Diagnostically useful results in real time
A method and apparatus for vascular assessment are disclosed. The apparatus, in some embodiments, receives, from a medical imaging device, a medical image of a coronary vessel tree of a subject and calculates a plurality of geometric measurements associated with individual portions of a vascular segment of the coronary vessel tree. The apparatus also determines a plurality of resistances associated with the plurality of geometric measurements associated with the individual portions of the vascular segment and determines 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. The apparatus further calculates based on the plurality of pressure drops, a functional index indicative of a presence or an absence of a stenosis within the vascular segment.
1. A vascular assessment apparatus comprising:
a processor configured to be communicatively coupled to a medical imaging device; and
a memory storing non-transitory computer-readable instructions, which when executed, cause the processor to:
receive, from the medical imaging device, medical images of a coronary vessel tree of a subject;
analyze the medical images to identify vessel segments within the coronary vessel tree including vessel segments that are located before or after at least one of bifurcations or trifurcations of the coronary vessel tree;
for each identified vessel segment:
analyze portions of the vessel segment to determine at least (i) a length and (ii) a radius or a diameter of the vessel segment at the analyzed portions, and
determine a pressure drop in the vessel segment at least in part based on a blood viscosity resistance,
wherein the pressure drop determination for at least some of the vessel segments is adjusted by summing a blood viscosity resistance with an additional resistance due to at least one of bifurcations, constrictions, or curvatures of the vessel segment;
calculate an index indicative of vascular function, based, at least in part, on a combination of the determined pressure drops for the identified vessel segments; and
cause the index indicative of vascular function to be displayed.
2. The apparatus of claim 1 , wherein the blood viscosity resistance is calculated at least in part by multiplying a blood viscosity (μ) by the length of the vessel segment (L i ) and a calculated or estimated blood flow (Q i ), and dividing a product thereof by the radius or diameter (d i ) of the vessel segment raised to a fourth power.
3. The apparatus of claim 2 , wherein the pressure drop for each vessel segment is determined at least in part based on the following relation:
Δ
P
t
=
128
μ
L
t
π
d
t
4
Q
t
.
4. The apparatus of claim 1 , wherein the additional resistance (R) is calculated according to the following Darcy-Weisbach formulation:
R
=
(
8
ρ
n
2
d
t
4
∑
K
t
)
Q
t
,
where p is a blood density and K t is a loss coefficient.
5. The apparatus of claim 1 , further comprising a user interface communicatively coupled to the processor and configured to display the index indicative of vascular function.
6. The apparatus of claim 1 , wherein the index indicative of vascular function includes fractional flow reserve (“FFR”) values.
7. A vascular assessment apparatus comprising:
a processor configured to be communicatively coupled to a medical imaging device; and
a memory storing non-transitory computer-readable instructions, which when executed,
cause the processor to:
receive, from the medical imaging device, a medical image of a coronary vessel tree of a subject,
calculate a plurality of geometric measurements associated with individual portions of a vascular segment of the coronary vessel tree,
determine a plurality of resistances associated with the plurality of geometric measurements associated with the individual portions of the vascular segment,
determine 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
calculate based on the plurality of pressure drops, a functional index indicative of a presence or an absence of a stenosis within the vascular segment.
8. The apparatus of claim 7 , 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.
9. The apparatus of claim 7 , 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 the processor is configured to determine an individual pressure drop based on the total resistance.
10. The apparatus of claim 9 , wherein the total resistance is a sum of the determined resistances for the individual portion of the vascular segment.
11. The apparatus of claim 9 , wherein the functional index is calculated based on a sum of the individual pressure drops.
12. The apparatus of claim 7 , wherein the processor is further configured to determine a blood viscosity resistance for each of the individual portions of the vascular segment.
13. The apparatus of claim 7 , wherein the processor is configured to determine the plurality of pressure drops for at least some of the individual portions of the vascular segment based on a blood viscosity resistance that is calculated according to a Poiseuille formulation and a resistance due to at least one of bifurcations, constrictions, or curvatures that is calculated according to a Darcy-Weisbach formulation.
14. The apparatus of claim 7 , wherein the processor is configured to determine the plurality of pressure drops for at least some of the individual portions of the vascular segment 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 i ) and a calculated or estimated blood flow (Q t ), and dividing a product thereof by a radius or diameter (d i ) of the vessel segment raised to a fourth power.
15. The apparatus of claim 14 , 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
=
128
μ
L
t
π
d
t
4
Q
t
.
16. The apparatus of claim 14 , wherein the processor is configured to adjust at least some of the plurality of pressure drops for at least some of the individual portions of the vascular segment based on calculated pressure drops due to at least one of bifurcations, constrictions, or curvatures of the vessel segment at a respective location of the calculated pressure drop.
17. The apparatus of claim 7 , wherein the processor is configured to cause the functional index to be displayed.
18. A computer-implemented method comprising:
receiving, via a processor from a medical imaging device, medical images of a coronary vessel tree of a subject;
analyzing, via the processor, the medical images to identify vessel segments within the coronary vessel tree including vessel segments that are located before or after at least one of bifurcations or trifurcations of the coronary vessel tree;
for each identified vessel segment:
analyzing, via the processor, portions of the vessel segment to determine at least (i) a length and (ii) a radius or a diameter of the vessel segment at the analyzed portions, and
determining, via the processor, a pressure drop in the vessel segment at least in part based on a blood viscosity resistance,
wherein the pressure drop determination for at least some of the vessel segments is adjusted by summing a blood viscosity resistance with an additional resistance due to at least one of bifurcations, constrictions, or curvatures of the vessel segment;
calculating, via the processor, an index indicative of vascular function, based, at least in part, on a combination of the determined pressure drops for the identified vessel segments; and
causing, via the processor, the index indicative of vascular function to be displayed.
19. The method of claim 18 , wherein the blood viscosity resistance is calculated at least in part by multiplying a blood viscosity (μ) by the length of the vessel segment (L i ) and a calculated or estimated blood flow (Q i ), and dividing a product thereof by the radius or diameter (d i ) of the vessel segment raised to a fourth power.
20. The method of claim 19 , wherein the pressure drop for each vessel segment is determined at least in part based on the following relation:
Δ
P
t
=
128
μ
L
t
π
d
t
4
Q
t
.
21. The method of claim 18 , wherein the additional resistance (R) is calculated according to the following Darcy-Weisbach formulation:
R
=
(
8
ρ
n
2
d
t
4
∑
K
t
)
Q
t
,
where p is a blood density and K i is a loss coefficient.