title: Image quality and radiation exposure using different low-dose scan protocols in dual-source CT coronary angiography: randomized study.
abstract: OBJECTIVE
  To compare image quality, radiation dose, and their relationship with heart rate of computed tomographic (CT) coronary angiographic scan protocols by using a 128-section dual-source CT scanner.
  
  
  METHODS
  Institutional review board approved the study; all patients gave informed consent. Two hundred seventy-two patients (175 men, 97 women; mean ages, 58 and 59 years, respectively) referred for CT coronary angiography were categorized according to heart rate: less than 65 beats per minute (group A) and 65 beats per minute or greater (group B). Patients were randomized to undergo prospective high-pitch spiral scanning and narrow-window prospective sequential scanning in group A (n = 160) or wide-window prospective sequential scanning and retrospective spiral scanning in group B (n = 112). Image quality was graded (1 = nondiagnostic; 2 = artifacts present, diagnostic; 3 = no artifacts) and compared (Mann-Whitney and Student t tests).
  
  
  RESULTS
  In group A, mean image quality grade was significantly lower with high-pitch spiral versus sequential scanning (2.67 ± 0.38 [standard deviation] vs 2.86 ± 0.21; P < .001). In a subpopulation (heart rate, <55 beats per minute), mean image quality grade was similar (2.81 ± 0.30 vs 2.94 ± 0.08; P = .35). In group B, image quality grade was comparable between sequential and retrospective spiral scanning (2.81 ± 0.28 vs 2.80 ± 0.38; P = .54). Mean estimated radiation dose was significantly lower (high-pitch spiral vs sequential scanning) in group A (for 100 kV, 0.81 mSv ± 0.30 vs 2.74 mSv ± 1.14 [P < .001]; for 120 kV, 1.65 mSv ± 0.69 vs 4.21 mSv ± 1.20 [P < .001]) and in group B (sequential vs retrospective spiral scanning) (for 100 kV, 4.07 mSv ± 1.07 vs 5.54 mSv ± 1.76 [P = .02]; for 120 kV, 7.50 mSv ± 1.79 vs 9.83 mSv ± 3.49 [P = .1]).
  
  
  CONCLUSIONS
  A high-pitch spiral CT coronary angiographic protocol should be applied in patients with regular and low (<55 beats per minute) heart rates; a sequential protocol is preferred in all others.
authors.affiliation: Department of Radiology, Erasmus Medical Center, Dr Molewaterplein 40, Room Hs 207, PO Box 2040, 3000 CA Rotterdam, the Netherlands.
authors.forename: Lisan A
authors.initials: LA
authors.lastname: Neefjes
authors.forename: Anoeshka S
authors.initials: AS
authors.lastname: Dharampal
authors.forename: Alexia
authors.initials: A
authors.lastname: Rossi
authors.forename: Koen
authors.initials: K
authors.lastname: Nieman
authors.forename: Annick C
authors.initials: AC
authors.lastname: Weustink
authors.forename: Marcel L
authors.initials: ML
authors.lastname: Dijkshoorn
authors.forename: Gert-Jan R
authors.initials: GJ
authors.lastname: Ten Kate
authors.forename: Admir
authors.initials: A
authors.lastname: Dedic
authors.forename: Stella L
authors.initials: SL
authors.lastname: Papadopoulou
authors.forename: Marcel
authors.initials: M
authors.lastname: van Straten
authors.forename: Filippo
authors.initials: F
authors.lastname: Cademartiri
authors.forename: Gabriël P
authors.initials: GP
authors.lastname: Krestin
authors.forename: Pim J
authors.initials: PJ
authors.lastname: de Feyter
authors.forename: Nico R
authors.initials: NR
authors.lastname: Mollet
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D016009:Chi-Square Distribution; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006339:Heart Rate; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D018709:Statistics, Nonparametric; D036542:Tomography, Spiral Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide