title: Percutaneous ablation therapy of hepatocellular carcinoma with irreversible electroporation: MRI findings.
abstract: OBJECTIVE
  Irreversible electroporation is a new ablation modality. Our purpose was to describe the MRI findings after irreversible electroporation treatment of hepatocellular carcinoma (HCC).
  
  
  METHODS
  In an 18-month period, we treated 24 HCC lesions in 20 patients who were not candidates for surgery. MRI was performed before and 1 month after irreversible electroporation. We used the liver-specific contrast medium gadoxetic acid. We evaluated the size, shape, signal intensity (T1-weighted, T2-weighted, and diffusion-weighted imaging), dynamic contrast enhancement pattern, and signal behavior during the liver-specific phase. Changes in the perilesional parenchyma, perfusion abnormalities, and complications were also recorded.
  
  
  RESULTS
  According to the modified Response Evaluation Criteria in Solid Tumors system, 22 of 24 lesions had a complete response, and two lesions showed a partial response and were retreated. The lesions showed a mean size increase of 10%, with a round or oval shape. On the T1-weighted images, we observed a hyperintense core and a hypointense rim. On the T2-weighted sequences, the signal was heterogeneously hypointense. On diffusion-weighted images, 83% of lesions showed restricted diffusion, with b values of 0-800 s/mm(2), whereas in 17% of the lesions, the signal was not clearly discernible for different b values. The apparent diffusion coefficient values did not show statistically significant differences between the baseline (800-1020 × 10(-3) mm(2)/s) and the reassessment after 1 month (900-1100 × 10(-3) mm(2)/s). The necrotic area did not show a signal increase after contrast material injection. Perfusion abnormalities, such as areas of transient hepatic intensity difference, were present in the tissue adjacent to six treated lesions. In two patients, a reduced or absent concentration of the contrast medium was observed during the liver-specific phase around the ablation zone. One patient had an arteriovenous shunt and another had biliary duct dilatation.
  
  
  CONCLUSIONS
  MRI detects characteristic morphologic and functional changes after irreversible electroporation treatment.
authors.affiliation: 1 First Department of Radiology, Istituto Nazionale Tumori Fondazione G. Pascale, Via Mariano Semmola, Naples 80131, Italy.
authors.forename: Vincenza
authors.initials: V
authors.lastname: Granata
authors.forename: Roberta
authors.initials: R
authors.lastname: Fusco
authors.forename: Orlando
authors.initials: O
authors.lastname: Catalano
authors.forename: Mauro
authors.initials: M
authors.lastname: Piccirillo
authors.forename: Mario
authors.initials: M
authors.lastname: De Bellis
authors.forename: Francesco
authors.initials: F
authors.lastname: Izzo
authors.forename: Antonella
authors.initials: A
authors.lastname: Petrillo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000473:pathology / Q000628:therapy*; D003287:Contrast Media; D018274:Electroporation / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology / Q000628:therapy*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: MRI; ablation; hepatocellular carcinoma; irreversible electroporation; liver; posttreatment assessment