Thermal modeling of lesion growth with radiofrequency ablation devices.
BACKGROUND
Temperature is a frequently used parameter to describe the predicted size of lesions computed by computational models. In many cases, however, temperature correlates poorly with lesion size. Although many studies have been conducted to characterize the relationship between time-temperature exposure of tissue heating to cell damage, to date these relationships have not been employed in a finite element model.


METHODS
We present an axisymmetric two-dimensional finite element model that calculates cell damage in tissues and compare lesion sizes using common tissue damage and iso-temperature contour definitions. The model accounts for both temperature-dependent changes in the electrical conductivity of tissue as well as tissue damage-dependent changes in local tissue perfusion. The data is validated using excised porcine liver tissues.


RESULTS
The data demonstrate the size of thermal lesions is grossly overestimated when calculated using traditional temperature isocontours of 42 degrees C and 47 degrees C. The computational model results predicted lesion dimensions that were within 5% of the experimental measurements.


CONCLUSIONS
When modeling radiofrequency ablation problems, temperature isotherms may not be representative of actual tissue damage patterns.
Chang
Isaac A
IA
Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Rockville, Maryland, USA. IAC@CDRH.FDA.GOV
Nguyen
Uyen D
UD
D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation; D019295:Computational Biology; D008099:Liver / Q000473:pathology; D008954:Models, Biological; D009336:Necrosis; D009369:Neoplasms / Q000473:pathology / Q000601:surgery; D013552:Swine; D013696:Temperature