title: Prospective ECG-triggered, axial 4-D imaging of the aortic root, valvular, and left ventricular structures: a lower radiation dose option for preprocedural TAVR imaging.
abstract: BACKGROUND
  Transcatheter valve interventions rely on imaging for patient selection, preprocedural planning, and intraprocedural guidance.
  
  
  OBJECTIVE
  We explored the use of prospective electrocardiogram (ECG)-triggered 4-dimensional (4-D) CT imaging in patients evaluated for transcatheter aortic valve replacement (TAVR).
  
  
  METHODS
  A total of 47 consecutive patients underwent 128-slice dual-source CT with wide-window dose-modulated prospective ECG-triggered, axial acquisition of the aortic root, reconstructed during diastolic and systolic cardiac phases. Image quality was evaluated, aortic root and left ventricular (LV) geometry and function were analyzed, and radiation exposure was estimated.
  
  
  RESULTS
  Image quality was generally good, with 41 of 47 (87%) patients scored as good or excellent. The mean aortic valve area was 0.93 ± 0.24 cm(2). Mean LV ejection fraction was 56.8% ± 16.4%, and mean LV mass was 130.4 ± 43.8 g. The minor diameter of the annulus was larger in systole (systole, 2.29 ± 0.24 cm; diastole, 2.14 ± 0.25 cm; P = 0.006), but the mean and major diameters did not vary significantly between systole and diastole. The mean estimated effective dose was 5.9 ± 2.4 mSv.
  
  
  CONCLUSIONS
  Multiphase, prospective ECG-triggered axial image acquisition is a lower dose acquisition technique for 4-D aortic root imaging in patients being considered for TAVR.
authors.affiliation: Imaging Institute, Cleveland Clinic, 9500 Euclid Ave, Desk J1-5, Cleveland, OH 44195, USA. bolenm@ccf.org
authors.forename: Michael A
authors.initials: MA
authors.lastname: Bolen
authors.forename: Zoran B
authors.initials: ZB
authors.lastname: Popovic
authors.forename: Arun
authors.initials: A
authors.lastname: Dahiya
authors.forename: Samir R
authors.initials: SR
authors.lastname: Kapadia
authors.forename: E Murat
authors.initials: EM
authors.lastname: Tuzcu
authors.forename: Scott D
authors.initials: SD
authors.lastname: Flamm
authors.forename: Sandra S
authors.initials: SS
authors.lastname: Halliburton
authors.forename: Paul
authors.initials: P
authors.lastname: Schoenhagen
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000000981:diagnostic imaging*; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging* / Q000601:surgery*; D001027:Aortography / Q000379:methods; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000379:methods; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D018579:Patient Selection; D011300:Preoperative Care; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*