Spatial Frequency Domain Imaging (SFDI)
Biological tissues are composed of a variety of chromophores--molecules that absorb light of characteristic wavelengths. If you measure the amount of light that a tissue absorbs, you can calculate concentrations of the chromophores present in the tissue. This is useful in many clinical applications because some of the more dominant chromophores in your tissue are markers of important clinical parameters, such as oxygenation. However, it is difficult to quantify the absorption of tissue because it is turbid. The attenuation of light in tissue is a function of both its absorption and scattering properties.
Spatial frequency domain imaging is a technique to separate the effects of scattering and absorption, and consequently, to approximately quantify a set of chromophores. The technique works by shining different patterns light on the tissue, recording a video of the remitted light, and processing the movie acquired. In the Frangioni Lab, we applied this technique to, among other things, plastic surgery applications. Specifically, we tested the ability of SFDI to provide an early assessment of the viability of skin flap transplants during breast reconstruction.