Angiographic Roadmap Object Visibility via Image Subtraction
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Solution Overview
Problem
Existing roadmap methods in interventional angiographic examinations face issues with poor visibility of objects like wires and catheters due to high contrast, leading to 'burnout' where these objects appear dark within a light vascular tree, and traditional methods fail to effectively enhance their visibility.
Innovation Solution
The method involves acquiring and processing multiple X-ray images to generate roadmap images by subtracting empty, filling, and native images, with additional image processing steps like filtering and grayscale adjustments to ensure the object is represented with a predefined grayscale value, independent of vessel contrast, and blending inverted DSA images with fluoroscopy images to improve visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional roadmap subtraction method is used, then vascular tree is visualized, but object visibility deteriorates due to burnout effect
Solution Approach 1:
The patent segments the image processing into three distinct phases: system dose regulation phase (acquiring pure anatomy images), filling phase (acquiring contrast-filled vessel images), and working phase (acquiring fluoroscopy images with objects). This segmentation allows separate optimization of each phase to avoid the burnout effect while maintaining object visibility.
Solution Approach 2:
The patent changes the grayscale parameter representation by assigning a predefined grayscale value to objects independent of vessel contrast. This parameter change prevents objects from appearing dark (burnout) within light vascular trees, as the object brightness is decoupled from the vessel contrast level.
2Illumination intensity
If high contrast is used to enhance vascular tree, then vessel visualization is improved, but object detection precision deteriorates
Solution Approach 1:
The patent applies parameter changes by assigning predefined grayscale values to objects that are independent of the vessel contrast parameters. This allows high vessel contrast to be maintained for better vessel visualization while object grayscale values remain constant and optimized for detection, resolving the trade-off between vessel contrast and object detection precision.
Solution Approach 2:
The processing is segmented into vessel image generation and object image generation pathways. The vessel image pathway optimizes for vessel contrast, while the object image pathway uses subtraction and predefined grayscale assignment to optimize for object detection, allowing both objectives to be achieved simultaneously without compromise.
3Measurement precision
If multiple image processing steps are added to enhance object visibility, then object detection is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary actions by acquiring pure anatomy images during the system dose regulation phase before the actual intervention. These pre-acquired images are stored and used later for subtraction during the working phase, eliminating the need for complex real-time processing and simplifying the overall system while improving object visibility.
Solution Approach 2:
The complex image processing is segmented into distinct, manageable steps: subtraction of pure anatomy images from fluoroscopy images, generation of vessel images through contrast phase processing, generation of object images through dedicated subtraction pathways, and final blending with predefined grayscale assignment. This segmentation makes the complex processing more manageable and implementable.
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 enhances the visibility of objects by maintaining their representation as deep black, regardless of vessel contrast, reducing noise and artifacts, and preventing 'burnout', thereby improving the clarity of wires and catheters within the vascular tree.
Implementation Method 1
an X-ray tube and a X-ray detector are mounted... an X-ray emitter 3 with X-ray tube and collimator
Implementation Method 2
an imaging system including at least one monitor... an image system for receiving and processing the image signals
Data Source
AI summary
A method for enhanced visualization of objects in interventional angiographic examinations is provided. X-ray images are recorded during the system dose regulation phase with pure anatomy and during the filling phase with the vessels filled with contrast agent. A mask image is produced from both of the images. Native X-ray images are produced during a working or intervention phase with an object, for example a wire, a catheter or a “coil”, moved in the vessel. The images have a matrix-shaped array of pixels. The pure anatomy images are subtracted from the filling images and from the native images for generating a first subtraction image and a second subtraction image respectively. The first and the second subtraction image are processed for generating a vessel image and an object image respectively. The vessel image and the object image are processed for generating a roadmap image which is played back on a monitor.