title: Noninvasive coronary angiography with 16-detector row CT: effect of heart rate.
abstract: OBJECTIVE
  To evaluate the effect of heart rate on the quality of coronary angiograms obtained with 16-detector row computed tomography (CT) by using temporally enhanced three-dimensional (3D) approaches.
  
  
  METHODS
  The local ethics committee approved the study, and informed consent was obtained from all patients. Fifty patients underwent coronary CT angiography (heart rate range, 45-103 beats per minute). Raw data from helical CT and electrocardiography (ECG) were saved in a combined data set. Retrospectively ECG-gated images were reconstructed at preselected phases (50% and 80%) of the cardiac cycle. A 3D voxel-based approach with cardiac phase weighting was used for reconstruction. Testing for correlation between heart rate, cardiac phase reconstruction window, and image quality was performed with Kruskal-Wallis analysis. Image quality (freedom from cardiac motion-related artifacts) was referenced against findings at conventional angiography in a secondary evaluation step. Regression analysis was performed to calculate heart rate thresholds for future beta-blocker application.
  
  
  RESULTS
  A significant negative correlation was observed between heart rate and image quality (r = 0.80, P < .001). Motion artifact-free images were available for 44 (88%) patients and were achieved consistently at a heart rate of 80 or fewer beats per minute (n = 39). Best image quality was achieved at 75 or fewer beats per minute. Segmental analysis revealed that 97% of arterial segments (diameter > or = 1.5 mm according to conventional angiography) were assessable at 80 or fewer beats per minute. Premature ventricular contractions and rate-contained arrhythmia did not impede diagnostic assessment of the coronary arteries in 10 (83%) of the 12 patients affected.
  
  
  CONCLUSIONS
  Motion-free coronary angiograms can be obtained consistently with 16-detector row CT scanners and adaptive multicyclic reconstruction algorithms in patients with heart rates of less than 80 beats per minute.
authors.affiliation: Department of Diagnostic Radiology, University Hospital of Ulm, Steinhoevelstrasse 9, D-89070 Ulm, Germany. martin.hoffmann@medizin.uni-ulm.de
authors.forename: Martin H K
authors.initials: MH
authors.lastname: Hoffmann
authors.forename: Heshui
authors.initials: H
authors.lastname: Shi
authors.forename: Robert
authors.initials: R
authors.lastname: Manzke
authors.forename: Florian T
authors.initials: FT
authors.lastname: Schmid
authors.forename: Leon
authors.initials: L
authors.lastname: De Vries
authors.forename: Michael
authors.initials: M
authors.lastname: Grass
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Brambs
authors.forename: Andrik J
authors.initials: AJ
authors.lastname: Aschoff
mesh_terms: D000328:Adult; D000368:Aged; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*