Bolus Function Initialization for Perfusion Assessment
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Solution Overview
Problem
Existing diagnostic methods using contrast agents in ultrasound imaging struggle to accurately model the second passage of contrast agents, leading to errors in perfusion parameter calculations due to the limitations of simple bolus functions, especially when the second passage occurs before the first passage is complete, resulting in unreliable and unstable fitting algorithms.
Innovation Solution
A data-processing method that initializes fitting parameters for a combined bolus function, consisting of a first and second simple bolus function, with a delay parameter, to accurately model both passages of the contrast agent, using a truncated mean transit time to set initial values and constraints for the fitting parameters, thereby stabilizing the fitting process and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple bolus function is used to model contrast agent passage, then the model is simple and easy to fit, but it cannot accurately model the second passage when it occurs before the first passage is complete, leading to errors in perfusion parameter calculations
Solution Approach 1:
The patent divides the contrast agent passage into multiple segments by using a combined bolus function that sums a first simple bolus function (for the first passage) and a second simple bolus function (for the second passage). This segmentation allows each function to model its respective passage independently, improving accuracy without overwhelming complexity
Solution Approach 2:
The patent performs preliminary action by estimating the peak instant of the combined bolus function and using this estimate to define a truncation interval. This preliminary step simplifies the fitting process by focusing on the most relevant time window before the second passage significantly interferes with the first passage modeling
2Adaptability or versatility
If the second passage is modeled without initialization, then the fitting algorithm can process any data, but the fitting becomes unstable and unreliable when passages overlap
Solution Approach 1:
The patent performs preliminary action by estimating the peak instant and using it to define a truncation interval before the actual fitting. This preliminary action provides a stable foundation for the fitting algorithm by establishing clear temporal boundaries, preventing instability during the fitting process
Solution Approach 2:
The patent uses feedback by calculating the truncated mean transit time from the fitted first passage and using this value to initialize the parameters of the second bolus function. This feedback loop ensures the second passage modeling is based on actual data from the first passage, improving reliability
3Productivity
If fitting parameters are not initialized using truncated mean transit time, then the fitting process is faster, but accuracy of perfusion parameter calculations deteriorates
Solution Approach 1:
The patent performs preliminary action by first fitting the first simple bolus function to obtain the peak instant and truncated mean transit time, then uses these values to initialize the combined bolus function parameters. This preliminary calculation provides accurate initialization without requiring a complete re-fit, balancing speed and precision
Solution Approach 2:
The patent applies parameter changes by transforming the truncated mean transit time into specific initialization values for the second bolus function parameters (amplitude, mean, standard deviation). This parameter transformation enables accurate modeling while maintaining computational efficiency
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 approach allows for precise modeling of both passages of the contrast agent, reducing errors in perfusion parameter calculations and enhancing the accuracy of blood perfusion analysis, even in cases where the second passage overlaps with the first, thereby improving the quality of diagnostic assessments.
Implementation Method 1
The contrast agent acts as an efficient ultrasound reflector, and it can be easily detected by applying ultrasound waves and measuring echo signals that are returned in response thereto
Data Source
AI summary
An embodiment includes analyzing a body part perfused with a contrast agent, which has been pre-administered as a bolus to circulate through the body-part with at least a first passage during an analysis interval. The analyzing includes providing at least one input signal indicative of a response to an interrogation signal of a corresponding location of the body part during the analysis interval, and fitting each input signal over the analysis interval by an instance of a combined bolus function of time, based on a combination of a first simple bolus function of time modeling the first passage of the contrast agent and at least one second simple bolus function of time each one modeling a corresponding second passage of the contrast agent.