Feasibility of Noninvasive Temperature Assessment During Radiofrequency Liver Ablation on Computed Tomography

Purpose: The purpose of this study was to assess the feasibility of noninvasive thermometry using high-resolution computer tomography (CT) for the monitoring of bovine liver during radiofrequency (RF) ablation. Methods: Radiofrequency probes were used to ablate bovine livers from 20 degrees C to 98 degrees C. During the heating process, images were acquired using a multidetector CT scanner with simultaneous measurement of temperature using calibrated thermal sensors. The CT scanner's thermal sensitivity was derived from the correlation between the CT numbers and temperature. The CT scanner's thermal sensitivity was used to compute a temperature map, and this temperature map was overlaid on the original CT scan using a dedicated software application. Results: The CT numbers of the bovine liver showed a linear decline with an increase in temperature and a CT thermal sensitivity of -0.60 +/- 0.026 Hounsfield unit/degrees C (R-2 = 0.87). Temperature maps were calculated using this correlation and were superimposed onto the CT scans presenting temperature distribution around the RF probe in the bovine liver. Conclusions: Noninvasive temperature determination is feasible during RF ablation of bovine liver using a high-resolution CT system. Therefore, the proposed method can be of potential use in clinical practice for noninvasive temperature mapping during ablation.