title: Intrapleural fluid infusion for MR-guided high-intensity focused ultrasound ablation in the liver dome.
abstract: OBJECTIVE
  Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation of tumors in the liver dome is challenging because of the presence of air in the costophrenic angle. In this study, we used a porcine liver model and a clinical MR-HIFU system to assess the feasibility and safety of using intrapleural fluid infusion (IPI) to create an acoustic window for MR-HIFU ablation in the liver dome.
  
  
  METHODS
  Healthy adult Dalland land pigs (n = 6) under general anesthesia were used with animal committee approval. Degassed saline (200-800 mL) was infused into the intrapleural space under ultrasound guidance. A clinical 1.5-T MR-HIFU system was used to perform sonications (4-mm treatment cells, 300-450 W, 20-30 seconds) in the liver dome under real-time MR thermometry. An intercostal firing technique was used to prevent rib heating in one experiment. Technical success was defined as a temperature increase (>10°C) in the target area. After termination, the animal was examined for thermal damage to liver, diaphragm, pleura, lung, or intercostal muscle.
  
  
  RESULTS
  An acoustic window was established in all animals. A temperature increase in the target area was achieved in all animals (max. 47°C-67°C). MR thermometry showed no heating outside the target area. Intercostal firing effectively reduced rib heating (55°C vs. 42°C). Postmortem examination revealed no unwanted thermal damage. One complication occurred, in the first experiment, because of an ill-suited needle (displacement of the needle).
  
  
  CONCLUSIONS
  The results indicate that IPI may be used safely to assist MR-HIFU ablation of tumors in the liver dome. For reliable tissue coagulation, IPI must be combined with an intercostal sonication technique. Considering the proportion of patients with tumors in the liver dome, IPI widens the applicability of MR-HIFU ablation for liver tumors considerably.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, E01.132, P.O. Box 85500, Utrecht 3508 GA, The Netherlands. Electronic address: j.wijlemans@umcutrecht.nl.
authors.forename: Joost W
authors.initials: JW
authors.lastname: Wijlemans
authors.affiliation: Imaging Division, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Martijn
authors.initials: M
authors.lastname: de Greef
authors.affiliation: Philips Medical Systems MR, Vantaa, Finland.
authors.forename: Gerald
authors.initials: G
authors.lastname: Schubert
authors.affiliation: Imaging Division, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Chrit T W
authors.initials: CT
authors.lastname: Moonen
authors.affiliation: Department of Radiology, University Medical Center Utrecht, E01.132, P.O. Box 85500, Utrecht 3508 GA, The Netherlands.
authors.forename: Maurice A A J
authors.initials: MA
authors.lastname: van den Bosch
authors.affiliation: Imaging Division, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Mario
authors.initials: M
authors.lastname: Ries
mesh_terms: D000818:Animals; D005240:Feasibility Studies; D057086:High-Intensity Focused Ultrasound Ablation; D021621:Imaging, Three-Dimensional; D008099:Liver / Q000601:surgery*; D053783:Magnetic Resonance Imaging, Interventional / Q000379:methods*; D010994:Pleura; D012965:Sodium Chloride / Q000008:administration & dosage*; D013552:Swine
chemical_list: D012965:Sodium Chloride
keywords: Magnetic resonance imaging; high-intensity focused ultrasound ablation; interventional; liver neoplasms