Calibration of Photoacoustic Signal Temperature Dependence for Quantitative Thermometry During Endovenous Laser Ablation Procedures

Tanyeem Shaik, Mohammad Mehrmohammadi, College of Engineering, Wayne State University,818 W Hancock St, Detroit, MI 48201

Chronic venous insufficiency (CVI) is a prevalent condition and the main cause of varicose veins. Endovenous laser ablation (EVLA) is a minimally invasive, ultrasound (US)-guided procedure for treating varicose veins. Current EVLA procedures lack a temperature feedback system for monitoring the real-time temperature, which relates to the thermal dose deposition inside the vein during ablation procedures. Therefore, EVLA procedures performed without any temperature monitoring may lead to an insufficient thermal dose which causes the recurrence of varicose veins (20-40% of cases) or recanalization. We propose to use photoacoustic (PA) imaging for monitoring the real-time temperature inside the vein. The ultimate goal of this project is to design and develop a PA calibrated temperature feedback system for monitoring the changes in temperature during EVLA procedures. In order to achieve “quantitative PA thermometry”, understanding the dependence of PA signal change as a function of the surrounding temperature plays a key role. Especially, since the optical properties of blood changes at higher temperatures, it is important to study such changes and use them in calibrating PA thermometry measurements.  In this study, a systematic evaluation of PA signal dependence on temperature in blood and in water-based tissues was performed. The project is divided into two major parts: (a) design an experimental temperature monitoring setup to validate the ability of PA imaging to monitor the real-time temperature changes in a blood medium and determine the baseline calibration curves in blood and water-based tissue. (b) design an optical absorption measurement device to evaluate the optical absorption properties of blood at higher temperatures to create a calibration curve between the changes in PA amplitude with temperature variations. Using the baseline calibration curves, we demonstrate the quantitative PA thermometry (qPAT) during EVLA in a set of excised tissue experiments. 


Additional Abstract Information

Presenter: Tanyeem Shaik

Institution: Wayne State University

Type: Poster

Subject: Biological & Chemical Engineering

Status: Approved

Time and Location

Session: Poster 2
Date/Time: Mon 3:00pm-4:00pm
Session Number: 2549