Multi-scale anatomical landmark detection in incomplete 3D-CT data

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Solution Overview

Problem

Traditional anatomical landmark detection techniques in medical images, especially those using deep learning, face challenges with incomplete data and high computational complexity, and rely on suboptimal heuristics for recognizing landmarks in partial field-of-view scans.

Innovation Solution

A multi-scale deep learning approach using a scale-space model and robust statistical shape modeling for spatially-coherent landmark detection, which reduces memory requirements and computational complexity by training deep neural networks at each scale level through deep reinforcement learning, and explicitly addresses missing landmarks by rewarding trajectories that exit the image space when necessary.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional deep learning techniques are used for anatomical landmark detection, then detection accuracy can be achieved, but computational complexity and memory requirements become prohibitively high

Engineering Contradiction:
Improvelandmark detection accuracyVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the detection task into multiple scale levels (coarse to fine), where each level processes landmarks at different resolutions. This hierarchical segmentation reduces computational complexity at each stage while maintaining overall detection accuracy through progressive refinement.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a scale dimension by processing landmarks at multiple resolutions (coarse, medium, fine scales). This dimensional approach allows the system to achieve accurate detection without requiring excessive computational resources at any single scale level.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If exhaustive search strategies are used for landmark detection, then comprehensive detection can be achieved, but detection speed becomes too slow for clinical workflow

Engineering Contradiction:
Improvedetection completenessVSAvoiddetection speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent performs preliminary detection at coarse scales first, identifying candidate landmarks before refining their positions at finer scales. This preliminary action eliminates the need for exhaustive search at full resolution, significantly improving detection speed while maintaining reliability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a dynamic multi-scale search strategy where the search resolution and scope adapt across different scale levels. The system dynamically transitions from broad coarse-scale searching to focused fine-scale refinement, optimizing both speed and completeness.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If conventional detection methods are applied to incomplete scans with partial field-of-view, then standard detection can proceed, but spatial consistency and accuracy of detected landmarks deteriorate

Engineering Contradiction:
Improvehandling of incomplete dataVSAvoidspatial consistency
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by treating different spatial regions and scale levels differently. Incomplete regions are processed with appropriate scale-level adaptations, while complete regions receive full-resolution processing, maintaining spatial consistency across the entire volume.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses a nested multi-scale approach where coarse-scale detection results guide fine-scale detection. This nesting allows the system to handle incomplete data at coarser scales and progressively refine detections in complete regions at finer scales, preserving spatial consistency.

Inventive Principle:
Principle #7Nested doll (Nesting)

4Measurement precision

If high-resolution detection is performed across the entire image space, then detection precision is maximized, but memory requirements and processing time become excessive

Engineering Contradiction:
Improvelandmark detection precisionVSAvoidmemory requirements
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent segments the image space into multiple scale levels, processing each level at appropriate resolution. This segmentation allows high precision detection only where needed (at fine scales for relevant landmarks) while using coarser representations elsewhere, reducing overall memory requirements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by performing high-resolution detection only for landmarks that are present and relevant in each local region, rather than uniformly processing the entire image space at maximum resolution. This selective approach maintains precision while reducing memory consumption.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3370206B1Spatially consistent multi-scale anatomical landmark detection in incomplete 3d-CT data
Publication Date: 2020.11.25 SIEMENS HEALTHCARE GMBH
  • EP3370206B1 patent drawingFigure 1
  • EP3370206B1 patent drawingFigure 2
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AI summary

A method and system for automated spatially-consistent multi-scale detection of anatomical landmarks in medical images is disclosed. A discrete scale-space representation of a medical image of a patient is generated. A plurality of anatomical landmarks are detected at a coarsest scale-level of the discrete scale-space representation of the medical image using a respective trained search model trained at the coarsest scale-level for each of the plurality of anatomical landmarks. Spatial coherence of the detected anatomical landmarks is enforced by fitting a learned robust shape model of the plurality of anatomical landmarks to the detected anatomical landmarks at the coarsest scale-level to robustly determine a set of the anatomical landmarks within a field-of-view of the medical image. The detected landmark location for each of the landmarks in the set of anatomical landmarks is refined at each remaining scale-level of the discrete scale-space representation of the medical image using, for each landmark, a respective trained search model trained at each remaining scale-level and constrained based on the predicted landmark location at a previous scale-level.