Non-invasive imaging is needed to monitor ablation zones in interventional treatment of liver masses. CT thermography can provide information about the tissue temperature based on the correlation with its tissue density as measured by the Hounsfield units. We hereby evaluated CT thermography during microwave ablation (MA) and cryoablation (CA) in a biophantom for ablation zone prediction.
Methods and materials
Fresh porcine livers were used for this phantom experiment (see fig. 1). To account for beam hardening artifacts, livers were placed on porcine ribs. Four fiberoptic thermometers (Optocon and Weidmann Tech., GER) at increasing distances from the ablation probe.
The respective ablation probe was inserted into the liver tissue next to the temperature probes.MA was performed using the CA20L1 probe with the Emprint Ablation system thermosphere (Covidien – Dublin, Ireland; now Medtronic) at 100 Watts with 2.45 GHz +/- 50 MHz. For CA, the CVA2400...
Pearson’s correlation generally yielded r=-0.79 [95% CI -0.85 to -0.71] for MA, and r=0.62 [CI 0.55 to 0.67] for CA, both at p
CT thermography is generally feasible with excellent correlation in heat ablation and good correlation in cryoablation. This study indicates the superiority of monitoring microwave ablation with CT thermography over monitoring cryoablation. Further analysis should be conducted in an invivo model.
Personal information and conflict of interest
J. Pohlan; Charité, Dpt. of Radiology, Berlin/DE - nothing to disclose T. Diekhoff; Berlin/DE - Research/Grant Support at Canon medical systems W. Kress; Berlin/DE - nothing to disclose K.-G. A. Hermann; Berlin/DE - nothing to disclose B. Hamm; Berlin/DE - nothing to disclose J. Mews; Berlin/DE - Employee at Canon medical systems
Fani F, Schena E, Saccomandi P, Silvestri S. CT-based thermometry: An overview. International Journal of Hyperthermia. 2014;30(4):219-227.
Bydder GM, Kreel L. The temperature dependence of computed tomography attenuation values. Journal of computer assisted tomography. 1979;3(4):506-510.
Pandeya GD, Greuter MJ, de Jong KP, Schmidt B, Flohr T, Oudkerk M. Feasibility of noninvasive temperature assessment during radiofrequency liver ablation on computed tomography. Journal of computer assisted tomography. 2011;35(3):356-360.