Apparatus for determining a functional index for stenosis assessment
An apparatus for determining a functional index for stenosis assessment of a vessel is provided. The apparatus comprises an input interface ( 40 ) and a processing unit ( 50 ). The input interface is configured to obtain image data ( 30 ) representing a two-dimensional representation of a vessel ( 6 ). The processing unit ( 50 ) is configured to determine a course of the vessel ( 6 ) and a width (w 1, w 2 ) of the vessel along its course in the image data and is further configured to determine the functional index for stenosis assessment of the vessel based on the width of the vessel in the image data.
1. An apparatus, comprising:
an input interface; and
a processing unit,
wherein the input interface is configured to obtain image data of at least a section of a vessel, wherein the image data comprises a single two-dimensional (2D) representation of at least the section of the vessel, and
wherein the processing unit is configured to generate, based on the single 2D representation, a functional index for stenosis assessment corresponding to a fluid flow through at least the section of the vessel,
wherein, to generate the functional index for stenosis assessment, the processing unit is configured to:
determine a geometric model of at least the section of the vessel based on the image data, wherein the geometric model comprises an inner diameter and a change of the inner diameter along a course of at least the section of the vessel, wherein the functional index for stenosis assessment is distinct from the inner diameter and the change of the inner diameter;
determine a resistance value of at least the section of the vessel based on the geometric model; and
determine the functional index for stenosis assessment based on:
the resistance value; and
a boundary condition comprising at least one of:
a volumetric flow rate associated with an inlet of at least the section of the vessel;
the volumetric flow rate associated with an outlet of at least the section of the vessel;
a pressure associated with the inlet; or
the pressure associated with the outlet.
2. The apparatus of claim 1 , wherein the processing unit is configured to:
apply a densitometry method to the image data to compensate for foreshortening effects in the image data when determining a width of the vessel.
3. The apparatus of claim 1 , wherein the processing unit is configured to:
apply a scaling factor to a width of the vessel in the image data; and
determine the functional index for stenosis assessment based on the width multiplied by the scaling factor.
4. The apparatus of claim 3 , wherein the processing unit is configured to:
receive a distance of the vessel from an image plane of the image data; and
determine the scaling factor based on the distance.
5. The apparatus of claim 3 , wherein the processing unit is configured to:
segment the vessel along a course of the vessel such that there are multiple vessel segments; and
apply a specific scaling factor to the width of each one of the multiple vessel segments.
6. The apparatus of claim 5 , wherein the processing unit is configured to segment the vessel based on a distance between a vessel segment and a projection surface.
7. The apparatus of claim 3 , wherein the processing unit is configured to:
detect a reference element within the image data; and
determine the scaling factor based on a known size of the reference element and the size of the reference element in the image data.
8. The apparatus of claim 1 , wherein the processing unit is configured to:
independently derive a respective functional index for stenosis assessment from a corresponding one of a plurality of 2D representations.
9. The apparatus of claim 8 , wherein the processing unit is configured to:
determine a variation between the respective functional indices for stenosis assessment from different ones of the plurality of 2D representations;
compare the variation to a predetermined maximal variation; and
generate an acceptance criterion based on the comparison.
10. The apparatus of claim 1 , wherein the processing unit is configured to calculate a quality score for the single 2D representation.
11. The apparatus of claim 1 , wherein the processing unit is configured to determine the functional index for stenosis assessment using a lumped element fluid dynamics model including the resistance value and the boundary condition.
12. The apparatus of claim 1 , wherein the single 2D representation comprises a projection image.