Apparatus for determining a functional index for stenosis assessment

A non-transitory computer-readable medium having stored thereon a computer program for:

• determining a geometric model of a vessel comprising a stenosis, wherein the geometric model comprises an inner diameter and a change of the inner diameter along a course of the vessel, wherein the change of the inner diameter is representative of the stenosis;
• determining a resistance value of the vessel based on the geometric model;
• determining a functional index for stenosis assessment corresponding to a flow of a fluid through the vessel, wherein the functional index for stenosis assessment is equivalent to a pressure drop of the fluid across the stenosis, wherein the functional index for stenosis assessment is determined based on:
• the resistance value;
• and
• a boundary condition comprising at least one of:
• a volumetric flow rate associated with an inlet of the vessel;
• the volumetric flow rate associated with an outlet of the vessel;
• a pressure associated with the inlet;
• or
• the pressure associated with the outlet;
• and
• outputting, on a display, an indication of the functional index for stenosis assessment,
• wherein the functional index for stenosis assessment is distinct from the inner diameter and the change of the inner diameter.