Speckle decorrelation rate for visualizing therapeutic thermal field with OCT

OCT is transitioning from a diagnostic tool to one that also aids in treatment. However, structural imaging is difficult to visualize the therapeutic field of minimally invasive thermal treatment, such as laser or radiofrequency ablation, due to the fact that the optical properties of the tissue are less altered during the temperature increase prior to denaturation of the tissue (~50℃). Here we propose to use speckle decorrelation rate, as a new contrast mechanism for visualizing the therapeutic thermal field. We performed ex vivo tissue experiments on an integrated laser ablation-OCT surveillance system. We found that, compared with the speckle decorrelation employed in existing works, the speckle decorrelation rate could be a more robust indicator: It has higher signal-to-noise ratios and is less sensitive to the selection of time interval (used in the decorrelation calculation). The superiority of our method has been verified on different types of biological tissues. Besides, it is label-free and can be readily applied to various setups of OCT systems. We think our method may be contributed to improving the precision and safety of thermal therapies.