Angiographic Blood Flow Evaluation Using Synchronized Contrast Fronts
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Solution Overview
Problem
Physicians skeptical of angiographic techniques for measuring blood flow parameters due to perceived unreliability, hindering their adoption despite lower procedural complexity compared to invasive methods.
Innovation Solution
A system that processes angiographic image data to calculate transit times or velocities in different haemodynamic states, generating synchronized angiograms to depict front motion, providing insights into the reliability of blood flow parameter calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Doppler ultrasound methods are used to measure blood flow velocity, then non-invasive measurement is achieved, but velocity resolution is insufficient for detecting slow flow and reflux
Solution Approach 1:
The measurement process is segmented into two distinct phases: a mapping pass that collects raw data over a larger region, and a reconstruction pass that processes this data to generate velocity information. This segmentation allows optimization of each phase independently, enabling high-resolution velocity measurement through sophisticated post-processing of the collected data.
Solution Approach 2:
A computer is introduced as an intermediary between the ultrasound transducer and the measurement output. The computer performs complex signal processing, including cross-correlation analysis of radiofrequency echo signals, to extract velocity information that cannot be directly obtained through conventional ultrasound display methods.
2Measurement precision
If conventional ultrasound imaging is used, then real-time visualization is achieved, but quantitative blood flow parameter measurement is not possible
Solution Approach 1:
Raw radiofrequency echo data is collected during a mapping pass before any velocity calculations are performed. This preliminary data collection phase stores the complete signal information needed for subsequent velocity reconstruction, allowing quantitative measurement without requiring real-time processing during the actual measurement acquisition.
Solution Approach 2:
The system continuously collects echo signals during the mapping pass, accumulating data that will be used for velocity reconstruction. This continuous data collection ensures that all necessary information is captured for accurate quantitative measurement, maintaining the utility of the measurement process throughout the data acquisition phase.
3Measurement precision
If high-frequency ultrasound waves are used, then spatial resolution is improved, but penetration depth is reduced
Solution Approach 1:
The system changes the operational parameters of the ultrasound transducer dynamically, switching between different center frequencies (e.g., 2.5 MHz for deep penetration, 7.5 MHz for high resolution) depending on the specific measurement requirements. This parameter adjustment allows optimization of both spatial resolution and penetration depth for different vascular imaging scenarios.
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
Enhances the reliability of angiographically-derived blood flow parameter measurements, allowing physicians to assess the physiological soundness of calculated values.
Implementation Method 1
a transducer is used to emit ultrasound waves into the body and receive echo signals
Implementation Method 2
cross-correlating a pair of radiofrequency (RF) echo signals to determine velocity information
Data Source
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AI summary
A system (100) for evaluating blood flow parameters includes one or more processors (110). The processor(s) analyse angiographic image data (120) representing a motion of a front (1301, 1302) of an injected contrast agent along a vessel (140) in each of a first haemodynamic state and a second haemodynamic state, to determine a transit time, or a transit velocity, for the vessel (140) in each state. A value of one or more blood flow parameters (160) for the vessel (140) is output. The value of the blood flow parameter(s) is calculated based on the values of the transit times or the values of the transit velocities. Sequences of first and second angiograms (1701, 1702) depict the motion of the fronts (1301, 1302) along the vessel (140) in the first haemodynamic state and the second haemodynamic state, respectively. The angiogram sequences are synchronised such that the fronts in both angiograms simultaneously leave the proximal position (150p) in the vessel.