CO2 Angiography Image Subtraction with Preceding-Frame Masks
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Solution Overview
Problem
The use of carbon dioxide as a contrast medium in angiography is affected by dynamic events during image acquisition, leading to inaccurate image subtraction and diagnostic representation due to patient movement and tissue changes, which traditional DSA techniques struggle to address effectively.
Innovation Solution
An algorithmic method for automatic image subtraction using CO2 as a contrast medium, where mask images are derived from immediately preceding contrast images, and subsequent clean images are generated through pixel-by-pixel subtraction, allowing real-time optimal image generation without manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional DSA techniques are used with CO2 contrast medium, then image subtraction can be performed, but accurate diagnostic representation is compromised due to patient movement and tissue changes during image acquisition
Solution Approach 1:
The patent applies preliminary action by acquiring a mask image before contrast medium injection and using it as a reference for subsequent subtraction. This pre-acquired mask image serves as a stable baseline that accounts for pre-contrast anatomical structures, enabling accurate subtraction even when patient movement occurs during the contrast injection phase.
Solution Approach 2:
The system implements feedback by continuously acquiring images during contrast medium injection and dynamically adjusting the subtraction process. The control unit processes each acquired image in real-time, comparing it with the mask image and generating corrected images that compensate for movement and tissue changes, thereby maintaining diagnostic accuracy throughout the procedure.
2Productivity
If real-time image acquisition is performed during CO2 injection, then dynamic vascular information is captured, but movement-related errors increase due to patient positioning changes
Solution Approach 1:
The patent ensures continuity of useful action by maintaining continuous image acquisition throughout the contrast medium injection process. The control unit continuously processes each acquired image through the subtraction algorithm, ensuring that real-time dynamic vascular information is captured while continuously compensating for movement-related errors through the mask image reference.
Solution Approach 2:
The mask image serves as an intermediary reference that mediates between the moving anatomical structures and the acquired images. By using the mask image as a stable reference point, the system can accurately subtract background structures from real-time images even when patient positioning changes occur, thereby maintaining image quality accuracy throughout the procedure.
3Measurement precision
If manual image processing is performed, then diagnostic accuracy can be improved, but procedure time increases and autonomous assessment is delayed
Solution Approach 1:
The patent implements self-service by enabling the system to automatically process and correct images without requiring manual intervention. The control unit autonomously performs the subtraction process, compares acquired images with the mask image, and generates corrected images in real-time, thereby maintaining high diagnostic accuracy while eliminating the time loss associated with manual processing.
Solution Approach 2:
The system replaces manual mechanical image processing with an automated computational algorithm. The control unit uses digital image processing techniques to automatically subtract the mask image from acquired images, generating corrected images through pixel-by-pixel calculation. This substitution of manual operations with automated computational methods maintains diagnostic accuracy while significantly reducing procedure time.
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
Enables accurate and efficient generation of clear, real-time angiographic images by minimizing noise and movement-related errors, facilitating autonomous diagnostic assessments during angiography procedures.
Implementation Method 1
The different absorption of the X radiation by the tissues and the gas bubble, which absorbs to a much lesser extent, highlights the vessel in which the bubble is passing
Implementation Method 2
CO2, like the iodinated contrast medium, is introduced through the catheter into the vessel, but instead of diluting in the blood it creates a gas bubble that moves dragged by the bloodstream
Implementation Method 3
During the displacement of the CO2 bubble inside the vessels of progressively smaller caliber, the gas diffuses through the wall, dissolving in the surrounding tissues and the bubble disappears
Data Source
Figure 1
Figure 2A~3C
Figure 2D~3F
AI summary
It is described a method for obtaining improved digital radiological images during a digital subtraction angiography (DSA) intervention, carried out by the introduction of a contrast medium consisting of CO2 or other fluid in an examination area (Z) of a human or animal body, and the creation of digital radiological images (IMC1, IMC2, IMC3... IMCn) of the examination area (Z) at the time of contrast medium input. A mask image (IMM1, IMM2, IMM3... IMMn) of the same area (Z) is subtracted from each image (IMC1, IMC2, IMC3... IMCn) with contrast medium and thus produce a series of "clean" digital radiological images (IMP1, IMP2, IMP3... IMPn) with limited noise. According to the method, each mask image (IMM1, IMM2, IMM3... IMMn) consists of the image with contrast (IMC (2-1), IMC (3-1)... IMC (n-1)) immediately preceding the image with contrast currently obtained or by weighted combination of the same.