3D Digital Subtraction Angiography Using Opposing Contrast Agents
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Solution Overview
Problem
Conventional three-dimensional digital subtraction angiography (3D DSA) is prone to movement and deformation artifacts, leading to poor image quality and the need for high doses of iodinated contrast agents, which can harm renal function and result in inaccurate imaging, especially in homogeneous organs like the liver.
Innovation Solution
The method involves using two contrast agents with opposite X-ray absorption properties, one causing increased absorption (e.g., iodinated) and the other reduced absorption (e.g., CO2 microbubbles), to enhance contrast and image quality, allowing for more effective motion compensation and reduced contrast agent dosage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 3D DSA uses a mask run without contrast agent and a filling run with iodinated contrast agent, then vascular systems can be visualized, but patient movement and deformation between runs cause subtraction artifacts and poor image quality
Solution Approach 1:
The patent inverts the conventional approach by using a positive contrast agent (iodinated) in the mask run instead of no contrast agent, and a negative contrast agent (CO2) in the filling run. This inversion allows both runs to have opacified vascular systems, enabling reliable image-based registration and motion compensation, thereby eliminating subtraction artifacts caused by patient movement between runs.
Solution Approach 2:
The mask run is performed first with a positive contrast agent to establish a reference state of the vascular system before any deformation or movement occurs. This preliminary opacification allows subsequent filling runs to be registered against this stable reference, compensating for movements that occur during the procedure.
2Measurement precision
If a mask run without contrast agent is performed, then the filling run can use high dose iodinated contrast agent for good vascular opacification, but this high dose adversely affects renal function
Solution Approach 1:
The patent changes the contrast agent parameters by introducing a negative contrast agent (CO2) in the filling run. This allows the mask run to use a positive contrast agent at lower doses, and the filling run to use CO2 which has different absorption characteristics, thereby reducing the total iodinated contrast agent dose while maintaining good vascular visualization.
Solution Approach 2:
CO2 acts as an intermediary contrast agent in the filling run. It provides the necessary vascular opacification for the filling phase without the renal toxicity associated with high-dose iodinated contrast agents, serving as a mediator between the need for good image quality and the need to protect renal function.
3Reliability
If 2D/2D registration is used between mask and filling images, then motion compensation can be attempted, but homogeneous organs like the liver provide poor registration quality due to lack of visible structures
Solution Approach 1:
By inverting the contrast agent assignment (positive in mask, negative in filling), the patent ensures that both mask and filling images have opacified vascular systems. This provides abundant anatomical landmarks for registration, completely overcoming the problem of homogeneous organs providing poor registration targets.
Solution Approach 2:
The patent utilizes the contrast difference between positive (iodinated) and negative (CO2) contrast agents to create visually distinct vascular structures in both mask and filling images. This contrast variation provides clear anatomical landmarks for accurate image registration, even in previously homogeneous regions like the liver.
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 improves image quality, reduces kidney damage risk, and enables more accurate diagnostics by enhancing contrast and allowing for better registration of vascular structures, even in challenging anatomical regions.
Implementation Method 1
one of the two contrast agents produces increased X-ray absorption
Implementation Method 2
the other contrast agent produces reduced X-ray absorption
Data Source
AI summary
The disclosure relates to a method for creating a three-dimensional digital subtraction angiography image of a vascular system of a patient. The method includes: providing a first reconstructed three-dimensional filling image which was acquired during at least partial contrast agent filling of the vascular system with a first contrast agent; providing a second reconstructed three-dimensional filling image which was acquired during at least partial contrast agent filling of the vascular system with a second contrast agent; and subtracting the first three-dimensional filling image from the second three-dimensional filling image so that a three-dimensional subtraction angiography image is produced, wherein the first contrast agent and the second contrast agent differ in that one of the two causes increased X-ray absorption and the other causes reduced X-ray absorption relative to a vascular system without contrast agent.