title: Preclinical evaluation of an MR-compatible microwave ablation system and comparison with a standard microwave ablation system in an ex vivo bovine liver model.
abstract: Evaluation of a newly developed MR-compatible microwave ablation system with focus on ablation performance and comparison with a corresponding standard microwave ablation system.
  
  
  
  A total of 52 ablations were performed with a non-cooled microwave ablation system in an ex vivo bovine liver model using the following settings: [A] 16G-standard antenna, 2 cm active tip, 2.4 m cable; [B] MR-compatible 16G-antenna, 2 cm active tip, 2.4 m cable; [C] MR-compatible 16G-antenna, 2 cm active tip, extended 6 m cable; and [D] MR-compatible 16G-antenna, 4 cm active tip, extended 6 m cable. Ablation durations were 3, 5 and 10 min, and additionally 15 min for [D]. Ablations zones were measured for short-axis diameter (SA) and long-axis diameter (LA). Settings [A]-[C] were compared regarding SA, volume (V) and generator energy output (E) with analysis of variance and Tukey-Kramer post hoc test. Ablation performance of the MR-compatible settings [C] and [D] were compared regarding SA, V, E and sphericity index (SA/LA) with unpaired t-test. p < 0.05 was considered as statistically significant.
  
  
  
  No significant differences were found between [A], [B] and [C] regarding SA and V (10 min; SA[A] = 25.8 ± 2.4 mm, SA[B] = 25.3 ± 1.9 mm, SA[C] = 25.0 ± 2.0 mm, p = 0.88; V[A] = 17.8 ± 4.4 cm³, V[B] = 16.6 ± 3.0 cm³, V[C] = 17.8 ± 2.7 cm³, p = 0.85); however, the highest energy output was measured for setting [C] (10 min; [A]: 9.9 ± 0.5 kJ, [B]: 10.1 ± 0.5 kJ, [C]: 13.1 ± 0.3 kJ, p < 0.001). SA, V and E were significantly larger with setting [D] than [C] with 10 min ablations (SA[C] = 25.0 ± 2.0 mm, SA[D] = 34.0 ± 2.9 mm, p = 0.003; V[C] = 17.8 ± 2.7 cm³, V[D] = 39.4 ± 7.5 cm³, p = 0.007; E[C] = 13.1 ± 0.3 kJ, E[D] = 16.7 ± 0.8 kJ, p = 0.002) without significant difference in sphericity index (SA/LA[C] = 0.46 ± 0.02, SA/LA[D] = 0.52 ± 0.04, p = 0.08).
  
  
  
  The tested MR-compatible system can be used without loss of ablation performance compared to the standard system.
authors.affiliation: a Department of Diagnostic and Interventional Radiology , Eberhard Karls University Tuebingen , Tuebingen , Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Hoffmann
authors.affiliation: a Department of Diagnostic and Interventional Radiology , Eberhard Karls University Tuebingen , Tuebingen , Germany.
authors.forename: David-Emanuel
authors.initials: DE
authors.lastname: Kessler
authors.affiliation: a Department of Diagnostic and Interventional Radiology , Eberhard Karls University Tuebingen , Tuebingen , Germany.
authors.forename: Jakob
authors.initials: J
authors.lastname: Weiss
authors.affiliation: a Department of Diagnostic and Interventional Radiology , Eberhard Karls University Tuebingen , Tuebingen , Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Clasen
authors.affiliation: b Department of Radiology, Minimally Invasive Therapies and Nuclear Medicine, SLK-Kliniken Heilbronn GmbH , Heilbronn , Germany.
authors.forename: Philippe L
authors.initials: PL
authors.lastname: Pereira
authors.affiliation: a Department of Diagnostic and Interventional Radiology , Eberhard Karls University Tuebingen , Tuebingen , Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.affiliation: a Department of Diagnostic and Interventional Radiology , Eberhard Karls University Tuebingen , Tuebingen , Germany.
authors.forename: Hansjörg
authors.initials: H
authors.lastname: Rempp
mesh_terms: D055011:Ablation Techniques; D000818:Animals; D001777:Blood Coagulation; D002417:Cattle; D008099:Liver / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008872:Microwaves; D023421:Models, Animal
keywords: MR-guided intervention; Microwave ablation; minimally invasive tumour therapy; percutaneous tumour ablation; tumour ablation