Quantitative CT Angiography with Sub-50ms Acquisition
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Solution Overview
Problem
Current angiography methods face limitations in temporal resolution, leading to difficulties in accurately imaging and measuring vascular structures, especially in time-resolved applications like coronary arteries, due to venous structure filling and overlap issues, and require extensive contrast medium use, which increases complications.
Innovation Solution
A system and method for generating quantitative CT angiographic images using a gantry-based CT system that acquires projection views in less than 50 milliseconds, performs scatter correction, and determines flow direction or velocity by backprojecting and weighting pixel values, allowing for the creation of ultrafast quantitative CT angiography with improved spatial and temporal resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional filtered backprojection method is used to reconstruct CT images, then image artifacts are suppressed with sufficient views (400-1000 views), but the acquisition time becomes too long for time-resolved angiography applications
Solution Approach 1:
The patent performs preliminary segmentation to identify vascular structures before reconstruction, then uses this segmentation information to guide the reconstruction process. This preliminary action allows the system to focus computational resources on vascular regions, enabling high-quality reconstruction with fewer projection views than conventional methods require.
Solution Approach 2:
The patent applies different reconstruction strategies to different regions: segmented vascular regions receive optimized reconstruction with fewer views, while non-vascular regions use standard reconstruction. This local quality approach allows the system to achieve high image quality in critical vascular areas without requiring the large number of views needed for uniform high-quality reconstruction of the entire field of view.
2Measurement precision
If more projection views are acquired to improve image quality, then image artifacts are reduced, but the temporal resolution decreases and venous structure filling increases
Solution Approach 1:
The patent replaces the mechanical approach of acquiring more projection views with a computational approach using segmented-based reconstruction. Instead of increasing the number of physical measurements, the system uses algorithms that leverage segmentation information to achieve high image quality from fewer views, thereby reducing scan duration and preventing venous structure filling.
3Measurement precision
If extensive contrast medium is used to enhance vascular visibility, then vascular structures are more clearly visualized, but complications and invasiveness increase
Solution Approach 1:
The patent enables the imaging system to serve itself by using the segmented vascular information to guide the reconstruction process. This self-service capability allows the system to achieve high vascular visibility through intelligent processing of limited contrast-enhanced data, reducing the need for extensive contrast medium administration that would otherwise be required to ensure adequate vascular visualization.
4Measurement precision
If cardiac gating is applied to suppress motion artifacts in coronary artery imaging, then image quality improves, but the complexity of the procedure increases
Solution Approach 1:
The patent extracts and removes motion artifacts from the imaging process by using segmentation-based reconstruction that can operate independently of cardiac gating. By separating the vascular identification function (segmentation) from the reconstruction process, the system eliminates the need for complex cardiac gating synchronization while maintaining high image quality in coronary artery imaging.
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 enables the production of high-resolution, time-resolved angiographic images with reduced contrast medium use, providing clear vascular anatomy and flow patterns, essential for minimally invasive procedures, while minimizing artifacts and complications.
Implementation Method 1
The intensity of the transmitted radiation is dependent upon the attenuation of the x-ray beam by the object and each detector produces a separate electrical signal that is a measurement of the beam attenuation
Implementation Method 2
As shown in FIG. 1A each acquired x-ray transmission profile 100 is backprojected onto the field of view (FOV) 102 by projecting each ray sum 104 in the profile 100 through the FOV 102 along the same ray path that produced the ray sum 104
Data Source
AI summary
Methods and systems are provided for generating quantitative computed tomography (CT) angiographic images using imaging systems that acquire a set of projection views forming CT angiographic image data of a patient using a projection duration of less than 50 milliseconds. The method may include producing a composite image from the CT angiographic image data that indicates an attenuation value at each composite image pixel of the patient, backprojecting each projection view in the CT angiographic image data and weighting a value backprojected into at image pixel by an attenuation value of a corresponding pixel in the composite image and summing backprojected values for each image pixel to produce a CT image of the patient. The method may further include performing a scatter correction and determining at least one of a flow direction or a velocity of flow with a vessel in the patient to provide the quantitative CT angiographic images.