Fluid analysis apparatus, fluid analysis method, and fluid analysis program

1. A fluid analysis apparatus comprising

at least one processor configured to:

analyze an image obtained by imaging a subject including a tubular structure in which a fluid flows, thereby deriving fluid information regarding flow of the fluid at each of pixel positions in the tubular structure;

derive, within the tubular structure included in the image, a matching degree between the fluid information at a plurality of pixel-of-interest positions set at a first sampling interval and the fluid information at a plurality of pixel positions within a predetermined region based on the pixel-of-interest positions;

set a second sampling interval for displaying the fluid information in accordance with the matching degree; and

sample the fluid information at the set second sampling interval, and cause a display to display the fluid information.

2. The fluid analysis apparatus according to claim 1 , wherein the processor is configured to set the first sampling interval in accordance with a size of a region intersecting a center line of the tubular structure included in the image.

3. The fluid analysis apparatus according to claim 2 , wherein the processor is configured to set the second sampling interval that is larger as the matching degree is larger.

4. The fluid analysis apparatus according to claim 3 , wherein the processor is configured to set the second sampling interval to the first sampling interval if the matching degree is greater than or equal to a predetermined threshold.

5. The fluid analysis apparatus according to claim 4 , wherein the processor is configured to cause the display to display representative fluid information that represents the fluid information within the region.

6. The fluid analysis apparatus according to claim 1 , wherein the processor is configured to set the second sampling interval that is larger as the matching degree is larger.

7. The fluid analysis apparatus according to claim 6 , wherein the processor is configured to set the second sampling interval to the first sampling interval if the matching degree is greater than or equal to a predetermined threshold.

8. The fluid analysis apparatus according to claim 7 , wherein the processor is configured to cause the display to display representative fluid information that represents the fluid information within the region.

9. The fluid analysis apparatus according to claim 6 , wherein the processor is configured to set the second sampling interval in accordance with a size of a region intersecting a center line of the tubular structure included in the image if the matching degree is less than a predetermined threshold.

10. The fluid analysis apparatus according to claim 9 , wherein the processor is configured to set the second sampling interval in a direction intersecting the center line of the tubular structure.

11. The fluid analysis apparatus according to claim 1 , wherein the processor is configured to cause the display to display the fluid information as a vector.

12. The fluid analysis apparatus according to claim 11 , wherein the processor is configured to thicken a width of the vector as the second sampling interval is larger.

13. The fluid analysis apparatus according to claim 1 , wherein

the image is a three-dimensional image obtained by imaging the subject by three-dimensional cine phase contrast magnetic resonance imaging, and

the processor is configured to derive, as the fluid information, a flow velocity vector of the fluid obtained by analyzing the three-dimensional image.

14. The fluid analysis apparatus according to claim 1 , wherein the processor is configured to derive, as the fluid information, a flow velocity vector of the fluid obtained by simulating the flow of the fluid by an analysis using computational fluid dynamics.

15. The fluid analysis apparatus according to claim 1 , wherein the tubular structure is a blood vessel, and the fluid is blood.

16. A fluid analysis method comprising:

analyzing an image obtained by imaging a subject including a tubular structure in which a fluid flows, thereby deriving fluid information regarding flow of the fluid at each of pixel positions in the tubular structure;

deriving, within the tubular structure included in the image, a matching degree between the fluid information at a plurality of pixel-of-interest positions set at a first sampling interval and the fluid information at a plurality of pixel positions within a predetermined region based on the pixel-of-interest positions; and

setting a second sampling interval for displaying the fluid information in accordance with the matching degree; and

sampling the fluid information at the set second sampling interval, and causing a display to display the fluid information.

17. A non-transitory computer readable recording medium storing a fluid analysis program for causing a computer to execute:

a procedure of analyzing an image obtained by imaging a subject including a tubular structure in which a fluid flows, thereby deriving fluid information regarding flow of the fluid at each of pixel positions in the tubular structure;

a procedure of deriving, within the tubular structure included in the image, a matching degree between the fluid information at a plurality of pixel-of-interest positions set at a first sampling interval and the fluid information at a plurality of pixel positions within a predetermined region based on the pixel-of-interest positions; and

a procedure of setting a second sampling interval for displaying the fluid information in accordance with the matching degree, sampling the fluid information at the set second sampling interval, and causing a display to display the fluid information.