Tympanic Membrane Thickness Mapping via Low-Coherence Interferometry
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Solution Overview
Problem
Current imaging techniques fail to accurately combine spatially-resolved depth information from different modalities to form a reliable three-dimensional representation of the tympanic membrane, particularly due to challenges in image mosaicking caused by the membrane's homogeneous and specular nature, which lacks sharp features and is sensitive to illumination variations.
Innovation Solution
A novel two-step mosaicking method combining coarse feature-based registration with finer intensity-based co-registration, using low-coherence interferometry to obtain depth-resolved profiles and generate a globally co-registered three-dimensional mapping of the tympanic membrane, accounting for refractive index and interpolating sparse data points to create a smoothly colored thickness distribution map.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If intensity-based image registration is used, then image alignment can be achieved, but the method is sensitive to image deterioration from non-uniform illumination and defocus
Solution Approach 1:
The patent introduces low-coherence interferometry as an intermediary measurement modality to obtain depth information that is independent of illumination conditions. This depth data serves as a robust reference for guiding the registration of optical images, decoupling the alignment process from sensitivity to illumination variations and defocus.
Solution Approach 2:
The patent changes the measurement parameter from intensity-based metrics (which are sensitive to illumination) to depth-based metrics obtained through low-coherence interferometry. This parameter change provides a more stable basis for image registration that is invariant to illumination conditions.
2Reliability
If feature-based image registration is used, then robustness to illumination variations is improved, but the method requires sharp distinctive features which the tympanic membrane lacks due to its homogeneous and specular nature
Solution Approach 1:
The patent uses low-coherence interferometry as an intermediary to generate depth maps that provide synthetic features for registration. These depth-derived features are distinctive and detectable even though the optical images of the tympanic membrane are homogeneous and lack sharp features.
Solution Approach 2:
The patent transitions from two-dimensional optical image registration to three-dimensional registration by incorporating depth information. This additional dimension provides distinctive geometric features that are detectable and useful for alignment, overcoming the featurelessness of the optical images.
3Measurement precision
If depth information from multiple modalities is combined, then three-dimensional representation accuracy is improved, but the problem of how to consistently register spatially-resolved depth information remains unsolved
Solution Approach 1:
The patent employs low-coherence interferometry depth measurements as an intermediary framework to guide the registration of optical images from different modalities. This intermediary depth data provides a common reference space that simplifies the integration of multi-modal information.
Solution Approach 2:
The patent merges optical imaging and low-coherence interferometry depth measurement into a unified multi-modal imaging system. By combining these modalities and registering them through a common coordinate framework, the system achieves accurate three-dimensional representation while managing complexity through integrated processing.
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 accurate, three-dimensional imaging of the tympanic membrane, providing valuable diagnostic information and improving understanding of middle-ear dynamics by overcoming previous limitations in image registration and depth measurement accuracy.
Implementation Method 1
LCI is a well-known optical coherence technique capable of measuring one-dimensional depth-resolved tissue structure
Implementation Method 2
combining visual imaging with low-coherence interferometry (LCI)
Data Source
AI summary
Methods and apparatus for combining a low coherence interferometry (LCI) technique for single-point thickness measurement with videootoscopy for recording the image of a tissue such as the tympanic membrane (TM). TM thickness distribution maps are obtained by mapping the LCI imaging sites onto an anatomically accurate wide-field image of the TM, generated by mosaicking a sequence of multiple small field-of-view video-otoscopy images.