Extrema Detection for Dynamic Anatomical Registration
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Solution Overview
Problem
In image-guided surgery, accurately registering a model of a dynamic anatomical structure with a medical device is challenging due to the structure's periodic or non-periodic movements, such as those of a beating heart or lungs, which complicates the identification of extrema points during expansion and contraction cycles.
Innovation Solution
A method and system using a flexible device with sensors to track displacements over time, identifying extrema time points by detecting sign changes in slope and determining extrema types through characteristics, without requiring additional hardware components, ensuring computational efficiency for real-time applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional registration methods are used for dynamic anatomical structures, then the system is simple to implement, but the registration accuracy deteriorates due to periodic or non-periodic movements
Solution Approach 1:
The system pre-identifies extrema types (maximum expansion, minimum contraction, inflection points) and their characteristics before processing real-time data. This preliminary classification enables the system to anticipate and correctly interpret displacement patterns during dynamic cycles, improving registration accuracy without requiring complex real-time analysis
Solution Approach 2:
The patent introduces an intermediary processing layer that analyzes displacement data to identify extrema points and their types. This intermediary step translates raw sensor data into meaningful registration parameters, bridging the gap between simple measurement and accurate dynamic registration
2Measurement precision
If additional hardware components are added to identify extrema types, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The existing sensor system performs multiple functions: it not only measures displacement but also self-serves by providing data for extrema identification and type classification. The same sensors that track position are used to derive velocity, acceleration, and extrema characteristics, eliminating the need for additional dedicated hardware
Solution Approach 2:
The sensor system is designed with multi-functionality, where a single sensor array serves both for basic displacement measurement and for sophisticated extrema analysis. The processed data from these sensors is used for multiple purposes including position tracking, velocity calculation, and extrema identification, reducing overall system complexity
3Measurement precision
If complex algorithms are used to identify extrema types in real-time, then the measurement precision improves, but the computational efficiency decreases
Solution Approach 1:
The system pre-establishes the framework for extrema identification by defining extrema types and their characteristics before real-time processing. This preliminary setup includes determining what constitutes a maximum, minimum, and inflection point, allowing the real-time algorithm to simply compare current data against these pre-defined criteria rather than performing complex analysis from scratch
Solution Approach 2:
The patent applies a practical level of computational analysis that is sufficient for real-time performance without being overly complex. By focusing on key extrema characteristics and using efficient comparison methods against pre-defined thresholds and patterns, the system achieves accurate extrema identification at computationally manageable levels
Data Source
AI summary
A medical system provides navigation assistance to a surgeon for navigating a flexible medical device through linked passages of an anatomical structure to a target area. For tracking, navigation, and other purposes, information of extrema is determined during expansion and contraction cycles of an object by receiving time sampled information from sensors distributed along a length of a flexible device so as to indicate the shape of the device over time while the device extends through a lumen of the object so as to conform to and resemble the shape of the lumen, displacements over time of a selected point at a selected insertion length of the flexible device into the lumen of the object relative to a reference point are determined, extrema time points are determined by identifying sign changes of the slope of the determined displacements over time, and extrema types are determined using extrema type characteristics.