Fluorescence Imaging Depth Resolution via Multi-Wavelength Excitation
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Solution Overview
Problem
Current optical imaging techniques using fluorescence struggle with depth information in biological tissues, leading to low signal-to-noise ratios and complex marker fabrication, as well as assumptions about absorption coefficients that degrade image quality.
Innovation Solution
The method involves exciting fluorescent markers with multiple wavelengths to emit simultaneous emission bands, allowing for the estimation of three-dimensional location and mean absorption coefficients of the tissue, thereby improving image reconstruction and reducing acquisition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluorescence reflectance imaging (FRI) technique is used to acquire global fluorescent image quickly, then acquisition time is reduced, but depth information is lost and markers on surface only can be located
Solution Approach 1:
The patent transitions from two-dimensional surface imaging (FRI) to three-dimensional depth-resolved imaging by using multiple excitation wavelengths. Different wavelengths penetrate to different depths, enabling the system to reconstruct the spatial distribution of fluorophores throughout the tissue volume, thus adding the depth dimension to the imaging capability.
Solution Approach 2:
The patent changes the excitation wavelength parameter to probe different tissue depths. By using a spectrum of excitation wavelengths rather than a single wavelength, the system can differentiate between fluorophores at different depths based on their distinct excitation spectra, thereby recovering depth information that would otherwise be lost in conventional FRI.
2Measurement precision
If tomography technique is used to produce three-dimensional image, then depth information is obtained, but acquisition time increases to 10-15 minutes and complex reconstruction algorithms are required
Solution Approach 1:
The patent extracts depth information directly from the spectral characteristics of fluorescence excitation and emission. Instead of using complex tomographic reconstruction algorithms that require multiple images from different source/detector positions, the method extracts depth by analyzing how different excitation wavelengths are absorbed and re-emitted at different depths, significantly simplifying the reconstruction process.
Solution Approach 2:
The patent replaces the mechanical scanning system of conventional tomography (which requires moving the light source and detector to multiple positions) with a spectral analysis approach. By using multiple excitation wavelengths and analyzing the resulting emission spectra, the system obtains depth information without mechanical scanning, reducing acquisition time from 10-15 minutes to a few seconds.
3Device complexity
If homogeneous distribution of fluorescence sources is assumed in entire body, then reconstruction algorithm can be simplified, but image quality degrades due to errors from incorrect absorption coefficient assumptions
Solution Approach 1:
The patent performs preliminary spectral measurements at multiple excitation wavelengths to characterize the absorption coefficients of different tissue regions before performing reconstruction. This preliminary action provides accurate, tissue-specific absorption coefficient values that can be used as input for the reconstruction algorithm, eliminating the need to assume homogeneous distribution and thereby improving image quality without significantly increasing algorithmic complexity.
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 enhances the accuracy and speed of image reconstruction by providing detailed depth information and specific absorption coefficients, improving the quality of optical imaging and reducing the complexity of marker fabrication.
Implementation Method 1
exciting fluorescent markers with multiple wavelengths to emit simultaneous emission bands
Implementation Method 2
The photons penetrate only a small distance (approximately 1 millimeter (mm) into the tissue
Implementation Method 3
analyzing the intensities of fluorescence relative to said emission bands
Data Source
AI summary
The present invention relates to a method of optically imaging at least one biological tissue, in particular to define areas of interest of tissue(s) to be analyzed by tomography.The method according to the invention comprises the following steps:a) introducing at least one fluorescent marker into the tissue(s);b) exciting the marker by incident light and detecting emission bands relating to fluorescence emitted by the marker in response to that excitation; thenc) analyzing the fluorescence in these emission bands; andthe step b) comprising:sequentially exciting said marker at n different incident excitation wavelengths λi, said marker being adapted to be excited by at least two of the wavelengths λi and to emit in response to each wavelength λi a series Si of m simultaneous emission bands Bj having different maximum wavelengths λ′j that are substantially the same from one series Si to another; anddetecting these series Si in order to deduce therefrom an estimate of the three-dimensional location of said marker in the tissue(s) and/or the mean absorption coefficients of the tissue(s) for the excitation wavelengths λi.