Cardiac CT Reconstruction with Synthetic Axial Overlap Registration
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Solution Overview
Problem
Step artifacts in cardiac CT imaging due to heart rate variability and respiratory motion cause misalignment and inconsistency between adjacent datasets in step-and-shoot acquisition modes, compromising the interpretation of coronary artery lesions.
Innovation Solution
A method involving synthetic enlargement of the projection field-of-view in the axial direction to increase the overlap volume between adjacent sub-volumes, followed by registration to improve alignment and reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If step-and-shoot acquisition mode is used to reduce radiation dose and improve image resolution, then image quality and dose efficiency are improved, but step artifacts appear at boundaries between stitched datasets
Solution Approach 1:
The patent applies preliminary action by performing synthetic FOV enlargement on projection datasets before image reconstruction. This preprocessing step expands the field of view in the axial direction, creating larger overlap volumes between adjacent sub-volumes before they are reconstructed and stitched together, thereby preventing step artifacts from forming in the final composite image
Solution Approach 2:
The patent employs copying by creating synthetic or virtual copies of projection data through field of view enlargement. This involves generating additional projection data that replicates and extends the original data coverage, allowing for larger overlap regions without requiring additional physical measurements, thus reducing step artifacts while maintaining the step-and-shoot acquisition benefits
2Adaptability or versatility
If heart rate variability and respiratory motion occur during scanning, then physiological realism is maintained, but misalignment and step artifacts appear between adjacent datasets
Solution Approach 1:
The patent performs preliminary registration preparation by enlarging the field of view and creating larger overlap volumes before the actual misalignment occurs due to physiological motion. This preliminary expansion provides a larger buffer zone for subsequent registration algorithms to work with, improving alignment accuracy even when heart rate variability and respiratory motion cause positional changes between acquisitions
Solution Approach 2:
The patent applies parameter changes by modifying the field of view parameter in the axial direction through synthetic enlargement. This parameter change creates larger overlap volumes that provide more data for registration, enabling better compensation for physiological motions such as heart rate variability and respiratory motion between adjacent sub-volume acquisitions
3Measurement precision
If overlap volume between adjacent sub-volumes is increased to improve registration, then registration accuracy improves, but data acquisition time and complexity increase
Solution Approach 1:
The patent uses copying by generating synthetic projection data that virtually extends the field of view. This creates larger overlap volumes between adjacent sub-volumes without requiring additional physical measurements or extending scan time. The synthetic copies provide the necessary overlap for accurate registration while maintaining the original data acquisition efficiency of the step-and-shoot mode
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
Enhances registration accuracy and reduces step artifacts in reconstructed CT images, allowing for more precise visualization and analysis of cardiac anatomy.
Implementation Method 1
applying a data modification operation to the CT projection data to yield modified CT projection data, the modification operation comprising synthetically enlarging a projection field-of-view of at least one projection of at least one of the first and second projection datasets (e.g. in the axial direction) to thereby result in a modified overlap volume between the first and second projection datasets
Implementation Method 2
each projection dataset providing data permitting image reconstruction of a respective sub-volume of the imaging zone
Implementation Method 3
registering at least the first and second CT volumetric image datasets to one another
Data Source
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AI summary
An image reconstruction method is provided for reducing step artefacts when reconstructing step-and-shoot CT image data. The method is based on artificially augmenting or expanding the field of view in an axial direction of at least one projection of at least one projection dataset corresponding to one axial position of the step-and-shoot CT protocol. Accordingly an axial overlap volume between a reconstruction (sub-)volume of the at least one projection dataset and an axially adjacent projection dataset is increased. This allows for more robust and accurate registration between the said overlapping reconstruction volumes. Accordingly step artefacts in the composite reconstructed volume comprising both adjacent sub-volumes is improved.