Diagnostically useful results in real time
A method and apparatus for vascular assessment are disclosed. The apparatus, in some embodiments, receives a plurality of 2-D angiographic images of a portion of a vasculature of a subject, and processes the images to produce a stenotic model over the vasculature. The stenotic model has measurements of the vasculature at one or more locations along vessels of the vasculature. The apparatus, in some embodiments, determines a flow characteristic of the stenotic model and calculates an index indicative of vascular function, based, at least in part, on the flow characteristic in the stenotic model.
1. A computer-implemented method comprising:
receiving, via a processor from a medical imaging device, a medical image of a coronary vessel tree of a subject;
calculating, via the processor, a plurality of geometric measurements associated with individual portions of a vascular segment of the coronary vessel tree;
determining, via the processor, a plurality of resistances associated with the plurality of geometric measurements associated with the individual portions of the vascular segment;
determining, via the processor, a plurality of pressure drops across the individual portions of the vascular segment based on the determined resistances and a calculated or estimated blood flow; and
calculating, via the processor, based on the plurality of pressure drops, a functional index indicative of a presence or an absence of a stenosis within the vascular segment.
2. The method of claim 1 , wherein the geometric measurements associated with the individual portions of the vascular segment include at least one of a radius or a diameter at the individual portions of the vascular segment.
3. The method of claim 1 , wherein for at least some of the individual portions of the vascular segment, a plurality of resistances is combined to form a total resistance, and wherein an individual pressure drop is determined, via the processor, based on the total resistance.
4. The method of claim 3 , wherein the total resistance is a sum of the determined resistances for the individual portion of the vascular segment.
5. The method of claim 3 , wherein the functional index is calculated based on a sum of the individual pressure drops.
6. The method of claim 1 , further comprising determining, via the processor, a blood viscosity resistance for each of the individual portions of the vascular segment.
7. The method of claim 1 , wherein the plurality of pressure drops for at least some of the individual portions of the vascular segment is determined, via the processor, based on a blood viscosity resistance that is determined according to a Poiseuille formulation and a resistance due to at least one of bifurcations, constrictions, or curvatures is determined, via the processor, according to a Darcy-Weisbach formulation.
8. The method of claim 1 , wherein the plurality of pressure drops for at least some of the individual portions of the vascular segment are determined, via the processor, based on a blood viscosity resistance that is calculated at least in part by multiplying a blood viscosity (μ) by a length of the vessel segment (L) and a calculated or estimated blood flow (Qi), and dividing a product thereof by a radius or diameter (di) of the vessel segment raised to a fourth power.
9. The apparatus of claim 8 , wherein the plurality of pressure drops for at least some of the individual portions of the vascular segment are determined, via the processor, at least in part based on the following relation:
Δ P t =120μL i /πd i 4 Q i .
10. The method of claim 8 , wherein at least some of the plurality of pressure drops for at least some of the individual portions of the vascular segment are adjusted respectively based on calculated pressure drops due to at least one of bifurcations, constrictions, or curvatures of the vessel segment at a location of the calculated pressure drop.
11. The method of claim 1 , further comprising causing, via the processor, the functional index to be displayed.
12. A non-transitory computer storage media storing instructions, which when executed by a system of one or more processors, cause the one or more processors to:
obtain an image of a vascular system, the image depicting a vascular segment;
calculate a plurality of geometric measurements associated with individual portions of the vascular segment;
determine a plurality of pressure drops across the individual portions of the vascular segment, wherein each of the plurality of pressure drops is determined based on resistances associated with the geometric measures and a calculated or estimated blood flow; and
calculate, based on the plurality of pressure drops, a functional index associated with stenosis of the vascular segment.
13. The computer storage media of claim 12 , wherein the instructions further cause the one or more processors to display the functional index.
14. The computer storage media of claim 12 , wherein the geometric measures are respective radii or diameters of the portions of the vascular segment.
15. The computer storage media of claim 12 , wherein for at least some of the individual portions of the vascular segment, a plurality of resistances are combined to form a total resistance, and wherein an individual pressure drop is determined based on the total resistance.
16. The computer storage media of claim 15 , wherein the plurality of resistances that are combined to form a total resistance comprise a blood viscosity resistance according to the Poiseuille formulation and a resistance due to at least one of bifurcations, constrictions or curvatures according to the Darcy-Weisbach formulation.
17. The computer storage media of claim 12 , wherein the plurality of pressure drops for at least some of the individual portions of the vascular segment are determined, via the processor, based on a blood viscosity resistance that is calculated at least in part by multiplying a blood viscosity (μ) by a length of the vessel segment (L) and a calculated or estimated blood flow (Qi), and dividing a product thereof by a radius or diameter (di) of the vessel segment raised to a fourth power.
18. The computer storage media of claim 17 , wherein the plurality of pressure drops for at least some of the individual portions of the vascular segment are determined, via the processor, at least in part based on the following relation:
Δ P t =120μ L i /πd i 4 Q i .
19. The computer storage media of claim 17 , wherein at least some of the plurality of pressure drops for at least some of the individual portions of the vascular segment are adjusted respectively based on calculated pressure drops due to at least one of bifurcations, constrictions, or curvatures of the vessel segment at a location of the calculated pressure drop.
20. The computer storage media of claim 12 , wherein the image of a vascular system includes at least one of computerized tomography (CT) images or an angiographic image.