Angiography Pulsatility Compensation for Reproducible Flow
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Solution Overview
Problem
Current methods for estimating pulsatility from angiographic image sequences lack reproducibility and reliability, making it difficult for physicians to accurately assess blood flow and compare pre- and post-treatment parameters, especially due to the influence of heart pulsatility on contrast agent dynamics.
Innovation Solution
A system and method that measures pulsatility from angiographies using contrast agent density variations, incorporating a model that accounts for the mixing and transport of blood and contrast agent under pulsatile conditions, with optional ECG signal integration to adjust heart cycle phases, allowing for time-axis transformation to reduce heartbeat dependency and enable reproducible blood flow assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If contrast agent injection is performed during angiography to visualize blood flow, then blood flow visualization is improved, but the measurement reliability deteriorates due to pulsatility-dependent contrast agent dynamics
Solution Approach 1:
The system extracts time-intensity curves from angiographic images and uses them as feedback to iteratively optimize model parameters characterizing pulsatility. This closed-loop approach allows the system to adapt the pulsatility model to the actual observed contrast agent dynamics in each patient, thereby improving measurement reliability while maintaining visualization quality
Solution Approach 2:
The invention changes the parameters of the pulsatility model by extracting time-intensity curves from actual angiographic data and using these to determine optimized model parameters. This allows the system to adapt to individual patient variations in pulsatility patterns, resolving the contradiction between visualization and measurement reliability
2Measurement precision
If pulsatility is measured from contrast agent density variations, then pulsatility estimation is achieved, but reproducibility deteriorates due to dependency on heart cycle phase at injection
Solution Approach 1:
The system performs preliminary extraction of time-intensity curves from the angiographic images before final pulsatility measurement. These curves serve as preliminary data that constrain and guide the optimization of pulsatility model parameters, ensuring that measurements are consistent with observed contrast agent behavior regardless of injection timing
Solution Approach 2:
The invention introduces dynamic adaptation of the pulsatility model by using observed time-intensity curves to determine optimal model parameters for each measurement. This dynamic approach allows the system to account for variations in heart cycle phase and injection timing, thereby improving reproducibility while maintaining measurement precision
3Ease of operation
If contrast agent injection timing is arbitrary, then injection simplicity is improved, but comparison capability deteriorates due to phase dependency of bolus propagation
Solution Approach 1:
The system uses time-intensity curves extracted from angiographic images as feedback to determine the optimal phase of the cardiac cycle for contrast agent injection. By analyzing the observed contrast agent dynamics, the system can identify injection timing that maximizes comparability across different measurements while maintaining operational simplicity
Solution Approach 2:
The system performs preliminary analysis of time-intensity curves to determine optimal injection timing parameters before actual contrast agent injection. This preliminary characterization of pulsatility allows the system to plan injection timing that ensures comparability, while the actual injection process remains simple and automated
Data Source
AI summary
A system, apparatus and method are provided for measuring and removing the influence of pulsatility on contrast agent flow in a region of interest of a vascular system of a patient. Once the change of blood speed over the cardiac cycle is known (pulsatility), this influence is removed from acquired image sequence for outcome control such that “quasi-stationary”, regular flow acquisition is passed on to subsequent visualization and analysis processes. A contrast agent injector is also provided that simultaneously measures and uses ECG to inject a known contrast agent at a fixed point over the cardiac cycle or such that a known amount of contrast agent will arrive at a known time at a region of interest in the vasculature of a patient, thus controlling one of the main unwanted variables in an acquisition of blood flow sequences.