title: Real-time monitoring of tissue displacement and temperature changes during MR-guided high intensity focused ultrasound.
abstract: The therapy endpoint most commonly used in MR-guided high intensity focused ultrasound is the thermal dose. Although namely correlated with nonviable tissue, it does not account for changes in mechanical properties of tissue during ablation. This study presents a new acquisition sequence for multislice, subsecond and simultaneous imaging of tissue temperature and displacement during ablation.
  
  
  
  A single-shot echo planar imaging sequence was implemented using a pair of motion-encoding gradients, with alternated polarities. A first ultrasound pulse was synchronized on the second lobe of the motion-encoding gradients and followed by continuous sonication to induce a local temperature increase in ex vivo muscle and in vivo on pig liver. Lastly, the method was evaluated in the brain of two volunteers to assess method's precision.
  
  
  
  For thermal doses higher than the lethal threshold, displacement amplitude was reduced by 21% and 28% at the focal point in muscle and liver, respectively. Displacement value remained nearly constant for nonlethal thermal doses values. The mean standard deviation of temperature and displacement in the brain of volunteers remained below 0.8 °C and 2.5 µm.
  
  
  
  This new fast imaging sequence provides real-time measurement of temperature distribution and displacement at the focus during HIFU ablation. Magn Reson Med 78:1911-1921, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France.|Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.|INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.|Image Guided Therapy SA, Pessac, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Bour
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France.|Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.|INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Marquet
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France.|Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.|INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.
authors.forename: Valéry
authors.initials: V
authors.lastname: Ozenne
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France.|Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.|INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.|Siemens Healthineers France, Saint-Denis, France.
authors.forename: Solenn
authors.initials: S
authors.lastname: Toupin
authors.affiliation: Image Guided Therapy SA, Pessac, France.
authors.forename: Erik
authors.initials: E
authors.lastname: Dumont
authors.affiliation: Institut Langevin, CNRS UMR 7587, INSERM U979, ESPCI ParisTech, Paris, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Aubry
authors.affiliation: Siemens Healthineers France, Saint-Denis, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Lepetit-Coiffe
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France.|Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.|INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, Bordeaux, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Quesson
mesh_terms: D000818:Animals; D001831:Body Temperature; D001921:Brain / Q000000981:diagnostic imaging; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013552:Swine; D013817:Thermography / Q000379:methods*
keywords: ARFI; MRgHIFU; ablation; thermometry