Spectral CT Calcium Quantification via Material Decomposition
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Solution Overview
Problem
Current methods for determining coronary artery calcification using CT scans are prone to motion artifacts, require contrast agents, and provide semi-quantitative calcium scores that are sensitive to imaging system characteristics, making them inefficient and unreliable for medical screening.
Innovation Solution
A method and device that analyze cardiac spectral CT data using material decomposition algorithms to isolate calcium-specific components, allowing for robust, motion-insensitive, and quantitative calcium content calculation without the need for contrast agents or specific imaging protocols, using spectral CT projection data to generate 3D images and calculate calcium scores that are reproducible and independent of imaging system variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If unenhanced low-dose CT scan is used for calcium scoring, then radiation dose is reduced and cost is lowered, but measurement precision and reliability of calcium quantification deteriorate due to motion artifacts and system dependencies
Solution Approach 1:
The patent applies parameter changes by utilizing spectral CT technology that measures X-ray attenuation at multiple energy levels. This allows the system to differentiate calcium from other tissues based on their unique energy-dependent attenuation characteristics, enabling accurate calcium quantification even in low-dose unenhanced scans by changing the measurement parameters from single-energy to multi-energy detection
Solution Approach 2:
The patent extracts calcium-specific information from the spectral CT data by applying material decomposition algorithms that isolate calcium attenuation signals from other tissues. This extraction process separates the calcium content measurement from confounding factors like motion artifacts and system variations, maintaining precision while using low-dose protocols
2Ease of manufacture
If conventional CT calcium scoring is performed, then calcium content can be estimated, but the results are sensitive to imaging system characteristics and provide only semi-quantitative scores rather than accurate quantitative measurement
Solution Approach 1:
The patent transforms the measurement approach from conventional single-energy CT to spectral CT with multi-energy detection. This parameter change enables the system to measure X-ray attenuation at multiple energy levels, providing sufficient data for material decomposition algorithms to calculate absolute calcium concentration values rather than semi-quantitative scores, thereby improving quantitative accuracy while maintaining ease of use
Solution Approach 2:
The patent introduces material decomposition algorithms as an intermediary processing step between data acquisition and calcium quantification. These algorithms act as a mediator that processes spectral CT data to isolate calcium-specific attenuation signals and compute accurate quantitative calcium content, bridging the gap between simple imaging and precise measurement
3Quantity of substance
If volumetric CT images are acquired with multiple axial scans or helical scan, then calcium scoring can be performed, but residual breathing or cardiac motion deteriorates the scores due to image blurring
Solution Approach 1:
The patent applies parameter changes by performing material decomposition in the projection domain before image reconstruction. This approach processes the raw spectral CT projection data to isolate calcium-specific signals at multiple energy levels, creating calcium-only projection data that is then reconstructed into images. This method maintains reliability by separating calcium information from motion-affected soft tissue signals before blurring occurs
Solution Approach 2:
The patent segments the spectral CT data into calcium-specific and non-calcium components through material decomposition. By separating calcium attenuation signals from other tissues in the projection domain, the system creates distinct calcium-only datasets that can be reconstructed into motion-resistant images, improving reliability by isolating the calcium measurement from motion-affected regions
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 reproducible quantitative calcium scoring from unenhanced, low-dose CT scans, reducing the impact of motion artifacts and system dependencies, making it suitable for routine cardiac spectral CT examinations without the need for breath-holding or electrocardiogram triggering.
Implementation Method 1
The attenuation, e.g. the linear attenuation coefficient or radiodensity, of calcium is dependent on the X-ray spectrum and on characteristics of the CT detection system
Data Source
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AI summary
Present invention relates to devices and methods for determining a calcium content by analyzing cardiac spectral CT data. CT projection data (9), obtainable by scanning a cardiac region of a subject using a spectral CT scanning unit, is modelled (12) by applying a material decomposition algorithm to the projection data to provide a calcium-specific component. Tomographic reconstructions (13) of the projection data, to provide a first 3D image (8), and of the calcium-specific component, to provide a second 3D image (6), are performed. The first 3D image (8) is segmented (14) to provide an image mask (5) corresponding to a cardiovascular structure of interest, a part of the second 3D image (6) is selected (15) based on the image mask (5), and a calcium content is calculated (16) in the cardiovascular structure of interest based on the selected part of the second 3D image (6).