CT Image Artifact Reduction via Iterative Metal Segmentation

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Solution Overview

Problem

Metal bodies in CT images cause significant artifacts due to high attenuation coefficients, leading to loss of relevant information and impaired diagnostic interpretation.

Innovation Solution

An iterative reconstruction method that utilizes prior knowledge about the shape and composition of metal objects, such as implants, to reduce artifacts by incorporating stored information about metallic bodies into the CT image reconstruction process, including filtering and dynamic weighting of constraints.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional CT reconstruction methods are used, then the imaging process is fast and simple, but metal artifacts severely degrade image quality and diagnostic value

Engineering Contradiction:
Improveimage qualityVSAvoidreconstruction complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing preliminary segmentation to identify metal objects and their parameters (shape, composition, location) before the main reconstruction process. This preliminary identification allows the reconstruction algorithm to pre-correct for expected artifacts, improving image quality without requiring complex post-processing. The metal object parameters are determined in advance and used to guide the reconstruction process.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If iterative reconstruction with prior knowledge is used, then artifact reduction is improved, but processing time and computational complexity increase

Engineering Contradiction:
Improveartifact reductionVSAvoidprocessing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies local quality by focusing computational resources only on regions affected by metal artifacts rather than processing the entire image uniformly. The segmentation identifies specific locations of metal objects, and the reconstruction algorithm applies artifact reduction techniques selectively in those local regions. This approach maintains high artifact reduction effectiveness while significantly reducing overall processing time compared to global iterative methods.

Inventive Principle:
Principle #3Local quality

3Reliability

If metal objects are completely removed from the image, then artifacts are eliminated, but relevant diagnostic information within or near metal objects is lost

Engineering Contradiction:
Improveartifact eliminationVSAvoiddiagnostic information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent applies copying by creating a separate segmentation mask that identifies metal objects and their parameters. This mask is then used to guide the reconstruction process, allowing the original anatomical structures to be preserved while correcting only the artifact portions. The metal object information is copied into the reconstruction model rather than being completely removed, enabling both artifact reduction and preservation of diagnostic information.

Inventive Principle:
Principle #26Copying

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 effectively reduces artifacts in CT images, improving the detail content and making relevant information available for diagnostic purposes while preserving anatomical structures.

Implementation Method 1

CT imaging is based on the different attenuation of X-rays by an object

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

Implementation Method 2

cross-sectional images are generated from a large number of X-ray images of the object taken in different directions using computer-based evaluation

Methodology Applied
Scientific EffectComputed tomography reconstruction: Tomography

Data Source

PatentEP3143592B1Method and apparatus for reducing artefacts in computed tomography images
Publication Date: 2018.12.05 UNIV ZU LUBECK
  • EP3143592B1 patent drawingFigure 1
  • EP3143592B1 patent drawingFigure 2~3
  • EP3143592B1 patent drawingFigure 4

AI summary

The invention relates to a method and an apparatus for reducing artefacts that are caused particularly by disturbance bodies and/or metal bodies in computed tomography (CT) images by means of a regulated iteration process that can be integrated particularly into a process for processing measurement data and preferably into a superordinate process for data alignment.