title: Effect of variation of portal venous blood flow on radiofrequency and microwave ablations in a blood-perfused bovine liver model.
abstract: OBJECTIVE
  To assess whether there is a significant difference in the effect of incremental changes of portal venous blood flow rates on the size of radiofrequency (RF) versus microwave (MW) ablation lesions in an ex vivo blood-perfused bovine liver model.
  
  
  METHODS
  This study was exempt from approval by the Institutional Animal Care and Use Committee. Sixty ablations (30 MW and 30 RF ablations) were performed ex vivo in 15 bovine livers perfused with autologous blood via the portal vein at 60, 70, 80, 90, and 100 mL/min per 100 g of liver tissue (three livers were used for each flow rate). Long-axis diameter (LAD), short-axis diameter (SAD), and volume were measured for each ablation lesion. A general linear mixed model was used to examine the effect of location, ablation device, and flow rate on LAD, SAD, and volume. Results were considered to indicate a significant difference at P less than .05.
  
  
  RESULTS
  Location was not a significant predictor of LAD, SAD, or volume (P ≥ .4). The slope of the relationship between flow rate and LAD, SAD, and volume was significantly different according to ablation device (P < .0001). For RF ablation lesions, the mean LAD, SAD, and volume demonstrated a significant inverse relationship with flow rate, while the measurements for MW ablation did not change with variation in flow rates.
  
  
  CONCLUSIONS
  The size of RF ablation lesions is highly variable, with a significant inverse relationship to the rate of portal venous blood flow. Conversely, the size of MW ablation lesions is unaffected by changes in portal venous blood flow. The consistency of the size of MW ablation lesions could translate into a higher local tumor eradication rate than that reported with RF ablation.
authors.affiliation: Department of Radiology, School of Medicine, University of Colorado, Mail Stop L954, 12401 E 17th Ave, PO Box 6510, Aurora, CO 80045, USA. gerald.dodd@ucdenver.edu
authors.forename: Gerald D
authors.initials: GD
authors.lastname: Dodd
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Dodd
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Lanctot
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Glueck
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D002417:Cattle; D006498:Hepatectomy / Q000295:instrumentation / Q000379:methods*; D016014:Linear Models; D008099:Liver / Q000098:blood supply* / Q000601:surgery*; D008102:Liver Circulation / Q000502:physiology*; D008872:Microwaves / Q000627:therapeutic use*; D011169:Portal Vein / Q000502:physiology*; D011846:Radio Waves