Stent Graft Apposition Parameter Calculation
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Solution Overview
Problem
Current methods for determining the position and apposition of stent grafts in complex aortic anatomy during endovascular aneurysm repair are inadequate, leading to risks of sealing failure, endoleaks, and migration due to assumptions of cylindrical aortic neck morphology and insufficient visualization of stent graft placement.
Innovation Solution
A method using numerical three-dimensional patient models to determine vessel morphology and tubular member positional parameters, calculating an apposition parameter that quantitatively assesses the relative position and quality of stent graft placement in the thoracoabdominal aorta and iliac arteries, incorporating parameters such as diameter, length, surface, and alignment to ensure accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection during medical imaging is used to check stent graft position, then the method is simple and quick, but the measurement precision and reliability of position determination is insufficient
Solution Approach 1:
The invention creates a digital three-dimensional copy of the patient's anatomy and stent graft from medical imaging data. This digital model allows precise measurement of position and apposition parameters without requiring complex physical measurement devices during the procedure. The virtual model replicates the anatomical structures and implant geometry, enabling accurate quantitative assessment.
Solution Approach 2:
The invention replaces manual visual inspection with automated computer-based calculation of position parameters. Instead of relying on physician visual assessment during imaging, the system automatically computes quantitative metrics such as apposition surface area, contact length, and position coordinates from the digital model, providing objective and precise measurements.
2Manufacturing precision
If cylindrical simplification of aortic neck morphology is assumed, then the planning process is simplified, but the manufacturing precision of stent graft sizing is compromised
Solution Approach 1:
The invention applies local quality analysis by examining specific regions of the aortic neck independently rather than assuming uniform cylindrical geometry. The system identifies and measures the proximal sealing zone, distal sealing zone, and aneurysm sac as distinct regions with different geometric characteristics, allowing precise stent graft sizing for each location based on actual local morphology.
Solution Approach 2:
The invention transitions from two-dimensional cross-sectional views to three-dimensional volumetric modeling of the aortic neck and stent graft. This dimensional upgrade enables accurate assessment of complex curved geometries, angles, and surface areas that cannot be captured by cylindrical assumptions or single-plane imaging.
3Reliability
If stent graft placement is assumed perpendicular to centerline, then the deployment process is simplified, but the reliability of sealing is reduced in complex anatomy
Solution Approach 1:
The invention introduces dynamic angle assessment by calculating the actual orientation of the stent graft relative to the aortic centerline in three dimensions. Rather than assuming a fixed perpendicular orientation, the system dynamically determines the deployment angle based on the specific patient anatomy and implant position, allowing adjustment of sizing and positioning recommendations to achieve optimal sealing.
Solution Approach 2:
The system provides feedback on the actual position and orientation of the stent graft by calculating position parameters such as angle of deployment, apposition surface area, and contact length. This feedback enables physicians to assess whether the implant achieves sufficient sealing and make adjustments if necessary, rather than relying on fixed assumptions about perpendicular placement.
4Measurement precision
If conventional follow-up methods examining endoleaks and aneurysm sac diameter are used, then the follow-up process is simple, but the ability to detect early position changes is insufficient
Solution Approach 1:
The invention establishes baseline position parameters (apposition surface area, contact length, position coordinates) immediately after implantation. These baseline measurements serve as reference values for future comparisons, enabling early detection of position changes or migration before they manifest as clinical complications such as endoleaks or aneurysm sac enlargement.
Solution Approach 2:
The system provides quantitative feedback on stent graft position by calculating and comparing position parameters over time. Instead of waiting for qualitative signs of failure, the automated calculation of apposition metrics provides objective feedback that can detect subtle position changes early, allowing timely intervention while maintaining efficient follow-up through remote assessment of digital models.
Data Source
AI summary
A method for determining an apposition parameter indicative for the position and apposition of a tubular member, such as a stent graft, inserted in a lumen of an anatomical vessel/duct of a patient. The method includes providing a numerical three-dimensional patient model of at least a part of the vessel including the tubular member; determining a vessel morphology parameter from the patient model, the parameter indicative for the anatomy of a predetermined part of the vessel at or near the tubular member in said vessel with respect to said patient model; determining a tubular member positional parameter from the patient model, the parameter indicative for the position of a predetermined part of the tubular member in the patient model; and calculating, based on the determined vessel morphology parameter and tubular member positional parameter, the relative position of the tubular member with respect to the vessel as the apposition parameter.