title: Irreversible Electroporation in Patients with Hepatocellular Carcinoma: Immediate versus Delayed Findings at MR Imaging.
abstract: OBJECTIVE
  To assess the postprocedure findings of irreversible electroporation (IRE) in patients with hepatocellular carcinoma (HCC) at magnetic resonance (MR) imaging.
  
  
  METHODS
  This retrospective study was Institutional Review Board approved, and informed consent was waived. Twenty patients with HCC were treated with IRE over a 2.5-year period. The median patient age was 62 years, and 75% of patients had cirrhosis with a Child-Pugh score of A. The median tumor diameter was 2.0 cm (range, 1.0-3.3 cm). Contrast material-enhanced multiphase MR imaging was performed on postprocedure days 1 and 30 and every 90 days thereafter. Ablation zone sizes and signal intensities were compared between each time point for both T1- and T2-weighted images. Trends in signal intensity and tumor dimensions over time were quantified by using generalized linear models.
  
  
  RESULTS
  MR imaging appearances of treated tumors include a zone of peripheral enhancement with centripetal filling on delayed contrast-enhanced images. Compared with postprocedure day 1, every 90 days there is a decrease of 28.9% (mean, axis) in the size of the enhancing ablation zone. Over time, there is a trend toward decreasing signal intensity in the peripheral ablation zone on both T2-weighted (P = .01) and contrast-enhanced T1-weighted (P < .08) images. Conversely, the tumor itself typically has increased signal intensity on the same sequences.
  
  
  CONCLUSIONS
  IRE of HCC results in a large region of enhancement on immediate postprocedure MR images that, over time, involutes and is associated with decreasing signal intensity of the peripheral ablation zone. This phenomenon may represent resolution of the reversible penumbra.
authors.affiliation: From the Section of Interventional Radiology (S.A.P., G.E.J., M.J.K.), Department of Surgery (R.S.Y.), and Department of Radiology (D.S.H.), University of Washington, Box 357115, 1959 NE Pacific St, Seattle, WA 98119.
authors.forename: Siddharth A
authors.initials: SA
authors.lastname: Padia
authors.affiliation: From the Section of Interventional Radiology (S.A.P., G.E.J., M.J.K.), Department of Surgery (R.S.Y.), and Department of Radiology (D.S.H.), University of Washington, Box 357115, 1959 NE Pacific St, Seattle, WA 98119.
authors.forename: Guy E
authors.initials: GE
authors.lastname: Johnson
authors.affiliation: From the Section of Interventional Radiology (S.A.P., G.E.J., M.J.K.), Department of Surgery (R.S.Y.), and Department of Radiology (D.S.H.), University of Washington, Box 357115, 1959 NE Pacific St, Seattle, WA 98119.
authors.forename: Raymond S
authors.initials: RS
authors.lastname: Yeung
authors.affiliation: From the Section of Interventional Radiology (S.A.P., G.E.J., M.J.K.), Department of Surgery (R.S.Y.), and Department of Radiology (D.S.H.), University of Washington, Box 357115, 1959 NE Pacific St, Seattle, WA 98119.
authors.forename: James O
authors.initials: JO
authors.lastname: Park
authors.affiliation: From the Section of Interventional Radiology (S.A.P., G.E.J., M.J.K.), Department of Surgery (R.S.Y.), and Department of Radiology (D.S.H.), University of Washington, Box 357115, 1959 NE Pacific St, Seattle, WA 98119.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Hippe
authors.affiliation: From the Section of Interventional Radiology (S.A.P., G.E.J., M.J.K.), Department of Surgery (R.S.Y.), and Department of Radiology (D.S.H.), University of Washington, Box 357115, 1959 NE Pacific St, Seattle, WA 98119.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Kogut
mesh_terms: D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D003287:Contrast Media; D018274:Electroporation / Q000379:methods*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D003287:Contrast Media