MRI-thermometry on ex vivo swine liver: Preliminary trials to assess the sensitivity of two sequences

Minimally invasive thermal procedures are gaining acceptance in tumor treatment. Among others, laser ablation (LA) is considered a valid alternative to surgical resection for inoperable patients. LA damages the tumor by increasing the tissue temperature. The temperature distribution within the tissue strongly influences the outcomes of the procedure. Hence, some thermometric techniques are employed in this scenario. Among them, MRI-based thermometry presents some advantages, such as the non-invasiveness. In this work, two sequences (EPI and FIESTA) have been used to monitor liver temperature. During the whole MRI procedure, the liver temperature has been monitored by MRcompatible, fiber optic-based sensors. The temperature measured by these sensors has been used as reference in order to assess the sensitivity of MRI-thermometry. Moreover, the influence of Region of interests (ROIs) size on precision has been investigated. Results show that the absolute value of thermal sensitivity of FIESTA is double with respect to the sensitivity obtained with EPI (about -15 °C-1 vs -7 °C-1). Regarding the influence of ROI size, results show that the wider the extension the better the precision.