Multi-wavelength Time-resolved Laser Speckle Imaging for Tissue Hemodynamics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current neuroimaging technologies for deep tissue hemodynamics and metabolism, such as MRI, PET, CT, and optical imaging methods, face limitations including high costs, invasiveness, limited penetration depth, and time-consuming reconstruction processes, which hinder continuous and noninvasive monitoring of tissue blood flow and oxygenation.
Innovation Solution
A noncontact, multi-wavelength time-resolved laser speckle contrast imaging (MTR-LSCI) system that uses picosecond-pulsed, coherent widefield near-infrared light and a time-gated single-photon avalanche diode camera to provide fast, high-resolution 2D mapping of tissue blood flow, oxygen saturation, and metabolic rate of oxygen consumption at different depths, eliminating the need for complex tomographic reconstructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional neuroimaging technologies (MRI, PET, CT) are used for deep tissue hemodynamics measurement, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex mechanical imaging systems (MRI, PET, CT) with an optical-based laser speckle contrast imaging system. This substitution uses light scattering properties of moving red blood cells to measure blood flow, eliminating the need for expensive, complex imaging hardware while maintaining measurement capability for hemodynamic parameters
Solution Approach 2:
The patent changes the measurement approach from direct imaging to indirect optical parameter measurement. By measuring laser speckle contrast (an optical parameter) and deriving blood flow information from it, the system achieves hemodynamics measurement with simpler equipment compared to direct imaging methods
2Ease of operation
If optical imaging methods are used for tissue hemodynamics monitoring, then ease of operation and portability are improved, but penetration depth is limited
Solution Approach 1:
The patent uses pulsed laser illumination instead of continuous illumination. The periodic pulsed action allows time-resolved measurement where early-arriving photons (which traveled shorter paths through tissue) can be distinguished from later-arriving photons, enabling depth-sensitive measurements while maintaining the portability and ease of operation of optical methods
3Measurement precision
If time-resolved measurement with pulsed lasers is implemented, then depth sensitivity is improved, but use of energy and system complexity increase
Solution Approach 1:
The patent implements time-resolved measurement with pulsed lasers but uses a single detector rather than multiple detectors at different time gates. This partial implementation achieves depth sensitivity through time-gated detection while avoiding the excessive energy consumption and complexity that would result from multiple synchronized detectors or more aggressive pulsing schemes
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 continuous, fast, and high-resolution imaging of cerebral hemodynamics with improved spatial resolution and depth sensitivity, allowing for noninvasive monitoring of tissue health and disease diagnosis, particularly suitable for neonatal care and other clinical applications.
Implementation Method 1
Laser speckle contrast imaging
Implementation Method 2
multi-wavelength time-resolved laser speckle contrast imaging
Implementation Method 3
time-gated camera...synchronized to a repetition frequency between 10 MHz and 80 MHz
Implementation Method 4
time-gated camera with a resolution of at least 256×512 single-photon-counting pixels
Data Source
AI summary
A noncontact, multi-wavelength time-resolved laser speckle contrast imaging (MTR-LSCI) technique provides for continuous, fast and high-resolution 2D mapping of tissue blood flow (BF) and tissue blood oxygen saturation (StO2) at different depths of target tissue. MTR-LSCI illuminates the tissue with picosecond-pulsed, coherent, widefield light at least at two different wavelengths in the near-infrared range (600-1100 nm) and synchronizes a high-resolution, gated single-photon avalanche diode (SPAD) camera to capture BF and StO2 maps at different depths of target tissue, wherein the imaging depth depends on light propagation inside a tissue volume, captured by the time-gated camera. The reconstruction of BF and StO2 maps can be dramatically expedited by incorporating highly parallelized computation and convolution functions. The performance of MTR-LSCI was evaluated using head-simulating phantoms with known properties and in-vivo rodents with varied hemodynamic challenges to the brain.