122 performs pattern extraction processing on the X-ray image so as to specify the image of the guide wire. The intravascular pressure measurement position specifying unit 122, for example, performs pixel value threshold processing, spatial filtering processing, or the like. Then, the intravascular pressure measurement position specifying unit 122 extracts the image of the guide wire from the X-ray image, obtains a two-dimensional curve indicating a shape of the image of the guide wire on the X-ray image, and extracts coordinates of the front end of the guide wire located at an end portion of the two-dimensional curve based on coordinate values of respective points on the two-dimensional curve.

The display controller 130 displays an acquisition position on the blood vessel-containing image and displays the indicator on the display unit in association with the acquisition position. The display controller 130, for example, displays the measurement position on the X-ray image and displays the FFR and the CFR thereon in association with the measurement position. First, a one cardiac cycle contrast image group extracting unit 141 of a cycle image processor 140 extracts a contrast image group (still image group) for one cardiac cycle on which the coronary artery overall is contrast-imaged preferably from the time-series X-ray image group stored in the X-ray image storage unit 22, as illustrated in FIG. 4. It is noted that the one cardiac cycle contrast image group extracting unit 141, for example, compares brightness value distributions of the respective X-ray images and determines an X-ray image group having low brightness value to be the contrast image group on which the coronary artery is contrast-imaged preferably.

As illustrated in FIG. 4, a coronary tree specifying unit 142 extracts a coronary artery region from each contrast image of the contrast image group extracted by the one cardiac cycle contrast image group extracting unit 141 so as to specify a coronary tree. The coronary tree specifying unit 142, for example, extracts the coronary artery region from each contrast image based on acquiring conditions such as the angle of the C arm 13, brightness values of pixels, continuity thereof, a vascular shape, and a change amount between the contrast images at adjacent time phases so as to specify the coronary tree. It is noted that the coronary tree is capable of being specified by an existing known technique.

A stenosis site specifying unit 143 specifies a stenosis site in the coronary artery region extracted by the coronary tree specifying unit 142. The stenosis site specifying unit 143, for example, specifies the stenosis site based on continuity of a vascular structure, in particular, change in the vascular diameter. It is noted that the stenosis site is capable of being specified by an existing known technique.

An inter-time-phase coronary tree/stenosis site mapping unit 144 relates the stenosis sites specified on the respective contrast images of the contrast image group for one cardiac cycle among different time phases. This makes it possible to track the time-series displacement of the stenosis site on the X-ray images. The inter-time-phase coronary tree/stenosis site mapping unit 144, for example, calculates a WarpField among the contrast images. The WarpField is a known image processing technique of performing non-linear positioning. The inter-time-phase coronary tree/stenosis site mapping unit 144, for example, extracts characteristic amounts from the respective contrast images and relates the extract characteristics among the different time phases so as to calculate a set of three-dimensional vectors indicating movement amounts of pixels.

As illustrated in FIG. 4, a measurement data/stenosis site mapping unit 145 relates the measurement data to the stenosis site specified on the contrast image (cycle image) based on the measurement position specified on the X-ray image (measurement time image) by the intravascular pressure measurement position specifying unit 122. The measurement data/stenosis site mapping unit 145, for example, specifies a contrast image (cycle image) of which time phase is identical to that of the measurement time image in the contrast image group for one cardiac cycle by using the ECG. Then, the measurement data/stenosis site mapping unit 145 relates the FFR and the CFR that are calculated from the measurement data measured at the measurement position to and the stenosis site on the contrast image (cycle image) that is closer to the measurement position based on the measurement position specified on the X-ray image (measurement time image). This makes it possible to display the FFR and the CFR on each of the X-ray images contained in the time-series X-ray image group.

On the other hand, a cardiac cycle corresponding image specifying unit 151 of a display image processor 150 specifies a time phase on one cardiac cycle to which a display image selected by a display image selector 116 corresponds by using the ECG. It is sufficient that the display image selector 116 receives a direction from the operator through the input unit 21 so as to appropriately select a display image from the time-series X-ray image group stored in the X-ray image storage unit 22, for example. In the first embodiment, the display image selector 116, for example, displays a selection menu (for example, “patient list” and “test list”) of the X-ray images stored in the X-ray image storage unit 22, receives a direction from the operator through the input unit 21, and selects a single contrast image (still image) as the display image.

A coronary tree specifying unit 152 extracts a coronary artery region from the contrast image at the time phase specified by the cardiac cycle corresponding image specifying unit 151 in the contrast image group extracted by the one cardiac cycle contrast image group extracting unit 141 with the same method as that by the coronary tree specifying unit 142 so as to specify a coronary tree. A stenosis site specifying unit 153 specifies a stenosis site in the coronary artery region extracted by the coronary tree specifying unit 152 with the same method as that by the stenosis site specifying unit 143.

As illustrated in FIG. 4, a display image mapping unit 154 relates the measurement position specified on the contrast image (cycle image) to the display image. The display image mapping unit 154, for example, specifies (positions) a position at a time phase of the display image to which the measurement position specified on the contrast image (cycle image) is moved with a three-dimensional vector by using the WarpField calculated by the inter-time-phase coronary tree/stenosis site mapping unit 144. Then, the display image mapping unit 154 specifies a plurality of measurement positions specified on the contrast images at different time phases on one display image. That is to say, the display image mapping unit 154 specifies positions at the time phase of the display image to which the respective measurement positions are moved by using the WarpField. This corrects deviation between a single contrast image selected as the display image and the respective contrast images on which the respective measurement positions are specified.

A display image generator 155 generates the display image and displays it on the display unit 16. FIG. 5 is a view illustrating a display example in the first embodiment. As illustrated in FIG. 5, in the first embodiment, the display image generator 155 displays the measurement positions of the pieces of measurement data on an X-ray image (still image) at a predetermined time phase. In addition, the display image generator 155 displays the physiological evaluation indicators (for example, FFR and CFR) calculated from the pieces of measurement data in association with the measurement positions. Furthermore, the display image generator 155 displays a stenosis rate in association with each stenosis site so as to display an anatomical evaluation indicator and the physiological evaluation indicators on the same X-ray image. As illustrated in FIG. 5, the display image generator 155 displays information (for example, treatment unnecessary and treatment necessary) relating to necessity of treatment. Marks (in FIG. 5, outlined circles) indicating the stenosis sites may be displayed in different colors in accordance with the necessity of treatment, the stenosis rate, and the like, for example. Furthermore, character strings and frames surrounding the character strings may be displayed in different colors in accordance with the necessity of treatment and values of the FFR and the CFR, for example. For example, they may be displayed in “red” when an attention should be paid.

A treatment necessity reference setting unit 117 sets a reference for determining necessity of treatment. The treatment necessity reference setting unit 117, for example, sets a reference that “when any of conditions: FFR<0.75; CFR≤2.00; and stenosis rate≥50% is satisfied, it is determined to be “treatment necessary””. A treatment necessity determination unit 118 determines the necessity of treatment based on the reference set by the treatment necessity reference setting unit 117. It is noted that a determination result by the treatment necessity determination unit 118 is transmitted to the display image generator 155.

FIG. 6 is a view illustrating another display example in the first embodiment. As illustrated in FIG. 6, in the first embodiment, the display image generator 155 may not only display various types of indicators (display of the various types of indicators are not illustrated in FIG. 6) around the stenosis sites but also display the blood vessels themselves while varying the colors and the densities in accordance with the measurement values of the intravascular pressure and the like. In FIG. 6, the blood vessels themselves are displayed while varying the color density for the convenience. Alternatively, the blood vessels may be displayed while varying densities of “red” and “yellow” or the like in accordance with the measurement values, for example.

FIG. 7 is a view illustrating still another display example in the first embodiment. As illustrated in FIG. 7, in the first embodiment, the display image generator 155 may display a tool for adjusting a result of automatic processing manually. That is to say, as described above, although the stenosis sites, the measurement positions of the pieces of measurement data, and the like are specified on the X-ray image automatically to be displayed in the first embodiment, there is a risk that an expected result is not necessarily displayed. For the purpose of coping with the case, the display image generator 155 displays a user interface (UI) as illustrated in FIG. 7. The UI, for example, extracts a vascular core line from the coronary tree specified by the coronary tree specifying unit 142 and displays the extracted vascular core line. The display image generator 155 receives slide operations of a bar “a” indicating the measurement position and a mark “b” indicating the stenosis site on the vascular core line. That is to say, the measurement positions and the stenosis sites should be present on the vascular core line (deviation from the core line in the vascular diameter is neglected), so that the display image generator 155 may provide a UI slidable on the vascular core line only.

As described above, according to the first embodiment, the measurement positions of the pieces of measurement data are displayed on the vascular image, so that the measurement positions of the physiological indicators can be grasped on the vascular image. Thus, according to the first embodiment, a result of the physiological evaluation and a result of the anatomical evaluation are related to be displayed. As a result, the operator is capable of grasping the position of the coronary artery at which the physiological evaluation indicators are obtained easily, for example. It is effective not only in the case of normal lesion but also in the cases of continuous lesion and multivessel lesion.

In this manner, according to the first embodiment, physiological evaluation indicators linked with a stenosis position on an X-ray image that is acquired in real time during percutaneous coronary intervention (PCI) and past images stored in a workstation or the like can be displayed. Furthermore, an intravascular pressure and a value of the blood flow velocity that are measured for calculating the physiological evaluation indicators can be also displayed at the measured position. As a result, inducibility of myocardial ischemia by the coronary artery stenosis can be evaluated from both of anatomical and physiological perspectives on a single image, and a procedure can be performed while displaying the necessity of treatment and a treatment state during the PCI. Furthermore, when physiological evaluation values are displayed on a past test image, the past state can be compared with the present state quantitatively physiologically.

Second Embodiment

In a second embodiment, a time-series X-ray image group (moving image) acquired in real time is supposed as display images. FIG. 8 is a view for explaining generation of the display images in the second embodiment. In this case, the display controller 130 makes temporal synchronization between the contrast image (cycle image) group and the display image group by using the ECG and displays stenosis sites specified on the contrast images (cycle images) and indicators such as the FFR and the CFR on right positions on the display images.

To be specific, the cardiac cycle corresponding image specifying unit 151 of the display image processor 150 specifies time phases in one cardiac cycle to which respective display images contained in the time-series display image groups correspond by using the ECG. Furthermore, as illustrated in FIG. 8, the display image mapping unit 154 relates the measurement positions specified on the contrast images (cycle images) to the respective display images contained in the time-series display image groups. The display image mapping unit 154, for example, specifies (positions) positions at time phases of the respective display images to which the measurement positions specified on the contrast images (cycle images) are moved with three-dimensional vectors by using the WarpField calculated by the inter-time-phase coronary tree/stenosis site mapping unit 144. Then, the display image mapping unit 154 specifies a plurality of measurement positions specified on the contrast images at different time phases on the respective display images. When the display images are displayed sequentially while measuring the pieces of measurement data, it is sufficient that the display controller 130 displays one measurement position on the display images first, and displays two measurement positions, and three measurement positions thereon sequentially.

Third Embodiment

In a third embodiment, a time-series X-ray image group (moving image) acquired in real time that is non-contrast images is supposed as display images. FIG. 9 is a view for explaining generation of the display images in the third embodiment. In this case, the display images are the non-contrast images, so that the vascular structure of the coronary artery is not displayed on the display images. The display controller 130 extracts pieces of structural information such as vascular contours from the contrast image (cycle image) group and displays the extracted pieces of structural information so as to be superimposed on the display image group that is the non-contrast images. The display controller 130 makes temporal synchronization between the contrast image (cycle image) group and the display image group by using the ECG so as to also make temporal synchronization between the structural information and the display images. With this, displacement and deformation of blood vessels are also reflected onto the structural information.

FIG. 10 is a view illustrating a display example in the third embodiment. As illustrated in FIG. 10, in the third embodiment, the display controller 130 displays physiological evaluation indicators, stenosis rates, necessity of treatment, and the like on each non-contrast display image on which the structural information such as the vascular contour is displayed in the superimposed manner in association with the measurement positions of the pieces of measurement data.

FIG. 11 is a view illustrating another display example in the third embodiment. As illustrated in FIG. 11, in the third embodiment, the display controller 130 may not only display various types of indicators (display of the various types of indicators are not illustrated in FIG. 11) around the stenosis sites but also display the blood vessels themselves while varying the colors and the densities in real time in accordance with the measurement values of the intravascular pressure and the like on each non-contrast display image.

Described is one use case of the X-ray diagnostic apparatus 100 serving as the medical image diagnostic apparatus according to the present application. As described above, various indicators are used as indicators relating to the blood flow. These indicators are used for detecting a vascular stenosis portion on a myocardial site that is cause of myocardial infarction early, for example. As an example, the presence or absence of the vascular stenosis portion is determined based on evaluation of lowering of the blood flow rate due to the stenosis site. When the value of the FFR (hereinafter, referred to as FFR value) is equal to or lower than the reference value, the position is determined to be a stenosis portion.

Conventionally, the presence or absence of the vascular stenosis portion has been determined as follows. That is, an operator operates a pressure sensor-equipped guide wire while checking a display displaying in real time an X-ray image (for example, X-ray fluoroscopic image) relating to a subject into whose blood vessel that is collected by the X-ray diagnostic apparatus the guide wire is inserted, and concurrently checks a display displaying an FFR value calculated from a pressure value of the subject that is measured by the pressure sensor. In this case, the FFR value and a vascular portion on which pressure that is used for calculation of the FFR value is measured are not related to each other. For this reason, even when the operator determines that the measured position is the stenosis portion based on the FFR value, it is difficult to grasp the position of the stenosis portion on the blood vessel instinctively.

For the purpose of solving this, the technique according to the present application is applied to the case so as to improve spatial visibility of an indicator effective for diagnosis of vascular stenosis. Hereinafter, described is the X-ray diagnostic apparatus 100 according to the use case with reference to FIG. 12 to FIG. 26. Note that the indicator effective for the diagnosis of the vascular stenosis is an indicator indicating the blood flow rate. Description herein is made by using the FFR value as a specific example of the indicator. The FFR value is given as a ratio of a pressure at a given point in a blood vessel that is a diagnosis target relative to a pressure (pressure of blood flow) at a point in an aorta. The pressure is measured by a pressure sensor 210a attached to the vicinity of the front end of the guide wire. In the use case, the guide wire is inserted into the blood vessel while checking a non-contrast fluoroscopic image. The fluoroscopic image is collected repeatedly at a constant cycle such as 1/30 sec while X rays are emitted intermittently under fluoroscopic X-ray conditions (relatively low dose). An X-ray image that is triggered by the operator to be acquired with pulse X rays under acquiring X-ray conditions (relatively high dose) under the fluoroscopic control is referred to as an acquisition image. The acquisition image that is collected while emphasizing blood vessels with a contrast material is the contrast image as described above. For example, the contrast image includes a digital angiography image (DA image) and a digital subtraction angiography (DSA) image obtained by taking a difference between DA images before and after injection of the contrast material and clarifying the blood vessels further.

As illustrated in FIG. 12, an X-ray diagnostic apparatus 100a includes a mount unit 10a and a calculator system 20a. As illustrated in FIG. 13, the mount unit 10a includes a C arm 13a that is supported by a mount 12a. In addition, the mount unit 10a includes a C arm controller 25a, an X-ray source 14a, an X-ray detector 15a, and a high-voltage generator 17a. The mount unit 10a is also referred to as a gantry portion. The calculator system 20a is also referred to as a system main body. Furthermore, the mount 12a is also referred to as a C-shaped arm supporting mechanism. The C arm 13a is also referred to as a C-shaped arm. The C arm controller 25a is also referred to as a rotation driving unit. The X-ray source 14a is also referred to as an X-ray tube device. The X-ray detector 15a is also referred to as an X-ray detecting unit.

The calculator system 20a includes an input unit 21a, a controller 23a, an X-ray image acquiring unit 24a, an X-ray image generator 26a, and an image processing apparatus 30. The input unit 21a is also referred to as an operation unit. The controller 23a is also referred to as a system controller. The X-ray image acquiring unit 24a is also referred to as an acquiring controller. The X-ray image generator 26a is also referred to as an image generator. The image processing apparatus 30 includes an X-ray image storage unit 22a, an FFR value storage unit 111a, an FFR value input unit 110a, an image processing controller 31, a position specifying unit 120a, an FFR value selector 32, a mark generator 33, a display controller 130a, and a display unit 16a. Furthermore, an external FFR value measuring device 200a is connected to the calculator system 20a through the FFR value input unit 110a.

The FFR value storage unit 111a is an example of the above-mentioned physiological indicator storage unit 111. The FFR value input unit 110a is an example of the above-mentioned physiological indicator receiver 110. The position specifying unit 120a is an example of the above-mentioned specifying unit 120.

The controller 23a controls operations of the apparatus overall, for example, an acquiring operation and an image processing operation collectively. The X-ray image acquiring unit 24a controls the high-voltage generator 17a, the X-ray detector 15a, the X-ray image generator 26a, and the C arm controller 25a in order to execute an acquiring operation in accordance with a direction from an operator that is input through the input unit 21a.

The input unit 21a functions as a man-machine interface when the operator inputs a direction to the X-ray diagnostic apparatus 100a. For example, the input unit 21a includes a track ball, various types of switches, buttons, a mouse, a keyboard, a foot pedal, a touch panel, and the like in order to load various types of directions, conditions, a setting direction of a region of interest (ROI), various image quality conditions, an acquiring (fluoroscopic) condition setting direction, and the like from the operator on the apparatus main body. Furthermore, the input unit 21a may include a wireless receiver and a wireless processor in order to enable the operator to operate from remote places.

The mount 12a supports the C arm 13a in a rotatable manner so as to be independent with respect to perpendicular three axes. The C arm controller 25a generates a driving force for rotating the C arm 13a based on the control of the X-ray image acquiring unit 24a. The C arm 13a is mounted with the X-ray source 14a on one end thereof. The X-ray source 14a is constituted by an X-ray tube and an X-ray diaphragm. The X-ray tube generates X rays when receiving application of a high voltage from the high-voltage generator 17a. The X-ray diaphragm is attached to an X-ray emission window of the X-ray tube and limits an X-ray emission field. The C arm 13a is mounted with the X-ray detector 15a on the other end thereof. The X-ray detector 15a is attached so as to be opposed to the X-ray source 14a. The X-ray detector 15a is a two-dimensional detector for detecting X rays that transmit through the subject. The X-ray detector 15a is a flat panel detector (FPD) or the like typically.

The X-ray image generator 26a generates two-dimensional spatial distribution relating to intensity of transmitted X rays, that is, a two dimensional X-ray image based on the output from the X-ray detector 15a. The image processing controller 31 receives a control signal from the controller 23a and controls constituent components relating to the image processing operation of the X-ray diagnostic apparatus 100a, in particular. The X-ray image storage unit 22a stores therein the X-ray image generated by the X-ray image generator 26a. The X-ray image generator 26a, for example, stores therein fluoroscopic image data and contrast image (for example, DA image) data. Hereinafter, description is made by using the DA image as an example of the contrast image. Each of the fluoroscopic image data and the DA image data is stored in association with an X-ray generation time code corresponding to the data and a cardiac phase code at the time of generation of the X rays. Then, the operator selects, as a reference image, a specific DA image from a plurality of DA images stored in the X-ray image storage unit 22a.

The position specifying unit 120a selects, as a processing target, a live image at a cardiac phase same as a cardiac phase (reference phase) of the subject at the time of acquiring of the reference image, and specifies a sensor position on the reference image (DA image) from a sensor position on the selected live image. A front end region of the guide wire at the present time is expressed on the live image with a characteristic brightness. First, the position specifying unit 120a extracts the front end region of the guide wire on the live image by the threshold processing. Then, the position specifying unit 120a specifies a front end position of the guide wire based on the shape characteristic and the movement direction of the extracted front end region. Furthermore, the position specifying unit 120a shifts the position to the rear side from the front end position of the guide wire by a distance unique to the guide wire, that is, a distance L (see, FIG. 26) from the front end position of the guide wire to an attachment position of the pressure sensor 210a of the guide wire so as to specify the sensor position on the live image.

Next, the position specifying unit 120a specifies the sensor position on the reference image that corresponds to the sensor position on the live image of the present frame. First, the position specifying unit 120a calculates the direction and the distance of the sensor position specified on the live image of the present frame with respect to a sensor position specified on a live image of the last frame. Then, the position specifying unit 120a displaces the last sensor position on the reference image in the calculated direction by the calculated distance by using the calculated direction and distance. With this, the position specifying unit 120a specifies the sensor position on the reference image that corresponds to the sensor position on the live image of the present frame. An initial sensor position on the reference image is set by being specified by the operator on the reference image. Second and subsequent sensor positions on the reference image are specified from the last sensor positions on the reference image in accordance with the displacement (direction and distance) of the sensor positions on the live images. The specification is repeated sequentially so as to identify a movement locus of the sensor position on the reference image.

The FFR value input unit 110a functions as an interface with the external FFR value measuring device 200a. The FFR value measuring device 200a measures an FFR value (myocardial portion fractional flow reserve) as an indicator indicating the blood flow rate. The degree of necessity of treatment is classified into three sections of “treatment necessary”, “necessity judgment necessary”, and “treatment unnecessary” in accordance with the degree of the FFR value. The FFR value measuring device 200a is constituted by the pressure sensor 210a and an FFR value calculator 211a. The FFR value is calculated based on a ratio of a pressure measurement value at each intravascular position relative to an aortic pressure serving as a reference. The pressure sensor 210a attached to the guide wire measures the pressure measurement value at each intravascular position. The FFR value calculator 211a calculates the FFR value by dividing the pressure measurement value at each intravascular position that is measured by the pressure sensor 210a by the aortic pressure measurement value that is measured by the pressure sensor 210a. Data of the FFR value is output in association with a code indicating a measurement time of the pressure measurement value at each intravascular position by the pressure sensor 210a.

The FFR value storage unit 111a stores therein pieces of data of a plurality of FFR values that are input through the FFR value input unit 110a. The pieces of data of the plurality of FFR values are related to the codes each of which indicates the measurement time of the pressure measurement value at each intravascular position by the pressure sensor 210a. The FFR value selector 32 selects an FFR value at the time same as a rising timing of the reference phase or the closest time thereto with reference to the measurement time code.

The mark generator 33 determines a mark having a color corresponding to the FFR value selected by the FFR value selector 32. The mark has a substantially rectangular shape having a width in accordance with a standard vascular diameter of a target blood vessel. The display controller 130a superimposes the mark generated by the mark generator 33 on the reference image stored in the X-ray image storage unit 22a cumulatively. The display unit 16a displays the reference image on which mark is superimposed cumulatively that is generated by the display controller 130a.

FIG. 14 is a view illustrating fluoroscopy procedures in the embodiment together with procedures of insertion of the guide wire and injection of a contrast material.

The schematic order of a series of operations according to the embodiment is as follows. (1) A vascular moving image is collected in a state in which the contrast material is injected through the catheter inserted into the blood vessel of the subject. The digital angiography (DA) is typically used as the X-ray acquiring technique in this case. (2) A frame on which an FFR target region of the subject is contrast-imaged most preferably among the DA images collected repeatedly in the procedure (1) is displayed on a reference monitor as a still image (reference image). (3) An FFR measurement target region is specified on the reference image in accordance with a direction from the operator. (4) The pressure sensor-equipped guide wire is inserted into a target site in the FFR measurement target region. (5) The measurement of the pressure (FFR value) is repeated through the pressure sensor while drawing the guide wire out. (6) The measured FFR values are color-coded in accordance with thresholds so as to be displayed on the reference image in the superimposed manner.

In a draw-out duration in the above-mentioned procedure (5), the FFR value measuring device 200a measures the FFR value repeatedly. Normally, the measurement cycle of the FFR value is a cycle shorter than a frame cycle in the X-ray fluoroscopy. Note that the placement duration and the draw-out duration may be continuous or may be separated temporally with interruption of the X-ray fluoroscopy.

FIG. 15 is a flowchart illustrating procedures from insertion of the catheter to completion of acquiring of the DA images. First, the mount unit 10a is moved to a position at which a desired vascular region of the subject can be observed with a direction from the operator through the input unit 21a and the X-ray fluoroscopic condition and the image collection condition are determined. Next, an X-ray fluoroscopic operation is started and a fluoroscopic image is collected under control of the controller 23a if the operator operates the mouse or the button as the input unit 21a (S11). As the X-ray fluoroscopic condition, an X-ray dose is lower than that of the X-ray acquiring for collecting a mask image and a contrast image, for example. The fluoroscopic image is displayed on the display unit 16a immediately.

The operator inserts the catheter to a target position under the X-ray fluoroscopy (S12). Next, a DA acquiring technique is selected and the DA acquiring is executed. In this case, a contrast material is injected through an injector synchronized with the X-ray diagnostic apparatus 100a, a contrast image is collected repeatedly, and a region on which the FFR should be measured is specified (S13). The DA image is obtained by high-dose pulse X rays, so that collection of the DA image is repeated several times at given timings normally. The data of each DA image is stored in the X-ray image storage unit 22a in association with a code indicating a DA image acquiring time and data of a cardiac phase of the subject at the time of the acquiring. It is noted that the data of the cardiac phase is supplied from an external electrocardiograph (not illustrated) connected to the X-ray diagnostic apparatus 100a.

A plurality of DA images are displayed as a list on the display unit 16a under control of the display controller 130a and one given DA image preferable for diagnosis of stenosis is selected as a reference image in accordance with a direction from the operator (S14). As illustrated in FIG. 16, description is made while the cardiac phase to which the reference image corresponds is assumed to be “AA%”. The reference image may be selected based on the operator's standard. For example, an image having small noise or an image on which vascular region is located at the center may be selected. Alternatively, the X-ray diagnostic apparatus 100a may have a function of calculating brightness, noise and the like of an image and may select the reference image automatically.

Next, the operator operates the pressure sensor-equipped guide wire so as to move the pressure sensor 210a attached to the front end of the guide wire to a target position (position determined by the operator on the DA image) in the blood vessel and place it.

The operator operates the mouse on the reference image displayed on the display unit 16a in an enlarged manner so as to specify a position (initial position) of the pressure sensor 210a and the sensor initial position on the reference image is registered (S15). Data of the registered initial sensor position is stored in the X-ray image storage unit 22a together with data of the reference image. It is sufficient that the X-ray diagnostic apparatus 100a stores the registration position as coordinates based on a given point on the image or the reference image. The registration position may or may not be displayed on the reference image.

FIG. 17 is a flowchart illustrating processing procedures in the draw-out duration of the guide wire in FIG. 14. The X-ray fluoroscopy is also executed by the controller 23a in the draw-out duration subsequent to the insertion duration (S31). With the execution of the X-ray fluoroscopy, a fluoroscopic image (live image) is generated repeatedly at a constant cycle. Each piece of data of the live image is stored in the X-ray image storage unit 22a in association with a code indicating the image generation time and data of the cardiac phase of the subject at the time of the image generation. In the draw-out duration, the pressure sensor 210a is moved in accordance with the draw-out operation of the guide wire from the placement position serving as a base point. The guide wire is drawn out gradually with the operation by the operator while the FFR value measuring device 200a measures the FFR value repeatedly in accordance with the output from the pressure sensor 210a (S32). The data of the FFR value is stored in the FFR value storage unit 111a in association with a code indicating the measurement time and data of the cardiac phase of the subject at the time of the measurement.

In the process at S33, the image processing controller 31 determines whether the cardiac phase is identical to the cardiac phase (AA%) of the reference image or in a range of ±5% of the cardiac phase (AA%) every time the live image is generated. Description is made by using the former case herein. The image processing controller 31 loads data of the live image generated at a timing identical to the cardiac phase (AA%) of the reference image from the X-ray image storage unit 22a and supplies it to the position specifying unit 120a. The position specifying unit 120a extracts the front end region of the guide wire from the supplied live image by the threshold processing (S34). The sensor position is specified from the extracted front end region (S35). The pressure sensor 210a is attached to a position distanced to the rear side from the front end of the guide wire by the distance L unique to the guide wire. For example, the sensor position is specified by correcting the above-mentioned distance L along the center axis of the guide wire from the extracted front end region of the guide wire.

As illustrated in FIG. 18 and FIG. 19, the position specifying unit 120a calculates the direction and the distance of a sensor position An specified on a live image PIn at this cardiac phase (AA%) with respect to a sensor position An-1 specified on a live image PIn-1 at the last cardiac phase (AA%) (S36).

Next, a sensor position on the reference image at this time is specified based on the calculated direction and the calculated distance and the last sensor position on the reference image (S37). That is to say, as illustrated in FIG. 20, a position after displacing a last sensor position Bn-1 on the reference image in accordance with the calculated direction and the calculated distance is specified as a present sensor position Bn on the reference image. It is noted that an initial sensor position B1 on the reference image is specified by the operator manually.

Thus, the sensor position on the reference image is specified from the sensor position on the reference image that has been specified at the last time based on the direction and the distance calculated from the last and present sensor positions specified on the live images continuously. This makes it possible to suppress expansion of deviation between the sensor position on the reference image and the sensor position on the live image. Main reasons of generation of the deviation include body motion of the subject itself due to temporal separation between acquiring of the reference image and generation of the live image and change of an anatomical position on the same site due to fluctuation of the cardiac cycle even at the same cardiac phase.

Next, a mark having a color in accordance with the FFR value measured at the time identical to the generation time of the live image processed at this time or the time closest thereto is superimposed on the sensor position specified at S37 on the reference image (S38). The FFR value is a value that is calculated based on a ratio of the pressure measurement value and the aortic pressure value. That is, the FFR value is given as a value from 0 to 1 normally. The FFR values from 0 to 1 are divided into a plurality of sections and a color phase is assigned to each section previously.

The processes at S31 to S38 are repeated through a process at S39 until the fluoroscopy is completed. The marks generated in sequence during the processes are superimposed on the reference image cumulatively.

FIG. 21 illustrates a time chart indicating repeat of the processes at S31 to S38. A reference image DAref is displayed steadily in the draw-out duration and marks M1, M2, M3 . . . with colors in accordance with FFR values k1, k2, k3 . . . at the same phase AA% are superimposed on respective sensor positions B1, B2, B3 . . . cumulatively on the reference image DAref in accordance with the repeat of the cardiac cycle. As illustrated in FIG. 22, the reference image is displayed on the same screen together with the fluoroscopic image (live image) and the time chart of the FFR value.

As described above, with the use case, measurement positions of the indicator such as the FFR value effective for diagnosis of the vascular stenosis are capable of being checked on the reference image. This improves special visibility of the FFR value so as to enhance usability. That is to say, according to the embodiment, on the X-ray image relating to the subject into which the guide wire including the pressure sensor 210a is inserted, the FFR values can be displayed as marks on vascular sites at which pressures to be used for calculation of the FFR values are measured in the superimposed manner. This makes it possible to check the FFR values on the blood vessel instinctively, thereby expecting improvement of measurement accuracy of vascular stenosis portions by the operator. Furthermore, in the embodiment, the sensor position on the reference image is specified from the sensor position on the reference image that has been specified at the last time in accordance with the direction and the distance calculated from the last and present sensor positions specified on the live images continuously. This makes it possible to suppress expansion of deviation between the sensor position on the live image that is the actual FFR measurement position and the sensor position on the reference image that is displayed.

A display mode of the FFR value on the reference image can be varied variously. For example, as illustrated in FIG. 23, when the operator operates the input unit 21a in a specific manner at a given timing during the measurement of the FFR value, a numerical value of the FFR value at that time may be displayed with a balloon at the sensor position on the reference image at that time. As illustrated in FIG. 24, a target on which the mark is to be displayed in a superimposed manner may be made to be capable of being switched from the reference image to the live image (fluoroscopic image). In addition, as illustrated in FIG. 25, a numerical value of the FFR value may be made to be capable of being switched from the reference image to the live image (fluoroscopic image) so as to be displayed in the superimposed manner.

Although the fluoroscopic image is collected repeatedly at a constant cycle such as 1/30 sec while X rays are emitted intermittently in the above-mentioned embodiments, the embodiment is not limited thereto. The fluoroscopic image may be collected while the X rays are emitted at a constant time interval. In such a case, while the operator operates to draw out the guide wire gradually, the fluoroscopic image is collected at a constant time interval. Then, the display controller 130a displays marks at sensor positions at which fluoroscopic images are collected on the reference image or the fluoroscopic images. The FFR value measuring device 200a may execute measurement of the FFR value repeatedly in accordance with the output of the pressure sensor 210a or may execute at a timing of the fluoroscopic image. This makes possible to reduce an exposure dosage of the subject.

Fourth Embodiment

In a fourth embodiment, a treatment state is further displayed. FIG. 27 is a block diagram illustrating a configuration of an X-ray diagnostic apparatus 100 according to the fourth embodiment. As illustrated in FIG. 27, the X-ray diagnostic apparatus 100 according to the fourth embodiment further includes respective parts for displaying and updating a treatment state in real time.

A guide wire front end position tracking unit 161 specifies a front end position of the guide wire in real time in an X-ray image acquired in real time. The front end position of the guide wire is capable of being specified by using an existing known technique as in the intravascular pressure measurement position specifying unit 122.

A stenosis site stent detector 162 extracts a treating tool for the stenosis site, such as a stent and a balloon, in the X-ray image. The stenosis site stent detector 162, for example, performs image analysis based on the front end position of the guide wire that is specified by the guide wire front end position tracking unit 161 so as to extract the treating tool. The treating tool is capable of being extracted by using an existing known technique as in the intravascular pressure measurement position specifying unit 122. Note that the treating tool needs to be extracted after the shape of the treating tool is checked.

A treatment state determination unit 163 determines a treatment state based on whether the treating tool is placed on the stenosis site on the image. The treatment state determination unit 163, for example, determines that treatment is done when the treating tool is determined to be placed as a result of detection by the stenosis site stent detector 162. On the other hand, the treatment state determination unit 163 determines that treatment is not done when the treating tool is determined not to be placed.

FIG. 28 is a view illustrating a display example in the fourth embodiment. In the fourth embodiment, as illustrated in FIG. 28, the display controller 130 further displays information (“treated” and “untreated”) indicating the treatment state in accordance with a determination result by the treatment state determination unit 163.

Fifth Embodiment

In a fifth embodiment, information of myocardial ischemia improvement prediction with treatment is further displayed. FIG. 29 is a diagram illustrating configurations of an X-ray diagnostic apparatus 100, a measuring device 200, and an ECG measuring device 300 according to the fifth embodiment. As illustrated in FIG. 29, the X-ray diagnostic apparatus 100 according to the fifth embodiment further includes the respective parts for predicting improvement of the myocardial ischemia in real time with treatment of the stenosis site and displaying a prediction result.

An ischemia analysis image storage unit 164 stores therein an ischemia analysis result image such as myocardial perfusion. The ischemia analysis result image is, for example, a computed tomography (CT) image, a combined image of the CT image and a single photon emission computed tomography (SPECT) image, or the like, and is an image acquired by an X-ray CT apparatus or an SPECT apparatus. In the fifth embodiment, it is assumed that positioning between the X-ray image acquired by the X-ray diagnostic apparatus 100 and the ischemia analysis result image stored in the ischemia analysis image storage unit 164 is already completed. The positioning is capable of being performed by using an existing known technique. For example, the positioning is capable of being performed based on information such as acquiring conditions including as an angle of the C arm 13, brightness distribution of a Ray-Sum image (sum value projected image), and shapes of heat and coronary artery.

An ischemia inducibility estimation unit 165 estimates an ischemia inducibility indicating the degree that ischemia is induced by stenosis. For example, known is a relation between coronary arteries and myocardial regions that are innervated by the coronary arteries anatomically. The ischemia inducibility estimation unit 165 calculates the ischemia inducibility (for example, induction rate) at each position in the ischemic myocardium based on the relation between the FFR of the stenosis on the coronary artery that innervates an myocardial region and a range and the degree of ischemia on the myocardial region.

The FFR is information received from the measuring device 200 and the range and degree of the ischemia are pieces of information obtained from the ischemia analysis result image. For example, it is sufficient that the ischemia inducibility estimation unit 165 calculates the induction rate by weighing a plurality of FFRs when a plurality of stenosis sites is present on one coronary artery. The ischemia inducibility estimation unit 165 previously learns an algorithm of calculating the ischemia inducibility based on the relation between the FFR and the range and degree of the ischemia and inputs these pieces of information to the algorithm so as to calculate the ischemia inducibility.

An ischemia improvement prediction unit 166 predicts improvement of the myocardial ischemia with the treatment of the stenosis site in real time by using the ischemia inducibility estimated by the ischemia inducibility estimation unit 165. In the case of multivessel lesion and multiple lesions, treatment is performed in the order from a stenosis site having a higher ischemia inducibility. The treatment does not achieve expected improvement of the ischemia in some cases. In the fifth embodiment, in order to evaluate the treatment result during the treatment, the FFR is measured and the ischemia inducibility estimation unit 165 calculates the ischemia inducibility again by using the measured FFR again every time the stenosis site is treated.

The ischemia improvement prediction unit 166 obtains a difference between the ischemia inducibility calculated before the treatment and the ischemia inducibility calculated after the treatment for each position in the ischemic myocardium so as to predict improvement of the myocardial ischemia at each position in the ischemic myocardium. Furthermore, the display controller 130 further displays the ischemia analysis result image together with the X-ray image, and displays a prediction result (that is, predicted degree of improvement) on the ischemia analysis result image.

FIG. 30 is a view for explaining myocardial ischemia improvement prediction in the fifth embodiment. A graph of a signal value as illustrated in FIG. 30 indicates a signal value as an ischemia analysis result of myocardial perfusion or the like. The signal value is analyzed from parameters such as a time to peak (TTP), a myocardial blood volume (MBV), and a mean transit time (MTT). As illustrated in