coronary artery CT images that can be used to calculate the WSS.

The calculation function 145b acquires the distribution of wall shear stress in the blood vessel. For example, the calculation function 145b extracts the center line of the coronary artery contained in the coronary artery CT image of the subject acquired by the acquisition function 145a. The calculation function 145b also calculates the WSS based on the coronary artery CT image of the subject acquired by the acquisition function 145a.

For example, the calculation function 145b calculates the WSS at each position of the coronary artery from a coronary artery CT image of the subject using a known method such as CFD (Computational Fluid Dynamics) or machine learning.

The extraction function 145c extracts representative values or characteristic vascular regions from the distribution of WSS in the blood vessels based on extraction criteria defined for each region according to the shape or properties of the blood vessel. Specifically, the extraction function 145c extracts values to be displayed from the spatial distribution of WSS for each position along the center line of the blood vessel based on the extraction criteria. The processing by the extraction function 145c will be described in detail later.

The image generation function 145d generates various images for display. For example, the image generation function 145d generates a three-dimensional image of the coronary artery by three-dimensionally reconstructing the vascular region of the coronary artery in a coronary artery CT image. For example, the image generation function 145d generates a VR image, an SR image, a CPR (Curved Planar Reconstruction) image, an MPR (Multi Planar Reconstruction) image, an SPR (Stretched Multi Planar Reconstruction) image, etc.

The display control function 145e changes the display form of the wall shear stress in the blood vessel based on the representative value of the wall shear stress or the extraction result of the characteristic blood vessel region. Specifically, the display control function 145e causes the display 144 to display the WSS according to the extraction result by the extraction function 145c. The processing by the display control function 145e will be described in detail later.

The above-mentioned processing circuitry 145 is realized, for example, by a processor. In this case, each of the above-mentioned processing functions is stored in the memory circuitry 142 in the form of a program executable by a computer. The processing circuitry 145 then realizes the function corresponding to each program by reading and executing each program stored in the memory circuitry 142. In other words, when the processing circuitry 145 has read each program, it has each of the processing functions shown in FIG. 1.

The processing circuit 145 may be configured by combining multiple independent processors, and each processor may execute a program to realize each processing function. Each processing function of the processing circuit 145 may be appropriately distributed or integrated into a single or multiple processing circuits. Each processing function of the processing circuit 145 may be realized by a combination of hardware and software such as circuits. Here, an example is described in which a program corresponding to each processing function is stored in a single storage circuit 142, but the embodiment is not limited to this. For example, a configuration may be used in which a program corresponding to each processing function is distributed and stored in multiple storage circuits, and the processing circuit 145 reads out and executes each program from each storage circuit.

As described above, the medical image processing device 140 extracts characteristic WSS or characteristic regions from each position of the blood vessel and changes the display form of the WSS. Below, an example of processing by the medical image processing device 140 is described.

(Step 1)
The medical image processing device 140 first acquires a three-dimensional medical image in displaying the WSS. Specifically, the acquisition function 145a acquires a coronary artery CT image of the subject from the X-ray CT device 110 or the medical image storage device 120 via the NW interface 141. More specifically, the acquisition function 145a acquires a three-dimensional coronary artery CT image that can be used to calculate the WSS. The acquisition function 145a may acquire any type of image as long as the image is a type that can calculate flow information such as the shape of the blood vessel and the flow velocity of the blood. For example, the acquisition function 145a can also acquire medical images (such as ultrasound images and MRI images) collected by a medical image diagnostic device other than the X-ray CT device 110.

(Step 2)
Next, the medical image processing device 140 extracts the center lines of blood vessels from the acquired three-dimensional medical image. Specifically, the calculation function 145b extracts the center lines of the coronary arteries included in the coronary artery CT image of the subject acquired by the acquisition function 145a. Here, the calculation function 145b can extract the center lines of the coronary arteries by various known methods, such as a method using CT values.

(Step 3)
Then, the medical image processing device 140 calculates the WSS from the acquired three-dimensional medical image. Specifically, the calculation function 145b calculates the WSS at each blood vessel position from the coronary artery CT image of the subject acquired by the acquisition function 145a by a known method using CFD, machine learning, or the like.

(Step 4)
The medical image processing device 140 then extracts a representative value from the calculated WSS. Specifically, the extraction function 145c extracts a representative value of the WSS in the blood vessel based on an extraction criterion determined for each region according to the shape of the blood vessel. For example, the extraction function 145c extracts a characteristic value from all WSS values in the horizontal cross section of 360° around the center line at each position of the center line of the coronary artery extracted by the calculation function 145b.

As an example, the extraction function 145c extracts the highest value (maximum WSS) from among all WSS values in the horizontal cross section of 360° about the center line as the representative value. The extraction function 145c can also extract the lowest value (minimum WSS) from among all WSS values in the horizontal cross section of 360° about the center line as the representative value. The extraction function 145c can also extract the average value of all WSS values in the horizontal cross section of 360° about the center line as the representative value. The extraction function 145c can also extract the WSS value with the largest difference from the WSS at adjacent blood vessel positions above, below, or to the left and right (i.e., the amount of change in WSS is large at adjacent positions).

(Step 5)
Then, the medical image processing device 140 displays the extracted WSS on a display device such as the display 144. Specifically, the image generating function 145d generates a three-dimensional display image including a vascular region in a three-dimensional medical image. For example, the image generating function 145d generates a display image such as a VR image or an SR image by three-dimensionally reconstructing a vascular region in a coronary artery CT image.

The display control function 145e displays the WSS using the display image generated by the image generation function 145d. For example, the display control function 145e acquires the WSS values for all positions of the blood vessel calculated by the calculation function 145b, and identifies the possible range of the WSS from the maximum and minimum values of the acquired WSS values. The display control function 145e then sets a color array (color lookup table) for the identified range, and displays a color image by assigning a color corresponding to the WSS value of each blood vessel position to each blood vessel position.

(Step 6)
The medical image processing device 140 changes the display form of the WSS based on the user's instruction. For example, the display control function 145e switches between displaying the normal spatial distribution of the WSS and displaying the WSS based on the extraction result by the extraction function 145c in response to a switching operation by the user via the input interface 143 (for example, a selection operation of a switching button, etc.). In addition, for example, the display control function 145e can also control to display the normal WSS when the user is performing an operation such as rotation or browsing on the WSS image, and to display the WSS based on the extraction result when the operation is stopped.

Below, an example of extraction and display of a representative WSS value is described. In such a case, the extraction function 145c extracts, for each position of the center line of the blood vessel, the maximum value, minimum value, average value, or the value with the largest difference from the adjacent value from the WSS value in the blood vessel wall that intersects with a cross section perpendicular to the center line. The display control function 145e changes the display form of the WSS in the blood vessel so that the maximum value, minimum value, average value, or the value with the largest difference from the adjacent value extracted for each position of the center line of the blood vessel is displayed.

Figure 3 is a diagram for explaining an example of the extraction process and display control process according to the first embodiment. As shown in the upper diagram of Figure 3, the extraction function 145c extracts the maximum value as a characteristic WSS from all WSSs in the horizontal cross section of 360° about the center line at each position on the center line. That is, the extraction function 145c extracts the maximum value from the WSS values on the circle indicated by the dotted line for each position along the center line. Note that while Figure 3 shows an example in which maximum values are extracted for five positions, in reality, maximum values are extracted for many positions along the center line of the blood vessel.

When the characteristic WSS value is extracted as described above, the display control function 145e changes the display form of the WSS so that the extracted value is displayed. For example, in response to a user instruction, the display control function 145e displays a color image showing the color corresponding to the maximum WSS value extracted at each position on the side of the coronary artery that can be observed by the user, as shown in the lower diagram of Figure 3.

Note that FIG. 3 shows a case where the maximum value of all WSS in the horizontal cross section at each position is extracted as the characteristic WSS, but the embodiment is not limited to this, and the minimum value may be extracted, or the average value of all WSS in the horizontal cross section may be extracted. In addition, the characteristic WSS value may be the WSS that has the largest difference (i.e., the largest amount of change) with the WSS of the adjacent blood vessel position above, below, or to the left and right.

This makes it possible to easily observe WSS in directions not displayed on the screen at each position of the coronary artery if characteristic values exist, reducing the risk of missing important information.

(Variation 1)
In the above embodiment, a description has been given of a case where a characteristic WSS is extracted from a coronary artery CT image at one time point in step 4. In Modification 1, a description will be given of a case where a characteristic WSS is extracted from coronary artery CT images at multiple time points.

In such a case, the extraction function 145c extracts a characteristic WSS value based on the comparison result of the WSS at the same position at multiple time points. Specifically, the extraction function 145c calculates the difference value of the WSS at the same position at multiple time points at each position. Then, the extraction function 145c extracts the characteristic WSS based on the difference value. More specifically, the extraction function 145c extracts a blood vessel position (blood vessel region) where the difference value is higher than a threshold value or lower than the threshold value. The threshold value may be determined in advance or may be specified by the user. In another example, for each position of the blood vessel center line, a region having a maximum difference value or a region having a minimum difference value may be extracted in the blood vessel wall intersecting with a cross section perpendicular to the center line. That is, the extraction function 145c extracts a region where the change in the WSS value is large or small over time.

4 is a diagram for explaining an example of the extraction process and the display control process according to the first embodiment. For example, as shown in FIG. 4, the extraction function 145c aligns a CT image of the coronary artery V2 acquired one month ago with a CT image of the coronary artery V2 acquired currently. The alignment is performed by a known method. For example, the LDDM (Large Deformation Diffeomorphic Metric Mapping) method or the FFD (Free-form Deformation) method can be used. Then, the extraction function 145c calculates the difference value of the WSS for each position using the WSS calculated by the calculation function 145b in each CT image. Here, the extraction function 145c extracts, for example, a region where the difference value is equal to or greater than a threshold value. In addition, the extraction function 145c may extract, for each position of the center line of the blood vessel, a region having a maximum difference value or a region having a minimum difference value in the blood vessel wall intersecting with a cross section perpendicular to the center line.

The display control function 145e changes the display form of the WSS in the blood vessel in response to a user instruction so that the WSS value in the extracted region is displayed. For example, the display control function 145e displays the current WSS at the blood vessel position where the difference value of the coronary artery V2 is equal to or greater than a threshold on the side observable by the user. Specifically, the display control function 145e identifies all regions having the difference value equal to or greater than the threshold in the blood vessel wall intersecting with the cross section perpendicular to the heart line for each position of the blood vessel center line, and displays them in order of the magnitude of the difference value in order of proximity to the user's line of sight.

In addition, when extracting a region based on a threshold, the display control function 145e can display the WSS in various other ways. For example, the display control function 145e identifies all regions having the difference value equal to or greater than the threshold in the vascular wall intersecting with a cross section perpendicular to the heart line for each position of the heart line of the blood vessel, and displays the regions in order of proximity to the line of sight. In addition, for example, the display control function 145e identifies all regions having the difference value equal to or greater than the threshold in the vascular wall intersecting with a cross section perpendicular to the heart line for each position of the heart line of the blood vessel, and displays the identified regions in order of proximity to the line of sight of the user, in order of the current WSS being high or low. In addition, for example, the display control function 145e identifies all regions having the difference value equal to or greater than the threshold in the vascular wall intersecting with a cross section perpendicular to the heart line for each position of the heart line of the blood vessel, and displays the identified regions in order of proximity to the line of sight of the user, in order of the current WSS being high and low.

When the display control function 145e extracts an area with the maximum difference value or an area with the minimum difference value, the display control function 145e may display the current WSS corresponding to the maximum difference value or the minimum difference value on the side that can be viewed by the user. The value to be displayed may be not only the current WSS but also the WSS at a past point in time (one month ago in the modified example), or it may be the difference value itself.

In addition, for areas other than the characteristic areas, a map of difference values may be displayed instead of a map of WSS. In this case, the display control function 145e displays a color image in which colors corresponding to the difference values are mapped. Note that, although FIG. 4 illustrates an example in which the difference is equal to or greater than the threshold, the same processing is performed when the difference is equal to or less than the threshold. In this way, by using the comparison results of WSS calculated at multiple points in time, it is possible to diagnose the progression of the lesion, the presence or absence of effects before and after treatment, etc.

(Variation 2)
In the above embodiment, a case has been described in which an arbitrary characteristic WSS value is extracted in step 4. In Modification 2, a case will be described in which WSS is extracted by changing characteristic conditions (extraction criteria) for each vascular branch or each vascular region.

Specifically, the extraction function 145c extracts a representative value in the blood vessel based on extraction criteria that are determined for each region according to the characteristics of the blood vessel. As an example, the extraction function 145c extracts a relatively high WSS value as a representative value for a region of the blood vessel that contains plaque, and extracts a relatively low WSS value as a representative value for a region of the blood vessel that does not contain plaque.

In such a case, the extraction function 145c first extracts plaque in the coronary artery. For example, the extraction function 145c extracts the position of plaque for each branch of the coronary artery by analyzing a coronary artery CT image of the subject. As one example, the extraction function 145c extracts the position of plaque from information on the diameter of the coronary artery. Also, for example, the extraction function 145c extracts the position of plaque by threshold processing using the coronary artery CT image. Alternatively, for example, the extraction function 145c may calculate the position of plaque using a classifier that has previously learned the characteristics of the distribution of pixel values inside the plaque using machine learning technology.

The extraction function 145c then extracts, for example, the highest WSS value as a representative value for positions where plaque has been extracted, and the lowest WSS value as a representative value for positions where plaque has not been extracted. This is based on reports that low WSS correlates with the risk of plaque progression, and high WSS correlates with the risk of plaque rupture. In other words, for areas where plaque already exists, high WSS values are displayed, making it possible to estimate the degree of rupture risk, while for areas where plaque has not yet formed, it is possible to estimate whether or not there is a risk of plaque forming in the future.

The display control function 145e changes the display form of the WSS in the blood vessel in response to a user instruction so that the extracted representative value is displayed. For example, the display control function 145e displays a color image in which a color corresponding to the representative value is mapped to the corresponding position of the blood vessel.

FIG. 5 is a diagram for explaining an example of the extraction process and the display control process according to the first embodiment. For example, as shown in the upper diagram of FIG. 5, the extraction function 145c extracts plaque in the coronary artery V3 by analyzing the coronary artery V3. Then, the extraction function 145c extracts the maximum value of the WSS calculated at each position of the vascular wall intersecting with the cross section perpendicular to the heart line, where plaque is extracted at each position of the vascular wall. Furthermore, the extraction function 145c extracts the minimum value of the WSS calculated at each position of the vascular wall intersecting with the cross section perpendicular to the heart line, where plaque is not extracted at each position of the vascular wall.

As shown in the lower diagram of FIG. 5, the display control function 145e controls to display the maximum WSS value at the cross-sectional position where plaque is extracted, and the minimum WSS value at the cross-sectional position where plaque is not extracted. For example, the display control function 145e displays a color image in which a color corresponding to the maximum WSS value is mapped to the side that can be observed by the user in the region including plaque in the VR image of coronary artery V3, and a color corresponding to the minimum WSS value is mapped to the side that can be observed by the user in the region not including plaque in the VR image.

Here, the extraction function 145c can determine the presence or absence of plaque for each vascular branch in the blood vessel, and extract a representative value for each vascular branch. In other words, the extraction function 145c can target the entire coronary artery. The extraction function 145c can also determine the presence or absence of plaque for each region along the running direction of the vascular branch in the blood vessel, and extract a representative value for each region along the running direction of the vascular branch.

In addition, when plaque is contained in the blood vessel, the extraction function 145c can perform extraction processing using extraction criteria according to the hardness of the plaque. Specifically, the extraction function 145c further determines the hardness of the plaque in the blood vessel and changes the extraction criteria according to the hardness of the plaque.

As described above, the extraction function 145c extracts a relatively high WSS for an area containing plaque based on a threshold value, but if the hardness of the extracted plaque is higher than the threshold value, the threshold value used to extract the representative value is made higher, and if the hardness of the extracted plaque is lower than the threshold value, the threshold value used to extract the representative value is made lower. This is because if an area with high WSS exists near soft plaque, there is a risk of plaque rupture, so when soft plaque is extracted, the threshold value is made lower so that even a lower value can be extracted. Note that the hardness of the plaque may be based on a calcium score obtained by analysis of a coronary artery CT image, for example.

Note that FIG. 5 describes a case where the maximum WSS value is extracted for cross-sectional positions where areas containing plaque are located, and the minimum WSS value is extracted for cross-sectional positions where areas not containing plaque are located. However, the embodiment is not limited to this, and it is also possible to extract a WSS higher than a threshold value for cross-sectional positions where areas containing plaque are located, and a WSS lower than the threshold value for cross-sectional positions where areas not containing plaque are located.

In such a case, the display control function 145e displays a color image in which, for example, colors corresponding to a plurality of WSS values higher than the threshold are mapped to the side observable by the user at the cross-sectional position where the plaque-containing region of the VR image of the coronary artery V3 is located, and colors corresponding to a plurality of WSS values lower than the threshold are mapped to the side observable by the user at the cross-sectional position where the plaque-free region of the VR image is located. For example, the display control function 145e displays the WSS in order of size in descending order of proximity to the user's line of sight. In other words, at the cross-sectional position where the plaque-containing region is located, the WSS may be displayed in descending order of size in descending order of proximity to the user's line of sight, and at the cross-sectional position where the plaque-free region is located, the WSS may be displayed in descending order of size in descending order of proximity to the user's line of sight.

When extracting WSS based on a threshold, the display control function 145e can display the WSS in various other ways. For example, the display control function 145e displays the positions of multiple WSSs higher than the threshold in order of proximity to the line of sight at a cross-sectional position where a region containing plaque of the VR image is located, and displays the positions of multiple WSSs lower than the threshold in order of proximity to the line of sight at a cross-sectional position where a region not containing plaque of the VR image is located. Also, for example, the display control function 145e displays the high values and low values of multiple WSSs higher than the threshold in alternating order at a cross-sectional position where a region containing plaque of the VR image is located, and displays the high values and low values of multiple WSSs lower than the threshold in alternating order at a cross-sectional position where a region not containing plaque of the VR image is located.

The extraction function 145c can also change the extraction criteria depending on the condition of the myocardium. Specifically, the extraction function 145c further determines the presence or absence of inflammation in the myocardium to which blood is supplied by the blood vessel, and if the myocardium has inflammation, changes the extraction criteria in the area of the blood vessel that does not contain plaque.

For example, the extraction function 145c determines whether inflammation is included in the control region of the myocardium governed by the coronary artery for which the WSS is displayed. As an example, the extraction function 145c uses an existing algorithm such as the Voronoi method to identify the control region of the coronary artery for which the WSS is displayed from a coronary artery CT image including the myocardium. Then, the extraction function 145c aligns the myocardial SPECT image with the myocardium in the coronary artery CT image, and determines whether inflammation is included in the identified control region.

Here, if the control region includes inflammation, the extraction function 145c changes the extraction criteria for the region of the blood vessel that does not include plaque. FIG. 6 is a diagram for explaining an example of the extraction process and the display control process according to the first embodiment. For example, as shown in FIG. 6, the extraction function 145c changes the extraction criteria for the region R1 that does not include plaque in the coronary artery V4 that includes myocardial inflammation in its control region.

As described above, in areas that do not contain plaque, the extraction function 145c extracts a relatively low WSS value based on a threshold value, but if there is inflammation in the myocardium, the threshold value used to extract the representative value is made higher. This is because plaque is more likely to occur when there is inflammation in the myocardium, and the threshold value is made higher when there is inflammation in the myocardium so that even higher WSS values can be extracted.

(Variation 3)
In the above embodiment, a case has been described in which the display is switched so that the characteristic WSS value at each position around the center line is brought to the front of the screen in response to a user instruction in step 6. In Modification 3, a case will be described in which the display is switched for each blood vessel position.

For example, the extraction function 145c and the display control function 145e can not only extract and display characteristic WSS values for each position along the center line of the blood vessel, but can also display only values at a specified position in the foreground. As an example, the display control function 145e can control the display to the user of only WSS values at each position along the center line that exceed a predetermined threshold value.

The display control function 145e can also switch the display based on the location where plaque is present. FIG. 7 is a diagram for explaining an example of the extraction process and display control process according to the first embodiment. For example, as shown in FIG. 7, the display control function 145e controls so that the maximum WSS value is displayed to the user only for the location where plaque is present.

In addition, the display control function 145e may perform control so that the maximum, minimum, or average WSS value, or the value with the largest difference from adjacent values, is displayed only for positions where there is a high probability of plaque, where there is a high probability of plaque rupture, or where there is inflammation in the myocardium.

(Variation 4)
In the above embodiment, a description has been given of a case where the WSS value is displayed in step 6. In the fourth modification, a description will be given of a case where the extraction criteria for characteristic WSS are displayed.

As described above, the medical image processing device 140 extracts a representative value of the WSS based on predetermined extraction criteria, and changes the display form of the WSS based on the extraction result. Here, the display control function 145e can also present the extraction criteria to the user. Specifically, the display control function 145e further displays the extraction criteria used to extract the representative value.

Figure 8 is a diagram showing an example of the display of extraction criteria according to the first embodiment. As shown in Figure 8, the display control function 145e also displays "WSS: aaa, plaque is included in the same cross section, so the maximum value is extracted as a representative value" and "WSS: bbb, normal region, so the minimum value is extracted as a representative value" when displaying coronary artery V3. This allows the user to see at a glance what values are displayed at each position of the blood vessel.

Next, the processing procedure of the medical image processing device 140 will be described with reference to FIG. 9. FIG. 9 is a flowchart showing the processing procedure of the processing performed by each processing function of the processing circuitry 145 of the medical image processing device 140 according to the first embodiment.

9, in this embodiment, when the acquisition function 145a receives an instruction to start processing from a user via the input interface 143, it acquires a coronary artery CT image of the subject from the X-ray CT device 110 or the medical image storage device 120 (step S101). This processing is realized, for example, by the processing circuitry 145 calling up a program corresponding to the acquisition function 145a from the memory circuitry 142 and executing it.

Then, the calculation function 145b extracts the central line of the coronary artery contained in the coronary artery CT image of the subject acquired by the acquisition function 145a (step S102), and calculates the WSS based on the coronary artery CT image (step S103). This process is realized, for example, by the processing circuitry 145 calling up a program corresponding to the calculation function 145b from the storage circuitry 142 and executing it.

Next, the extraction function 145c extracts a representative value from the spatial distribution of WSS based on the criteria assigned to each region based on the blood vessel shape or characteristics (step S104). This process is realized, for example, by the processing circuitry 145 calling up a program corresponding to the extraction function 145c from the storage circuitry 142 and executing it.

Then, the display control function 145e displays the WSS calculated by the calculation function 145b (step S105), and changes the display form based on the representative value extracted by the extraction function 145c (step S106). This process is realized, for example, by the processing circuitry 145 calling up a program corresponding to the display control function 145e from the storage circuitry 142 and executing it.

As described above, according to the first embodiment, the extraction function 145c extracts a representative value of wall shear stress in a blood vessel or a blood vessel region based on extraction criteria set for each region according to the shape or properties of the blood vessel. The display control function 145e changes the display form of the wall shear stress in a blood vessel based on the extraction result of the representative value of wall shear stress or the blood vessel region. Therefore, the medical image processing device 140 according to the first embodiment can display the wall shear stress according to the extraction criteria, making it possible to display the wall shear stress in an easy-to-observe manner.

Furthermore, according to the first embodiment, the extraction function 145c extracts a relatively high wall shear stress value as a representative value for a region of the blood vessel that contains plaque, and extracts a relatively low wall shear stress value as a representative value for a region of the blood vessel that does not contain plaque. The display control function 145e changes the display form of the wall shear stress in the blood vessel so that the extracted representative value is displayed. Therefore, the medical image processing device 140 according to the first embodiment makes it possible to display appropriate wall shear stress values for each of a region that contains plaque and a region that does not contain plaque.

Furthermore, according to the first embodiment, the extraction function 145c determines the presence or absence of plaque for each vascular branch in the blood vessel, and extracts a representative value for each vascular branch. Furthermore, the extraction function 145c determines the presence or absence of plaque for each region along the running direction of the vascular branch in the blood vessel, and extracts a representative value for each region along the running direction of the vascular branch. Therefore, the medical image processing device 140 according to the first embodiment makes it possible to extract an appropriate representative value.

Furthermore, according to the first embodiment, the extraction function 145c further determines the hardness of the plaque in the blood vessel and changes the extraction criteria according to the hardness of the plaque. Therefore, the medical image processing device 140 according to the first embodiment makes it possible to display the value of wall shear stress taking into account the hardness of the plaque.

Furthermore, according to the first embodiment, the extraction function 145c extracts a vascular region in which the curvature is higher than a threshold value. The display control function 145e changes the display form of the wall shear stress in the blood vessel for a vascular region in which the curvature is higher than a threshold value so that the wall shear stress in the region on the inside of the bend is displayed. Therefore, the medical image processing device 140 according to the first embodiment makes it possible to display the wall shear stress in the region on the inside of the bend in a vascular region with high curvature.

Furthermore, according to the first embodiment, the extraction function 145c calculates the difference in wall shear stress calculated at multiple points in time for the same blood vessel at each same position, and extracts a blood vessel region where the calculated difference is higher than a threshold value or a blood vessel region where the calculated difference is lower than a threshold value. The display control function 145e changes the display form of the wall shear stress in the blood vessel so that the wall shear stress in the extracted blood vessel region is displayed. Therefore, the medical image processing device 140 according to the first embodiment makes it possible to display the value of a region where the wall shear stress shows a characteristic change over time.

Furthermore, according to the first embodiment, the extraction function 145c further determines the presence or absence of inflammation in the myocardium to which blood is supplied by the blood vessel, and if the myocardium has inflammation, changes the extraction criteria in the region of the blood vessel that does not contain plaque. Therefore, the medical image processing device 140 according to the first embodiment makes it possible to display the value of wall shear stress taking into account inflammation in the myocardium.

Furthermore, according to the first embodiment, the extraction function 145c further extracts, for each position of the center line of the blood vessel, from the values of wall shear stress in the blood vessel wall intersecting with a cross section perpendicular to the center line, the maximum value, the minimum value, the average value, or the value with the largest difference from the adjacent value. The display control function 145e further changes the display form of the wall shear stress in the blood vessel so that the maximum value, the minimum value, the average value, or the value with the largest difference from the adjacent value extracted for each position of the center line of the blood vessel is displayed. Therefore, the medical image processing device 140 according to the first embodiment makes it possible to display characteristic wall shear stress values.

Furthermore, according to the first embodiment, the display control function 145e further displays the representative value or the extraction criteria used to extract the vascular region. Therefore, the medical image processing device 140 according to the first embodiment allows the user to understand the displayed wall shear stress value.

Second Embodiment
In the above-described first embodiment, a case where a characteristic WSS value is extracted and displayed is described. In the second embodiment, a case where a WSS value at a characteristic blood vessel position is displayed is described. Note that the medical image processing apparatus 140 according to the second embodiment differs from the first embodiment in the processing contents by the extraction function 145c and the display control function 145e. The following description will focus on this point.

In the second embodiment, in step 4, the extraction function 145c extracts a characteristic vascular region in the blood vessel based on extraction criteria determined for each region according to the shape of the blood vessel. As an example, the extraction function 145c extracts a vascular region in the blood vessel whose curvature is higher than a threshold value. In such a case, the extraction function 145c calculates the curvature at each position of the coronary artery. Then, the extraction function 145c extracts a region in which the calculated curvature is higher than a predetermined threshold value as a characteristic vascular region. Note that the characteristic vascular position may be identified for the entire coronary artery, or the position with the largest or smallest curvature may be identified for each blood vessel branch.

The display control function 145e displays the WSS value of a characteristic blood vessel position. For example, the display control function 145e changes the display form of the WSS in the blood vessel so that the WSS in the blood vessel region where the curvature is higher than a threshold value is displayed.

FIG. 10 is a diagram for explaining an example of the extraction process and the display control process according to the second embodiment. For example, as shown in the upper diagram of FIG. 10, the extraction function 145c calculates the curvature for each position on the center line in the coronary artery V5, and compares the calculated curvatures with a threshold to extract a position P1 where the curvature is higher than the threshold. Then, as shown in the lower diagram of FIG. 10, the display control function 145e changes the display form so that the WSS value at the position P1 where the curvature is higher than the threshold is observable by the user. That is, the display control function 145e displays the WSS value at the position P1 at a position that is orthogonal to the center line and observable by the user on the cross section of the blood vessel including the position P1.

For example, when displaying a color image in which a color corresponding to the WSS value is mapped onto a VR image of coronary artery V5, display control function 145e displays a color image in which a color corresponding to the WSS value of position P1 is mapped onto the side of the cross section of the blood vessel that is perpendicular to the center line of coronary artery V5 and includes position P1 and that is observable by the user. In such a case, display control function 145e acquires the WSS values of all positions of the blood vessel calculated by calculation function 145b, and specifies the possible range of WSS from the maximum and minimum values of the acquired WSS values. Then, display control function 145e sets a color arrangement (color lookup table) for the specified range, and maps a color corresponding to the WSS value of position P1 to position P1 of coronary artery V2.

Note that in FIG. 10, only position P1 is shown as an area where the curvature is higher than the threshold, but in reality, all positions in coronary artery V5 where the curvature is higher than the threshold are extracted.

In addition, the extraction criteria according to the shape of the blood vessel may be used not only to extract blood vessel regions with a curvature higher than a threshold value, but also to extract blood vessel regions with a curvature lower than a threshold value. In such a case, the display control function 145e may cause the display 144 to display the WSS value of the position on the side of the cross section of the blood vessel that is perpendicular to the core line and includes a position where the curvature is lower than the threshold value and that is observable by the user. Here, the threshold value used to extract the region with high curvature and the threshold value used to extract the region with low curvature may be set to different values.

In addition, the extraction criteria according to the shape of the blood vessel may use not only the curvature but also the blood vessel diameter. In such a case, for example, the extraction function 145c may compare the size of the blood vessel diameter with a threshold value and extract a characteristic region based on the comparison result. In addition, extraction according to the shape of the blood vessel may be performed for a specific blood vessel branch, or may be performed for the entire coronary artery, i.e., all blood vessel branches.

The display control function 145e according to the second embodiment also highlights and displays the extracted vascular region in step 6 described above. For example, when displaying the WSS of the vascular region extracted by the extraction function 145c, such as a vascular region with a curvature higher than a threshold value or a region containing plaque, the display control function 145e highlights and displays the display target.

FIGS. 11 to 13 are diagrams showing an example of the display control process according to the second embodiment. For example, as shown in FIG. 11, the display control function 145e emphasizes the extracted vascular region by changing the display form of the region in response to a switching operation by the user. As one example, the display control function 145e emphasizes the region by displaying information indicating the extracted vascular region (a circle in the figure) or by enlarging the extracted vascular region in response to a switching operation by the user.

Here, when multiple regions are extracted by the extraction function 145c and the distance between those regions is close, enlarging and displaying each of them may result in reduced visibility. Therefore, when the distance between the multiple vascular regions to be enlarged is smaller than a threshold, the display control function 145e enlarges the multiple vascular regions in a single enlarged region. For example, as shown in FIG. 12, when the distance between two extracted regions is close and they overlap when enlarged, the display control function 145e enlarges them in a single enlarged region that includes the two regions.

The distance between the regions may be dynamically changed based on the magnification ratio of the display image on the screen. In such a case, the memory circuitry 142 stores information indicating the relationship between the magnification ratio and the distance between the regions in advance. The display control function 145e reads out distance information corresponding to the magnification ratio of the region to be enlarged from the memory circuitry 142, and when the distance between the multiple regions to be enlarged is shorter than the read distance, the multiple regions are enlarged into a single enlarged region.

The process of highlighting the display target may be any method that can highlight the target by switching the display form of the WSS at each calculated position. For example, the display control function 145e highlights the extracted representative value or vascular region using color, texture, pattern, or additional information.

As an example, the display control function 145e highlights an area using a color that is extremely dissociated from a color lookup table that assigns colors according to the WSS value (for example, using black in the case of a lookup table that normally changes from blue to red, or using red in the case of grayscale). The display control function 145e can also highlight an area by changing the transparency or shade of the color.

When WSS is represented by texture or pattern (for example, when WSS is represented by the size of an arrow or circle), the display control function 145e changes only the texture or pattern of the highlighted area. As an example, when WSS values are represented by the type of arrow as shown in FIG. 13, the display control function 145e changes the thickness of the arrow indicating the highlighted WSS value. The display control function 145e can also highlight the highlighted WSS value by displaying letters or marks around it.

(Variation 1)
In step 4 of the second embodiment, the case where characteristic positions are extracted based on the shape of the coronary artery has been described. In the first modification, the case where characteristic positions are extracted based on the blood vessel diameter or blood vessel properties will be described.

In such a case, for example, the extraction function 145c identifies the location where plaque or calcification exists from information such as the size of the blood vessel diameter, and extracts the identified location as a characteristic location. The extraction function 145c also calculates the probability of plaque rupture using machine learning technology, etc., identifies only the location where high-risk plaque, such as plaque with a high rupture probability, exists, and extracts the identified location as a characteristic location. The extraction function 145c also identifies the location with the largest or smallest change in WSS from the WSS obtained from the coronary artery CT image at the past time point, and extracts the identified location as a characteristic location. The extraction function 145c also identifies the area where inflammation is occurring from the distribution of pixel values in the myocardial area around the coronary artery, and extracts the location of the blood vessel included in that area as a characteristic location. Furthermore, when an area of inflammation is identified from another medical image, such as a myocardial SPECT image, the extraction function 145c identifies the area of inflammation by aligning the medical image with the coronary artery CT image, and extracts the identified position as a characteristic position.

(Variation 2)
In step 6 of the second embodiment, the WSS value at the characteristic position is emphasized. In the second modification, a case where the characteristic position is in a place that is difficult to visually recognize will be described.

For example, when it is difficult to observe the vascular region to be highlighted due to other structures (e.g., other blood vessels, the heart, etc.), the display control function 145e can also deform the shape of the blood vessel. FIG. 14 is a diagram for explaining an example of a blood vessel deformation process according to the second embodiment. For example, as shown in FIG. 14, when displaying the WSS of multiple blood vessels that overlap in the line of sight, the display control function 145e changes the shape of the multiple blood vessels so that they do not overlap in the line of sight, and displays the WSS of each blood vessel.

The display control function 145e can deform the shape of the blood vessels using a probabilistic method that uses a deformation model, image processing technology, and the like. The deformation of the blood vessels shown in FIG. 14 may be switched in response to a user operation.

(Variation 3)
In step 6 of the second embodiment described above, the WSS value at a single characteristic position is highlighted and displayed. In the third modification, a location with multiple characteristic positions will be described.

For example, when there are multiple vascular regions to be highlighted, the display control function 145e can identify an observation direction in which all or most of the regions can be observed, and switch the image to be displayed to an image in the identified direction.

The display control function 145e can also display the enlarged region side by side in another region. That is, the display control function 145e displays the enlarged representative value or vascular region separately from the blood vessels. FIG. 15 is a diagram showing an example of a display control process according to the second embodiment. For example, as shown in FIG. 15, the display control function 145e displays the enlarged vascular region in a display region different from the region in which the entire coronary artery is displayed.

Here, the display control function 145e can further display identification information for identifying the vascular regions that are displayed separately. For example, as shown in FIG. 15, the display control function 145e displays the segment numbers (#3, #5, and #8 in the figure) defined by the AHA (American Heart Association) for each enlarged vascular region of the coronary artery.

The display control function 145e may also display only the WSS of the highlighted area. FIG. 16 is a diagram showing an example of a display control process according to the second embodiment. For example, the display control function 145e controls so that only the enlarged area is displayed, as shown in FIG. 16. In this case, for example, the display control function 145e can be implemented by changing all areas other than the enlarged area to a single color (e.g., black) similar to the background color.

(Variation 4)
In step 6 of the second embodiment, the WSS value at a characteristic position is emphasized and displayed. In the fourth modification, a medical image is further displayed.

For example, if there is plaque, it may be difficult to understand the force acting on the plaque just by displaying the enlarged VR image. Therefore, the display control function 145e can display cross-sectional images of the enlarged blood vessel region side by side. In other words, the display control function 145e displays medical images showing cross-sections of the corresponding blood vessels side by side with the WSS.

Figure 17 is a diagram showing an example of display control processing according to the second embodiment. For example, as shown in Figure 17, the display control function 145e displays a color image of the enlarged vascular region and an MPR image depicting the vascular region side by side.

Here, the display control function 145e displays medical images in which the cross section is changed according to the shape or properties of the vascular region to be displayed. For example, the display control function 145e displays a CPR image of a vascular region having plaque cut at a cross section where the vascular diameter is shortest. In addition, the display control function 145e displays an MPR image of a vascular region with a curvature higher than a threshold cut at a cross section horizontal to the curvature of the blood vessel.

The display control function 145e can also display a schematic diagram when it is difficult to display a cross-sectional image due to limitations in resolution, etc. FIG. 18 is a diagram showing a display example of a schematic diagram of a blood vessel cross section according to the second embodiment. For example, as shown in FIG. 18, the display control function 145e displays a schematic diagram of a blood vessel region cut at a cross section where the blood vessel diameter is the shortest, or a schematic diagram of a blood vessel region cut at a cross section that is horizontal to the curvature of the blood vessel. In this way, even a schematic diagram can be used to observe the tendency of forces acting on plaque, etc., so the user can check the cross-sectional image on a separate screen as necessary.

(Variation 5)
In the fifth modification, a case where the WSS is displayed stereoscopically will be described.

For example, the display control function 145e can also highlight the blood vessel region using stereoscopic vision. By displaying two VR images side by side, it is possible to obtain a three-dimensional vision (stereoscopic vision) using the parallax of the human eyes. Therefore, the display control function 145e changes the display form of the highlighted region in only one of the two images displayed side by side, thereby displaying a VR image in which the region is highlighted when viewed stereoscopically. For example, the display control function 145e displays two VR images that are each generated by rendering the blood vessel region to be highlighted from positions shifted by a parallax angle according to the stereoscopic vision. In this way, the display control function 145e can display an image in which the blood vessel region is highlighted by stereoscopic vision.

As described above, according to the second embodiment, the display control function 145e highlights and displays the extracted representative value or vascular region. Therefore, the medical image processing device 140 according to the second embodiment makes it possible to display information with high visibility.

Furthermore, according to the second embodiment, the display control function 145e emphasizes the extracted representative value or vascular region by enlarging it. Therefore, the medical image processing device 140 according to the second embodiment makes it possible to display information with higher visibility.

Furthermore, according to the second embodiment, the display control function 145e enlarges multiple vascular regions in a single enlarged region when the distance between the multiple vascular regions to be enlarged is smaller than a threshold value. Therefore, the medical image processing device 140 according to the second embodiment makes it possible to display an image that is easy to observe for multiple vascular regions.

Furthermore, according to the second embodiment, the display control function 145e uses color, texture, pattern, or additional information to highlight the extracted representative value or vascular region. Therefore, the medical image processing device 140 according to the second embodiment makes it possible to highlight the vascular region using various highlighting methods.

Furthermore, according to the second embodiment, when displaying the wall shear stress in multiple blood vessels that overlap in the line of sight, the display control function 145e changes the shapes of the multiple blood vessels so that they do not overlap in the line of sight, and displays the wall shear stress in each blood vessel. Therefore, the medical image processing device 140 according to the second embodiment makes it possible to check the information on the entire blood vessel at a glance.

Furthermore, according to the second embodiment, the display control function 145e displays the enlarged representative value or vascular region separately from the blood vessels. Therefore, the medical image processing device 140 according to the second embodiment makes it possible to further improve the visibility of the enlarged region.

Furthermore, according to the second embodiment, the display control function 145e further displays identification information for identifying the vascular regions that are displayed separately. Therefore, the medical image processing device 140 according to the second embodiment can provide vascular information, enabling the vascular regions to be displayed in a more easily understandable manner.

Furthermore, according to the second embodiment, the display control function 145e displays medical images showing cross sections of corresponding blood vessels in parallel with the wall shear stress. Therefore, the medical image processing device 140 according to the second embodiment can provide morphological information of the blood vessel region, enabling improvement of diagnostic efficiency.

Furthermore, according to the second embodiment, the display control function 145e displays a medical image in which the cross section is changed according to the shape or characteristics of the vascular region to be displayed. Therefore, the medical image processing device 140 according to the second embodiment makes it possible to display an appropriate medical image according to the shape and characteristics of the vascular region.

Furthermore, according to the second embodiment, the display control function 145e displays a CPR image of a vascular region having plaque, cut at a cross section where the vascular diameter is the shortest. Furthermore, the display control function 145e displays an MPR image of a vascular region having a curvature higher than a threshold, cut at a cross section horizontal to the curvature of the blood vessel. Therefore, the medical image processing device 140 according to the second embodiment makes it possible to display appropriate medical images.

Third Embodiment
In the above-mentioned first and second embodiments, a case where information according to the WSS value is added to a blood vessel image and displayed is described. In the third embodiment, a graph display of WSS is described. Note that the medical image processing apparatus 140 according to the third embodiment differs from the first and second embodiments in the processing contents by the display control function 145e. The following description will focus on this point.

The display control function 145e according to the third embodiment further displays a graph showing the maximum and minimum values of wall shear stress in the vascular wall intersecting with a cross section perpendicular to the heart line for each position of the heart line of the blood vessel. FIG. 19 is a diagram showing an example of a graph display according to the third embodiment. For example, as shown in FIG. 19, the display control function 145e displays the WSS value on the vertical axis and grams showing the position of the heart line in the distance direction on the horizontal axis.

Here, the display control function 145e displays a graph showing a curve L1 indicating the maximum value at each position and a curve L2 indicating the minimum value at each position. This allows the user to grasp at a glance the state of the maximum and minimum values of WSS throughout the entire blood vessel.

The display control function 145e can further display on a graph the distribution of WSS values in the vascular wall that intersects with a cross section perpendicular to the heart line. For example, as shown in FIG. 19, the display control function 145e plots and displays the WSS distribution at position a in the blood vessel on a graph. Here, the user can arbitrarily specify the position at which the WSS distribution is displayed. This allows the user to grasp at a glance the distribution state of WSS at a desired position in the blood vessel.

As described above, according to the third embodiment, the display control function 145e further displays a graph showing the maximum and minimum values of wall shear stress in the vascular wall intersecting with a cross section perpendicular to the center line for each position of the center line of the blood vessel. Therefore, the medical image processing device 140 according to the third embodiment makes it possible to grasp at a glance the maximum and minimum values of WSS at each position of the blood vessel.

Furthermore, according to the third embodiment, the display control function 145e further displays on the graph the distribution of wall shear stress values in the vascular wall intersecting with the cross section perpendicular to the heart line. Therefore, the medical image processing device 140 according to the third embodiment makes it possible to grasp the distribution state of WSS in the blood vessel at a glance.

(Fourth embodiment)
In the fourth embodiment, various other forms of display of the WSS and medical image will be described. For example, the display control function 145e according to the fourth embodiment displays a characteristic position in the WSS in a predetermined direction in a medical image showing a cross section of a blood vessel. Here, the characteristic position in the WSS is, for example, a position where the WSS value is relatively high, a position where the WSS value is relatively low, a position showing a value that is suspected of a disease, a position of an area including plaque, etc.

20 is a diagram showing an example of the display control process according to the fourth embodiment. FIG. 20 shows a case where a short-axis cross-sectional image (cross-cut image), which is a cross-section perpendicular to the center line of a blood vessel, is displayed as a medical image showing a cross-section of a blood vessel. For example, as shown in FIG. 20, the display control function 145e displays a VR image of a coronary artery in the display area A1, and displays short-axis cross-sectional images at each position of the coronary artery in the display areas A21 to A26. The display control function 145e can display an image in which each pixel of the short-axis cross-sectional image is expressed according to the WSS value corresponding to each pixel position. For example, a color image expressed in a color according to the WSS value can be displayed. In addition, an image expressed in transparency, brightness, grayscale value, texture, symbol, mark, etc. according to the WSS value may be displayed. Of course, these are examples, and any image expressed by a method according to the WSS value may be displayed.

Here, the display control function 145e displays a characteristic position in the WSS in a predetermined direction in the short-axis cross-sectional image. For example, as shown in FIG. 20, the display control function 145e displays a characteristic position in each short-axis cross-section below the short-axis cross-sectional image. As an example, the image generation function 145d generates short-axis cross-sectional images along the center line of the coronary artery, with a predetermined position in the circumferential direction of the coronary artery on the upper side. The display control function 145e compares the WSS at each position in the circumferential direction of the coronary artery for the generated short-axis cross-sectional images, and rotates and displays the short-axis cross-sectional images with the center of the image as the rotation axis so that the characteristic position based on the comparison result is shown below the image.

The position to be displayed in the predetermined direction on the short-axis cross-sectional image is arbitrarily selected by the user. For example, the display control function 145e displays a GUI for selecting the position to be displayed in the predetermined direction on the short-axis cross-sectional image, and the user selects the position to be displayed in the predetermined direction by operating the GUI via the input interface 143. The display direction is not limited to the lower side of the short-axis cross-sectional image shown in FIG. 20, and can be arbitrarily selected.
In addition, the display control function 145e can identifiably display positions on the three-dimensional image corresponding to characteristic positions in the WSS. For example, as shown in FIG. 20, the display control function 145e can indicate positions on the VR image corresponding to the lower positions of each of the short-axis cross-sectional images displayed in the display areas A21 to A26 with arrows.

Furthermore, the display control function 145e can also display information regarding the amount of image movement in order to display a characteristic position in the WSS in a predetermined direction in a medical image showing a cross section of a blood vessel. As described above, the display control function 145e rotates and displays the short-axis cross-sectional image with the image center as the rotation axis so that the characteristic position is shown in a predetermined direction (e.g., downward) in the image. Thus, the display control function 145e can further display information regarding the amount of rotation as the above-mentioned amount of movement.

For example, the display control function 145e changes the display form of the frame of each display area according to the amount of rotation of each short-axis tomographic image displayed in the display areas A21 to A26 in FIG. 20. As one example, the display control function 145e changes the color of the outer frame of the display area A21 according to the amount of rotation of the short-axis tomographic image displayed in the display area A21. Similarly, the display control function 145e changes the color of the outer frame of the display areas A22 to A26 according to the amount of rotation of the other short-axis tomographic images. In addition, the display control function 145e can also display a numerical value indicating the amount of rotation in association with the display areas A21 to A26.

In the above example, a case has been described in which a short-axis cross-sectional image is displayed as a medical image showing a cross-section of a blood vessel, but the display control function 145e can also display a CPR image as a medical image showing a cross-section of a blood vessel. FIG. 21 is a diagram showing an example of a display control process according to the fourth embodiment. For example, as shown in FIG. 21, the display control function 145e displays a VR image of a coronary artery in the display area A1, and displays a CPR image of the coronary artery in the display area A3.

Here, the display control function 145e can display the characteristic position in the WSS in the CPR image in a predetermined direction in the medical image showing the cross section of the blood vessel, similar to the display of the short-axis cross-sectional image. For example, as shown in FIG. 21, the display control function 145e displays the characteristic position in the WSS on the left side of the CPR image of the coronary artery. That is, the image generation function 145d generates a CPR image in which the cross-sectional direction of the blood vessel is changed so that the characteristic position in the WSS is in a predetermined direction (for example, the left side) in the CPR image. Then, the display control function 145e displays the generated CPR image. The display control function 145e can display the CPR image as a color image colorized in a color according to the value of the WSS. The characteristic position to be displayed in the predetermined direction and the direction to be displayed are selected arbitrarily by the user.

In addition, the display control function 145e can display the positional correspondence between the images in a distinguishable manner, similar to the display of the short-axis cross-sectional images. For example, the display control function 145e displays the positional correspondence between the images by showing arrows on the VR image and the CPR image, as shown in FIG. 21.

Furthermore, the display control function 145e can display information regarding the amount of movement required for a characteristic position to be shown in a predetermined direction (e.g., the left side) in the image, similar to the display of a short-axis cross-sectional image. For example, the display control function 145e changes the display form of the frame of the display area A3 according to the amount of change in the cross-sectional direction of the blood vessel to generate the CPR image of FIG. 21. As an example, the display control function 145e changes the color of each vertical position of the outer frame of the display area A3 according to the amount of change in the cross-sectional direction at each position in the running direction of the blood vessel.

As described above, according to the fourth embodiment, the display control function 145e displays a characteristic position in the wall shear stress in a predetermined direction in a medical image showing a cross section of a blood vessel. Therefore, the medical image processing device 140 according to the fourth embodiment makes it possible to easily identify the state of continuity of the area of interest (characteristic position) of the user.

According to the fourth embodiment, the display control function 145e further displays information on the amount of movement of the position for displaying the characteristic position in the wall shear stress in a predetermined direction in the medical image showing the cross section of the blood vessel. Therefore, the medical image processing device 140 according to the fourth embodiment makes it possible to easily grasp the distribution state of the characteristic position. Here, as information on the amount of movement, an example was described in which the amount of rotation in the case of the short-axis cross section and the amount of change in the cross-sectional direction of the blood vessel in the case of the CPR image are treated as the amount of movement. The amount of movement may be any amount of movement for displaying the characteristic position on the original image in accordance with a predetermined direction, and is not limited to only the amount of rotation on the cross section of the short-axis image or the amount of change in the cross-sectional direction of the blood vessel. For example, when controlling to display the characteristic position in a way that is easy to view, that is, on the near side of the screen, by changing the observation angle in the volume rendering image or rotating a predetermined blood vessel part along the blood vessel axis, the amount of change in the observation angle or the amount of rotation of the blood vessel part along the blood vessel axis may be treated as the amount of movement.

Furthermore, according to the fourth embodiment, the display control function 145e displays a three-dimensional image of the blood vessel together with a medical image showing a cross section of the blood vessel, and identifiably displays positions on the three-dimensional image that correspond to characteristic positions in wall shear stress. Therefore, the medical image processing device 140 according to the fourth embodiment makes it possible to easily grasp the three-dimensional distribution state of characteristic positions.

Other Embodiments
In the above embodiment, an example of using a coronary artery CT image as a medical image related to the blood vessels of the heart has been described, but the embodiment is not limited to this. For example, any type of medical image may be used as long as it is a type of image from which the shape of the blood vessels and flow information such as the blood flow velocity can be calculated. For example, an ultrasound image obtained by an ultrasound diagnostic image or an MR image obtained by an MRI device may be used.

In addition, in the above-described embodiment, an example was described in which information about the WSS was displayed on the display 144 of the medical image processing device 140, but the embodiment is not limited to this. For example, information about the WSS may be displayed on the display of the medical information display device 130.

In the above-described embodiment, an example was described in which the extraction unit and display control unit in this specification are realized by the extraction function and display control function of a processing circuit, respectively, but the embodiment is not limited to this. For example, the extraction unit and display control unit in this specification may be realized by hardware only, software only, or a combination of hardware and software, in addition to being realized by the extraction function and display control function described in the embodiment.

The term "processor" used in the description of the above embodiment means, for example, a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), or a programmable logic device (for example, a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)). Here, instead of storing a program in a memory circuit, the program may be directly built into the processor circuit. In this case, the processor realizes its function by reading and executing the program built into the circuit. In addition, each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may be configured as a single processor by combining multiple independent circuits to realize its function.

Here, the program executed by the processor is provided in advance in a ROM (Read Only Memory) or a storage circuit. The program may be provided in a format that can be installed in these devices or in a format that can be executed, recorded on a non-transient storage medium that can be read by a computer, such as a CD (Compact Disk)-ROM, a FD (Flexible Disk), a CD-R (Recordable), or a DVD (Digital Versatile Disk). The program may also be provided or distributed by being stored on a computer connected to a network, such as the Internet, and downloaded via the network. For example, the program is composed of modules including each of the above-mentioned processing functions. In terms of actual hardware, the CPU reads and executes the program from a storage medium, such as a ROM, so that each module is loaded onto a main storage device and generated on the main storage device.

In addition, in the above-mentioned embodiment and modified examples, each component of each device shown in the figures is a functional concept, and does not necessarily have to be physically configured as shown in the figures. In other words, the specific form of distribution or integration of each device is not limited to that shown in the figures, and all or part of it can be functionally or physically distributed or integrated in any unit depending on various loads, usage conditions, etc. Furthermore, each processing function performed by each device can be realized in whole or in any part by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware using wired logic.

Furthermore, among the processes described in the above-mentioned embodiments and variations, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically using known methods. In addition, the information including the processing procedures, control procedures, specific names, various data, and parameters shown in the above documents and drawings can be changed as desired unless otherwise specified.

According to at least one of the embodiments described above, wall shear stress can be displayed in an easy-to-observe manner.

Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and spirit of the invention.

With regard to the above embodiment, the following notes are disclosed as one aspect and optional feature of the invention.

(Appendix 1)
an acquisition unit for acquiring a distribution of wall shear stress of a blood vessel;
an extraction unit that extracts a representative value or a vascular region from a distribution of wall shear stress in the blood vessel based on an extraction criterion determined for each region according to a shape or property of the blood vessel;
a display control unit that changes a display form of the wall shear stress in the blood vessel based on the representative value of the wall shear stress or the extraction result of a characteristic blood vessel region;
A medical image processing device comprising:
(Appendix 2)
the extraction unit extracts a relatively high wall shear stress value as a representative value for a region of the blood vessel that includes plaque, and extracts a relatively low wall shear stress value as a representative value for a region of the blood vessel that does not include plaque;
The display control unit may change a display form of the wall shear stress in the blood vessel so that the extracted representative value is displayed.
(Appendix 3)
The extraction unit may determine the presence or absence of plaque for each blood vessel branch in the blood vessel, and extract the representative value for each blood vessel branch.
(Appendix 4)
The extraction unit may determine the presence or absence of plaque for each region along a running direction of a blood vessel branch in the blood vessel, and extract the representative value for each region along a running direction of the blood vessel branch.
(Appendix 5)
The extraction unit may further determine a hardness of plaque in the blood vessel, and change the extraction criterion depending on the hardness of the plaque.
(Appendix 6)
The extraction unit extracts a blood vessel region having a curvature higher than a threshold value in the blood vessel,
The display control unit may change a display form of the wall shear stress in the blood vessel such that, for a blood vessel region in which the curvature is higher than a threshold value, the wall shear stress in a region on the inside of the bend is displayed.
(Appendix 7)
The extraction unit calculates a difference in wall shear stress calculated at a plurality of time points for the same position of the same blood vessel, and extracts a blood vessel region in which the calculated difference is higher than a threshold or a blood vessel region in which the calculated difference is lower than a threshold;
The display control unit may change a display form of the wall shear stress in the blood vessel so that the wall shear stress in the extracted blood vessel region is displayed.
(Appendix 8)
The extraction unit may further determine the presence or absence of inflammation in the myocardium to which blood is supplied by the blood vessel, and, if the myocardium has inflammation, change an extraction criterion for a region of the blood vessel that does not contain plaque.
(Appendix 9)
The extraction unit further extracts, for each position of the center line of the blood vessel, a maximum value, a minimum value, an average value, or a value having a largest difference from an adjacent value from values of wall shear stress in the blood vessel wall intersecting a cross section perpendicular to the center line;
The display control unit may further change the display form of the wall shear stress in the blood vessel so that the maximum value, minimum value, average value, or value with the largest difference from adjacent values extracted for each position of the center line of the blood vessel is displayed.
(Appendix 10)
The display control unit may further display the representative value or an extraction criterion used to extract the vascular region.
(Appendix 11)
The display control unit may display the extracted representative value or blood vessel region in an emphasized manner.
(Appendix 12)
The display control unit may emphasize the extracted representative value or blood vessel region by enlarging the representative value or blood vessel region.
(Appendix 13)
The display control unit may enlarge the multiple vascular regions into a single enlarged region when a distance between the multiple vascular regions to be enlarged is smaller than a threshold value.
(Appendix 14)
The display control unit may emphasize the extracted representative value or blood vessel region using a color, a texture, a pattern, or additional information.
(Appendix 15)
When displaying wall shear stress in multiple blood vessels that overlap in the line of sight, the display control unit may change the shape of the multiple blood vessels so that they do not overlap in the line of sight, and display the wall shear stress in each blood vessel.
(Appendix 16)
The display control unit may display the enlarged representative value or blood vessel region so as to be distinguished from the blood vessels.
(Appendix 17)
The display control unit may further display identification information for identifying the blood vessel region that is displayed in a differentiated manner.
(Appendix 18)
The display control unit may display, in parallel with the wall shear stress, a medical image showing a cross section of a corresponding blood vessel.
(Appendix 19)
The display control unit may display a medical image in which a cross section is changed according to a shape or a property of a blood vessel region to be displayed.
(Appendix 20)
The display control unit may display a curved planar reconstruction (CPR) image of a blood vessel region having plaque, the blood vessel being cut at a cross section at which the blood vessel diameter is shortest.
(Appendix 21)
The display control unit may display a multi planar reconstruction (MPR) image obtained by cutting a blood vessel region having a curvature higher than a threshold value along a cross section parallel to the curvature of the blood vessel.
(Appendix 22)
The display control unit may further display a graph indicating, for each position of a center line of the blood vessel, maximum and minimum values of wall shear stress in a blood vessel wall intersecting a cross section perpendicular to the center line.
(Appendix 23)
The display control unit may further display, on the graph, a distribution of values of wall shear stress in a vascular wall intersecting a cross section perpendicular to the center line.
(Appendix 24)
The display control unit may display a characteristic position in the wall shear stress in a predetermined direction in a medical image showing a cross section of a blood vessel.
(Appendix 25)
The display control unit may further display information regarding an amount of movement of the position for displaying a characteristic position in the wall shear stress in a predetermined direction in a medical image showing a cross section of the blood vessel.
(Appendix 26)
The display control unit may display a three-dimensional image of the blood vessel together with a medical image showing a cross-section of the blood vessel, and may display a position on the three-dimensional image corresponding to a characteristic position in the wall shear stress in an identifiable manner.
(Appendix 27)
an extraction unit that extracts a representative value or a vascular region based on a spatial distribution of wall shear stress in the blood vessel;
a display control unit that changes a display form of the wall shear stress in the blood vessel based on the representative value of the wall shear stress or an extraction result of the blood vessel region;
A medical image processing device comprising:
(Appendix 28)
A medical image processing system including a medical image processing device and a medical information display device,
The medical image processing device,
Obtain the distribution of wall shear stress in the blood vessel,
extracting a representative or characteristic vascular region from the distribution of wall shear stress in the blood vessel based on extraction criteria determined for each region according to the shape or properties of the blood vessel;
The medical information display device,
changing a display form of the wall shear stress in the blood vessel based on the representative value of the wall shear stress or the extraction result of the blood vessel region;
Medical image processing system.
(Appendix 29)
Obtain the distribution of wall shear stress in the blood vessel,
Extracting a representative value or a vascular region from the distribution of wall shear stress in the blood vessel based on extraction criteria determined for each region according to the shape or properties of the blood vessel;
changing a display form of the wall shear stress in the blood vessel based on the representative value of the wall shear stress or the extraction result of a characteristic blood vessel region;
A medical image processing method comprising:

100 Medical image processing system 130 Medical information display device 140 Medical image processing device 145 Processing circuit 145c Extraction function 145e Display control function

Claims (29)

an acquisition unit for acquiring a distribution of wall shear stress of a blood vessel;
an extracting unit that extracts a representative value from among a plurality of wall shear stress values in a blood vessel wall in a horizontal cross section about an axis of the center line for each position along the center line of the blood vessel;
a display control unit that changes a display form of the wall shear stress in the blood vessel in response to an operation by a user so that each representative value for each position along the center line of the blood vessel is displayed ;
A medical image processing device comprising: the extraction unit extracts, for a region including plaque at each position along the center line of the blood vessel, a relatively high wall shear stress value as a representative value from among a plurality of wall shear stress values in the blood vessel wall in a horizontal cross section about the center line, and extracts, for a region not including plaque at each position along the center line of the blood vessel, a relatively low wall shear stress value as a representative value from among a plurality of wall shear stress values in the blood vessel wall in a horizontal cross section about the center line;
The medical image processing apparatus according to claim 1 , wherein the display control unit changes a display form of the wall shear stress in the blood vessel so that the extracted representative value is displayed. The medical image processing device according to claim 2, wherein the extraction unit determines the presence or absence of plaque for each vascular branch in the blood vessel and extracts the representative value for each vascular branch. The medical image processing device according to claim 2, wherein the extraction unit determines the presence or absence of plaque for each region along the running direction of the vascular branch in the blood vessel, and extracts the representative value for each region along the running direction of the vascular branch. 5. The medical image processing apparatus according to claim 2, wherein the extraction unit further determines a hardness of plaque in the blood vessel, and changes an extraction criterion depending on the hardness of the plaque. The extraction unit extracts a blood vessel region having a curvature higher than a threshold value in the blood vessel,
The medical image processing device according to claim 1 , wherein the display control unit changes a display form of the wall shear stress in the blood vessel for a blood vessel region in which the curvature is higher than a threshold value so that the wall shear stress in a region inside the bend is displayed. The extraction unit calculates a difference in wall shear stress calculated at a plurality of time points for the same position of the same blood vessel, and extracts a blood vessel region in which the calculated difference is higher than a threshold or a blood vessel region in which the calculated difference is lower than a threshold;
The medical image processing apparatus according to claim 1 , wherein the display control unit changes a display form of the wall shear stress in the blood vessel so that the wall shear stress in the extracted blood vessel region is displayed. The medical image processing device according to claim 2, wherein the extraction unit further determines the presence or absence of inflammation in the myocardium to which blood is supplied by the blood vessel, and if the myocardium has inflammation, changes the extraction criteria for areas of the blood vessel that do not contain plaque. the extraction unit extracts , for each position along the center line of the blood vessel, a maximum value, a minimum value, an average value, or a value having a largest difference from an adjacent value from values of wall shear stress in the blood vessel wall in a horizontal cross section about the center line ;
The medical image processing device according to any one of claims 1 to 8, wherein the display control unit changes the display form of the wall shear stress in the blood vessel so as to display the maximum value, minimum value, average value, or the value with the largest difference from adjacent values extracted for each position along the center line of the blood vessel. 10. The medical image processing apparatus according to claim 1, wherein the display control unit further displays an extraction criterion used to extract the representative value . The medical image processing device according to any one of claims 1 to 10, wherein the display control unit displays the extracted representative value or vascular region in an emphasized manner. The medical image processing device according to claim 11, wherein the display control unit emphasizes the extracted representative value or blood vessel region by enlarging it. The medical image processing device according to claim 12, wherein the display control unit enlarges the multiple vascular regions in a single enlarged region when the distance between the multiple vascular regions to be enlarged is smaller than a threshold value. The medical image processing device according to claim 11, wherein the display control unit uses color, texture, pattern, or additional information to highlight the extracted representative value or vascular region. The medical image processing device according to any one of claims 1 to 14, wherein when the display control unit is to display the wall shear stress in multiple blood vessels that overlap in the line of sight, the display control unit changes the shapes of the multiple blood vessels so that they do not overlap in the line of sight, and displays the wall shear stress in each blood vessel. The medical image processing device according to claim 12 or 13, wherein the display control unit displays the enlarged representative value or vascular region separately from the blood vessels. The medical image processing device according to claim 16, wherein the display control unit further displays identification information for identifying the vascular regions that are displayed in a differentiated manner. The medical image processing device according to any one of claims 1 to 17, wherein the display control unit displays a medical image showing a cross section of the corresponding blood vessel in parallel with the wall shear stress. The medical image processing device according to claim 18, wherein the display control unit displays a medical image in which the cross section is changed according to the shape or characteristics of the vascular region to be displayed. The medical image processing device according to claim 19, wherein the display control unit displays a CPR (Curved Planar Reconstruction) image of a blood vessel region having plaque, the image being cut at a cross section where the blood vessel diameter is shortest. The medical image processing device according to claim 19, wherein the display control unit displays an MPR (Multi Planar Reconstruction) image cut at a cross section parallel to the curvature of the blood vessel for a blood vessel region having a curvature higher than a threshold value. The medical image processing device according to any one of claims 1 to 21, wherein the display control unit further displays a graph showing maximum and minimum values of wall shear stress in the vascular wall in a horizontal cross section centered on the center line, for each position along the center line of the blood vessel. The medical image processing apparatus according to claim 22 , wherein the display control unit further controls the graph to display a distribution of wall shear stress values in the vascular wall in a horizontal cross section with the center line as an axis . The medical image processing device according to claim 1, wherein the display control unit displays a characteristic position in the wall shear stress in a predetermined direction in a medical image showing a cross section of a blood vessel. The medical image processing device according to claim 24, wherein the display control unit further displays information regarding the amount of movement of the position for displaying a characteristic position in the wall shear stress in a predetermined direction in a medical image showing a cross section of the blood vessel. The medical image processing device according to claim 24, wherein the display control unit displays a three-dimensional image of the blood vessel together with a medical image showing a cross section of the blood vessel, and identifiably displays positions on the three-dimensional image corresponding to characteristic positions in the wall shear stress. an extracting unit that extracts, for each position along a center line of a blood vessel, a representative value from among a plurality of wall shear stress values in a blood vessel wall in a horizontal cross section about an axis of the center line;
a display control unit that changes a display form of the wall shear stress in the blood vessel in response to an operation by a user so that each representative value for each position along the center line of the blood vessel is displayed ;
A medical image processing device comprising: A medical image processing system including a medical image processing device and a medical information display device,
The medical image processing device,
Obtain the distribution of wall shear stress in the blood vessel,
extracting a representative value from among a plurality of wall shear stress values in the blood vessel wall in a horizontal cross section about the center line for each position along the center line of the blood vessel;
The medical information display device,
changing a display form of the wall shear stress in the blood vessel in response to an operation by a user so that each representative value for each position along the center line of the blood vessel is displayed ;
Medical image processing system. Obtain the distribution of wall shear stress in the blood vessel,
extracting a representative value from among a plurality of wall shear stress values in the blood vessel wall in a horizontal cross section about the center line for each position along the center line of the blood vessel;
changing a display form of the wall shear stress in the blood vessel in response to an operation by a user so that each representative value for each position along the center line of the blood vessel is displayed ;
A medical image processing method comprising:

Images