CT and 3DRA Fusion for Arterial Segmentation

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Solution Overview

Problem

In three-dimensional rotational angiography (3DRA), the overlap of bone and vessel intensity distributions due to beam hardening and insufficient calibration hinders accurate segmentation of artery/vessel information, while CT provides high contrast but is obscured by high-density skull data, making it difficult to visualize arterial structures effectively.

Innovation Solution

A system and method combining data from CT and 3DRA using registration, thresholding, and masking to align and filter data sets, allowing for selective visualization of tissue types by utilizing complementary information from each modality, and rendering data transparent to enhance clarity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If 3DRA is used for vessel visualization, then vessel information can be obtained, but bone and vessel intensity distributions overlap due to beam hardening, hindering accurate segmentation

Engineering Contradiction:

Improvevessel segmentation accuracyVSAvoidbeam hardening effect

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by dividing the skull bone into multiple density-based regions (outer table, diploe, inner table) and treating each differently. This allows selective handling of beam hardening effects in different bone regions, improving vessel segmentation accuracy by compensating for intensity distortions in a region-specific manner.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes parameters by introducing density-based classification and region-specific compensation factors. By categorizing voxels into different bone density regions and applying different correction parameters to each, the system resolves the intensity overlap between bone and vessels caused by beam hardening.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If CT data is used for orientation, then high contrast between bony structures and soft tissue is provided, but high density skull data prevents clear view of arterial structures

Engineering Contradiction:

Improvetissue contrastVSAvoidarterial structure visibility

Core Design Contradiction:

Illumination intensityVSLoss of information

Solution Approach 1:

The patent applies local quality by rendering different tissue types with different transparency properties. The skull bone is rendered with higher transparency while soft tissues and vessels maintain higher opacity, allowing simultaneous visualization of both bony structures for orientation and arterial structures for diagnosis without mutual obstruction.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses color and transparency changes to differentiate tissue types in the fused rendering. By assigning distinct visual properties (transparency, color) to different tissue types based on their density characteristics, the system enables clear differentiation and simultaneous visualization of bone and vessel structures.

Inventive Principle:

Principle #32Color changes

3Loss of information

If both CT and 3DRA data sets are combined, then complementary information is obtained, but registration is hindered by artefacts and different acquisition conditions

Engineering Contradiction:

Improvecomplementary information contentVSAvoiddata processing complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by performing preprocessing steps on the 3DRA data before registration, including skull bone segmentation and density-based region classification. This preliminary processing creates a simplified, artifact-reduced representation that facilitates more accurate and robust registration with CT data.

Inventive Principle:

Principle #10Preliminary action

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 enables clear visualization of arterial structures by separating bone and vessel information, improving segmentation accuracy and providing a clearer view of blood vessel structures within the skull, facilitating better diagnostic imaging.

Implementation Method 1

the phenomenon of beam-hardening caused by the skull, in combination with insufficient calibration and reconstruction procedures

Methodology Applied

Scientific EffectBeam hardening: Absorption (EM radiation)

Data Source

PatentUS8055044B2Flexible 3D rotational angiography and computed tomography fusion

Publication Date: 2011.11.08 KONINKLIJKE PHILIPS NV

AI summary

One of two data sets, originating from two different radiological methods is processed to generate interim results, yielded by an operation on one of the data sets. The interim results are used to modify the other data set. Different imaging capabilities of the employed radiological methods promote a particular task, e.g. the segmentation of a given type of tissue. When the combined data of both methods is displayed, clinical users benefit from the complementary information. Care is taken, that only relevant information is presented to the user, as to avoid irrelevant data obscuring any data of interest. Therefore, the data to be displayed is filtered based on content, e.g. the type of tissue, and on location. Three-dimensional computer tomography and three-dimensional rotational angiography are particularly applicable radiological methods.