Tomographic fluorescence imaging in tissue phantoms: a novel reconstruction algorithm and imaging geometry

Area of Science:

• Biomedical Optics
• Medical Imaging
• Computational Biology

Background:

• Frequency-domain photon migration (FDPM) tomography is crucial for non-invasive tissue imaging.
• Accurate reconstruction of fluorescence absorption coefficients is essential for diagnostics.
• Existing methods face challenges with complex fluorophore distributions.

Purpose of the Study:

• To develop and demonstrate a novel image reconstruction algorithm for FDPM tomography.
• To reconstruct three-dimensional (3-D) images of fluorescence absorption coefficients.
• To validate the algorithm using a clinically relevant phantom with varying fluorophore distributions.

Main Methods:

• Developed a nonlinear least-squares optimization problem using penalty/modified barrier functions (PMBF) and coupled diffusion equations.
• Employed a gradient-based truncated Newton method with trust regions for large-scale optimization (39,919 unknowns, 2,973 measurements).
• Utilized area illumination and area collection with a gain-modulated image-intensified charge-coupled device (ICCD) camera.

Main Results:

• Successfully reconstructed 3-D images of fluorescence absorption coefficients.
• Demonstrated accurate reconstruction under conditions of both perfect and imperfect fluorophore distribution.
• Achieved 3-D reconstruction from reflectance measurements in a clinically relevant phantom.

Conclusions:

• The novel algorithm enables accurate 3-D fluorescence tomography.
• This represents the first 3-D reconstruction from reflectance measurements in a clinically relevant phantom.
• The method shows promise for advanced biomedical imaging applications.