title: Radiofrequency ablation of hepatocellular carcinoma: The feasibility of magnetic resonance imaging with gadolinium ethoxybenzyl diethylene triamine pentaacetic acid for evaluating the ablative margin.
abstract: OBJECTIVE
  The aim of this study was to evaluate the feasibility of gadolinium ethoxybenzyl diethylene triamine pentaacetic acid (Gd-EOB-DTPA) in magnetic resonance imaging (MRI) to assess the ablative margin of radiofrequency (RF) ablation to hepatocellular carcinoma (HCC).
  
  
  METHODS
  RF ablation was performed in the livers of six pigs after the i.v. administration of Gd-EOB-DTPA 20 min before ablation. Three pigs were killed 2 h after administration (group A), and the other pigs were killed 7 days after ablation (group B). Thereafter, correlation between pathological findings and MRI was investigated. Moreover, the Gd concentrations were examined in ablated and non-ablated regions. An initial clinical evaluation was conducted for 28 HCC nodules. Percutaneous RF ablation was performed 20 min after administration, and T(1)-weighted images were taken 2, 24 and 72 h post-treatment.
  
  
  RESULTS
  On T(1)-weighted images of the porcine liver, the RF ablated lesions showed hyperintense regions with hypointense rims, which histopathologically corresponded to sinusoidal congestion. The Gd concentrations in ablated regions in group A were significantly higher than those in non-ablated regions, while the concentrations in both regions in group B fell to nearly undetectable levels. In 27 of the 28 HCC nodules, the treated area consisted of a hypointense region, indicative of the tumor, and a surrounding hyperintense rim 2 h after ablation. Subsequently, a thin hypointense region was observed in the outermost layer 24 and 72 h after ablation.
  
  
  CONCLUSIONS
  Administration of Gd-EOB-DTPA in conjunction with RF ablation of HCC may be feasible for the assessment of an accurate ablative margin.
authors.affiliation: Department of Gastroenterology, Juntendo University Nerima Hospital             Department of Gastroenterology, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Hironao
authors.initials: H
authors.lastname: Okubo
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Kokubu
authors.forename: Masae
authors.initials: M
authors.lastname: Komiyama
authors.forename: Hisafumi
authors.initials: H
authors.lastname: Yamagata
authors.forename: Akira
authors.initials: A
authors.lastname: Uchiyama
authors.forename: Akihisa
authors.initials: A
authors.lastname: Miyazaki
authors.forename: Sumio
authors.initials: S
authors.lastname: Watanabe