Image processing apparatus and image processing method

1. An image processing apparatus comprising:

processing circuitry configured to:

acquire volume data in time phases including a blood vessel image;

position the volume data in time phases;

perform a blood flow analysis on a basis of the volume data in time phases after the positioning thereby generating volume data of time to peak;

perform a dominance region analysis on a blood vessel on a basis of the volume data of time to peak, thereby generating volume data indicating a dominance region; and

generate three-dimensional image data indicating a blood vessel image of a region corresponding to a predetermined dominance region of dominance regions included in the volume data indicating the dominance region.

2. The image processing apparatus according to claim 1 , wherein the processing circuitry is configured to define, as the region corresponding to the predetermined dominance region, one of: the predetermined dominance region itself; a region obtained by performing a dilation process on the predetermined dominance region; and a region obtained by performing an erosion process thereon.

3. The image processing apparatus according to claim 1 , wherein the processing circuitry is configured to

perform the blood flow analysis, thereby generating not only the volume data of time to peak but also volume data indicating a blood flow rate.

4. The image processing apparatus according to claim 3 , wherein the processing circuitry is configured to:

set a region of interest concerning the dominance region on a basis of the volume data indicating the dominance region; and

calculate an average value of blood flow rates for the region of interest, on a basis of the volume data indicating the blood flow rate.

5. The image processing apparatus according to claim 4 , wherein the processing circuitry is configured to:

calculate a right-left division plane along which right and left hemispheres of the volume data in the time phases after the positioning are to be divided;

determine a normal hemisphere on a basis of an average value of blood flow rates for each divided hemisphere, based on the volume data indicating the blood flow rate;

set a normal hemisphere's region of interest concerning the dominance region to the normal hemisphere, on a basis of the volume data indicating the dominance region;

set an abnormal hemisphere's region of interest that is symmetrical to the normal hemisphere's region of interest with respect to the right-left division plane; and

calculate an average value of blood flow rates for each of the normal hemisphere's region of interest and the abnormal hemisphere's region of interest.

6. The image processing apparatus according to claim 5 , wherein the processing circuitry is configured to determine, as the normal hemisphere, a hemisphere whose average value of blood flow rates is larger.

7. The image processing apparatus according to claim 3 , wherein the processing circuitry is configured to determine, when a position is selected using the volume data indicating the blood vessel image, a dominance region corresponding to the position as the predetermined dominance region, from the volume data indicating the dominance region.

8. The image processing apparatus according to claim 3 , wherein the processing circuitry is configured to determine, when a position is selected using the volume data indicating the dominance region, a dominance region corresponding to the position as the predetermined dominance region, from the volume data indicating the dominance region.

9. The image processing apparatus according to claim 3 , wherein the processing circuitry is configured to perform a blood flow analysis on each of the dominance regions on a basis of the volume data indicating the dominance region, to generate volume data elements respectively indicating blood flow rates of the dominance regions, and combine the volume data elements respectively indicating the blood flow rates of the dominance regions to generate the volume data indicating the blood flow rate.

10. An image processing method comprising:

acquiring volume data in time phases including a blood vessel image from a storage;

position the volume data in time phases;

perform a blood flow analysis on a basis of the volume data in time phases after the positioning thereby generating volume data of time to peak;

perform a dominance region analysis on a blood vessel on a basis of the volume data of time to peak, thereby generating volume data indicating a dominance region;

generating three-dimensional image data indicating a blood vessel image of a region corresponding to a predetermined dominance region of dominance regions included in the volume data indicating the dominance region; and

displaying the three-dimensional image data as a three-dimensional image on a display.