Radio-Frequency (RF) ablation is a therapy that destroys pathologic tissue by heat.
Cardiac ablation is a widely used treatment method for a number of cardiac arrhythmias.
Hepatic ablation is becoming an increasingly popular for treatment of liver tumors.
Mathematical ablation models have been developed to predict dimensions of inflicted
tissue damage (i.e. RF lesion). In most models the 50 degreesC isotherm has been used
to determine boundary between viable and dead tissue. It is well known that accurate
damage prediction has to take the temperature history (i.e. thermal dose) into account.
We implemented the widely used Arrhenius damage model into our Finite Element Method
computer models of cardiac and hepatic RF ablation. We simulated cardiac ablation
for 45 s, and hepatic ablation for 12 min. We compared the lesion boundary determined
by the damage model to the 50 degreesC isotherm. For the cardiac model, the isotherm
overestimated the lesion diameter by 4.8%. For hepatic ablation model, the isotherm
underestimated the lesion diameter by 4 %. For short treatment times below 30 s in
cardiac ablation, and for long treatment times in hepatic ablation above 20 min, the
thermal dose should be used to determine lesion dimensions since the isotherm results
in large errors in these cases.
