Method and system for determining time-based index for blood circulation from angiographic imaging data

Abstract

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.

What is claimed is: 
     
         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.