Perfusion CT Data Processing for Reduced Radiation Dose
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Solution Overview
Problem
Current computed tomography (CT) examinations, particularly in stroke patients, involve high doses of contrast agent and radiation due to the need for multiple scans, including dynamic perfusion measurements and static CT angiography, which cannot be adequately replaced by dynamic angiography alone.
Innovation Solution
A method that processes measurement data from perfusion CT to generate arterial and venous time-attenuation curves (TACs) and dynamic CTA images by averaging over multiple time phases, allowing for the reduction or elimination of static CT angiography, thereby minimizing contrast agent and radiation exposure, while maintaining high image quality and time resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic perfusion measurement and static CT angiography are both performed, then vessel pathology can be accurately diagnosed, but the amount of contrast agent injected and radiation dose increase significantly
Solution Approach 1:
The patent merges dynamic perfusion measurement and static CT angiography into a single integrated examination protocol. By performing both examinations in one CT scan session with one contrast agent injection, the method eliminates the need for separate examinations, thereby reducing total contrast agent amount and radiation dose while maintaining complete diagnostic capability for both perfusion parameters and vessel pathology
Solution Approach 2:
The patent makes the perfusion CT examination multi-functional by extracting multiple types of diagnostic information from the same measurement data. The dynamic CTA images generated from perfusion data serve dual purposes: visualizing vessel anatomy like static CTA and providing temporal information for perfusion analysis, thereby eliminating the need for separate dedicated CTA examination
2Loss of time
If dynamic CTA is used to replace static CTA, then examination time is reduced, but image quality and vessel visualization are insufficient
Solution Approach 1:
The patent employs dynamic CTA that captures multiple time phases of contrast agent circulation. By acquiring images at different time points and selectively using individual time phases or averaged images, the method provides both temporal dynamics and high-quality vessel visualization, overcoming the limitation of static single-time-point imaging
Solution Approach 2:
The patent utilizes periodic sampling of images at multiple time phases during contrast agent circulation. This periodic acquisition allows selection of optimal time phases for vessel visualization and enables averaging of multiple phases to improve signal-to-noise ratio and image quality while maintaining reduced examination time
3Measurement precision
If high flow rate contrast agent injection is used for perfusion measurement, then perfusion parameters can be calculated, but the contrast agent bolus becomes short and sharp, limiting vessel section visualization
Solution Approach 1:
The patent utilizes the temporal dynamics of contrast agent circulation by acquiring images at multiple time phases. This dynamic approach allows the short, sharp bolus to be tracked through different vessel sections at different times, effectively visualizing the entire vascular path despite the compact bolus shape required for accurate perfusion measurement
Solution Approach 2:
The patent adds the time dimension to vessel visualization by generating dynamic CTA images that show contrast agent propagation through time. This temporal dimension allows visualization of vessel sections that would be missed in static imaging, as the moving bolus illuminates different vascular segments at different time points
Data Source
AI summary
A method is disclosed for processing measurement data from perfusion computed tomography, in which both perfusion parameters, in order to calculate which arterial and venous TACs are generated, and dynamic CTA images are generated from the measurement data. In at least one embodiment of the proposed method, averaging is performed over the dynamic CTA images from a plurality of temporally successive time phases in order to obtain averaged CTA images, wherein the time phases over which averaging is performed are determined from the arterial or venous TAC(s). In some cases, the method can dispense with an additional static CTA and so the amount of the injected contrast agent and the radiation dose can be reduced.