Method and system for determining regional rupture potential of blood vessel
There is provided a method for determining a regional rupture potential (RRP) indicative of the state of local weakening of a blood vessel based on parameters that correlate with the expansion and local weakening of the vessel. The method comprises: receiving a plurality of images of the blood vessel into a multiphase stack. A geometrical model of the lumen and the outer wall of the vessel are generated and smoothed to obtain a volume mesh and surface mesh respectively. An ILT thickness distribution, a local deformation at each phase and a wall strain distribution indicative of a maximal principal strain at the outer wall are determined. Blood flow values in the lumen are obtained and a wall shear stress distribution indicative of wall shear disturbances in the lumen is calculated. The RRP is determined based on the ILT thickness distribution, the wall shear stress, and the wall strain.
1. A computer-implemented method for determining a rupture potential indicative of a state of weakening of at least one region of a blood vessel of a given subject, the method being executed by a server, the method comprising:
receiving, by the server, a plurality of images of the blood vessel of the given subject, the plurality of images having been acquired by a medical imaging apparatus;
organizing, by the server, the plurality of images into a multiphase stack, a given phase of the multiphase stack being representative of the blood vessel at a given time in a cardiac cycle;
generating, by the server, a volume mesh of a lumen of the blood vessel, a surface mesh of the lumen of the blood vessel and a surface mesh of an outer wall of the blood vessel, using the multiphase stack;
calculating, by the server, based on the surface mesh of the lumen and the surface mesh of the outer wall, a thickness parameter;
determining, by the server, a local deformation at each phase of the multiphase stack by mapping voxels of the surface mesh of the outer wall to the multiphase stack;
calculating, by the server, based on the local deformation at each phase, a wall strain parameter indicative of a maximum principal strain at the outer wall;
generating a blood flow parameter based at least in part on the volume mesh of the lumen, the blood flow parameter comprising a respective set of blood flow values in the lumen for a cardiac cycle;
calculating, by the server, based on the blood flow parameter, a wall shear stress parameter indicative of wall shear disturbances in the lumen; and
determining, by the server, based on the thickness parameter, the wall strain parameter, and the wall shear stress parameter, a rupture potential parameter of the blood vessel, the rupture potential parameter being indicative of a state of weakening of the at least one region of the blood vessel.
2. The method of claim 1 , wherein the generating the blood flow parameter comprises one of:
generating a computational flow dynamics (CFD) simulation of blood flow in the lumen to obtain the respective set of blood flow values in the lumen for the cardiac cycle; and
performing a 4D-flow MRI acquisition to obtain the respective set of blood flow values in the lumen for the cardiac cycle.
3. The method of claim 1 , wherein
the method further comprises, prior to calculating the wall strain parameter:
determining, based on each phase of the multiphase stack and the surface mesh of the outer wall, a local deformation at each phase of the surface mesh; and wherein
the calculating the wall strain parameter is based on the local deformation at each phase of the surface mesh.
4. The method of claim 1 , wherein the calculating the thickness parameter comprises calculating an intraluminal thrombus (ILT) thickness based on: a distance between the surface mesh of the outer wall and the surface mesh of the lumen.
5. The method of claim 1 , wherein
the method further comprises prior to the determining the rupture potential parameter:
receiving a population-based thickness parameter, a population-based wall strain parameter, and a population-based wall shear stress parameter; and wherein
the determining the rupture potential parameter is further based on the population-based thickness parameter, the population-based wall strain parameter, and the population-based wall shear stress parameter.
6. The method of claim 1 , wherein
the method further comprises, prior to the estimating the rupture potential parameter:
defining, by the server, a plurality of patches on the blood vessel; wherein
the calculating the thickness parameter, the wall strain parameter, and the wall shear stress parameter, comprises calculating a patch-averaged thickness parameter, a patch-averaged wall strain parameter and a patch-averaged wall shear stress parameter using the plurality of patches; and wherein
the rupture potential parameter is based on the patch-averaged thickness parameter, the patch-averaged wall strain parameter and the patch-averaged wall shear stress parameter.
7. The method of claim 6 , wherein the calculating the patch-averaged thickness parameter, the patch-averaged wall strain parameter and the patch-averaged wall shear stress parameter is further based on the population-based thickness parameter, the population-based wall strain parameter, and the population-based wall shear stress parameter.
8. The method of claim 7 , further comprising determining respective distribution quartiles for each of the patch-averaged thickness parameter, the patch-averaged wall strain parameter and the patch-averaged wall shear stress parameter.
9. The method of claim 8 , further comprising: classifying each of the patch-averaged thickness parameter, the patch-averaged wall strain parameter and the patch-averaged wall shear stress parameter based on the respective distribution quartiles.
10. The method of claim 1 , wherein the rupture potential parameter is determined based on:
RRP
=
[
ILT
category
+
S
TRAIN
category
+
(
5
-
TAWS
S
category
)
]
-
3
9
·
100
where ILT category is a respective category assigned to the thickness parameter,
STRAIN category is a respective category assigned to the wall strain parameter, and
TAWSS category is a respective category assigned to the wall shear stress parameter.
11. A system for determining a rupture potential indicative of a state of weakening of at least one region of a blood vessel of a given subject, the system comprising:
a processor;
a computer-readable storage medium connected to the processor, the computer-readable storage medium including instructions;
the processor, upon executing the instructions, being configured for:
receiving a plurality of images of the blood vessel of the given subject, the plurality of images having been acquired by a medical imaging apparatus;
organizing the plurality of images into a multiphase stack, a given phase of the multiphase stack being representative of the blood vessel at a given time in a cardiac cycle;
generating a volume mesh of a lumen of the blood vessel, a surface mesh of the lumen of the blood vessel and a surface mesh of an outer wall of the blood vessel, using the multiphase stack;
calculating based on the volume mesh of the lumen and the surface mesh of the outer wall, a thickness parameter;
determining a local deformation at each phase of the multiphase stack by mapping voxels of the surface mesh of the outer wall to the multiphase stack;
calculating based on the local deformation at each phase, a wall strain parameter indicative of a maximum principal strain at the outer wall;
generating a blood flow parameter based at least in part on the volume mesh of the lumen, the blood flow parameter comprising a respective set of blood flow values in the lumen for a given moment in time;
calculating based on the blood flow parameter, a wall shear stress parameter indicative of wall shear disturbances in the lumen;
determining based on the thickness parameter, the wall strain parameter, and the wall shear stress parameter, a rupture potential parameter of the blood vessel, the rupture potential parameter being indicative of a state of weakening of at least one region of the blood vessel.
12. The system of claim 11 , wherein the generating the blood flow parameter comprises one of:
generating a computational flow dynamics (CFD) simulation of blood flow in the lumen to obtain the respective set of blood flow values in the lumen for the cardiac cycle; and
performing a 4D-flow MRI acquisition to obtain the respective set of blood flow values in the lumen for the cardiac cycle.
13. The system of claim 11 , wherein the processor is further configured for, prior to the calculating the wall strain parameter:
determining, based on each phase of the multiphase stack and the surface mesh of the outer wall, a local deformation at each phase of the surface mesh; and wherein
the calculating the wall strain parameter is based on the local deformation at each phase of the surface mesh.
14. The system of claim 11 , wherein the thickness parameter is determined based on: a distance between the surface mesh of the outer wall and the surface mesh of the lumen.
15. The system of claim 11 , wherein the processor is further configured for, prior to the determining the regional rupture potential parameter:
receiving a population-based thickness parameter, a population-based wall strain parameter, and a population-based wall shear stress parameter; and wherein
the determining the regional rupture potential parameter is further based on the population-based thickness parameter, the population-based wall strain parameter, and the population-based wall shear stress parameter.
16. The system of claim 11 , wherein the processor is further configured for, prior to the estimating the rupture potential parameter:
defining a plurality of patches on the blood vessel; wherein
the calculating the thickness parameter, the wall strain parameter, and the wall shear stress parameter, comprises calculating a patch-averaged thickness parameter, a patch-averaged wall strain parameter and a patch-averaged wall shear stress parameter using the plurality of patches; and wherein
the regional rupture potential parameter is based on the patch-averaged thickness parameter, the patch-averaged wall strain parameter and the patch-averaged wall shear stress parameter.
17. The system of claim 16 , wherein the calculating the patch-averaged thickness parameter, the patch-averaged wall strain parameter and the patch-averaged wall shear stress parameter is further based on the population-based thickness parameter, the population-based wall strain parameter, and the population-based wall shear stress parameter.
18. The system of claim 17 , wherein the processor is further configured for determining respective distribution quartiles for each of the patch-averaged thickness parameter, the patch-averaged wall strain parameter and the patch-averaged wall shear stress parameter.
19. The system of claim 18 , wherein the processor is further configured for classifying each of the patch-averaged thickness parameter, the patch-averaged wall strain parameter and the patch-averaged wall shear stress parameter based on the respective distribution quartiles.
20. The system of claim 11 , wherein the rupture potential parameter is determined based on:
RRP
=
[
ILT
category
+
S
TRAIN
category
+
(
5
-
TAWS
S
category
)
]
-
3
9
·
100
where ILT category is a respective category assigned to the thickness parameter,
STRAIN category is a respective category assigned to the wall strain parameter, and
TAWSS category is a respective category assigned to the wall shear stress parameter.