In this work we compare four proposed methods for wide-field imaging that are based on different photon propagation models and that depend on different sets of assumed parameters such as absorption and reduced scattering coefficients. We investigated these for methods, with particular attention to sensitivities to errors in assumed parameters of calibration estimates. To this end we acquired an in vivo time series of a pig skin flap with a venous occlusion. StO2 estimates of all methods were compared to estimates from spatial frequency domain imaging of the same time series.
Correct assumptions on scatter power and accurate calibration were found to be the most important prerequisites for accurate StO2 estimates. Although all models were able to measure relative changes in StO2 when the occlusion was applied and released, only the models that incorporated assumed reduced scattering coefficients estimated StO2 values within 5% of the expected values (estimated using SFDI).
An important aspect of the compared methods is their ability to be used for real-time imaging. With the addition of real-time calibration and robust tissue scattering estimates, real-time wide-field imaging of oxygenation saturation can prove to provide important added value in the clinic.