title: Fluid preinjection for microwave ablation in an ex vivo bovine liver model assessed with volumetry in an open MRI system.
abstract: OBJECTIVE
  We aimed to detect possible differences in microwave ablation (MWA) volumes after different fluid preinjections using magnetic resonance imaging (MRI).
  
  
  METHODS
  MWA volumes were created in 50 cuboid ex vivo bovine liver specimens (five series: control [no injection], 10 mL water, 10 mL 0.9% NaCl, 10 mL 6% NaCl, and 10 mL 12% NaCl preinjections; n=10 for each series). The operating frequency (915 megahertz), ablation time (7 min), and energy supply (45 watts) were constant. Following MWA, two MR sequences were acquired, and MR volumetry was performed for each sequence.
  
  
  RESULTS
  For both sequences, fluid preinjection did not lead to significant differences in MWA ablation volumes compared to the respective control group (sequence 1: mean MWA volumes ranged from 7.0±1.2 mm [water] to 7.8±1.3 mm [12% NaCl] vs. 7.3±2.1 mm in the control group; sequence 2: mean MWA volumes ranged from 4.9±1.4 mm [12% NaCl] to 5.5±1.9 mm [0.9% NaCl] vs. 4.7±1.6 mm in the control group). The ablation volumes visualized with the two sequences differed significantly in general (P < 0.001) and between the respective groups (control, P ≤ 0.001; water, P < 0.001; 0.9% NaCl, P < 0.001; 6% NaCl, P ≤ 0.001; 12% NaCl, P < 0.001). The volumes determined with sequence 1 were closer to the expected ablation volume of 8 mL compared to those determined with sequence 2.
  
  
  CONCLUSIONS
  For the fluid qualities and concentrations assessed, there is no evidence that fluid preinjection results in larger coagulation volumes after MWA. Because ablation volumes determined by MRI vary with the sequence used, interventionalists should gain experience in how to interpret postinterventional imaging findings (with the MR scanner, sequences, and parameters used) to accurately estimate the outcome of the interventions they perform.
authors.affiliation: Department of Radiology, Charité University Medicine, Berlin, Germany.
authors.forename: Federico
authors.initials: F
authors.lastname: Collettini
authors.forename: Hendrik
authors.initials: H
authors.lastname: Rathke
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schnackenburg
authors.forename: Andreas
authors.initials: A
authors.lastname: Thomas
authors.forename: Liane
authors.initials: L
authors.lastname: Albrecht
authors.forename: Britta
authors.initials: B
authors.lastname: Suttmeyer
authors.forename: Martin
authors.initials: M
authors.lastname: Jonczyk
authors.forename: Felix
authors.initials: F
authors.lastname: Guettler
authors.forename: Ulf
authors.initials: U
authors.lastname: Teichgräber
authors.forename: Thomas
authors.initials: T
authors.lastname: Kroncke
authors.forename: Bernd
authors.initials: B
authors.lastname: Hamm
authors.forename: Maximilian
authors.initials: M
authors.lastname: de Bucourt
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D002417:Cattle; D004867:Equipment Design; D007267:Injections; D008099:Liver / Q000473:pathology / Q000601:surgery*; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D008872:Microwaves / Q000627:therapeutic use*; D009929:Organ Size; D012965:Sodium Chloride / Q000008:administration & dosage; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014867:Water / Q000008:administration & dosage
chemical_list: D014867:Water; D012965:Sodium Chloride