METHOD AND SYSTEM FOR DETERMINING TIME-BASED INDEX FOR BLOOD CIRCULATION FROM ANGIOGRAPHIC IMAGING DATA
A predetermined time-based index ratio such as time-based fractional flow reserve (FFR) is determined for evaluating a level of blood circulation between at least two locations such as a proximal location and a distal location in a selected blood vessel in the region of interest. One time-based FFR is obtained by normalizing a risk artery ratio by a reference artery ratio.
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The current invention is generally related to an image data processing method and system, and more particularly related to a method or a system for determining a time-based index for blood circulation from imaging data.
BACKGROUND OF THE INVENTIONRelevant prior art has attempted to develop various methods to quantify an extent of blockage of blood circulation. For example, the blockage is often seen as stenosis in a coronary artery, and the extent of blockage is quantified by a predetermined parameter or index. One such widely used index is fractional flow reserve (FFR) for indicating a physiologic significance of coronary artery stenosis.
One area of the prior art attempts has used directly measured pressured data to determine a blockage parameter in a certain blood vessel. By inserting an intracoronary pressure guide wire into a guiding catheter that was introduced to the aorta, the distal coronary pressure and the aortic pressure are measured. After calibration, the pressure guide wire is advanced into coronary artery across stenosis to the most distal artery. As the pressure guide wire tip is kept away from touching the vessel wall, the distal coronary and aortic pressures are recorded simultaneously under maximum coronary vasodilatation. Unfortunately, this measurement technique is an invasive procedure as the pressure wire needs to be inserted into the coronary artery across stenosis and bears some risk.
Another area of the prior art attempts has estimated the FFR from a ratio of a coronary blood flow to a total arterial lumen volume based upon angiographic image data. Unfortunately, in order to quantify the total arterial lumen volume and an associated coefficient, complicated processing procedures are required.
Yet another area of the prior art attempts has utilized angiographic image data in order to study blood circulation. In some attempts, time-density-curves (TDC) or time-intensity-curves (TIC) are constructed for selected regions of interests (ROI) from the angiographic image data. Based upon the TDC or TIC, the blood circulation level is compared among the selected regions. In some of the perfusion imaging techniques, although TDCs are generated from the perfusion images, the TDCs reflect density changes in selected regions or tissues rather than individual blood vessels as ROI. On the other hand, a blood flow speed or a rate of change in blood flow speed is evaluated based upon angiographic image data in individual coronary arteries in one perfusion imaging technique, the blood flow speed is determined based upon a distance traveled along a particular artery by the contrast agent over time. That is, the blood flow speed is deteimined directly from the visual identification of the contrast agent along a blood vessel without the use of time density data such as TDCs.
In view of the above prior art techniques, it remains desirable to implement a clinical index that is useful in evaluating stenosis in a particular blood vessel so as to objectively determine if a certain medical procedure should be performed on a patient.
Referring now to the drawings, wherein like reference numerals designate corresponding structures throughout the views, and now referring to
In general, X-ray transmission images are generated in the following manner. The X-ray beam limiting device 13 selectively radiates X-ray beams generated by the X-ray tube 12 onto a region of interest including the heart of the subject P. The X-ray detector 16 includes a plurality of X-ray detecting elements for detecting X-ray beams that have passed through the subject P, converting the detected X-ray beams into an electrical signal, storing the electrical signal, and transmitting the stored electrical signal to the image generating unit 24. Thus, an image data acquiring unit includes at least the X-ray detector for acquiring imaging data indicating blood circulation in a region of interest (ROI) including at least in a predetermined risk blood vessel. The image generating unit 24 generates X-ray transmission images based upon the electrical signal and stores the generated X-ray transmission images into the image storage unit 25. The input unit 22 includes one or more of devices such as a touch panel, a touch screen, a mouse, a keyboard, a button, a trackball, and a joystick that are used by an operator like a medical doctor or a technologist who operates the X-ray diagnostic apparatus for the purpose of inputting various types of commands. One of the commands is to specify a region of interest using a particular user interface unit in the input unit 22. The input unit 22 transfers the commands that have been received from the operator to the system controlling unit 21.
In further detail, the user interface unit 34 in one embodiment includes the display unit 23 and the input unit 22 for providing certain features according to the current invention. Using the user interface unit 34 such as a Graphical User Interface (GUI), the operator manually specifies a ROI in the displayed image for evaluating blood circulation in a blood vessel or a tissue region according to the current invention. The display unit 23 indicates a contour of an input region or a ROI that has been specified for evaluating blood circulation in a manner that is fused with the displayed image. In one embodiment, the display unit also displays the blood circulation evaluation results either in numerical values of a predetermined time-based index and or in a predetermined graphical form. In one predetermined graphical form, the time-based index value is plotted in the Y axis while the selected regions (ROIs) are plotted in the X axis as illustrated in
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The C-shaped arm 15 supports the X-ray tube 12, the X-ray beam limiting device 13, and the X-ray detector 16 while the C-shaped arm rotating and moving mechanism 17 rotates and moves the C-shaped arm 15 under the control of the C-shaped-arm and top-plate mechanism controlling unit 19.
In summary, the X-ray diagnostic apparatus according to the first embodiment generates X-ray transmission images by radiating the X-ray beams onto the heart of the subject P in which a contrast agent has been injected into the coronary arteries. Further, the X-ray diagnostic apparatus according to the first embodiment determines blood circulation levels in regions of interest such as a blood vessel or tissue regions based upon a predetermined time-base index such as fractional flow reserve (FFR) according to the current invention.
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The multi-slice X-ray CT apparatus further includes a high voltage generator 109 and a current regulator 111 that respectively control a tube voltage and a tube current in the X-ray tube 101 through a slip ring 108 so that the X-ray tube 101 generates X ray in response to a system controller 110. The X rays are emitted towards the subject S, whose cross sectional area is represented by a circle. The X-ray detector 103 is located at an opposite side from the X-ray tube 101 across the subject S for detecting the emitted X rays that have transmitted through the subject S. The X-ray detector 103 further includes individual detector elements or units that are conventional integrating detectors.
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The above described data is sent to a preprocessing device 106, which is housed in a console outside the gantry 100 through a non-contact data transmitter 105. The preprocessing device 106 performs certain corrections such as sensitivity correction on the raw data. A storage device 112 then stores the resultant data that is also called projection data at a stage immediately before reconstruction processing. The storage device 112 is connected to the system controller 110 through a data/control bus, together with a reconstruction device 114, an input device 115, a display device 116, a blood circulation determination device 117, a treatment deteiuiination device 118 and the scan plan support apparatus 200. The scan plan support apparatus 200 includes a function for supporting an imaging technician to develop a scan plan.
In one embodiment of the current invention, a perfusion-related equipment is required to perform the injection of a predetermined contrast agent into the subject S. For example, a predetermined contrast agent is injected in bolus into the left ventricular cavity in a coronary study prior to scanning. The details of a perfusion technique is not going to be described in details here, but well-known perfusion techniques are generally applicable to the current invention.
One embodiment of the blood circulation determination device 117 further includes a combination of various software and hardware components. According to one aspect of the current invention, the blood circulation determination device 117 of the CT apparatus advantageously determines a predetermined time-based fractional flow reserve (FFR) based upon the angiographic image data that is acquired by the X-ray CT apparatus. In general, the blood circulation determination device 117 in one embodiment of the current invention initially generates time density data such as time-density curves (TDCs) at predetermined locations along a selected blood vessel from the angiographic image data. The predetermined locations generally include at least a proximal location and a distal location. The proximal location is proximal to a suspected stenosis location in the selected blood vessel and is substantially free from any blockage for blood circulation. On the other hand, the distal location is distal to the suspected stenosis location in the selected blood vessel and is potentially affected by the blockage for blood circulation. Ultimately, the blood circulation determination device 117 determines a predetermined time-based index such as time-based FFR for evaluating a level of blood circulation between two locations such as the proximal location and the distal location in a selected blood vessel in the region of interest. Thus, a total of two data points is used to determine a time-based FFR in the first embodiment of the blood circulation determination device 117 according to the current invention.
In a second embodiment of the blood circulation determination device 117 also further includes a combination of various software and hardware components. According to one aspect of the current invention, the blood circulation determination device 117 of the CT apparatus advantageously determines a predetermined time-based fractional flow reserve (FFR) based upon the angiographic image data that is acquired by the X-ray CT apparatus. In general, the blood circulation determination device 117 in a second embodiment of the current invention initially generates time density data such as time-density curves (TDCs) at predetermined locations along a pair of selected blood vessels from the angiographic image data. The pair of selected blood vessels generally includes a predetermined risk blood vessel and a predetermined reference blood vessel. The predetermined risk blood vessel is a blood vessel under investigation for a suspected stenosis that contributes to some blockage in blood circulation. On the other hand, the predetermined reference blood vessel is a separate blood vessel from the predetermined risk blood vessel and is used as a reference to assure the evaluation for a suspected stenosis in the predetermined risk blood vessel. In general, the predetermined reference blood vessel is selected from a group of healthy blood vessels that is comparable in size and location to the predetermined risk blood vessel and is substantially from stenosis.
In the second embodiment of the current invention, the blood circulation determination device 117 also generates time density data such as time-density curves (TDCs) at the predetermined locations along each of the selected pair of the blood vessels from the angiographic image data. The predetermined locations generally include at least a proximal location and a distal location along each of the two selected blood vessels. In the predetermined risk blood vessel, the proximal location is proximal to a suspected stenosis location and is substantially free from any blockage for blood circulation. On the other hand, the distal location in the predetermined risk blood vessel is distal to the suspected stenosis location and is potentially affected by the blockage for blood circulation. In the predetermined reference blood vessel, the proximal and distal locations are each a location that is respectively comparable to the proximal location and the distal location of the predetermined risk blood vessel. Ultimately, the blood circulation determination device 117 determines a predetermined time-based index such as time-based FFR for evaluating a level of blood circulation between two locations such as the proximal location and the distal location in a selected blood vessel in the region of interest. Thus, a total of four data points is used to determine a time-based FFR in the second embodiment of the blood circulation determination device 117 according to the current invention.
One embodiment of the treatment determination device 118 further includes various software and hardware components. According to one aspect of the current invention, the treatment determination device 118 of the CT apparatus advantageously determines as to whether or not a certain medical procedure should be performed on the patient based upon the blockage index that the blood circulation determination device 117 has outputted for a particular blood vessel. For example, if the blood circulation determination device 117 outputted a particular FFR value, the treatment determination device 118 advantageously determines as to whether or not a stent should be inserted into the measured coronary artery based upon the FFR value and outputs a proposed medical decision. The treatment determination device 118 optionally displays the relevant information including the proposed medical decision via the display device 116.
As will be further described below, the current invention is not limited to the specific features of the above disclosures. The blood circulation determination device 117 according to the current invention is not limited certain aspects of the time density data to determine a predetermined fractional flow reserve (FFR). For example, one embodiment of the blood circulation determination device 117 utilizes the time-to-peak (TTP) information, mean-transit-time (MTT) information and or upward slope information of the time-density curves (TDC), another embodiment optionally uses different aspects of the time density data that has been generated from the angiographic image data with respect to the blood vessels and the surrounding tissues. By the same token, the treatment determination device 118 optionally considers other factors or information in addition to the output index from the blood circulation determination device 117.
By the same token, the current invention is not limited to the specific features of the above disclosed embodiments of the CT apparatus. In other words, the current invention is applicable to other modalities including ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), angiography and positron emission tomography (PET). In fact, one embodiment of the current invention is implemented on a C-arm X-ray system in angiography. In this regard, the time density data such as time-density curves (TDCs) is generated from certain imaging data including but not limited to angiographic image data and angiographic imaging data.
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Similarly, the exemplary X-ray image as illustrated in
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In general, a data set of myocardial perfusion images is a time sequence of images of heart blood flow from the entrance of a coronary artery into myocardium. The image data include images before contrast agent injection and, of contrast agent inflow and outflow. All the measurement images are selected at a substantially identical cardiac phase with retrospective cardiac gating. A change in image intensity in contrast agent pixels represents heart blood flow. Time density curve measurements of blood flow are implemented on background subtraction images with motion compensation.
The perfusion image data initial processing unit 1000 extracts a first region of interest (ROI) 1000A including a risk coronary artery and supported myocardium 1 as well as a second region of interest (ROI) 1000B including a healthy or reference coronary artery and supported myocardium 2. The perfusion image data initial processing unit 1000 outputs the extracted image data of the first region of interest (ROI) 1000A and the second region of interest (ROI) 1000B to the time-density curves (TDC) generation unit 1100. The pair of selected arteries generally includes a predetermined risk artery and a predetermined reference artery. The predetermined risk artery is a blood vessel under investigation for a suspected stenosis that contributes to some blockage in blood circulation. On the other hand, the predetermined reference artery is a separate blood vessel from the predetermined risk artery and is used as a reference to assure the evaluation for a suspected stenosis in the predetermined risk artery. In general, the predetermined reference artery is selected from a group of healthy blood vessels that is comparable in size and location to the predetermined risk artery and is substantially from stenosis.
The time-density curves (TDC) generation unit 1100 generates four time-density curves. That is, the time-density curves (TDC) generation unit 1100 generates a first pair of a proximal artery TDC 1A and a corresponding myocardial TDC 1B for the risk coronary artery based upon the first region of interest (ROI) 1000A. By the same token, the time-density curves (TDC) generation unit 1100 also generates a second pair of a proximal artery TDC 2A and a corresponding myocardial TDC 2B for the reference coronary artery based upon the second region of interest (ROI) 1000A. The proximal artery TDC 1A is a time-density curve that is generated based upon the density data at a proximal artery location where is upstream with respect to a suspected stenosis along the risk coronary artery. The corresponding myocardial TDC 1B is a time-density curve that is generated based upon the density data at a corresponding distal location where is downstream with respect to the proximal artery location along the risk coronary artery. T Similarly, the proximal artery TDC 2A is a time-density curve that is generated based upon the density data of the reference artery at a proximal artery location where is comparable to the risk proximal artery location. The corresponding myocardial TDC 2B is a time-density curve that is generated based upon the density data at a corresponding distal location where is downstream with respect to the proximal artery location along the reference coronary artery. The time-density curves (TDC) generation unit 1100 further includes a TDC fitting unit 1100A to further process the above four TDCs 1A, 1B, 2A and 2B with a predetermined fitting model such as gamma-variate model.
The TDC index generation unit 1200 generally calculates a risk ratio based upon selected time indexes. The TDC index generation unit 1200 further includes a time index ratio calculation unit 1200A for selecting a time index of each of the fitted TDCs 1A, 1B, 2A and 2B and for determining a time index ratio based upon the selected time indexes. That is, the TDC index generation unit 1200 selects an time index of a TDC such as a time-to-peak (TTP) index or a mean-transit-time (MMT) index and determines a time value for the selected time index from each of the fitted TDCs 1A, 1B, 2A and 2B. Subsequently, the time index ratio calculation unit 1200A calculates a time index ratio of the risk coronary artery TIRA based upon the selected index pair in the TDCs 1A and 1B. Similarly, the time index ratio calculation unit 1200A also calculates a time index ratio of the reference coronary artery TIRB based upon the selected index pair in the TDCs 2A and 2B.
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In the above exemplary embodiment, myocardial perfusion images are used to illustrate a process in which the time-based FFR is determined. This exemplary process and embodiment are mere illustration, and the current invention is not limited to the use of myocardial angiographic image data or the determination of the time-based FFR for the coronary arteries. The current invention is applicable to evaluate blood circulation in blood vessels in various organs.
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To account for some perfusion characteristics, the following Equation (2) includes additional term.
where
is a ration of extraction fractions of myocardium for the reference artery and the risk artery.
The FFR of Equation (2) is optionally modified based upon xTTP as defined in the following Equation (3):
The FFR is optionally determined based upon MMT as defined in the following Equation (4):
The FFR is alternatively determined based upon slopes as defined in the following Equation (5):
The above definition of the fractional flow reserve (FFR) is a ratio that is based upon the assumed relation between a risk artery and a healthy reference artery in a ratio of the blood volume and a ratio of the blood flow time as obtained from the time density data. The following equation (6) provides the relation:
where VS is a blood volume parameter at a risk artery having stenosis while VP is a blood volume parameter at a proximal location to the stenosis in the risk artery. Vref
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In general, a data set of myocardial perfusion images is a time sequence of images of heart blood flow from the entrance of a coronary artery into myocardium. The image data include images before contrast agent injection and, of contrast agent inflow and outflow. All the measurement images are selected at a substantially identical cardiac phase with retrospective cardiac gating. A change in image intensity in contrast agent pixels represents heart blood flow. Time density curve measurements of blood flow are implemented on background subtraction images with motion compensation.
The perfusion image data initial processing unit 1001 extracts a region of interest (ROI) 1001A including a risk coronary artery and supported myocardium. The perfusion image data initial processing unit 1001 outputs the extracted image data of the region of interest (ROI) 1001A to the time-density curves (TDC) generation unit 1101. The predetermined risk artery is a blood vessel under investigation for a suspected stenosis that contributes to some blockage in blood circulation.
The time-density curves (TDC) generation unit 1101 generates two time-density curves. That is, the time-density curves (TDC) generation unit 1101 generates a pair of a proximal artery TDC 1A and a corresponding myocardial TDC 1B for the predetermined risk coronary artery based upon the region of interest (ROI) 1001A. The proximal artery TDC 1A is a time-density curve that is generated based upon the density data at a proximal artery location where is upstream with respect to a suspected stenosis along the risk coronary artery. The corresponding myocardial TDC 1B is a time-density curve that is generated based upon the density data at a corresponding distal location where is downstream with respect to the proximal artery location along the risk coronary artery. The time-density curves (TDC) generation unit 1101 further includes a TDC fitting unit 1101A to further process the above four TDCs 1A and 1B with a predetermined fitting model such as gamma-variate model.
The TDC index generation unit 1201 generally calculates a ratio based upon selected time indexes. The TDC index generation unit 1201 further includes a time index ratio calculation unit 1201A for selecting a time index of each of the fitted TDCs 1A and 1B, and for determining a time index ratio based upon the selected time indexes. That is, the TDC index generation unit 1201 selects an time index of a TDC such as a time-to-peak (TTP) index or a mean-transit-time (MMT) index and determines a time value for the selected time index from each of the fitted TDCs 1A and 1B. Subsequently, the time index ratio calculation unit 1201A calculates a time index ratio of the risk coronary artery TIRA based upon the selected index pair in the TDCs 1A and 1B.
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In step S20, the blood circulation determination process in one embodiment of the current invention initially generates time density data such as time-density curves (TDCs) at predetermined locations along a selected blood vessel from the angiographic image data. The predetermined locations generally include at least a proximal location and a distal location. The proximal location is proximal to a suspected stenosis location in the selected blood vessel and is substantially free from any blockage for blood circulation. On the other hand, the distal location is distal to the suspected stenosis location in the selected blood vessel and is potentially affected by the blockage for blood circulation.
In step S30, one embodiment of the blood circulation determination process further includes steps or actions that are performed by a combination of various software and hardware components. According to one aspect of the current invention, the blood circulation determination process advantageously determines a predetermined time-based fractional flow reserve (FFR) based upon the angiographic image data that is previously acquired.
Ultimately, the blood circulation determination process determines a predeteimined time-based index ratio such as time-based FFR for evaluating a level of blood circulation between at least two locations such as the proximal location and the distal location in a selected blood vessel in the region of interest in a step S40. In the evaluation, a certain treatment is considered based upon the time-based index ratio. For example, a FFR threshold value of 0.75 is often used among clinicians although some doctors prefer a FFR threshold value of 0.8. In this regard, a range of FFR threshold value from 0.75 to 0.8 is considered to be a concerned range where a patient may require medical treatment. The treatment to a patient in the concerned FFR range depends on a totality of a particular patient's conditions. In general, if a FFR value is larger than the clinically accepted FFR threshold value, no serious treatment is generally needed and a patient can go home with some medication. On the other hand, if a FFR value is smaller than the clinically accepted FFR threshold value, a patient generally needs serious medical attention and requires some serious coronary procedure such as surgery.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and that although changes may be made in detail, especially in matters of shape, size and arrangement of parts, as well as implementation in software, hardware, or a combination of both, the changes are within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
Claims
1. A system for evaluating blood circulation in a blood vessel, comprising;
- an image data acquiring unit for acquiring imaging data indicating blood circulation in a region of interest (ROI) including at least in a predetermined risk blood vessel;
- a user interface unit for at least specifying the ROI;
- an image processing unit connected to said image data acquiring unit for performing ECG gating, motion compensation and background subtraction on the imaging data;
- a time density generating unit connected to said image processing unit for generating time density data in the ROI from the imaging data at a proximal location and a distal location at least with respect to the predetermined risk blood vessel, wherein the proximal location is proximal to a suspected stenosis in the predetermined risk blood vessel while the distal location is distal to the suspected stenosis; and
- a time-based index determining unit connected to said time density generating unit for determining based upon the time density data a time-based index for evaluating a level of the blood circulation between the proximal location and the distal location in the ROI.
2. The system for evaluating blood circulation in a blood vessel according to claim 1 wherein the imaging data includes contrast image data after a contrast agent is injected using a predetermined bolus technique, wherein the imaging data is acquired using said image data acquiring unit of a predetermined modality including X-ray diagnostic apparatuses, ultrasound diagnostic apparatuses, computed tomography (CT) apparatuses, magnetic resonance imaging (MRI) apparatuses, angiography apparatuses and positron emission tomography (PET) apparatuses.
3. A method of evaluating blood circulation in a blood vessel, comprising;
- acquiring imaging data indicating blood circulation in a region of interest including at least in a predetermined risk blood vessel;
- determining time density data from the imaging data at a proximal location and a distal location with respect to the predetermined risk blood vessel, wherein the proximal location is proximal to a suspected stenosis in the predetermined risk blood vessel while the distal location is distal to the suspected stenosis; and
- determining based upon the time density data a time-based index for evaluating a level of the blood circulation between the proximal location and the distal location in the predetermined risk blood vessel in the region of interest.
4. The method of evaluating blood circulation in a blood vessel according to claim 3 wherein the time density data includes time density curves indicating density of a predetermined agent over a course of time at each of the proximal location and the distal location.
5. The method of evaluating blood circulation in a blood vessel according to claim 4 wherein the time-based index is a time-based fractional flow reserve (time-based FFR) as defined by a ratio of time between corresponding points in the time density curves at the proximal location and the distal location.
6. The method of evaluating blood circulation in a blood vessel according to claim 5 wherein the time-based FFR indicates a level of blockage in blood circulation in the predetermined risk blood vessel between the proximal location and the distal location.
7. The method of evaluating blood circulation in a blood vessel according to claim 6 wherein the proximal location is inside the predetermined risk blood vessel.
8. The method of evaluating blood circulation in a blood vessel according to claim 6 wherein the proximal location is inside the predetermined risk blood vessel and proximal to a branching point.
9. The method of evaluating blood circulation in a blood vessel according to claim 6 wherein the proximal location is inside a predetermined healthy blood vessel substantially free from stenosis.
10. The method of evaluating blood circulation in a blood vessel according to claim 6 wherein the distal location is inside the predetermined risk blood vessel distal to a blockage.
11. The method of evaluating blood circulation in a blood vessel according to claim 6 wherein the distal location is in a predetermined area inside the predetermined risk blood vessel and the predetermined area is distal to the proximal location.
12. The method of evaluating blood circulation in a blood vessel according to claim 6 wherein the distal location is over a predetermined line inside the predetermined risk blood vessel distal to the proximal location.
13. The method of evaluating blood circulation in a blood vessel according to claim 6 wherein the distal location is a tissue area outside the predetermined risk blood vessel but distal to the proximal location.
14. The method of evaluating blood circulation in a blood vessel according to claim 5 wherein the corresponding points in time include one of time-to-peak, mean-transit-time and upward slope in the time density curves.
15. The method of evaluating blood circulation in a blood vessel according to claim 3 where the imaging data includes a reference blood vessel and is acquired from two views.
16. A method of evaluating blood circulation in a blood vessel, comprising;
- acquiring imaging data indicating blood circulation in a region of interest including a predetermined risk blood vessel and a predetermined reference blood vessel that is substantially from stenosis, comparable in size and located near the predetermined risk blood vessel;
- determining time density data of the predetermined risk blood vessel and the predetermined reference blood vessel from the imaging data in the region of interest; and
- determining based upon the time density data a time-based index for evaluating a level of the blood circulation in the predetermined risk blood vessel with respect to the predetermined reference blood vessel in the region of interest.
17. The method of evaluating blood circulation in a blood vessel according to claim 16 wherein the imaging data includes contrast image data after a contrast agent is injected using a predetermined bolus technique.
18. The method of evaluating blood circulation in a blood vessel according to claim 16 wherein the imaging data is acquired using a predetermined modality including X-ray diagnostic apparatuses, ultrasound diagnostic apparatuses, computed tomography (CT) apparatuses, magnetic resonance imaging (MRI) apparatuses, angiography apparatuses and positron emission tomography (PET) apparatuses.
19. The method of evaluating blood circulation in a blood vessel according to claim 16 wherein the time density data includes time density curves indicating density of a predetermined agent over a course of time in the predetermined risk blood vessel and the predetermined reference blood vessel.
20. The method of evaluating blood circulation in a blood vessel according to claim 19 wherein a pair of the time density curves is generated for each of the predetermined risk blood vessel and the predetermined reference blood vessel and the two density curves respectively correspond the time density data at a proximal location and a distal location along each of the predetermined risk blood vessel and the predetermined reference blood vessel.
21. The method of evaluating blood circulation in a blood vessel according to claim 20 wherein the time-based index is a time-based fractional flow reserve (time-based FFR) as defined by a first ratio of time between corresponding points in the time density curves for the predetermined risk blood vessel and a second ratio of time between the corresponding points in the time density curves for the predetermined reference blood vessel.
22. The method of evaluating blood circulation in a blood vessel according to claim 21 wherein the corresponding points in time include one of time-to-peak and mean-transit-time in the time density curves.
23. The method of evaluating blood circulation in a blood vessel according to claim 19 wherein the predetermined risk blood vessel and the predetermined reference blood vessel branching from a common blood vessel, a pair of the time density curves being generated for both of the predetermined risk blood vessel and the predetermined reference blood vessel and the two density curves respectively correspond the time density data at a distal location that is distal to a suspected stenosis in the predetermined risk blood vessel and a comparable distal location in the predetermined reference blood vessel.
24. The method of evaluating blood circulation in a blood vessel according to claim 23 wherein the time-based index is a time-based fractional flow reserve (time-based FFR) as defined by a ratio of time between corresponding points in the time density curves for the predetermined risk blood vessel and the predetermined reference blood vessel.
25. The method of evaluating blood circulation in a blood vessel according to claim 24 wherein the corresponding points in time include one of time-to-peak, mean-transit-time and upward slope in the time density curves.
26. The method of evaluating blood circulation in a blood vessel according to claim 16 where the imaging data for the predetermined reference blood vessel is acquired from two views.
27. The method of evaluating blood circulation in a blood vessel according to claim 16 where a ratio of a blood volume parameter at a distal location and a proximal location in the predetermined reference blood vessel is approximated by the time density data.
Type: Application
Filed: Sep 25, 2012
Publication Date: Mar 27, 2014
Applicants: THE JOHNS HOPKINS UNIVERSITY (BALTIMORE, MD), TOSHIBA MEDICAL SYSTEMS CORPORATION (OTAWARA-SHI)
Inventors: Jingwu YAO (BUFFALO GROVE, IL), Takuya SAKAGUCHI (UTSUNOMIYA-SHI), Jeff TROST (BALTIMORE, MD), Richard T. GEORGE (BALTIMORE, MD), Joao A.C. LIMA (BALTIMORE, MD), Omair YOUSUF (BALTIMORE, MD)
Application Number: 13/626,623
International Classification: G06K 9/46 (20060101);