TAM - A thermal ablation monitoring tool: In vivo evaluation

Abstract

There is a worldwide increasing interest in the use of non- and minimally invasive thermo therapies like radio frequency (RF), laser or focused ultrasound ablation for tumor treatment. Magnetic resonance (MR-)based on-line monitoring of such thermal ablation procedures enables therapists to readjust treatment parameters instantly to optimize therapy outcome. We designed a universal software tool called TAM (Thermal Ablation Monitoring) for MR monitoring of several thermal ablation methods, like RF ablation, laser interstitial induced thermal therapy (LITT) or focused ultrasound surgery (FUS). Based on the proton resonance frequency (PRF) shift method temperature maps, thermal dose and induced tissue damage are calculated and displayed. Moreover, TAM offers simultaneous on-line and off-line evaluation. Accuracy and usability of TAM were evaluated in vitro and in vivo. LITT and FUS experiments were carried out in tissue phantoms and in animals. On-line guidance and monitoring of FUS and LITT were tested. The contours of displayed lethal thermal dose compared to contrast enhanced T1-weighted MR images and macroscopic visible in vivo lesion size was over all smaller than 2 mm. Hence, the accurate monitoring functionality of TAM was demonstrated.