title: Image quality, motion artifacts, and reconstruction timing of 64-slice coronary computed tomography angiography with 0.33-second rotation speed.
abstract: OBJECTIVE
  We sought to evaluate the impact of patients' heart rate (HR) on coronary CTA image quality (IQ) and motion artifacts using a 64-slice scanner with 0.33/360 degrees rotation.
  
  
  METHODS
  Coronary CTA data sets of 32 patients (HR <or= 65 beats per minute [bpm], n = 15; HR > 65 bpm to <or=75 bpm, n = 10; HR > 75 bpm, n = 7) examined on a 64-slice scanner (Sensation 64, Siemens Medical Solutions, Forchheim, Germany) with 0.33s/360 degrees gantry rotation speed were analyzed. All patients had suspicion of coronary artery disease. Data acquisition was performed using 64 x 0.6-mm collimation, and contrast enhancement was provided by injection of 80 mL of iopromide (5 mL/s + NaCl). Images were reconstructed throughout the RR interval using half-scan and dual-segment reconstruction. IQ was rated by 2 observers using a 3-point scale from excellent (1) to nondiagnostic (3) for coronary segments. Quality was correlated to the HR, time point of optimal IQ analyzed, and the benefit of dual-segment reconstruction evaluated.
  
  
  RESULTS
  Overall mean IQ was 1.31 +/- 0.32 for all HR, with IQ being 1.08 +/- 0.12 for HR <or= 65 bpm, 1.62 +/- 0.27 for HR > 65 bpm <or= 75 bpm and 1.36 +/- 0.31 for HR > 75 bpm (P = 0.0003). Dual-segment reconstruction did not significantly improve IQ in any HR group (P = NS). Mean IQ was significantly better for LAD than for RCA (P < 0.0001) and LCX (P < 0.01). A total of 3.5% (11/318) of coronary artery segments were rated nondiagnostic by at least one reader based on motion artifacts. Although in HR < 65 bpm, the best IQ was predominately in diastole (93%), in HR > 75 bpm, the best IQ shifted to systole in most cases (86%).
  
  
  CONCLUSIONS
  Temporal resolution at 0.33-second rotation allows for diagnostic IQ within a wide range of HR using half-scan reconstruction. With increasing HR the time point of best IQ shifts from mid-diastole to systole.
authors.affiliation: Department of Clinical Radiology, University Hospitals-Grosshadern, Germany. Bernd.Wintersperger@med.uni-muenchen.de
authors.forename: Bernd J
authors.initials: BJ
authors.lastname: Wintersperger
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.forename: Franz
authors.initials: F
authors.lastname: von Ziegler
authors.forename: Thorsten
authors.initials: T
authors.lastname: Johnson
authors.forename: Carsten
authors.initials: C
authors.lastname: Rist
authors.forename: Alexander
authors.initials: A
authors.lastname: Leber
authors.forename: Thomas
authors.initials: T
authors.lastname: Flohr
authors.forename: Andreas
authors.initials: A
authors.lastname: Knez
authors.forename: Maximilian F
authors.initials: MF
authors.lastname: Reiser
authors.forename: Christoph R
authors.initials: CR
authors.lastname: Becker
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging; D005260:Female; D006339:Heart Rate; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011786:Quality Control; D011856:Radiographic Image Enhancement / Q000379:methods*; D036542:Tomography, Spiral Computed / Q000379:methods
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide