title: Determining the critical effective temperature and heat dispersal pattern in monopolar radiofrequency ablation using temperature-time integration.
abstract: The radiofrequency ablation (RFA) lesion size is posited to be disproportionate to the total delivered energy, and temperature-time integration (TTI) may have a more critical effect on lesion size. The present study aimed to evaluate this hypothesis by determining the temperature threshold and temperature distribution over tissues during the RFA lesioning process. Using anex vivochicken tissue model and anin vivorabbit model with RFA applied for 2 min under various target temperature settings, the resultant lesions were evaluated histologically using Masson's trichrome stain. The temperature distribution over the tissue during the RFA lesioning process was also determined using a VT02 Visual IR Thermometer. It was revealed that the thermal injury threshold for RFA in the chicken tissues was ~65°C, but that it ranged from 55-65°C in mammals. Using infra-red thermal imaging, the temperature gradient (from the center to the periphery) during the RFA lesioning process demonstrated a uniform heat diffusion pattern. This data supports the proposed hypothesis that TTI is a critical parameter in determining RFA lesion size and can be applied clinically using the following equation: [Target temperature - 55 (°C)] × time (sec) is proportional to RFA lesion size.
authors.affiliation: Department of Biochemistry, Taipei Medical University, Taipei 110, Taiwan, R.O.C.
authors.forename: How
authors.initials: H
authors.lastname: Tseng
authors.affiliation: Department of Pathology, Taipei Medical University Hospital, Taipei 110, Taiwan, R.O.C.
authors.forename: Sey-En
authors.initials: SE
authors.lastname: Lin
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Cathay General Hospital, Taipei 106, Taiwan, R.O.C.; School of Medicine, Fu-Jen Catholic University, Taipei 242, Taiwan, R.O.C.
authors.forename: Yen-Liang
authors.initials: YL
authors.lastname: Chang
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Cathay General Hospital, Taipei 106, Taiwan, R.O.C.
authors.forename: Ming-Hsu
authors.initials: MH
authors.lastname: Chen
authors.affiliation: Department of Otolaryngology, Taipei Medical University Hospital, Taipei 110, Taiwan, R.O.C.; Department of Otolaryngology, School of Medicine, Taipei Medical University, Taipei 110, Taiwan, R.O.C.
authors.forename: Shih-Han
authors.initials: SH
authors.lastname: Hung
keywords: radiofrequency ablation; temperature control; temperature threshold; temperature time