FFR Calculation Using Geometric Derivative Functions
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Solution Overview
Problem
Current methods for computing pressure drop and fractional flow reserve (FFR) in blood vessels are invasive, costly, and inaccurate, especially for complex lesions, as they require extensive computation and manual assessment, and fail to distinguish between different degrees of stenosis severity.
Innovation Solution
A novel method that computes pressure drop by receiving geometrical parameters and mean blood velocity, using multiple scales of derivative difference functions to account for focal and diffuse lesions, and calculates FFR based on pressure deviations, allowing for fast and accurate FFR calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If computational fluid dynamic analysis is performed on a geometrical model of a reconstructed coronary system, then pressure drop and FFR can be calculated, but the computation involves a great amount of computation to solve complex fluid dynamic equations
Solution Approach 1:
The patent replaces complex computational fluid dynamic simulations with a mathematical model based on the simplified Bernoulli equation. This substitution eliminates the need for complex numerical computations while maintaining the ability to calculate pressure drop and FFR accurately, thus resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent changes the approach from solving complex fluid dynamic equations to using a simplified mathematical relationship between pressure, velocity, and geometric parameters. By transforming the problem into a parameter-based calculation rather than a full CFD simulation, the system achieves accurate pressure drop measurement without the computational burden of solving complex differential equations.
2Measurement precision
If pressure is measured invasively by a wire with pressure sensor, then direct pressure data is obtained, but the intervention involves a significant amount of work and is associated with a risk of damaging the vessel
Solution Approach 1:
The patent creates a virtual copy of the coronary system using geometrical models derived from angiography images. Instead of physically inserting sensors into the vessel, the system reconstructs a digital replica of the coronary anatomy and performs calculations on this model. This copying approach eliminates the invasive procedure and associated vessel damage risk while maintaining the ability to obtain accurate pressure measurement data through computational methods.
Solution Approach 2:
The patent introduces an intermediary computational model that mediates between the goal of obtaining pressure data and the harmful invasive procedure. The geometrical model serves as an intermediary representation that allows pressure calculations to be performed without direct physical contact with the vessel, thus eliminating the harmful effect of vessel damage while preserving measurement accuracy.
3Quantity of substance
If manual assessment of stenosis length and degree is performed, then geometrical parameters can be obtained, but the subjectivity in determining the length and degree of stenosis leads to inaccurate results, particularly in diffuse intermediate stenosis
Solution Approach 1:
The patent enables the system to automatically extract geometrical parameters from angiography images through computational algorithms. Instead of relying on manual assessment by operators, the system performs self-service extraction of stenosis characteristics, including length and degree, using image processing techniques. This automation eliminates subjectivity and improves measurement precision, particularly for diffuse intermediate stenosis where manual assessment is most prone to error.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables fast and accurate computation of pressure drop and FFR, effectively addressing the limitations of existing technologies by accounting for different stenosis severities and reducing computational complexity and invasiveness.
Implementation Method 1
a pressure deviation between a first blood flow pressure at the proximal end and a second blood flow pressure at the first location is determined
Data Source
AI summary
A method for computing fractional flow reserve (FFR), including receiving geometrical parameters of a blood vessel segment including a proximal end and a distal end, the geometrical parameters including a first geometrical parameter, a second geometrical parameter and a third geometrical parameter; and with the proximal end as a reference point, deriving a reference lumen diameter function and a geometrical parameter difference function based on the geometrical parameters and the distance from the position along the segment of blood vessel to the reference point. Derivatives of the geometrical parameter difference function are calculated in multiple scales. FFR is computed as a ratio of a second blood flow pressure at the first location of the blood vessel to a first blood flow pressure at the proximal end of the segment based on the multiple scales of derivative difference functions and the maximum mean blood flow velocity.