Retinal Imaging Spatial Frequency Adjustment
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Solution Overview
Problem
Current retinal imaging techniques struggle to provide quantitative data due to limitations in spatial resolution, imaging depth, and the small size of the retina, making it difficult to accurately measure optical characteristics and distinguish autofluorescence from labeled fluorescence.
Innovation Solution
A method and system that project a repetitive pattern with spatial frequencies greater than 0.33µtr onto the retina, using phase-shifted images to form demodulated images, and applying a tissue optical transport model to determine tissue optical properties, thereby enhancing the sensitivity to angular scattering distribution and allowing for accurate measurement of sub-diffuse scattering, absorption, and fluorescence parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional SFDI techniques are used for retinal imaging, then large areas of tissue can be exposed, but the spatial resolution is low and imaging depth extends significantly beyond the retina
Solution Approach 1:
The patent changes the spatial frequency parameter from conventional SFDI values (0-0.2 mm⁻¹) to higher values (0.33μtr and above), which fundamentally alters the light transport regime from diffuse to sub-diffuse. This parameter change enables simultaneous achievement of high spatial resolution and appropriate imaging depth for retinal tissue while maintaining wide-field imaging capability
2Measurement precision
If high spatial frequency patterns are projected onto the retina, then sensitivity to angular scattering distribution is enhanced, but the complexity of the imaging system increases
Solution Approach 1:
The patent employs periodic spatial patterns (sinusoidal or other repetitive shapes) projected onto the retina at controlled spatial frequencies. This periodic illumination approach enables quantitative measurement of sub-diffuse scattering properties through phase-shifted imaging, achieving high measurement precision while maintaining a relatively simple implementation using standard spatial light modulators or digital mirror devices
3Measurement precision
If conventional imaging techniques are used, then autofluorescence and labeled fluorescence cannot be distinguished, but quantitative measurement of fluorescence is required for accurate diagnosis
Solution Approach 1:
The patent uses tissue optical properties (scattering and absorption coefficients) as an intermediary to correct the measured fluorescence signal. By first measuring these optical properties using the sub-diffuse SFDI technique, the system can then apply correction factors to distinguish intrinsic autofluorescence from labeled fluorescence, enabling accurate quantitative fluorescence measurement without requiring complex spectral unmixing or additional imaging modalities
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 the acquisition of high-quality, quantitative images of the retina with improved sensitivity and accuracy, allowing for precise measurement of optical properties and differentiation between autofluorescence and labeled fluorescence, which is crucial for diagnosing retinal conditions.
Implementation Method 1
A high spatial frequency of the phase shifted images induces an additional sensitivity to the angular scattering distribution related to sub-diffuse light transport
Implementation Method 2
The periodic signal is shifted in phase and the phase-shifted images are combined to form a demodulated image
Implementation Method 3
fluorescence markers can be used to label individual substances
Data Source
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AI summary
A method and system are proposed for imaging the retinal structure of an eye. A light source is provided and a repetitive pattern is projected on the retina by said hght source having illuminated and non-illuminated portions with a spatial frequency larger than 0.5 mm-1. For the illuminated and non-illuminated portions a fluorescence level is measured; and a fluorescence level is derived as a corrected value for illuminated and non -illuminated areas.