title: Radiofrequency ablation: effect of tumor- and organ-specific pharmacologic modulation of arterial and portal venous blood flow on coagulation diameter in an N1-S1 tumor model.
abstract: OBJECTIVE
  To investigate inherent differences in vasculature of tumors versus normal parenchyma and efficacy of radiofrequency (RF) ablation with glucagon, adenosine, and a combination of the two compared with normal saline solution (NS) controls in an N1-S1 tumor model implanted in Sprague-Dawley rat livers.
  
  
  METHODS
  A total of 17 tumors were established in the left lobes of rats. Tumor perfusion relative to surrounding liver parenchyma was evaluated with contrast-enhanced ultrasound with intermittent-bolus technique before and after administration of glucagon, adenosine, a combination of the two, or NS. Tumors were ablated with a 22-gauge RF probe with 1 cm of exposed tip at 80 °C for 2 min. Tumor size, zone of necrosis, and viable tumor were measured in tumors after 2,3,5-triphenyltetrazolium chloride staining. Results were compared with degree of tumor perfusion.
  
  
  RESULTS
  The normalized tumor perfusion ratio did not significantly change with administration of NS (1.38% ± 3.93). Vasomodulation resulted in significant decreases in normalized tumor perfusion ratio: 66.22% ± 24.57 (P < .01) with glucagon, 71.45% ± 22.72 (P < .01) with adenosine, and 74.98% ± 16.58 (P < .01) with glucagon plus adenosine. After tumor ablation, there was an increase in size of the ablated area by 100%-165% in the three treatment groups compared with NS controls. Differences among treatment groups were not statistically significant.
  
  
  CONCLUSIONS
  Tumor blood flow may be significantly altered by using systemic injection of appropriate medications. This tumor- and organ-specific approach to tumor vasomodulation may be used to enhance current therapeutic options.
authors.affiliation: Department of Radiology, University Hospitals Case Medical Center, Case Western Reserve University, Cleveland, OH 44106, USA. luke.wilkins@uhhospitals.org
authors.forename: Luke R
authors.initials: LR
authors.lastname: Wilkins
authors.forename: Hanping
authors.initials: H
authors.lastname: Wu
authors.forename: John R
authors.initials: JR
authors.lastname: Haaga
authors.forename: Agata
authors.initials: A
authors.lastname: Exner
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D017115:Catheter Ablation; D045744:Cell Line, Tumor; D003287:Contrast Media; D005934:Glucagon / Q000494:pharmacology; D006499:Hepatic Artery / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000503:physiopathology; D007275:Injections, Intravenous; D008102:Liver Circulation / Q000187:drug effects*; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008833:Microcirculation / Q000187:drug effects*; D009336:Necrosis; D055420:Perfusion Imaging / Q000379:methods; D011169:Portal Vein / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D013997:Time Factors; D047368:Tumor Burden; D014463:Ultrasonography; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D003287:Contrast Media; D014665:Vasodilator Agents; D005934:Glucagon; D000241:Adenosine