Choroidal Vessel Extraction from OCT Data
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Solution Overview
Problem
Current ophthalmological imaging techniques, such as ICGA, are invasive and provide poor depth resolution, leading to unclear vessel outlines and pseudo vessel artifacts in OCT images of the choroidal layer, making it difficult to accurately diagnose eye diseases like glaucoma and AMD.
Innovation Solution
An optical coherence tomography apparatus and image-processing program that selectively visualize and analyze the choroidal vessels by extracting and binarizing image data from OCT-measured data, using thresholding and filtering techniques to separate choroidal vessels from retinal vessels and pseudo vessels, allowing for quantitative evaluation of vessel diameter and network thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ICGA is used to visualize choroidal vessels, then vessel visibility is improved, but the method becomes invasive and depth resolution deteriorates
Solution Approach 1:
The patent creates simulated angiographic images by processing OCT tomographic data to replicate the visual information of traditional angiography (ICGA) without requiring actual dye injection. The image processing algorithms generate en-face views and angiographic representations from the OCT data, providing a non-invasive copy of the vascular information that would otherwise require invasive procedures to obtain.
2Measurement precision
If ICGA is used for choroidal vessel imaging, then vessel visualization is improved, but depth resolution deteriorates leading to unclear vessel outlines
Solution Approach 1:
The patent processes three-dimensional OCT tomographic data to create two-dimensional en-face images and angiographic representations. By transforming the 3D volumetric data into 2D cross-sectional views at specific depths, the system maintains depth resolution information while providing the en-face visualization characteristic of angiography. This dimensional transformation allows clear vessel outlines to be preserved from the high-resolution OCT data.
3Object-affected harmful factors
If standard OCT imaging is used for choroidal layer visualization, then non-invasive measurement is achieved, but pseudo vessel artifacts increase making accurate diagnosis difficult
Solution Approach 1:
The patent applies image processing algorithms to extract and isolate true choroidal vessels from pseudo vessel artifacts in OCT images. By analyzing the specific characteristics of choroidal vasculature and applying filtering techniques, the system separates genuine vascular structures from artifacts caused by overlying retinal vessels and other non-vascular features, thereby improving diagnostic accuracy while maintaining non-invasive measurement.
4Quantity of substance
If invasive angiography is used to obtain vessel information, then comprehensive vascular data is achieved, but patient stress and side effect risk increase
Solution Approach 1:
The patent generates comprehensive vascular information by processing OCT data through algorithms that simulate angiographic outcomes. The system produces en-face images, angiographic representations, and quantitative vascular measurements that replicate the information obtained from invasive angiography, eliminating the need for dye injection and associated patient stress while maintaining data comprehensiveness.
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
Enables non-invasive, high-contrast imaging of choroidal vessels similar to Doppler OCT, facilitating accurate quantitative evaluation of vascular structures, thereby improving ophthalmological diagnosis without the need for invasive procedures.
Implementation Method 1
The basic OCT 43 is based on Michelson's interferometer... interference signals appear only when the distance from the reference arm and that from the object arm are roughly equal... measuring the interference signal intensity using the photodetector 52 while changing the differential optical path length (τ) between the reference arm and object arm gives interference signals relative to the differential optical path length (interferogram)
Data Source
AI summary
From OCT-measured data, only the image data of the choroidal vascular network present in the layer of the choroidal layer is selectively extracted, thereby accurately obtaining the thickness of the choroidal vessels and thickness of the choroidal vascular network from the image data, to allow for quantitative evaluation of the choroidal vascular network. The optical coherence tomography apparatus has an optical coherence tomography device, and a computer that processes the three-dimensional OCT tomographic images obtained based on the OCT-measured data acquired by the optical coherence tomography device. The computer functions as a means for selectively separating out only the images of the choroidal vessels from the three-dimensional OCT tomographic images to acquire image data of the choroidal vessels, and also as a means for obtaining the data to be used in the quantitative evaluation of the shape of the choroidal vessels based on the image data of the choroidal vessels.