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

Abstract

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.

Advanced optoacoustic methods for multiscale imaging of in vivo dynamics

“…Thus, the signal amplitude can be modulated by changing the temperature in the sample. This effect has been exploited for non-invasive temperature monitoring in clinical procedures involving radiofrequency ablation [264], high-intensity focused ultrasound (HIFU) [265], cryoablation [266] or laser-induced thermotherapy (LITT) [267]. At the microscopic level, temperature changes in individual cells can be measured with an accuracy of 0.2°C [257].…”

“…For instance, using endogenous tissue contrast and the temperature-dependence of the optoacoustic signal, it was possible to dynamically monitor tissue ablation procedures. In endovenous laser therapy (ELT), elimination of incompetent truncal veins is achieved via intravenous laser coagulation leading to cell destruction and collagen shrinkage, which was successfully monitored by 4D optoacoustics [267] (Fig. 20a).…”

“…(a) 4D optoacoustic monitoring of endovenous laser therapy (ELT) treatment aimed at eliminating incompetent truncal veins. Adapted with permission from [267]. © 2015 John Wiley & Sons, Inc. (b) Optoacoustic images of breast cancer xenografts receiving scrambled control (top) and intratumoral self-complementary AAV serotype 2 (scAAV2) septuplet-tyrosine mutant vectors encoding siRNAs against ATF6 (bottom).…”

Endocardial irrigated catheter for volumetric optoacoustic mapping of radio-frequency ablation lesion progression

“…Radiofrequency (RF) catheter ablation is routinely used in a myriad of clinical interventions such as cancer therapy [1], endovenous removal of varicose veins [2,3] or treatment of cardiac disorders [4]. The procedure is generally preferred over alternative thermal ablation approaches due to its low cost, minimal invasiveness and simplicity of operation [5].…”

Super-resolution thermographic imaging using blind structured illumination

“…Another possible application could be volumetric temperature mapping, where photoacoustic imaging methods have been suggested for measuring the temperature at deep locations. [32][33][34][35] Direct thermographic imaging could offer a non-contact alternative technology.…”