Maurilio Deandrea1, Pierpaolo Trimboli2,3,4, Alberto Mormile1, Alice Tomasi Cont1, Lisa Milan2, Camille Buffet5, Luca Giovanella2,6, Paolo Piero Limone1, Sylvain Poirée5, Laurence Leenhardt5, Gilles Russ7. 1. Endocrinology, Diabetes and Metabolism Department and Center for Thyroid Diseases, A.O. Ordine Mauriziano, Turin, Italy. 2. Clinic for Nuclear Medicine and Competence Centre for Thyroid Disease, Imaging Institute of Southern Switzerland, Ente Ospedaliero Cantonale, Bellinzona and Lugano, Switzerland. 3. Clinic for Endocrinology, Ente Ospedaliero Cantonale, Lugano, Switzerland. 4. Faculty of Biomedical Sciences, Università della Svizzera Italiana (USI), Lugano, Switzerland. 5. Thyroid and Endocrine Tumors Unit, La Pitie-Salpetriere Hospital, Sorbonne University, Paris, France. 6. Clinic for Nuclear Medicine, University Hospital and University of Zurich, Zurich, Switzerland. 7. Thyroid and Endocrine Tumors Unit, La Pitie-Salpetriere Hospital, Sorbonne University, Paris, France. gilles.russ@wanadoo.fr.
Abstract
OBJECTIVES: Radiofrequency ablation (RFA) is effective in reducing the volume of benign thyroid nodules. However, what parameters can influence the response to RFA is still unclear. The present study aimed to (1) investigate which ultrasound and technical parameters are potential determinants of the volumetric reduction; (2) develop a dose-response model, and (3) analyze the effects of RFA on ultrasound features. METHODS: In this retrospective study, three institutions treated patients with benign thyroid nodules according to the same protocol. The technical parameters were power and energy. The 1-year volume reduction ratio (VRR) was the reference standard of the response. The correlations of different parameters with VRR were analyzed and the association between several parameters and a VRR above 50% studied by uni- and multivariate analyses. The probit regression estimated the probability to achieve an effective response. RESULTS: One hundred fifteen patients were enrolled. The median power was 50 W and median total delivered energy 27,531 J. At 1-year follow-up, the median VRR was 64.0% and 87 (75.7%) nodules showed a VRR above 50%. Among all parameters, only baseline volume, total energy, and energy per volume were independently associated to a VRR > 50% (p = 0.001, p = 0.0178, p < 0.001 respectively). The probit regression analysis demonstrated that delivering 756 J/ml and 2670 J/ml gave a probability of VRR > 50% in 50% and 99% of patients, respectively. CONCLUSIONS: Considering the baseline nodular volume and delivering the adequate energy per volume allow optimizing technical and clinical success. KEY POINTS: • The effectiveness of radiofrequency ablation in treating benign thyroid nodules is negatively correlated to the volume of the nodule and positively correlated to the energy delivered per volume. • When planning the treatment, the total energy to deliver can be calculated by using a simple formula: nodular volume × 2670 J.
OBJECTIVES: Radiofrequency ablation (RFA) is effective in reducing the volume of benign thyroid nodules. However, what parameters can influence the response to RFA is still unclear. The present study aimed to (1) investigate which ultrasound and technical parameters are potential determinants of the volumetric reduction; (2) develop a dose-response model, and (3) analyze the effects of RFA on ultrasound features. METHODS: In this retrospective study, three institutions treated patients with benign thyroid nodules according to the same protocol. The technical parameters were power and energy. The 1-year volume reduction ratio (VRR) was the reference standard of the response. The correlations of different parameters with VRR were analyzed and the association between several parameters and a VRR above 50% studied by uni- and multivariate analyses. The probit regression estimated the probability to achieve an effective response. RESULTS: One hundred fifteen patients were enrolled. The median power was 50 W and median total delivered energy 27,531 J. At 1-year follow-up, the median VRR was 64.0% and 87 (75.7%) nodules showed a VRR above 50%. Among all parameters, only baseline volume, total energy, and energy per volume were independently associated to a VRR > 50% (p = 0.001, p = 0.0178, p < 0.001 respectively). The probit regression analysis demonstrated that delivering 756 J/ml and 2670 J/ml gave a probability of VRR > 50% in 50% and 99% of patients, respectively. CONCLUSIONS: Considering the baseline nodular volume and delivering the adequate energy per volume allow optimizing technical and clinical success. KEY POINTS: • The effectiveness of radiofrequency ablation in treating benign thyroid nodules is negatively correlated to the volume of the nodule and positively correlated to the energy delivered per volume. • When planning the treatment, the total energy to deliver can be calculated by using a simple formula: nodular volume × 2670 J.