Alpha Angle Measurement Using 3D Bone Surface Models
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Solution Overview
Problem
Conventional methods for measuring the alpha angle in MRI images suffer from high intra- and inter-reader variability due to dependence on a single plane and non-distinctive landmarks, making them time-consuming and inaccurate for quantifying joint function and diagnosing conditions like femoroacetabular impingement.
Innovation Solution
A fast landmark detection-based approach using deep learning technologies for automatic alpha angle measurements, leveraging 2D radial slices to improve algorithmic performance and generate accurate 3D bone surface images, which estimate the head center and neck axis to construct an alpha angle model for precise angle determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual alpha angle measurement is performed in a single plane, then the measurement process is simple, but the intra- and inter-reader variability is very high
Solution Approach 1:
The patent transitions from measuring alpha angle in a single 2D plane to performing measurements across multiple radial slices in 3D space. By acquiring MR images in multiple planes and generating 3D bone surface models, the system enables alpha angle assessment from multiple angular perspectives, thereby reducing variability associated with single-plane measurements while maintaining operational feasibility through automated processing.
2Measurement precision
If alpha angle is measured on each slice of radial slice group to better describe 3D morphology, then the three-dimensional morphology description is improved, but the process becomes time extensive
Solution Approach 1:
The patent performs preliminary actions by automatically generating 3D bone surface models from MR images before conducting alpha angle measurements. The system pre-processes the imaging data to create accurate 3D representations of the femoral head and neck, which then serve as the basis for rapid alpha angle calculation across multiple radial slices. This preliminary 3D modeling enables subsequent measurements to be performed efficiently without requiring time-consuming manual segmentation for each slice.
Solution Approach 2:
The patent creates a 3D digital copy or model of the bone structure from MR images. This virtual 3D replica allows for repeated measurements and analysis without requiring additional physical imaging or manual re-segmentation. The 3D model serves as a reusable representation that can be measured from multiple angles and planes, significantly reducing the time required for comprehensive alpha angle assessment.
3Extent of automation
If shape-model based 3D segmentation is used for automated alpha angle measurement, then automation is improved, but the process requires time-consuming processing and inflexible smoothness constraints
Solution Approach 1:
The patent replaces traditional shape-model-based segmentation methods with a different automated approach that uses radial slice generation and 3D surface modeling from MR images. Instead of relying on pre-defined shape models with inherent smoothness constraints, the system uses image-based 3D reconstruction that naturally captures the bone geometry. This substitution maintains full automation while eliminating the time-consuming nature and inflexible constraints of shape-model fitting.
Data Source
AI summary
In a method for alpha angle measurements of a bone joint based on magnetic resonance imaging (MRI) data of the bone joint, a three-dimensional (3D) bone surface image of the bone joint is generated based on two-dimensional (2D) segmentations on radial plane slices of the bone joint. Based on the 3D bone surface image, a head center of a head of the bone joint and a neck axis of a neck of the bone joint are estimated. An alpha angle model is constructed based on the estimated head center and neck axis. Further, the alpha angle measurement is determined for each of the radial plane slices of the bone joint based on the constructed alpha angle model.