Geometry and Temperature Distribution during Radiofrequency Tissue Ablation: An Experimental ex Vivo Model

Purpose: To investigate the temperature distribution and geometry of lesions created by radiofrequency (RF) tissue ablation. Materials and Methods: We developed an ex-vivo thermal model based on the ability of egg whites to coagulate at 62° to 65°C. This property allows us to observe and record the formation of "lesions" created by different commercially available RF generators and probes. Results: The lesions created by the Radionics Cool-Tip™ RF system were mostly cylindrical or barrelshaped, while RITA® StarBurst XL™ and StarBurst XLi™ electrodes produced cone-like or mushroom-shaped lesions. The time required to achieve maximum lesion size was between 3 and 5 minutes in most trials. The formation of lesions stopped when thermodynamic equilibrium was achieved. Conclusions: The geometry of lesions does not correlate precisely with manufacturer reports, which describe spherical lesions for both RF systems. The 12-minute treatment cycle recommended by company's algorithm may not be necessary because lesio...