title: Ultrasound-navigated radiofrequency ablation of thyroid nodules with integrated electromagnetic tracking: comparison with conventional ultrasound guidance in gelatin models.
abstract: OBJECTIVE
  A thyroid-like gelatin model was used to determine potential superiority of a new navigation system for ultrasound (US)-guided electrode insertion called EchoTrack, featuring a US probe with an integrated electromagnetic field generator, in comparison with conventional US when performing radiofrequency ablation.
  
  
  METHODS
  In order to compare 20 navigated ablations with 20 ablations under conventional US guidance, a thyroid-like gelatin model was used. In each group, 10 in-plane and 10 out-of-plane punctures were performed. Metal seeds measuring 8.5 [Formula: see text] 1.8 mm served as ablation targets. The number of redirections until final electrode placement, targeting accuracy and electrode placement time were measured.
  
  
  RESULTS
  The number of redirections could be significantly ([Formula: see text]) reduced from 2.7 ± 1.3 in the conventional group to 0.2 ± 0.5 in the EchoTrack group. Accuracy increased from 3.9 ± 4.7 to 2.0 ± 1.9 mm. The total placement time increased from 39 ± 20.5 to 79.2 ± 26 s.
  
  
  CONCLUSIONS
  EchoTrack is able to reduce the redirections needed to place the electrode in comparison with conventional US and provides high placement accuracy. Our new navigation system has high potential to reduce the risk of harming critical structures and to improve guidance during ablation of difficult nodules, as treatment planning as well as the safety of out-of-plane punctures are improved.
authors.affiliation: Department of Nuclear Medicine, University Hospital Frankfurt/Main, Theodor-Stern-Kai 7, 60590, Frankfurt/Main, Germany. chr.erbelding@gmail.com.
authors.forename: Christian
authors.identifier: http://orcid.org/0000-0002-4525-3517
authors.initials: C
authors.lastname: Erbelding
authors.affiliation: Department of Computer Assisted Medical Interventions (CAMI), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.
authors.forename: Alfred
authors.initials: A
authors.lastname: Franz
authors.affiliation: Department of Computer Assisted Medical Interventions (CAMI), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Seitel
authors.affiliation: Department of Computer Assisted Medical Interventions (CAMI), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Bopp
authors.affiliation: Department of Nuclear Medicine, University Hospital Frankfurt/Main, Theodor-Stern-Kai 7, 60590, Frankfurt/Main, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Kohlhase
authors.affiliation: Department of Nuclear Medicine, University Hospital Frankfurt/Main, Theodor-Stern-Kai 7, 60590, Frankfurt/Main, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Grünwald
authors.affiliation: Department of Computer Assisted Medical Interventions (CAMI), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 581, 69120, Heidelberg, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Maier-Hein
mesh_terms: D017115:Catheter Ablation / Q000379:methods*; D004574:Electromagnetic Fields; D005780:Gelatin; D006801:Humans; D016606:Thyroid Nodule / Q000000981:diagnostic imaging / Q000601:surgery*; D018084:Ultrasonography, Interventional / Q000379:methods*
chemical_list: D005780:Gelatin
keywords: Computer-assisted interventions; Electromagnetic tracking; Gelatin phantoms; Radiofrequency ablation; Thyroid; Ultrasonography