Photon Counting CT Dual Contrast Agent Imaging

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Solution Overview

Problem

Conventional Computed Tomography (CT) systems face challenges in simultaneously visualizing anatomy and multiple materials due to the limitations of using multiple contrast agents, such as short-lived nanoparticle agents that require time to bind, leading to a low contrast-to-noise ratio for vascular and tissue imaging.

Innovation Solution

A Photon Counting CT (PCCT) system is configured with multiple threshold values for long-acting blood pool agents and nanoparticles, allowing for the simultaneous acquisition and visualization of anatomy by processing imaging data into separate datasets based on these agents, including short-lived contrast agents like gadolinium or iodine, which are designed to wash out quickly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple types of contrast enhancement materials are used simultaneously, then the ability to visualize multiple structures (vasculature and tissue) is improved, but the contrast-to-noise ratio deteriorates due to washout of short-lived agents before nanoparticle agents bind

Engineering Contradiction:
Improveability to visualize multiple structuresVSAvoidcontrast-to-noise ratio
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent changes the temporal parameter of contrast agent persistence by selecting a long-lived blood pool contrast agent that remains in the vasculature for extended periods (hours to days), matching the binding time of nanoparticle agents to tissue targets. This parameter alignment ensures both agents are present simultaneously, resolving the washout timing conflict and enabling dual visualization with adequate contrast-to-noise ratio

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs preliminary action by injecting the long-lived blood pool contrast agent first, establishing persistent vascular enhancement before introducing nanoparticle agents that require time to bind to tissue targets. This sequencing ensures vascular structures are already enhanced when nanoparticle binding occurs, eliminating the need to wait for nanoparticle binding before achieving vascular contrast

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If nanoparticle contrast agents are used for tissue enhancement, then tissue visualization is improved, but the imaging time must be delayed until binding occurs, causing vascular contrast agents to wash out

Engineering Contradiction:
Improvetissue enhancement capabilityVSAvoidimaging time delay
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-injecting the long-lived blood pool contrast agent to establish persistent vascular enhancement before introducing nanoparticle agents. This eliminates the waiting period required for nanoparticle binding, as vascular contrast is already in place and will persist throughout the extended imaging window needed for tissue enhancement to develop

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses a long-lived contrast agent with persistence exceeding the minimum required time, maintaining vascular contrast enhancement for hours to days rather than minutes. This excessive duration ensures vascular contrast remains adequate throughout the entire nanoparticle binding process and subsequent imaging, providing a wide temporal window for successful dual-contrast imaging

Inventive Principle:
Principle #16Partial or excessive action

3Adaptability or versatility

If conventional CT systems are used with multiple contrast agents, then the ability to differentiate structures is improved, but the system complexity and difficulty of simultaneous acquisition increase

Engineering Contradiction:
Improvestructure differentiation capabilityVSAvoidsystem complexity for simultaneous acquisition
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces conventional energy-integrating detector physics with photon-counting detector physics, which inherently provides spectral information through energy binning. This substitution enables automatic separation of multiple contrast agents based on their distinct energy signatures, eliminating the need for complex manual protocols and multiple scans while providing clear differentiation of structures enhanced by different agents

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 the simultaneous and independent reconstruction of images for different contrast agents, improving the contrast-to-noise ratio and allowing for simultaneous visualization of vasculature and macrophage-based hotspots within a single scan.

Implementation Method 1

Photon Counting Computed Tomography (PCCT)

Methodology Applied
Scientific EffectPhoton counting:

Implementation Method 2

The degree to which an x-ray beam is reduced by an object during imaging is referred to as attenuation

Methodology Applied
Scientific EffectX-ray attenuation: Absorption (EM radiation)

Implementation Method 3

The plurality of threshold values for energy levels are determined based on the respective k-edges of the plurality of contrast agents

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP3131467B1Photon counting computed tomography using a combination of contrast agents for simultaneous visualization of anatomy and a plurality of materials
Publication Date: 2021.03.03 SIEMENS HEALTHCARE GMBH
  • EP3131467B1 patent drawingFigure 1
  • EP3131467B1 patent drawingFigure 2
  • EP3131467B1 patent drawingFigure 3

AI summary

A method for performing Photon Counting Computed Tomography (PCCT) using a combination of contrast agents includes configuring a PCCT device with a plurality of threshold values corresponding to a plurality of contrast agents. These contrast agents comprise a long-acting blood pool contrast agent and a nanoparticle contrast agent. The PCCT device is used to perform an imaging scan on an anatomical subject in the presence of the plurality of contrast agents to acquire image data. Next, the imaging data is processed into a plurality of datasets based on the plurality of threshold values. The datasets comprise a first dataset corresponding to the long-acting blood pool contrast agent, and a second dataset corresponding to the nanoparticle contrast agent.