title: Conspicuity of zones of ablation after radiofrequency ablation in porcine livers: comparison of an extracellular and an SPIO contrast agent.
abstract: OBJECTIVE
  To compare conspicuity of zones of ablation on nonenhanced, gadopentetate dimeglumine-(Gd-DTPA) and ferucarbotran-(SPIO)-enhanced magnetic resonance (MR) images.
  
  
  METHODS
  In all, 33 radiofrequency ablations (RFA) were performed in 17 healthy porcine livers at 1.5T MR imaging 1 day and 2 and 4 weeks after RFA: T2-weighted (w) ultra turbo spin echo (UTSE), proton density (PD)-w UTSE, T1-w gradient echo (GRE) pre- and 5 minutes postcontrast administration, dynamic T1-w GRE during Gd-DTPA (Magnevist) or SPIO (Resovist) administration, T2-w UTSE, and PD-w UTSE sequences 10 minutes after SPIO administration. Regions of interest (ROIs) for contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were drawn in consensus by two radiologists.
  
  
  RESULTS
  PD-w SPIO-enhanced images (23.5 +/- 5.5) showed higher liver-to-lesion CNR than T1-w GRE Gd-DTPA-enhanced images (13.5 +/- 6.1) 1 day after RFA (P < or = 0.05). At all other timepoints, liver-to-lesion CNR of PD-w and T2-w SPIO-enhanced images did not differ significantly from T1-w GRE Gd-DTPA-enhanced images (P > or = 0.05). Nonenhanced T2-w images revealed lower liver-to-lesion CNR (7.0 +/- 7.5/6.5 +/- 5.9/6.8 +/- 5.0, 1 day/2 weeks/4 weeks, respectively) than T2-w SPIO-enhanced (17.4 +/- 4.8/15.3 +/- 4.5/14.2 +/- 5.7), PD-w SPIO-enhanced (23.5 +/- 5.5/16.9 +/- 3.6, 1 day/2 weeks), and T1-w Gd-DTPA-enhanced (15.3 +/- 3.6/12.7 +/- 3.5, 2/4 weeks) images (P < or = 0.05). Liver-to-lesion CNR of SPIO-enhanced dynamic T1-w GRE images after 30, 80, 150, and 240 seconds did not change significantly over time (P > or = 0.05).
  
  
  CONCLUSIONS
  One day after RFA lesion conspicuity on PD-w ferucarbotran-enhanced images is better than on T1-w GRE Gd-DTPA-enhanced images. At all other timepoints, ferucarbotran is not superior to gadolinium. Ferucarbotran- and gadolinium-enhanced images improve lesion conspicuity compared with nonenhanced T2-w images at all timepoints.
authors.affiliation: Department of Radiology, University of Cologne, Kerpener Strasse 62, Cologne, Germany. cbangard@gmx.de
authors.forename: Christopher
authors.initials: C
authors.lastname: Bangard
authors.forename: Dirk L
authors.initials: DL
authors.lastname: Stippel
authors.forename: Frank
authors.initials: F
authors.lastname: Berg
authors.forename: Hans U
authors.initials: HU
authors.lastname: Kasper
authors.forename: Martin
authors.initials: M
authors.lastname: Hellmich
authors.forename: Jürgen H
authors.initials: JH
authors.lastname: Fischer
authors.forename: Arnulf
authors.initials: A
authors.lastname: Hölscher
authors.forename: Klaus
authors.initials: K
authors.lastname: Lackner
authors.forename: Axel
authors.initials: A
authors.lastname: Gossmann
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D003287:Contrast Media; D003911:Dextrans; D052203:Ferrosoferric Oxide; D019786:Gadolinium DTPA; D007089:Image Enhancement; D007501:Iron; D008099:Liver / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D010087:Oxides; D013552:Swine
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; D007501:Iron; C065507:ferumoxides; D019786:Gadolinium DTPA; D052203:Ferrosoferric Oxide