title: Microwave Ablation: Comparison of Simultaneous and Sequential Activation of Multiple Antennas in Liver Model Systems.
abstract: OBJECTIVE
  To compare microwave ablation zones created by using sequential or simultaneous power delivery in ex vivo and in vivo liver tissue.
  
  
  METHODS
  All procedures were approved by the institutional animal care and use committee. Microwave ablations were performed in both ex vivo and in vivo liver models with a 2.45-GHz system capable of powering up to three antennas simultaneously. Two- and three-antenna arrays were evaluated in each model. Sequential and simultaneous ablations were created by delivering power (50 W ex vivo, 65 W in vivo) for 5 minutes per antenna (10 and 15 minutes total ablation time for sequential ablations, 5 minutes for simultaneous ablations). Thirty-two ablations were performed in ex vivo bovine livers (eight per group) and 28 in the livers of eight swine in vivo (seven per group). Ablation zone size and circularity metrics were determined from ablations excised postmortem. Mixed effects modeling was used to evaluate the influence of power delivery, number of antennas, and tissue type.
  
  
  RESULTS
  On average, ablations created by using the simultaneous power delivery technique were larger than those with the sequential technique (P < .05). Simultaneous ablations were also more circular than sequential ablations (P = .0001). Larger and more circular ablations were achieved with three antennas compared with two antennas (P < .05). Ablations were generally smaller in vivo compared with ex vivo.
  
  
  CONCLUSIONS
  The use of multiple antennas and simultaneous power delivery creates larger, more confluent ablations with greater temperatures than those created with sequential power delivery.
authors.affiliation: From the Departments of Radiology (C.M.H., M.M., M.B., F.T.L., M.G.L., J.L.H., T.Z., C.L.B.), Biomedical Engineering (F.T.L., C.L.B.), and Medical Physics (M.B., C.L.B.), University of Wisconsin, Wisconsin Institutes for Medical Research, 1111 Highland Ave, WIMR 1141, Madison, WI 53705.
authors.forename: Colin M
authors.initials: CM
authors.lastname: Harari
authors.affiliation: From the Departments of Radiology (C.M.H., M.M., M.B., F.T.L., M.G.L., J.L.H., T.Z., C.L.B.), Biomedical Engineering (F.T.L., C.L.B.), and Medical Physics (M.B., C.L.B.), University of Wisconsin, Wisconsin Institutes for Medical Research, 1111 Highland Ave, WIMR 1141, Madison, WI 53705.
authors.forename: Michelle
authors.initials: M
authors.lastname: Magagna
authors.affiliation: From the Departments of Radiology (C.M.H., M.M., M.B., F.T.L., M.G.L., J.L.H., T.Z., C.L.B.), Biomedical Engineering (F.T.L., C.L.B.), and Medical Physics (M.B., C.L.B.), University of Wisconsin, Wisconsin Institutes for Medical Research, 1111 Highland Ave, WIMR 1141, Madison, WI 53705.
authors.forename: Mariajose
authors.initials: M
authors.lastname: Bedoya
authors.affiliation: From the Departments of Radiology (C.M.H., M.M., M.B., F.T.L., M.G.L., J.L.H., T.Z., C.L.B.), Biomedical Engineering (F.T.L., C.L.B.), and Medical Physics (M.B., C.L.B.), University of Wisconsin, Wisconsin Institutes for Medical Research, 1111 Highland Ave, WIMR 1141, Madison, WI 53705.
authors.forename: Fred T
authors.initials: FT
authors.lastname: Lee
authors.affiliation: From the Departments of Radiology (C.M.H., M.M., M.B., F.T.L., M.G.L., J.L.H., T.Z., C.L.B.), Biomedical Engineering (F.T.L., C.L.B.), and Medical Physics (M.B., C.L.B.), University of Wisconsin, Wisconsin Institutes for Medical Research, 1111 Highland Ave, WIMR 1141, Madison, WI 53705.
authors.forename: Meghan G
authors.initials: MG
authors.lastname: Lubner
authors.affiliation: From the Departments of Radiology (C.M.H., M.M., M.B., F.T.L., M.G.L., J.L.H., T.Z., C.L.B.), Biomedical Engineering (F.T.L., C.L.B.), and Medical Physics (M.B., C.L.B.), University of Wisconsin, Wisconsin Institutes for Medical Research, 1111 Highland Ave, WIMR 1141, Madison, WI 53705.
authors.forename: J Louis
authors.initials: JL
authors.lastname: Hinshaw
authors.affiliation: From the Departments of Radiology (C.M.H., M.M., M.B., F.T.L., M.G.L., J.L.H., T.Z., C.L.B.), Biomedical Engineering (F.T.L., C.L.B.), and Medical Physics (M.B., C.L.B.), University of Wisconsin, Wisconsin Institutes for Medical Research, 1111 Highland Ave, WIMR 1141, Madison, WI 53705.
authors.forename: Timothy
authors.initials: T
authors.lastname: Ziemlewicz
authors.affiliation: From the Departments of Radiology (C.M.H., M.M., M.B., F.T.L., M.G.L., J.L.H., T.Z., C.L.B.), Biomedical Engineering (F.T.L., C.L.B.), and Medical Physics (M.B., C.L.B.), University of Wisconsin, Wisconsin Institutes for Medical Research, 1111 Highland Ave, WIMR 1141, Madison, WI 53705.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Brace
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D002417:Cattle; D004867:Equipment Design; D008099:Liver / Q000601:surgery*; D008872:Microwaves / Q000627:therapeutic use*; D023421:Models, Animal; D013552:Swine