Residual Iodine Artifact Correction in Spectral CT Virtual Non-Contrast Imaging
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Solution Overview
Problem
Conventional spectral CT imaging produces Virtual Non-Contrast (VNC) images with residual iodine artifacts, particularly in small vessels of the liver, due to limitations in photo-electric effect/Compton scatter decomposition, which reduces the accuracy and confidence of clinician interpretations.
Innovation Solution
A system that decomposes line integrals into Compton scatter and photo-electric effect components, de-noises these images, identifies residual iodine voxels, and corrects the images using residual iodine voxels to produce a VNC image with reduced or eliminated iodine artifacts, either by subtracting from the Compton scatter and adding to the photo-electric effect images or controlling regularization during iterative reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If spectral CT imaging is used to generate Virtual Non-Contrast images by separating iodine from calcium, then the need for a second non-contrast scan is eliminated and patient X-ray dose is reduced, but residual iodine artifacts appear in the VNC images reducing clinical confidence
Solution Approach 1:
The patent extracts and removes the identified residual iodine artifacts from the VNC image by isolating them as a separate component and subtracting them from the final image, thereby eliminating the harmful artifacts while preserving the diagnostic quality of the VNC image
Solution Approach 2:
The system implements a feedback mechanism where the VNC image is analyzed to detect residual iodine artifacts, and the detected artifacts are then used to correct the original VNC image, creating an iterative refinement process that improves image accuracy and clinical confidence
2Measurement precision
If joint photo-electric effect/Compton scatter denoising is applied to spectral image data, then noise is reduced in the decomposed images, but anti-correlated noise causes iodine residuals to appear in the VNC images
Solution Approach 1:
The patent converts the harmful anti-correlated noise from joint denoising into a beneficial signal by detecting the characteristic patterns of residual iodine artifacts that result from this noise, and then using these detected patterns to guide the removal process, thereby transforming the source of artifacts into the key to their elimination
3Illumination intensity
If Compton scatter image values are increased in regions of small vessels, then the image appears to contain calcium, but this causes the region to be incorrectly identified and not removed during VNC image generation
Solution Approach 1:
The patent introduces an intermediary analysis step that examines the photo-electric effect image in conjunction with the Compton scatter image to distinguish true calcium from residual iodine artifacts, using the unique spectral signatures of each material to resolve the misidentification caused by elevated Compton scatter values
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
The approach effectively reduces or eliminates residual iodine artifacts in VNC images, enhancing the accuracy and confidence of clinical interpretations by improving the image quality without the need for a second non-contrast scan, thereby reducing patient X-ray dose.
Implementation Method 1
The x-ray tube rotates around an examination region located between the x-ray tube and the one or more detectors and emits radiation that traverses the examination region and a subject and/or object disposed in the examination region. The one or more detectors detect radiation that traverses the examination region
Implementation Method 2
The detected radiation also includes spectral information since the absorption of the radiation by the subject and/or object is dependent on the energy of the photons traversing there through
Implementation Method 3
decompose the line integrals into a photo-electric effect line integrals and a Compton scatter line integrals
Data Source
AI summary
A system (300) includes input/output configured to receive line integrals from a contrast enhanced spectral scan by an imaging system. The system further includes (300) a processor (326) configured to: decompose (334) the line integrals into at least Compton scatter and a photo-electric effect line integrals; reconstruct the Compton scatter and a photo-electric effect line integrals to generate spectral image data, including at least Compton scatter and photo-electric effect images; de-noise (332) the Compton scatter and photo-electric effect images; identify (402) residual iodine voxels in the de-noised Compton scatter and the photo-electric effect images corresponding to residual iodine artifact; and produce a virtual non-contrast image using the identified residual iodine voxels.