title: Intracardiac acoustic radiation force impulse imaging: a novel imaging method for intraprocedural evaluation of radiofrequency ablation lesions.
abstract: BACKGROUND
  Arrhythmia recurrence after cardiac radiofrequency ablation (RFA) for atrial fibrillation has been linked to conduction through discontinuous lesion lines. Intraprocedural visualization and corrective ablation of lesion line discontinuities could decrease postprocedure atrial fibrillation recurrence. Intracardiac acoustic radiation force impulse (ARFI) imaging is a new imaging technique that visualizes RFA lesions by mapping the relative elasticity contrast between compliant-unablated and stiff RFA-treated myocardium.
  
  
  OBJECTIVE
  To determine whether intraprocedure ARFI images can identify RFA-treated myocardium in vivo.
  
  
  METHODS
  In 8 canines, an electroanatomical mapping-guided intracardiac echo catheter was used to acquire 2-dimensional ARFI images along right atrial ablation lines before and after RFA. ARFI images were acquired during diastole with the myocardium positioned at the ARFI focus (1.5 cm) and parallel to the intracardiac echo transducer for maximal and uniform energy delivery to the tissue. Three reviewers categorized each ARFI image as depicting no lesion, noncontiguous lesion, or contiguous lesion. For comparison, 3 separate reviewers confirmed RFA lesion presence and contiguity on the basis of functional conduction block at the imaging plane location on electroanatomical activation maps.
  
  
  RESULTS
  Ten percent of ARFI images were discarded because of motion artifacts. Reviewers of the ARFI images detected RFA-treated sites with high sensitivity (95.7%) and specificity (91.5%). Reviewer identification of contiguous lesions had 75.3% specificity and 47.1% sensitivity.
  
  
  CONCLUSIONS
  Intracardiac ARFI imaging was successful in identifying endocardial RFA treatment when specific imaging conditions were maintained. Further advances in ARFI imaging technology would facilitate a wider range of imaging opportunities for clinical lesion evaluation.
authors: Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA.
authors: Stephanie A
authors: SA
authors: Eyerly
authors: Tristram D
authors: TD
authors: Bahnson
authors: Jason I
authors: JI
authors: Koontz
authors: David P
authors: DP
authors: Bradway
authors: Douglas M
authors: DM
authors: Dumont
authors: Gregg E
authors: GE
authors: Trahey
authors: Patrick D
authors: PD
authors: Wolf
mesh_terms: D000818:Animals; D006348:Cardiac Surgical Procedures; D017115:Catheter Ablation; D004285:Dogs; D054459:Elasticity Imaging Techniques; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted; D007432:Intraoperative Period; D009206:Myocardium / Q000473:pathology; D012680:Sensitivity and Specificity