Medical image processing apparatus and medical image processing method

1. A medical image processing apparatus comprising;

processing circuitry configured to:

calculate fluid information including a velocity vector based on three-dimensional phase image data in multiple time phases, the three-dimensional phase image data being collected by phase contrast magnetic resonance imaging, and the three-dimensional phase image data representing a fluid flowing through a lumen,

identify a wall region of the lumen based on a gradient vector on a section including the lumen, the gradient vector being calculated from a magnitude and a direction of the velocity vector, and

calculate wall shear stress using the wall region and the fluid information.

2. The medical image processing apparatus according to claim 1 ,

wherein the processing circuitry is configured to identify the wall region based on the gradient vector on a minor axis section of the lumen.

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

transform, based on the wall region three-dimensional image data collected by imaging, the three-dimensional image data different from the three-dimensional phase image data, and

display a value of the calculated wall shear stress on the transformed three-dimensional image data in superposition.

4. The medical image processing apparatus according to claim 1 , wherein the processing circuitry is configured to:

calculate the fluid information including the velocity vector based on the three-dimensional phase image data in the multiple time phases, the three-dimensional phase image data representing a fluid flowing through a blood vessel as the lumen, and

identify the wall region of the blood vessel based on the velocity vector.

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

set a region of interest based on the velocity vector, and

identify the wall region based on the velocity vector in the region of interest.

6. The medical image processing apparatus according to claim 5 ,

wherein the processing circuitry is configured to identify the wall region in each of slices based on the gradient vector on a minor axis section of the blood vessel, the gradient vector being calculated from the magnitude and the direction of the velocity vector on each of minor axis sections in the region of interest.

7. The medical image processing apparatus according to claim 5 ,

wherein the processing circuitry is configured to establish a set of voxels whose velocity vector is equal to or larger in magnitude than a threshold as a region of interest by selecting the set of voxels from among voxels based on the velocity vector.

8. The medical image processing apparatus according to claim 7 , wherein the processing circuitry is configured to:

set one region of interest based on data of the velocity vector in multiple time phases, and

set one region of interest at a same position of the velocity vector.

9. The medical image processing apparatus according to claim 1 ,

wherein the processing circuitry is configured to display the wall region on a display.

10. The medical image processing apparatus according to claim 1 , wherein the processing circuitry is configured to:

calculate, based on the velocity vectors, velocity absolute values of fluid of respective voxels included in the section,

calculate gradient vectors of the respective voxels, the gradient vectors each including a direction with the largest change in magnitude of the velocity absolute value among directions on the section, and

identify, based on the gradient vectors, a wall region of the lumen.

11. The medical image processing apparatus according to claim 1 , wherein the processing circuitry is configured to:

plot the magnitudes of the gradient vectors on the respective voxels included in the section, thereby generating a distribution, and

identify, based on the distribution, the wall region in the section.

12. A medical image processing apparatus comprising:

processing circuitry configured to:

calculate fluid information including a velocity vector based on three-dimensional image data in multiple time phases, the three-dimensional image data representing a fluid flowing through a lumen,

identify the wall region of the lumen based on a gradient vector on a minor axis section of the lumen, the gradient vector being calculated from a magnitude and a direction of the velocity vector, and

calculate wall shear stress using the wall region and the fluid information.

13. A medical image processing method comprising:

calculating fluid information including a velocity vector based on three-dimensional phase image data in multiple time phases, the three-dimensional phase image data being collected by phase contrast magnetic resonance imaging, and the three-dimensional phase image data representing a fluid flowing through a lumen;

identifying a wall region of the lumen based on a gradient vector on a section including the lumen, the gradient vector being calculated from a magnitude and a direction of the velocity vector, and

calculating wall shear stress using the wall region and the fluid information.