title: Integration of three-dimensional left atrial magnetic resonance images into a real-time electroanatomic mapping system: validation of a registration method.
abstract: BACKGROUND
  The alignment of three-dimensional (3D) left atrial images acquired by magnetic resonance (MR) with the anatomical information yielded by 3D mapping systems is one of the most critical issues in image integration techniques for catheter ablation of atrial fibrillation (AF). We assessed the accuracy of a simplified method of superimposing 3D MR left atrial images on real-time left atrial electroanatomic maps (registration).
  
  
  METHODS
  MR data on the left atrium in 40 patients with drug-refractory AF were imported into the CartoMerge (Biosense Webster, Inc., Diamond Bar, CA, USA) electroanatomic mapping system. Registration was obtained by combining "visual alignment" of one endocardial point and "surface registration" of a limited number of points sampled on the posterior wall of the left atrium. The accuracy of the registration process was assessed through a statistical algorithm incorporated into the CartoMerge system, and through the percentage of pulmonary veins (PVs) in which electrical isolation was achieved after anatomical ablation.
  
  
  RESULTS
  The mean registration surface-to-point distance and ablation surface-to-point distance were 1.33 +/- 0.96 mm and 1.47 +/- 1.15 mm, respectively. Upon completion of the circumferential anatomical ablation around the PVs, electrical PV isolation was confirmed by a multipolar circular mapping catheter in 129 of 146 PVs (89%).
  
  
  CONCLUSIONS
  Our registration method, which is mainly based on the surface registration of the posterior wall of the left atrium, enables almost 90% of PVs to be isolated by means of an anatomically based catheter ablation approach.
authors.affiliation: Dipartimento di Cardiologia, Ospedale Civile di Mirano, Venice, Italy. bertagliaferro@alice.it
authors.forename: Emanuele
authors.initials: E
authors.lastname: Bertaglia
authors.forename: Glauco
authors.initials: G
authors.lastname: Brandolino
authors.forename: Franco
authors.initials: F
authors.lastname: Zoppo
authors.forename: Francesca
authors.initials: F
authors.lastname: Zerbo
authors.forename: Pietro
authors.initials: P
authors.lastname: Pascotto
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology; D018780:Body Surface Potential Mapping / Q000379:methods*; D003199:Computer Systems; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006325:Heart Atria / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018511:Systems Integration