Blood Flow Velocity Normalization Using Cardiac Cycle
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Solution Overview
Problem
Conventional methods for determining blood flow velocity in vessels, such as X-ray angiography and virtual Fractional Flow Reserve, do not accurately account for variations throughout the cardiac cycle, leading to inaccurate assessments and potential overestimation of coronary lesion significance, which can result in unnecessary interventions.
Innovation Solution
A method and system that normalize blood flow velocity with respect to a complete cardiac cycle by using a 3D model of the vessel, specifying a segment with start and termination landmarks, and calculating average velocity based on segment length and perfusion time, without requiring additional modalities beyond X-ray angiogram sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional frame count method is used to calculate blood flow velocity, then the calculation process is simple, but the measurement precision is poor because it does not account for cardiac cycle variations
Solution Approach 1:
The patent applies dynamics by transitioning from a static frame count method to a dynamic normalization process that accounts for cardiac cycle variations. The blood flow velocity calculation is normalized to a reference cardiac cycle, allowing the measurement to adapt to the periodic nature of blood flow while maintaining a systematic calculation approach.
Solution Approach 2:
The patent changes the parameter of blood flow velocity from a raw frame-count-based value to a normalized value that is adjusted according to cardiac cycle characteristics. This parameter transformation enables the measurement to reflect physiological variations while preserving the simplicity of the original method.
2Measurement precision
If invasive pressure measurements are used to obtain FFR, then the functional blood flow assessment is accurate, but the device complexity and patient risk increase
Solution Approach 1:
The patent creates a virtual copy of the invasive FFR measurement process by using non-invasive X-ray angiography images to calculate blood flow velocity. The normalized velocity data serves as a surrogate for direct pressure measurements, providing functional assessment information without physical intrusion.
Solution Approach 2:
The patent replaces the mechanical invasive pressure measurement system with a computational approach based on image analysis. Instead of physically inserting wires to measure pressure, the system uses optical images and mathematical normalization to derive functional blood flow information.
3Measurement precision
If additional imaging modalities are used to improve blood flow velocity accuracy, then the measurement precision improves, but the device complexity and cost increase
Solution Approach 1:
The patent makes the existing X-ray angiography system multi-functional by extracting both anatomical information (vessel geometry) and functional information (blood flow velocity) from the same images. The normalization process enables the standard imaging modality to provide comprehensive diagnostic data without additional equipment.
Data Source
AI summary
Method, system, device and medium for determining a blood flow velocity in a vessel are provided. An example method includes receiving a 3D model of the vessel, which is reconstructed based on X-ray angiography images of the vessel. The method further includes specifying a segment of the 3D model by a start landmark and a termination landmark. Moreover, the method includes determining the blood flow velocity based on length of the segment and perfusion time for the segment by normalizing the blood flow velocity to correspond to a cardiac cycle. The method has a better accuracy in calculating blood flow velocity, and requires no additional modalities other than the original X-ray angiogram sequences used to visualize coronary arteries.