title: Feasibility of real-time MR thermal dose mapping for predicting radiofrequency ablation outcome in the myocardium in vivo.
abstract: BACKGROUND
  Clinical treatment of cardiac arrhythmia by radiofrequency ablation (RFA) currently lacks quantitative and precise visualization of lesion formation in the myocardium during the procedure. This study aims at evaluating thermal dose (TD) imaging obtained from real-time magnetic resonance (MR) thermometry on the heart as a relevant indicator of the thermal lesion extent.
  
  
  METHODS
  MR temperature mapping based on the Proton Resonance Frequency Shift (PRFS) method was performed at 1.5 T on the heart, with 4 to 5 slices acquired per heartbeat. Respiratory motion was compensated using navigator-based slice tracking. Residual in-plane motion and related magnetic susceptibility artifacts were corrected online. The standard deviation of temperature was measured on healthy volunteers (N = 5) in both ventricles. On animals, the MR-compatible catheter was positioned and visualized in the left ventricle (LV) using a bSSFP pulse sequence with active catheter tracking. Twelve MR-guided RFA were performed on three sheep in vivo at various locations in left ventricle (LV). The dimensions of the thermal lesions measured on thermal dose images, on 3D T1-weighted (T1-w) images acquired immediately after the ablation and at gross pathology were correlated.
  
  
  RESULTS
  MR thermometry uncertainty was 1.5 °C on average over more than 96% of the pixels covering the left and right ventricles, on each volunteer. On animals, catheter repositioning in the LV with active slice tracking was successfully performed and each ablation could be monitored in real-time by MR thermometry and thermal dosimetry. Thermal lesion dimensions on TD maps were found to be highly correlated with those observed on post-ablation T1-w images (R = 0.87) that also correlated (R = 0.89) with measurements at gross pathology.
  
  
  CONCLUSIONS
  Quantitative TD mapping from real-time rapid CMR thermometry during catheter-based RFA is feasible. It provides a direct assessment of the lesion extent in the myocardium with precision in the range of one millimeter. Real-time MR thermometry and thermal dosimetry may improve safety and efficacy of the RFA procedure by offering a reliable indicator of therapy outcome during the procedure.
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux University, F-33600, Pessac-Bordeaux, France. toupin.solenn@gmail.com.|Centre de recherche Cardio-Thoracique de Bordeaux, INSERM, U1045, F-33000, Bordeaux, France. toupin.solenn@gmail.com.|Siemens Healthineers France, F-93210, Saint-Denis, France. toupin.solenn@gmail.com.
authors.forename: Solenn
authors.identifier: http://orcid.org/0000-0001-9967-0044
authors.initials: S
authors.lastname: Toupin
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux University, F-33600, Pessac-Bordeaux, France.|Centre de recherche Cardio-Thoracique de Bordeaux, INSERM, U1045, F-33000, Bordeaux, France.|Image Guided Therapy, F-33600, Pessac, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Bour
authors.affiliation: Siemens Healthineers France, F-93210, Saint-Denis, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Lepetit-Coiffé
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux University, F-33600, Pessac-Bordeaux, France.|Centre de recherche Cardio-Thoracique de Bordeaux, INSERM, U1045, F-33000, Bordeaux, France.
authors.forename: Valéry
authors.initials: V
authors.lastname: Ozenne
authors.affiliation: Institute of Mathematics of Bordeaux, UMR 5251, F-33400, Talence, France.
authors.forename: Baudouin
authors.initials: B
authors.lastname: Denis de Senneville
authors.affiliation: Siemens Healthineers, Erlangen, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Schneider
authors.affiliation: Siemens Healthineers France, F-93210, Saint-Denis, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Vaussy
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux University, F-33600, Pessac-Bordeaux, France.|Centre de recherche Cardio-Thoracique de Bordeaux, INSERM, U1045, F-33000, Bordeaux, France.|Electrophysiology and Ablation Unit, Bordeaux University Hospital (CHU), F-33600, Pessac, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Chaumeil
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux University, F-33600, Pessac-Bordeaux, France.|Centre de recherche Cardio-Thoracique de Bordeaux, INSERM, U1045, F-33000, Bordeaux, France.|Electrophysiology and Ablation Unit, Bordeaux University Hospital (CHU), F-33600, Pessac, France.
authors.forename: Hubert
authors.initials: H
authors.lastname: Cochet
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux University, F-33600, Pessac-Bordeaux, France.|Centre de recherche Cardio-Thoracique de Bordeaux, INSERM, U1045, F-33000, Bordeaux, France.|Electrophysiology and Ablation Unit, Bordeaux University Hospital (CHU), F-33600, Pessac, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Sacher
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux University, F-33600, Pessac-Bordeaux, France.|Centre de recherche Cardio-Thoracique de Bordeaux, INSERM, U1045, F-33000, Bordeaux, France.|Electrophysiology and Ablation Unit, Bordeaux University Hospital (CHU), F-33600, Pessac, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Jaïs
authors.affiliation: IHU Liryc, Electrophysiology and Heart Modeling Institute, Foundation Bordeaux University, F-33600, Pessac-Bordeaux, France.|Centre de recherche Cardio-Thoracique de Bordeaux, INSERM, U1045, F-33000, Bordeaux, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Quesson
mesh_terms: D000818:Animals; D016477:Artifacts; D001831:Body Temperature; D062906:Cardiac Catheters; D017115:Catheter Ablation / Q000295:instrumentation; D005240:Feasibility Studies; D006339:Heart Rate; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D023421:Models, Animal; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D034561:Sheep, Domestic; D062125:Thermometry / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors
keywords: Arrhythmia; Cardiac; Catheter; Electrophysiology; MR thermometry; Radiofrequency ablation