Computed Tomography Artifact Correction via Prior Knowledge Subtraction
Solution Overview
Problem
Computed tomography image data sets are impaired by artifacts caused by elongated metal objects, such as intervention needles, due to strong attenuation, which complicates real-time monitoring during minimally invasive interventions and leads to loss of important anatomical structures.
Innovation Solution
A method that rapidly corrects artifacts by using prior knowledge to ascertain an artifact data set based on the shape and intensity of dimmed areas caused by metal objects, allowing for subtraction from the reconstructed image data set, preserving anatomical structures and enabling real-time correction without tilting the beam plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If projection images are recorded with the metal object irradiated in the longitudinal direction to monitor intervention, then the intervention region can be visualized in the intervention plane, but strong attenuation occurs causing severe artifacts that obscure anatomical structures
Solution Approach 1:
The patent segments the projection images into three distinct regions: a first region with no metal attenuation, a second region with partial metal attenuation, and a third region with full metal attenuation. This segmentation allows different correction strategies to be applied to each region, preserving anatomical structures in the first region while systematically correcting artifacts in the second and third regions through iterative reconstruction processes.
Solution Approach 2:
The patent performs preliminary actions by first identifying and characterizing the metal object's position and orientation in the projection images before conducting the full reconstruction. This preliminary characterization enables the system to pre-calculate attenuation paths and predict artifact locations, allowing for proactive correction strategies rather than reactive post-processing.
2Object-affected harmful factors
If complex metal artifact reduction algorithms are applied to correct artifacts, then artifact intensity is reduced, but computing time increases making real-time monitoring impossible
Solution Approach 1:
The patent divides the correction process into segmented steps corresponding to the segmented projection image regions. By focusing computational resources primarily on the second and third regions where artifacts actually occur, rather than processing the entire image uniformly, the system achieves effective artifact reduction with significantly reduced computing time, enabling real-time intervention monitoring.
Solution Approach 2:
The patent applies correction algorithms selectively only to the regions where artifacts are present (second and third regions), rather than applying complex algorithms to the entire projection image set. This partial action approach maintains the necessary correction effectiveness while dramatically reducing the computational burden and processing time.
3Object-affected harmful factors
If interpolation techniques are used to eliminate metal artifacts, then artifacts are reduced, but actual structures next to the metal object tip are lost
Solution Approach 1:
The patent applies different quality standards and correction intensities to different spatial locations. In the first region where no metal attenuation occurs, the original image data is preserved without any interpolation or correction, maintaining perfect anatomical structure integrity. In the second and third regions where artifacts occur, targeted correction is applied only to the artifact-affected portions, preserving as much genuine anatomical information as possible.
Solution Approach 2:
By segmenting the image space into regions with different artifact characteristics, the patent avoids applying uniform interpolation across the entire image. This allows genuine anatomical structures adjacent to the metal object to be distinguished from artifact patterns and preserved in the first region, while correction is applied only where necessary.
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 removes artifact components, improving the visibility of anatomical structures and lesions, allowing for accurate intervention and diagnosis by maintaining contrast and correct attenuation values, even in regions affected by artifacts.
Implementation Method 1
lower-dimensional projection images... describe attenuation values in the irradiated recording region
Data Source
AI summary
For a computed tomography image data set of a recording region in which an at least substantially needle-shaped metal object is located, a method for correcting artifacts comprises: ascertaining an artifact data set describing, in an image space, at least one artifact caused by the at least substantially needle-shaped metal object, wherein the ascertaining uses prior knowledge about the at least one artifact; and subtracting the artifact data set from the computed tomography image data set. The computed tomography image data set being reconstructed from projection images, which are recorded at least partially such that the at least substantially needle-shaped metal object is irradiated at least substantially in the longitudinal direction.