Digital Subtraction Angiography Noise Reduction via Guided Filtering
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Solution Overview
Problem
Digital subtraction angiography (DSA) methods face challenges in maintaining image quality due to low radiation doses, which result in high image noise, making it difficult to accurately visualize blood vessels and detect conditions like constricted vessels or aneurysms.
Innovation Solution
A method that involves receiving filler images with different contrast medium concentrations, determining a mask image to edit out secondary structures, and using a guidance image for noise reduction through guided image filtering, while maintaining edge sharpness, to produce high-contrast, noise-reduced subtraction images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a low radiation dose is used in digital subtraction angiography, then the radiation load on patients and medical staff is reduced, but the image quality deteriorates due to high image noise
Solution Approach 1:
The patent applies preliminary action by acquiring multiple pre-images before contrast medium injection and using them to create an optimized mask image. This pre-processing step establishes a high-quality reference that enables subsequent noise reduction in the subtraction images without requiring additional radiation exposure during the actual angiography sequence.
Solution Approach 2:
The patent uses copying by creating multiple copies of pre-images and using them to generate a mask image that represents the anatomical structures without contrast medium. This mask image is then used to subtract background structures from the filler images, effectively copying the anatomical information while eliminating the need for high-dose radiation during the diagnostic phase.
2Reliability
If the radiation dose is reduced to minimize harm, then patient safety is improved, but the ability to detect vascular conditions deteriorates due to noisy images
Solution Approach 1:
The patent merges multiple pre-images together to create a composite mask image that contains enhanced anatomical information. By combining several low-dose pre-images, the signal from anatomical structures is reinforced while random noise tends to average out, creating a reliable mask that enables accurate vascular condition detection in the subsequent subtraction images.
Solution Approach 2:
The mask image serves as an intermediary that mediates between the low-dose filler images and the final diagnostic output. This intermediate structure contains the anatomical background information that is subtracted from the filler images, allowing the detection of vascular conditions without directly using the noisy low-dose filler images alone.
3Measurement precision
If multiple pre-images are acquired to create a mask image, then image quality and noise reduction are improved, but the examination time increases
Solution Approach 1:
The patent applies periodic action by acquiring pre-images at regular intervals before contrast medium injection. This periodic acquisition allows for the creation of a robust mask image through temporal averaging, where the periodic sampling of anatomical structures enables noise reduction while maintaining a manageable examination time through efficient temporal processing.
4Measurement precision
If a mask image is created from multiple pre-images, then noise reduction is achieved, but the processing complexity increases
Solution Approach 1:
The patent replaces complex mechanical or manual image processing methods with automated computational algorithms. The evaluation device automatically performs the acquisition, registration, averaging, and subtraction operations using digital image processing algorithms, eliminating the need for manual intervention and reducing processing complexity despite the multiple images involved.
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 reduces image noise and enhances image quality, allowing for better visualization of blood vessels and the determination of contrast medium concentration timing curves, thereby improving the assessment of vascular health with reduced radiation exposure.
Implementation Method 1
digital subtraction angiography, which uses ionizing radiation, e.g., x-rays
Implementation Method 2
a contrast medium is injected into the vessel, through which the vessel is made visible and is mapped in the recorded images
Data Source
AI summary
A method is provided for representing a first structure of a body region by digital subtraction angiography. The method includes: receiving a filler image of the body region created by an angiography apparatus, which represents a second structure of the body region and the first structure with a first contrast medium concentration in the first structure; determining a mask image of the body region representing the second structure; determining a subtraction image by editing out of the second structure from the filler image by the mask image; determining a guidance image representing the first structure based on the subtraction image; reducing image noise of the subtraction image by the guidance image; and representing the first structure based on the noise-reduced subtraction image.