Volumetric optoacoustic imaging feedback during endovenous laser therapy - an ex vivo investigation.

Endovenous laser therapy (ELT) was introduced in clinical practice for treating incompetent veins about fifteen years ago. Despite the considerable clinical evidence collected so far, no rigorous guidelines are yet available regarding the optimal energy deposition protocols while incidence of recanalization, lack of vessel occlusion and collateral damage remains variable among patients. Online monitoring and feedback-based control over the lesion progression may improve clinical outcomes. Yet the currently employed monitoring tools, such as Doppler ultrasound, often do not provide sufficient contrast as well as three-dimensional imaging capacity for accurate lesion assessment during thermal treatments. Here we investigate on the utility of volumetric optoacoustic tomography for real-time monitoring of the ELT procedures. Experiments performed in subcutaneous veins of an ox foot model revealed the accurate spatio-temporal maps of the lesion progression and characteristics of the vessel wall. Optoacoustic images further correlated with the temperature elevation measured in the area adjacent to the coagulation spot and made it possible to track the position of the fiber tip during its pull back in real time and in all three dimensions. Overall, we showcase that volumetric optoacoustic tomography is a promising tool for providing online feedback during endovenous laser therapy.