Noncontact 3D Diffuse Correlation Tomography for Deep Tissue Blood Flow
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Solution Overview
Problem
Current imaging techniques for deep tissue injuries, such as chronic wounds, burns, and mastectomy skin flap necrosis, face challenges due to the need for contact measurements, which can lead to infections and deformation, and lack noninvasive, continuous, and quantitative methods for assessing tissue hemodynamics.
Innovation Solution
The development of noncontact diffuse correlation tomography (DCT) systems using near-infrared light and charge-coupled-device (CCD) technology for three-dimensional reflectance imaging of blood flow distribution in deep tissues, avoiding contact with the tissue and enabling imaging up to 1.5 cm depth, with systems comprising source and detector arrays and computing methods for reconstructing blood flow indices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact measurements using a probe are used, then tissue blood flow and oxygenation can be measured, but the risk of infection and tissue deformation increases
Solution Approach 1:
The patent uses near-infrared light as an intermediary to measure tissue blood flow without direct contact. The light penetrates the tissue and interacts with blood chromophores, allowing measurement of blood flow and oxygenation through optical signals rather than physical contact with a probe.
Solution Approach 2:
The patent replaces the mechanical contact-based probe measurement system with a non-contact optical measurement system. Instead of using a physical probe that touches the tissue, the system uses near-infrared light sources and detectors to measure tissue hemodynamics through optical absorption and scattering properties.
2Object-affected harmful factors
If noncontact imaging is used, then infection risk and tissue deformation are reduced, but imaging depth and resolution are limited
Solution Approach 1:
The patent transitions from surface-level 2D imaging to 3D volumetric imaging of tissue blood flow. By using multiple source-detector pairs arranged in a three-dimensional configuration and applying diffuse correlation tomography algorithms, the system reconstructs blood flow distribution throughout the volume of the tissue, achieving both non-contact measurement and deep tissue penetration.
Solution Approach 2:
The patent utilizes the wavelength-dependent optical properties of tissue to achieve deep penetration. By selecting near-infrared wavelengths (typically 650-950 nm) where tissue absorption is minimized and scattering dominates, the light can penetrate several centimeters into the tissue. The system also varies source-detector separation distances to probe different depths, with larger separations accessing deeper tissues.
3Loss of information
If diffuse correlation tomography is used for deep tissue imaging, then blood flow distribution can be visualized, but system complexity and computational requirements increase
Solution Approach 1:
The patent divides the tissue volume into discrete voxel elements and calculates blood flow parameters for each voxel independently using the diffusion correlation equation. The measurement data from multiple source-detector pairs are processed segment by segment through iterative reconstruction algorithms, allowing the complex 3D inverse problem to be solved in manageable steps.
Solution Approach 2:
The patent develops a unified diffuse correlation tomography framework that can simultaneously measure blood flow at multiple depths and locations using the same hardware configuration. The system uses a single set of near-infrared light sources and detectors that can probe the entire tissue volume by varying the source-detector separation distances and positions, eliminating the need for multiple specialized sensors.
4Area of stationary object
If multiple source-detector pairs are used for 3D imaging, then measurement coverage and depth are improved, but measurement time and data processing load increase
Solution Approach 1:
The patent employs time-resolved or frequency-domain modulation of the near-infrared light sources, allowing multiplexed measurement of multiple source-detector pairs. By modulating the light sources at different frequencies and detecting the modulated signals, the system can simultaneously acquire data from multiple channels without sequential scanning, significantly reducing total measurement time.
Solution Approach 2:
The patent combines the measurement data from all source-detector pairs into a single unified inverse problem that is solved simultaneously using diffuse correlation tomography reconstruction algorithms. Rather than processing each measurement separately, the system integrates all measurements into one comprehensive 3D blood flow distribution map, reducing redundant computations and accelerating data 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
Enables noninvasive, continuous, and quantitative imaging of deep tissue blood flow, reducing the risk of infection and deformation, and providing accurate diagnosis and treatment monitoring for deep tissue injuries.
Implementation Method 1
at least two near-infrared light sources are projected and focused onto a tissue surface of a subject
Implementation Method 2
a detector array to detect the diffused NIR light from the tissue through a second set of optical lenses
Implementation Method 3
The imaging probe may then apply beams of NIR light through a set of optical lenses to the tissue and the detector array to detect the diffused NIR light from the tissue
Data Source
AI summary
The present invention provides for three-dimensional reflectance diffuse optical imaging of deep tissue blood flow distribution that removes the need for probe-tissue contact, thereby allowing for such technology to be applied to sensitive, vulnerable, damaged, or reconstructive tissue. The systems utilize noncontact application and detection of near-infrared light through optical lens and detection through a linear array or two-dimensional array of avalanche photodiodes or a two-dimensional array of detectors provided by charge-coupled-device (CCD). Both further feature a finite-element-method (FEM) based facilitation to provide for three-dimensional flow image reconstruction in deep tissues with arbitrary geometries.