Iterative Noise Reduction for Accurate CT Quantitative Maps

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Solution Overview

Problem

In medical imaging, particularly in computed tomography (CT), non-linear transformations introduce noise-induced bias in quantitative maps, which is difficult to eliminate without sacrificing spatial resolution, especially in low-dose protocols that produce high image noise, and existing ad-hoc solutions are unreliable across varying patient and imaging conditions.

Innovation Solution

A method for automatic optimization of noise reduction in medical imaging data involves iteratively increasing the noise reduction level until the mean quantitative bias difference falls below a threshold, applying the last effective noise reduction level to generate optimized quantitative maps that balance bias, noise, contrast, and spatial resolution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If intense noise reduction is applied to the original CT image data before quantitative analysis, then noise-induced bias in quantitative maps is reduced, but spatial resolution and image contrast are sacrificed

Engineering Contradiction:
Improvequantitative map accuracyVSAvoidspatial resolution
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent applies different noise reduction parameters (strength levels) to different regions or types of image data. By changing the noise reduction parameter dynamically rather than using a fixed high intensity, the system reduces noise-induced bias in quantitative maps while preserving spatial resolution and image contrast in critical areas.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements a dynamic optimization process where the noise reduction level is automatically adjusted based on the specific imaging data characteristics, patient anatomy, and quantitative analysis requirements. This dynamic adaptation allows the system to find the optimal balance between noise reduction and resolution preservation for each case.

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If smoothing or averaging is applied on Region of Interest in the final quantitative map, then noise is reduced, but quantitative bias cannot be eliminated

Engineering Contradiction:
Improveimage noiseVSAvoidquantitative bias
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent applies noise reduction to the original CT image data before performing the quantitative analysis, rather than attempting to correct bias in the final quantitative maps. This preliminary action prevents noise-induced bias from being introduced in the first place, making the subsequent quantitative analysis more accurate without requiring post-processing smoothing that would not eliminate bias.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If ad-hoc solutions such as tailored pre-sets are used, then specific imaging conditions can be addressed, but reliability is compromised due to significant variation in original data across patients and protocols

Engineering Contradiction:
Improveimaging protocol adaptabilityVSAvoidsolution reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements an automated feedback loop that continuously monitors the quantitative analysis results and adjusts the noise reduction parameters accordingly. By using feedback from the actual imaging data and quantitative maps, the system automatically optimizes the noise reduction level for each patient and protocol combination, eliminating the need for manual pre-sets and improving both adaptability and reliability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-optimization by automatically determining the optimal noise reduction parameters based on the specific imaging data characteristics, without requiring manual intervention or pre-configured settings. This self-service capability allows the system to adapt to varying patient and protocol conditions while maintaining reliable and consistent quantitative results.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS10789683B2Method for automatic optimization of quantitative map generation in functional medical imaging
Publication Date: 2020.09.29 KONINKLIJKE PHILIPS NV
  • US10789683B2 patent drawing
  • US10789683B2 patent drawing
  • US10789683B2 patent drawing

AI summary

The current application relates to an optimization procedure where the noise reduction strength is incrementally increased and applied in the noise reduction scheme. A non-linear quantitative map is then computed followed by the quantitative bias estimation. The optimization conditions are then checked and the noise reduction “strength” is increased if the bias difference is higher than a predefined threshold.