This project seeks to apply SFDI methodologies within sub millimeter volumes of tissue. The challenge in this regime is that standard SFDI models of light scattering and light transport no longer adequately describe the behavior of light when only a few scattering events occur. Our group is developing models and methods to describe the behavior of structured light to extend SFDI techniques into the sub-diffusive regime. This problem is approached from both theoretical (modeling and simulation) and experimental perspectives.
As scattering within this regime may no longer be described in terms of spatial frequency response alone, we have added new measurement geometries and complementary physical parameters to be able to better isolate and characterize these more subtle light scattering parameters in biological tissues. The addition of angular resolution/sensitivity to standard SFDI measurements is but one approach our group is exploring.
Why is there interest in sub-diffusive modeling and measurement of in vivo tissue? This approach presents the opportunity to:
- Alter volume of tissue interrogated by “detected” light (photon gating) and not just the frequency of the illumination pattern and thereby reduce the issues posed in quantitative image reconstruction in optical tomography
- Increase the sensitivity and depth resolution of wide field imaging techniques within superficial volumes: bridge gap between macroscopic and microscopic imaging (i.e. multiply vs singularly scattered light)
- Extract more subtle, detailed parameters from tissue scattering, in vivo:
- Extracellular order and regularity, e.g. collagen formation and orientation
- Shape, complexity of subcellular objects, e.g. Pleomorphism, organelle structure