title: Tumour hyperthermia and ablation in rats using a clinical MR-HIFU system equipped with a dedicated small animal set-up.
abstract: OBJECTIVE
  We report on the design, performance, and specifications of a dedicated set-up for the treatment of rats on a clinical magnetic resonance high intensity focused ultrasound (MR-HIFU) system.
  
  
  METHODS
  The small animal HIFU-compatible 4-channel MR receiver volume coil and animal support were designed as add-on to a clinical 3T Philips Sonalleve MR-HIFU system. Prolonged hyperthermia (T ≈ 42°C, 15 min) and thermal ablation (T = 65°C) was performed in vivo on subcutaneous rat tumours using 1.44 MHz acoustic frequency. The direct treatment effect was assessed with T(2)-weighted imaging and dynamic contrast enhanced (DCE-) MRI as well as histology.
  
  
  RESULTS
  The developed HIFU-compatible coil provided an image quality that was comparable to conventional small animal volume coils (i.e. without acoustic window), and a SNR increase by a factor of 10 as compared to the coil set-up used for clinical MR-HIFU therapy. The use of an animal support minimised far field heating and allowed precise regulation of the animal body core temperature, which varied <1°C during treatment.
  
  
  CONCLUSIONS
  The results demonstrated that, by using a designated set-up, both controlled hyperthermia and thermal ablation treatment of malignant tumours in rodents can be performed on a clinical MR-HIFU system. This approach provides all the advantages of clinical MR-HIFU, such as volumetric heating, temperature feedback control and a clinical software interface for use in rodent treatment. The use of a clinical system moreover facilitates a rapid translation of the developed protocols into the clinic.
authors.affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, the Netherlands.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Hijnen
authors.forename: Edwin
authors.initials: E
authors.lastname: Heijman
authors.forename: Max O
authors.initials: MO
authors.lastname: Köhler
authors.forename: Mika
authors.initials: M
authors.lastname: Ylihautala
authors.forename: Gösta J
authors.initials: GJ
authors.lastname: Ehnholm
authors.forename: Arjan W
authors.initials: AW
authors.lastname: Simonetti
authors.forename: Holger
authors.initials: H
authors.lastname: Grüll
mesh_terms: D000818:Animals; D004867:Equipment Design; D005260:Female; D005910:Glioma / Q000628:therapy; D057086:High-Intensity Focused Ultrasound Ablation / Q000295:instrumentation* / Q000379:methods; D006979:Hyperthermia, Induced / Q000295:instrumentation; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009369:Neoplasms / Q000628:therapy*; D051381:Rats; D011916:Rats, Inbred F344