title: Factors associated with initial incomplete ablation for benign thyroid nodules after radiofrequency ablation: First results of CEUS evaluation.
abstract: OBJECTIVE
  To assess the factors associated with initial incomplete ablation (ICA) after radiofrequency ablation for benign thyroid nodules (BTNs).
  
  
  METHODS
  69 BTNs (mean volume 6.35±5.66 ml, range 1.00-25.04 ml) confirmed by fine-needle aspiration cytology (FNAC) in fifty-four patients were treated with ultrasound-guided percutaneous radiofrequency ablation (RFA) and the local treatment efficacy was immediately assessed by intra-procedural contrast-enhanced ultrasound (CEUS). The RFA was performed with a bipolar electrode (CelonProSurge 150-T20, output power: 20 W). CEUS was performed with a second generation contrast agent under low acoustic power (i.e. coded phase inversion, CPI). Characteristics of clinical factors, findings on conventional gray-scale ultrasound, color-Doppler ultrasound, and CEUS were evaluated preoperatively. Factors associated with initial ICA and initial ICA patterns on CEUS were assessed. Volume reduction ratios (VRRs) of ICA nodules were compared with those with complete ablation (CA).
  
  
  RESULTS
  The RFA procedures were accomplished with a mean ablation time and mean total energy deposition of 11.13±3.39 min (range, 5.38-22.13 min) and 12612±4466 J (range, 6310-26130 J) respectively. CEUS detected initial ICA in 21 of 69 (30.8%) BTNs and 16 (76.2%) of the 21 BTNs with initial ICA achieved CA after additional RFA, leading to a final CA rate of 92.8% (64/69). The factors associated with initial ICA were predominantly solid nodule, nodule close to danger triangle area, nodule close to carotid artery, and peripheral blood flow on color-Doppler ultrasound (all P < 0.05). The mean VRRs of all BTNs were 23.4%, 54.4% and 81.9% at the 1-, 3- and 6-month follow-up, respectively. All BTNs achieved therapeutic success in this series in that all had VRRs of >50% at the 6-month follow-up, among which 7 nodules (10.1%) had VRRs of >90%. There were significant differences in VRRs between ICA nodules and CA nodules at the 3- and 6-month follow-up (all P < 0.05).
  
  
  CONCLUSIONS
  The factors associated with initial ICA after RFA for BTNs were predominantly solid nodules, nodule close to danger triangle area, nodule close to carotid artery, and peripheral blood flow on color-Doppler ultrasound. CEUS assists quick treatment response evaluation and facilitates subsequent additional RFA and final CA of the nodules. Nodules with CA achieve a better outcome in terms of VRR in comparison with those with ICA.
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Ultrasound Research and Education Institute, Tongji University School of Medicine, Shanghai, China.|Thyroid Institute, Tongji University School of Medicine, Shanghai, China.|Shanghai Research Center for Thyroid Diseases, Shanghai, China.
authors.forename: Chong-Ke
authors.initials: CK
authors.lastname: Zhao
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Ultrasound Research and Education Institute, Tongji University School of Medicine, Shanghai, China.|Thyroid Institute, Tongji University School of Medicine, Shanghai, China.|Shanghai Research Center for Thyroid Diseases, Shanghai, China.
authors.forename: Hui-Xiong
authors.initials: HX
authors.lastname: Xu
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Ultrasound Research and Education Institute, Tongji University School of Medicine, Shanghai, China.|Thyroid Institute, Tongji University School of Medicine, Shanghai, China.|Shanghai Research Center for Thyroid Diseases, Shanghai, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Lu
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Ultrasound Research and Education Institute, Tongji University School of Medicine, Shanghai, China.|Thyroid Institute, Tongji University School of Medicine, Shanghai, China.|Shanghai Research Center for Thyroid Diseases, Shanghai, China.
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Sun
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Ultrasound Research and Education Institute, Tongji University School of Medicine, Shanghai, China.|Thyroid Institute, Tongji University School of Medicine, Shanghai, China.|Shanghai Research Center for Thyroid Diseases, Shanghai, China.
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: He
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Ultrasound Research and Education Institute, Tongji University School of Medicine, Shanghai, China.|Thyroid Institute, Tongji University School of Medicine, Shanghai, China.|Shanghai Research Center for Thyroid Diseases, Shanghai, China.
authors.forename: Le-Hang
authors.initials: LH
authors.lastname: Guo
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Ultrasound Research and Education Institute, Tongji University School of Medicine, Shanghai, China.|Thyroid Institute, Tongji University School of Medicine, Shanghai, China.|Shanghai Research Center for Thyroid Diseases, Shanghai, China.
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: Li
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Ultrasound Research and Education Institute, Tongji University School of Medicine, Shanghai, China.|Thyroid Institute, Tongji University School of Medicine, Shanghai, China.|Shanghai Research Center for Thyroid Diseases, Shanghai, China.
authors.forename: Xiao-Wan
authors.initials: XW
authors.lastname: Bo
authors.affiliation: Department of Medical Ultrasound, Shanghai Tenth People's Hospital, Ultrasound Research and Education Institute, Tongji University School of Medicine, Shanghai, China.|Thyroid Institute, Tongji University School of Medicine, Shanghai, China.|Shanghai Research Center for Thyroid Diseases, Shanghai, China.
authors.forename: Wen-Wen
authors.initials: WW
authors.lastname: Yue
mesh_terms: D000328:Adult; D017115:Catheter Ablation / Q000379:methods*; D003287:Contrast Media / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016606:Thyroid Nodule / Q000473:pathology / Q000628:therapy*; D016896:Treatment Outcome; D018615:Ultrasonography, Doppler, Color / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: Radiofrequency ablation; contrast-enhanced ultrasound; incomplete ablation; thyroid; ultrasound