title: Prospectively gated axial CT coronary angiography: comparison of image quality and effective radiation dose between 64- and 256-slice CT.
abstract: OBJECTIVE
  To compare image quality and effective radiation dose for prospectively gated axial CT coronary angiography on 64- and 256-slice CT.
  
  
  METHODS
  The patient cohort consisted of 80 consecutive patients undergoing imaging with 256-slice CT and 80 patients with 64-slice CT. The two patient groups were demographically matched according to age, gender, body mass index and heart rate. For both groups, two observers independently assessed image quality for all coronary segments on a five-point ordinal scale. The two groups were compared with regard to image quality and effective radiation dose. Image quality scores less than 3 were considered non-diagnostic.
  
  
  RESULTS
  Mean effective radiation dose did not significantly differ between the two groups (3.4 +/- 0.8 mSv in both groups; p > 0.1). Vessel-based image quality was significantly better in patients undergoing 256-slice CT compared with those undergoing 64-slice CT (p < 0.001). The proportion of assessable coronary segments significantly increased from 95.6% in the 64-slice group to 98.9% in the 256-slice group (p < 0.05).
  
  
  CONCLUSIONS
  Prospectively gated axial CT coronary angiography performed on 256-slice CT provides significantly improved and more stable image quality at an equivalent effective radiation dose compared with 64-slice CT.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital of Ulm, Steinhövelstr. 9, 89075, Ulm, Germany. oliver.klass@uniklinik-ulm.de
authors.forename: Oliver
authors.initials: O
authors.lastname: Klass
authors.forename: Matthew
authors.initials: M
authors.lastname: Walker
authors.forename: Anne
authors.initials: A
authors.lastname: Siebach
authors.forename: Tina
authors.initials: T
authors.lastname: Stuber
authors.forename: Sebastian
authors.initials: S
authors.lastname: Feuerlein
authors.forename: Markus
authors.initials: M
authors.lastname: Juchems
authors.forename: Martin H K
authors.initials: MH
authors.lastname: Hoffmann
mesh_terms: D015992:Body Mass Index; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D007479:Iopamidol / Q000008:administration & dosage / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol