title: Time-resolved MR venography of the pulmonary veins precatheter-based ablation for atrial fibrillation.
abstract: OBJECTIVE
  To evaluate time-resolved magnetic resonance angiography (TR-MRA) of the pulmonary venous circulation using the time-resolved angiography with interleaved stochastic trajectories (TWIST) method and compare it with the more commonly used conventional contrast-enhanced magnetic resonance angiography (CE-MRA) approach in atrial fibrillation patients referred for preablation pulmonary vein mapping.
  
  
  METHODS
  This study was approved by the Institutional Review Board. Twenty-six patients (15 males; age 59.6 ± 12.7 years) referred for preablation pulmonary vein mapping underwent both conventional CE-MRA and TR-MRA with TWIST. Imaging was performed on a 1.5 T (Magnetom Avanto, Siemens Healthcare, Erlangen, Germany) MRI scanner. Source partition and maximum intensity projection (MIP) images were evaluated retrospectively. For quantitative analysis, pulmonary vein ostium orthogonal dimensions were measured using double oblique multiplanar reformatting. The results were analyzed using paired t-tests, Lin's concordance correlation coefficient, and Bland-Altman plots. For qualitative analysis, both source partition images and MIP images were assessed by two observers (A.P. and M.G.). The presence of common ostiums or accessory veins was recorded and analyzed using unweighted Cohen's kappa. Pulmonary vein conspicuity was scored on a scale of 1-4 (1 = poor, 2 = fair, 3 = good, 4 = excellent) and analyzed using paired t-tests, intraclass correlation coefficients, and quadratic weighted kappa statistics.
  
  
  RESULTS
  Orthogonal venous diameters were comparable for both TR-MRA and conventional CE-MRA (1.34 ± 0.37 vs. 1.38 cm ± 0.36, respectively). Results of paired t-tests, Lin's concordance correlation coefficient, and Bland-Altman analysis revealed relatively close comparison between methods. The magnitude of the mean difference for any of the statistical comparisons did not exceed 0.10 cm. The visualization of variant pulmonary vein anatomy was very similar for both techniques. Agreement between techniques was determined to be "good" to "very good" (κ = 0.78-0.85). Conspicuity scores for each pulmonary vein were also very close. Paired t-tests, intraclass correlation coefficients, and quadratic weighted kappa statistics all revealed strong agreement between methods.
  
  
  CONCLUSIONS
  TR-MRA using TWIST produces comparable anatomic images and pulmonary venous dimensions to the more widely used CE-MRA technique. Additionally, the TWIST technique improves arterio-venous separation, does not need exact bolus timing, requires less gadolinium, and gives additional information on vein perfusion.
authors.affiliation: Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA. michael.schonberger@gmail.com
authors.forename: Michael
authors.initials: M
authors.lastname: Schonberger
authors.forename: Asad
authors.initials: A
authors.lastname: Usman
authors.forename: Maurizio
authors.initials: M
authors.lastname: Galizia
authors.forename: Andrada
authors.initials: A
authors.lastname: Popescu
authors.forename: Jeremy
authors.initials: J
authors.lastname: Collins
authors.forename: James C
authors.initials: JC
authors.lastname: Carr
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000473:pathology*; D002309:Cardiology / Q000379:methods; D002404:Catheterization; D003952:Diagnostic Imaging / Q000379:methods; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010477:Perfusion; D010690:Phlebography / Q000379:methods*; D011667:Pulmonary Veins / Q000473:pathology*; D013269:Stochastic Processes; D013997:Time Factors