title: Characterization of radiofrequency ablation lesions with gadolinium-enhanced cardiovascular magnetic resonance imaging.
abstract: OBJECTIVE
  This study was designed to evaluate the characteristics of gadolinium-enhanced imaging of radiofrequency ablations.
  
  
  BACKGROUND
  Gadolinium-enhanced magnetic resonance imaging (MRI) has been used successfully to evaluate tissue necrosis after myocardial infarction. In electrophysiology, radiofrequency energy is used to create a targeted myocardial necrosis for the treatment of various arrhythmias.
  
  
  METHODS
  Using a power-controlled, cooled-tip 7-F catheter system, radiofrequency lesions (10 to 40 W for 30 s) were created on the epicardium of the right ventricle in eight mongrel dogs. After injection of 0.225 mmol/kg gadolinium, T1-weighted fast gradient echo images were obtained during a follow-up of 10 h using an intrathoracic high-resolution coil. Radiofrequency ablations were analyzed on the MR images and compared with gross anatomy and histopathology.
  
  
  RESULTS
  Four distinct phases of signal enhancement were observed. After gadolinium injection, radiofrequency lesions were delineated clearly as contrast-free areas of low signal intensity (contrast-to-noise ratio [CNR] = -21.1 +/- 19.8). Signal enhancement in the lesion periphery started 4.0 +/- 1.8 min after injection and progressively extended toward the lesion center at a rate of 0.02 mm/min. Full delayed enhancement was observed after 98 +/- 21 min (CNR = +17.8 +/- 9.0). During the follow-up period, CNR started to decrease, but the lesions were detectable for as long as 10 h of follow-up. During the first three phases of enhancement, MRI correlated well with the pathological findings (r = 0.88, r = 0.88, and r = 0.86 [p < 0.001], respectively).
  
  
  CONCLUSIONS
  Radiofrequency ablation can be evaluated accurately by using gadolinium-enhanced MRI, which may allow the noninvasive assessment of procedural success. The dissimilar wash-in and wash-out kinetics compared with myocardial infarction suggest a different pathophysiological process with complete loss of microvasculature.
authors.affiliation: Division of Cardiology, Department of Radiology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA. tdickfel@medicine.umaryland.edu
authors.forename: Timm
authors.initials: T
authors.lastname: Dickfeld
authors.forename: Ritsushi
authors.initials: R
authors.lastname: Kato
authors.forename: Menekhem
authors.initials: M
authors.lastname: Zviman
authors.forename: Shenghan
authors.initials: S
authors.lastname: Lai
authors.forename: Glenn
authors.initials: G
authors.lastname: Meininger
authors.forename: Albert C
authors.initials: AC
authors.lastname: Lardo
authors.forename: Ariel
authors.initials: A
authors.lastname: Roguin
authors.forename: David
authors.initials: D
authors.lastname: Blumke
authors.forename: Ronald
authors.initials: R
authors.lastname: Berger
authors.forename: Hugh
authors.initials: H
authors.lastname: Calkins
authors.forename: Henry
authors.initials: H
authors.lastname: Halperin
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D004285:Dogs; D022062:Electrophysiologic Techniques, Cardiac; D005682:Gadolinium; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009206:Myocardium / Q000473:pathology*; D009336:Necrosis; D010496:Pericardium
chemical_list: D005682:Gadolinium