Ultrasound and Photoacoustic Imaging for Enhanced Image-guided Endovenous Laser Ablation Procedures

摘要

Nearly 20% of the United States' population is affected by varicose veins at some point in their lives. Currently, ultrasound (US) imaging is used as clinical imaging modality to help surgeons visualize and place the ablation catheter within the diseased vein accurately. However, US imaging of catheters has limitations such as angular dependency, especially for treating perforating veins. In addition, the laser ablation procedure is often performed without any real-time temperature monitoring, which could lead to non-sufficient thermal dose or heat induced thrombosis. We propose using combined US and Photoacoustic (PA) imaging for accurate localization of the laser ablation fibers within the veins. More specifically, we proposed coupling both ablation CW laser and pulsed laser into a single ablation catheter to perform both ablation and PA localization and of the catheter and thermometry. Our studies clearly indicated that while US imaging visualizes the body of the catheter, PA signal is only generated at the interface between the fiber tip and the tissue. As a result, PA images of the catheter indicate the location of the tip of the catheter only, without any possibility of error and mislocation. We initially investigated and compared the utility of US and PA in tracking fiber tip in a set of vessel-mimicking phantoms. Our results indicated artifact-free and accurate detection of the fiber tip using PA in contrast to US. Using the PA signal temperature dependency, we also demonstrated the utility of PA for real-time monitoring of temperature increase during laser ablation procedures.