Non-invasive Pressure Drop Estimation via WERP Analysis
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Solution Overview
Problem
Current methods for estimating pressure drop in blood vessels, such as catheter measurements and Doppler echocardiography, are invasive, costly, and limited by operator dependence and mathematical assumptions, necessitating the development of non-invasive and more accurate techniques.
Innovation Solution
A semi-automatic method based on the Work-Energy Relative Pressure (WERP) principle, which uses 4D PC-MRI or echocardiography data to estimate pressure differences by integrating kinetic, advective, and viscous energy rates, and can be simplified for use with 2D or 3D Doppler echocardiographic images, reducing data requirements and improving accessibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If catheter measurements are used for pressure drop estimation, then measurement precision is improved, but ease of operation deteriorates due to invasiveness and associated risks
Solution Approach 1:
The patent replaces the mechanical catheter-based pressure measurement system with a non-invasive imaging-based system. Specifically, it uses 4D flow MRI or echocardiography to obtain velocity fields, then applies the WERP formulation (a fluid dynamics equation) to compute pressure differences from these velocity measurements, eliminating the need for invasive catheter insertion while maintaining measurement capability
Solution Approach 2:
The patent introduces velocity field measurements as an intermediary quantity. Instead of measuring pressure directly (which requires catheters), the system measures blood flow velocity non-invasively using imaging modalities, then uses the WERP equation to derive pressure differences from these velocity measurements, serving as a bridge between non-invasive observation and pressure assessment
2Ease of operation
If Doppler echocardiography is used for pressure difference estimation, then ease of operation is improved, but measurement precision deteriorates due to operator dependence and mathematical assumptions
Solution Approach 1:
The patent transitions from static or simplified pressure estimation methods to a dynamic approach that utilizes time-dependent velocity fields. The WERP formulation incorporates temporal derivatives of kinetic energy and accounts for unsteady flow conditions, allowing the system to capture the dynamic nature of blood flow and improve accuracy under varying flow conditions rather than relying on steady-state assumptions
Solution Approach 2:
The patent advances from one-dimensional Doppler velocity measurements to three-dimensional velocity field characterization. By utilizing 4D flow MRI or 3D echocardiography data that captures velocity vectors in all spatial directions, the system obtains comprehensive flow information that eliminates operator dependence on beam alignment and enables more accurate pressure difference calculation through the full WERP formulation
3Measurement precision
If 4D PC-MRI data is used for pressure difference estimation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the complex WERP computation into distinct, manageable components: (1) acquisition of 4D velocity field data from imaging modalities, (2) calculation of kinetic energy and its temporal derivative, (3) calculation of advective energy rate using velocity gradients, (4) calculation of viscous dissipation rate, and (5) integration of all components in the WERP equation to obtain pressure differences. This segmentation allows each component to be computed independently using standard numerical methods
Solution Approach 2:
The patent enables the system to self-sufficiently compute all necessary parameters from the acquired velocity field data without requiring additional invasive measurements or complex external equipment. The velocity field contains all information needed to calculate kinetic energy, advective effects, viscous dissipation, and ultimately pressure differences, allowing the computational system to derive complete hemodynamic information from a single non-invasive imaging dataset
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
The WERP method provides accurate and operator-independent pressure difference estimates, enhancing the non-invasive assessment of cardiovascular conditions by leveraging widely available imaging modalities and reducing computational complexity, thus broadening patient accessibility and improving diagnostic accuracy.
Implementation Method 1
A first example useful to understand the claimed invention there is provided a method of determining pressure difference across a tube arising from fluid flow within the tube, comprising: obtaining three-dimensional time dependent fluid velocity data at a plurality of points along the tube; processing the three-dimensional time dependent fluid velocity data to determine: i) a flow rate (Q) of the fluid through the tube; ii) the kinetic energy (K) of the fluid flow through the tube; iii) an advective energy rate (A) of the fluid flow through the tube; and iv) a viscous dissipation rate (V) pertaining to the fluid flow; and calculating the pressure difference in dependence on all of the flow rate (Q), kinetic energy (K), advective energy rate (A), and viscous dissipation rate (V).
Data Source
Figure 1~1(B)
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AI summary
Embodiments of the invention provide a method of determining pressure difference across a tube arising from fluid flow within the tube, comprising: obtaining three- dimensional time dependent fluid velocity data at a plurality of points along the tube; processing the three-dimensional time dependent fluid velocity data to determine: i) a flow rate (Q) of the fluid through the tube; ii) the kinetic energy (K) of the fluid flow through the tube; iii) an advective energy rate (A) of the fluid flow through the tube; and iv) a viscous dissipation rate (V) pertaining to the fluid flow; and calculating the pressure difference in dependence on all of the flow rate (Q), kinetic energy (K), advective energy rate (A), and viscous dissipation rate (V). Further embodiments are also described.