title: Prospectively gated transverse coronary CT angiography versus retrospectively gated helical technique: improved image quality and reduced radiation dose.
abstract: OBJECTIVE
  To retrospectively compare image quality, radiation dose, and blood vessel assessability for coronary artery computed tomographic (CT) angiograms obtained with a prospectively gated transverse (PGT) CT technique and a retrospectively gated helical (RGH) CT technique.
  
  
  METHODS
  This HIPAA-compliant study received a waiver for approval from the institutional review board, including one for informed consent. Coronary CT angiograms obtained with 64-detector row CT were retrospectively evaluated in 203 clinical patients. A routine RGH technique was evaluated in 82 consecutive patients (44 males, 38 females; mean age, 55.6 years). The PGT technique was then evaluated in 121 additional patients (71 males, 50 females; mean age, 56.7 years). All images were evaluated for image quality, estimated radiation dose, and coronary artery segment assessability. Differences in image quality score were evaluated by using a proportional odds logistic regression model, with main effects for three readers, two techniques, and four arteries.
  
  
  RESULTS
  The mean effective dose for the group with the PGT technique was 2.8 mSv; this represents an 83% reduction as compared with that for the group with the RGH technique (mean, 18.4 mSv; P < .001). The image quality score for each of the arteries, as well as the overall combined score, was significantly greater for images obtained with PGT technique than for images obtained with RGH technique. The combined mean image quality score was 4.791 for images obtained with PGT technique versus 4.514 for images obtained with RGH technique (proportional odds model odds ratio, 2.8; 95% confidence interval: 1.7, 4.8). The percentage of assessable coronary artery segments was 98.6% (1196 of 1213) for images obtained with PGT technique versus 97.9% (1741 of 1778) for images obtained with RGH technique (P = .83).
  
  
  CONCLUSIONS
  PGT coronary CT angiography offers improved image quality and substantially reduced effective radiation dose compared with traditional RGH coronary CT angiography.
authors.affiliation: Fairfax Radiological Consultants P.C., 2722 Merrilee Dr, Suite 230, Fairfax, VA 22031, USA. jpearls@yahoo.com
authors.forename: James P
authors.initials: JP
authors.lastname: Earls
authors.forename: Elise L
authors.initials: EL
authors.lastname: Berman
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Urban
authors.forename: Charlene A
authors.initials: CA
authors.lastname: Curry
authors.forename: Judith L
authors.initials: JL
authors.lastname: Lane
authors.forename: Robert S
authors.initials: RS
authors.lastname: Jennings
authors.forename: Colin C
authors.initials: CC
authors.lastname: McCulloch
authors.forename: Jiang
authors.initials: J
authors.lastname: Hsieh
authors.forename: John H
authors.initials: JH
authors.lastname: Londt
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed / Q000379:methods*; D014283:Triiodobenzoic Acids
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; C044834:iodixanol