title: Usefulness of administration of SPIO prior to RF ablation for evaluation of the therapeutic effect: an experimental study using miniature pigs.
abstract: OBJECTIVE
  To evaluate the usefulness of administration of superparamagnetic iron oxide (SPIO) and magnetic resonance (MR) imaging for assessing the efficacy of radiofrequency (RF) liver ablation.
  
  
  METHODS
  Using a protocol approved by the animal research committee of our university, nine RF liver ablations were performed in three miniature pigs. Six ablations were performed after administration of SPIO in two pigs (group A). Three ablations were performed in the other pig without administration of SPIO (group B). All pigs were sacrificed 4 days after the procedure. Harvested livers were scanned with a 1.5T MR system before and after fixation with 10% buffered formalin, and MR images were precisely compared with histological specimens.
  
  
  RESULTS
  There were no histological differences between the two groups. All ablated liver lesions showed coagulation necrosis at the external layer. There were no viable cells inside the coagulation necrosis. All ablated lesions had a hypointense rim on fast low angle shot (FLASH) images. The rims of group A were thicker than those of group B. The rims of group B corresponded histologically to congestion and hemorrhagic necrosis area. The rims of the group A corresponded to hemorrhagic necrosis and coagulation necrosis areas. In group A, the hypointense rim reflected necrotic Kupffer cells that took up SPIO before RF liver ablation.
  
  
  CONCLUSIONS
  Administration of SPIO made it possible to precisely evaluate ablated liver parenchyma by hypointense rim on FLASH images. This method is helpful for the evaluation of safety margin after RF ablation for liver tumors.
authors.affiliation: Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago 683-8503, Japan. sugkaki@med.tottori-u.ac.jp
authors.forename: Suguru
authors.initials: S
authors.lastname: Kakite
authors.forename: Shinya
authors.initials: S
authors.lastname: Fujii
authors.forename: Satoru
authors.initials: S
authors.lastname: Nakamatsu
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Kanasaki
authors.forename: Eijirou
authors.initials: E
authors.lastname: Yamashita
authors.forename: Eiji
authors.initials: E
authors.lastname: Matsusue
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Ouchi
authors.forename: Toshio
authors.initials: T
authors.lastname: Kaminou
authors.forename: Shiho
authors.initials: S
authors.lastname: Tokunaga
authors.forename: Masahiko
authors.initials: M
authors.lastname: Koda
authors.forename: Toshihide
authors.initials: T
authors.lastname: Ogawa
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D003287:Contrast Media / Q000008:administration & dosage*; D003911:Dextrans / Q000008:administration & dosage*; D005260:Female; D008099:Liver / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000008:administration & dosage*; D013552:Swine; D013556:Swine, Miniature
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C065507:ferumoxides