title: In vitro artefact assessment of a new MR-compatible microwave antenna and a standard MR-compatible radiofrequency ablation electrode for tumour ablation.
abstract: OBJECTIVE
  To evaluate and compare artefact configuration and diameters in a magnetic resonance (MR)-compatible prototype microwave (MW) applicator and a standard MR-compatible radiofrequency (RF) applicator for MR-guided tumour ablation.
  
  
  METHODS
  Both applicators were tested in a phantom study at 1.5T with three sequences: T1-weighted three-dimensional volume interpolated breath-hold examination (VIBE), T1-weighted fast low angle shot (FLASH), T2-weighted turbo spin echo (TSE). Applicator orientation to main magnetic field (B0) and slice orientation were varied. Needle tip location error (TLE) was assessed, and artefact diameters were calculated. Influence of imaging parameters on artefacts was assessed with analysis of variance (ANOVA) and post hoc testing.
  
  
  RESULTS
  MW applicator: the shaft artefact diameter measured 2.3 +/- 0.8 mm. Tip artefact diameter and length measured 2.2 ± 0.8 mm and 2.4 ± 1.3 mm, respectively. A prominent oval artefact (diameter: 16.5 +/- 1.8 mm, length: 19.1 +/- 2.5 mm) appeared close to the tip. TLE: - .3 +/- 0.6 mm. RF applicator: shaft and tip diameter measured 8.9 +/- 4.7 mm and 9.0 +/- .0 mm, respectively. TLE: -0.1 +/- 0.8 mm. Minimal artefacts were measured with RF applicator orientation parallel to B0 (P < 0.0001), whereas no such influence was found for MW applicator. For both applicators, significantly large artefacts were measured with T1 FLASH (P = 0.03).
  
  
  CONCLUSIONS
  The MW applicator's artefact is satisfactory and seems useable for MR-guided ablation procedures.
  
  
  CONCLUSIONS
  MW applicator's artefact appearance is independent of angulation to main magnetic field. MW applicator's prominent distal artefact may increase visibility under MR-guidance. RF and MW applicator's artefacts are precise concerning tip depiction. Largest artefact diameters are measured with T1-weighted fast low angle shot sequence.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany. Ruediger.Hoffmann@med.uni-tuebingen.de.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Hoffmann
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Hansjörg
authors.initials: H
authors.lastname: Rempp
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Eibofner
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: David-Emanuel
authors.initials: DE
authors.lastname: Keßler
authors.affiliation: Department of Clinical Epidemiology and Applied Biometry, Eberhard Karls University, Silcherstr. 5, 72076, Tübingen, Germany.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Blumenstock
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Jakob
authors.initials: J
authors.lastname: Weiß
authors.affiliation: Department of Radiology, Minimally Invasive Therapies, and Nuclear Medicine, SLK-Kliniken Heilbronn GmbH, Am Gesundbrunnen 20-26, 74078, Heilbronn, Germany.
authors.forename: Philippe L
authors.initials: PL
authors.lastname: Pereira
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.affiliation: Department of Diagnostic and Interventional Radiology, Eberhard Karls University, Hoppe-Seyler-Strasse 3, 72076, Tübingen, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Clasen
mesh_terms: D000704:Analysis of Variance; D016477:Artifacts; D017115:Catheter Ablation / Q000295:instrumentation* / Q000379:methods; D003287:Contrast Media; D004566:Electrodes; D006801:Humans; D007089:Image Enhancement; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D008872:Microwaves; D009339:Needles; D009942:Organometallic Compounds; D019047:Phantoms, Imaging
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol
keywords: Artefact; Magnetic resonance imaging; Magnetic resonance imaging, interventional; Microwave ablation; Tumour ablation