Dual energy computed tomography thermometry during hepatic microwave ablation in an ex-vivo porcine model

Abstract

BackgroundMicrowave thermoablation (MTA) is a treatment method used to destroy hepatic tumors. ObjectiveTo investigate temperature changes during MTA of ex-vivo porcine liver using dual-energy computed tomography (DECT) imaging. MethodsThree MTA experiments were performed using ex-vivo porcine liver (15 × 15 × 15 cm3) and DECT imaging with 80/Sn140 kVp spectral and 0.5-weighted reconstructions. Images were acquired from basic organ temperature to 100 °C with 10 °C difference during microwave heating and cooling phases. Three fluoro-optic thermometers were used for temperature measurements; two were placed at 1 cm and third one positioned at 2 cm distance from the applicator. Tissue temperature, ablation-region-conspicuity (ARC), ablation-region dimensions and image quality were determined. Regression analysis was performed determining thermal sensitivity during heating and cooling phases. ResultsDetermined thermal sensitivities during heating phase were: −0.59 Hounsfield Unit/°C (80 kVp), −0.60HU/°C (0.5-weighted) and −0.59HU/°C (140 kVp); furthermore, during cooling: −0.56HU/°C (80 kVp), −0.55HU/°C (0.5-weighted) and −0.55HU/°C (140 kVp). ARC showed significantly higher (all P < 0.05) values for thermometer positions −1 and −2 compared to −3; however, comparison between positions −1 and −2 was insignificant (P > 0.05). Signal-to-noise ratios were higher for 0.5-weighted but ARC values were higher for 80 kVp images. ConclusionMicrowave thermal sensitivity on tissue was inversely linear with DECT image datasets. Heating phase showed higher influence of temperature on HU compared to cooling; ARC and ablation-region were increased with increase in temperature.