Comparison of ultrasound temperature imaging with infrared thermometry during radio frequency ablation

Abstract

Radio frequency ablation (RFA) is a widely used alternative modality in the treatment of tumors. During RFA, temperature monitoring is essential to ensure accurate and appropriate thermal dosage. Ultrasound temperature imaging based on the detection of echo time-shift has been demonstrated to have good ability to monitor the temperature distribution. However, no study has proven that the region of ultrasound temperature imaging can correspond well to the practical temperature distribution in the tissue. In this study, we aim to combine ultrasound and infrared systems to clarify the correlation between ultrasound temperature imaging and the practical temperature distribution in a tissue. Five porcine livers (n = 5) were ablated using an RFA system and monitored with an ultrasound system to acquire raw backscattered data for temperature imaging. Meanwhile, an infrared imaging system was used to obtain the practical temperature map of the tissue. The results showed that the temperature distribution detected by ultrasound echo time-shift agreed with those obtained from the infrared image. When the tissue temperature was higher than 45 degrees C, ultrasound temperature imaging is difficult to describe the behavior of the heat transfer in a homogeneous medium. In this study, we used the experimental setup based on combining ultrasound and infrared systems to confirm the reliability and limitations of ultrasound temperature imaging in RFA monitoring. Such an experimental design may be considered as an indispensable platform for the development and optimization of ultrasound temperature imaging techniques in RFA monitoring. (C) 2014 The Japan Society of Applied Physics