title: Predictors of thrombosis in hepatic vasculature during microwave tumor ablation of an in vivo porcine model.
abstract: OBJECTIVE
  To evaluate and model the risk of in vivo thrombosis in each hepatic vessel type during hepatic microwave ablation as a function of vessel diameter, velocity, and vessel-antenna spacing.
  
  
  METHODS
  A single microwave ablation antenna was inserted into a single porcine lobe (n = 15 total) adjacent to a hepatic artery, hepatic vein, or portal vein branch. Conventional ultrasound and Doppler ultrasound were used to measure the vessel diameter, blood flow velocity, and vessel-antenna spacing. A microwave ablation zone was created at 100 W for 5 minutes. Thrombus formation was evaluated on ultrasound performed immediately after the procedure. Logistic regression was used to evaluate the predictive value of vessel diameter, blood flow velocity, and vessel-antenna spacing on vascular thrombosis.
  
  
  RESULTS
  Thrombosis was identified in 53% of portal veins, 13% of hepatic veins, and 0% of hepatic arteries. The average peak blood flow rate of the hepatic artery was significantly greater than the average peak blood flow rate of the hepatic vein and portal vein. Peak blood flow velocity < 12.45 cm/s, vessel diameter < 5.10 mm, and vessel-antenna spacing < 3.75 mm were strong predictors of hepatic vein thrombosis. However, these individual factors were not predictive of the more common portal vein thrombosis.
  
  
  CONCLUSIONS
  Hepatic arteries do not appear to be at risk for thrombosis during microwave ablation procedures. Portal vein thrombosis was more common than hepatic vein thrombosis during microwave ablation treatments but was not as predictable based on vessel diameter, flow velocity, or vessel-antenna spacing alone.
authors.affiliation: Department of Radiology, University of Wisconsin, 1111 Highland Avenue, WIMR 1310-O, Madison, WI 53705; Department of Biomedical Engineering, University of Wisconsin, 1111 Highland Avenue, WIMR 1310-O, Madison, WI 53705.
authors.forename: Jason
authors.initials: J
authors.lastname: Chiang
authors.affiliation: Department of Radiology, University of Wisconsin, 1111 Highland Avenue, WIMR 1310-O, Madison, WI 53705.
authors.forename: Bridgett J
authors.initials: BJ
authors.lastname: Willey
authors.affiliation: Department of Radiology, University of Wisconsin, 1111 Highland Avenue, WIMR 1310-O, Madison, WI 53705.
authors.forename: Alejandro Muñoz
authors.initials: AM
authors.lastname: Del Rio
authors.affiliation: Department of Radiology, University of Wisconsin, 1111 Highland Avenue, WIMR 1310-O, Madison, WI 53705.
authors.forename: J Louis
authors.initials: JL
authors.lastname: Hinshaw
authors.affiliation: Department of Radiology, University of Wisconsin, 1111 Highland Avenue, WIMR 1310-O, Madison, WI 53705.
authors.forename: Fred T
authors.initials: FT
authors.lastname: Lee
authors.affiliation: Department of Radiology, University of Wisconsin, 1111 Highland Avenue, WIMR 1310-O, Madison, WI 53705; Department of Biomedical Engineering, University of Wisconsin, 1111 Highland Avenue, WIMR 1310-O, Madison, WI 53705. Electronic address: clbrace@wisc.edu.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Brace
mesh_terms: D055011:Ablation Techniques / Q000009:adverse effects* / Q000379:methods; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D006499:Hepatic Artery / Q000000981:diagnostic imaging / Q000601:surgery; D006503:Hepatic Veins / Q000000981:diagnostic imaging / Q000601:surgery; D008099:Liver / Q000098:blood supply* / Q000601:surgery; D008113:Liver Neoplasms / Q000601:surgery*; D008872:Microwaves / Q000627:therapeutic use*; D011169:Portal Vein / Q000000981:diagnostic imaging / Q000601:surgery; D011237:Predictive Value of Tests; D013552:Swine; D013927:Thrombosis / Q000209:etiology*; D014463:Ultrasonography
keywords: ROC; receiver operator characteristic