Diffuse photon density wavefront speed as a contrast for tomographic imaging of heterogeneous diffusive media

Area of Science:

• Biomedical Optics
• Medical Imaging Physics
• Computational Imaging

Background:

• Diffuse optical imaging is crucial for non-invasive tissue characterization.
• Exploiting novel contrast mechanisms can enhance imaging resolution and specificity.
• Previous methods have not utilized the speed of diffuse photon density wavefronts (DPDWFs) as a contrast agent.

Purpose of the Study:

• To develop and validate an imaging algorithm for tomographically reconstructing contrast maps based on DPDWF speed.
• To introduce DPDWF speed as a novel contrast mechanism for biological tissue imaging.
• To demonstrate the algorithm's capability in identifying tissue heterogeneities.

Main Methods:

• Implementation of an imaging algorithm for tomographic reconstruction.
• Utilizing early photon arrival times (EPATs) from time-domain measurements.
• Formulating the inverse problem as algebraic equations solved via constrained linear least squares.

Main Results:

• Experimental validation in 3D media with tissue-like optical properties.
• Successful reconstruction of contrast maps based on DPDWF speed.
• Demonstrated ability to provide tomographic information on heterogeneity locations and distributions.

Conclusions:

• The developed algorithm effectively reconstructs contrast maps using DPDWF speed.
• DPDWF speed is a viable and novel contrast mechanism for diffuse optical imaging.
• The method shows promise for non-invasive detection and characterization of tissue heterogeneities.