title: Radiation dose and image quality at high-pitch CT angiography of the aorta: intraindividual and interindividual comparisons with conventional CT angiography.
abstract: OBJECTIVE
  The objective of our study was to evaluate radiation dose and quantitative image quality parameters at high-pitch CT angiography (CTA) of the aorta compared with conventional CTA.
  
  
  METHODS
  We studied the examinations of 110 patients (65 men and 45 women; mean age ± SD, 64 ± 15 years) who had undergone CTA of the entire aorta on a second-generation dual-source CT system; 50 examinations were performed in high-pitch mode. The mean arterial attenuation, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM) were calculated for the high-pitch CTA and conventional CTA groups. Radiation exposures were compared.
  
  
  RESULTS
  All studies were considered of diagnostic quality. At high-pitch CTA, the mean tube voltage and tube current-exposure time product were 118 ± 7 kV (SD) and 197 ± 78 mAs compared with 120 ± 1 kV and 258 ± 78 mAs, respectively, at conventional CTA (p < 0.05). The mean volume CT dose index, dose-length product, and effective dose were 8.1 ± 2.4 mGy, 561.1 ± 178.6 mGy × cm, and 9.6 ± 3.0 mSv at high-pitch CTA and 18.3 ± 7.7 mGy, 1162.6 ± 480.1 mGy × cm, and 19.8 ± 8.2 mSv at conventional CTA (p < 0.001). Attenuation was similar for both protocols, whereas significantly less contrast medium was injected for high-pitch CTA than for standard-pitch CTA (87.3 ± 16 mL vs 97.9 ± 16 mL, respectively; p < 0.01). The SNR and CNR were significantly lower in the high-pitch CTA examinations (p < 0.01), whereas the FOM was nonsignificantly higher. Twenty patients underwent both high-pitch CTA and conventional CTA, with a 45% reduction in radiation dose (p < 0.001).
  
  
  CONCLUSIONS
  High-pitch CTA of the aorta yields 45-50% reduction of radiation exposure as well as contrast medium savings with maintained vessel attenuation.
authors.affiliation: Department of Radiology and Radiological Science, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MSC 226, Charleston, SC 29401, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Apfaltrer
authors.forename: E Lexworth
authors.initials: EL
authors.lastname: Hanna
authors.forename: U Joseph
authors.initials: UJ
authors.lastname: Schoepf
authors.forename: J Reid
authors.initials: JR
authors.lastname: Spears
authors.forename: Stefan O
authors.initials: SO
authors.lastname: Schoenberg
authors.forename: Christian
authors.initials: C
authors.lastname: Fink
authors.forename: Rozemarijn
authors.initials: R
authors.lastname: Vliegenthart
mesh_terms: D000368:Aged; D000465:Algorithms; D015901:Angiography, Digital Subtraction; D001018:Aortic Diseases / Q000000981:diagnostic imaging*; D001027:Aortography / Q000379:methods*; D015992:Body Mass Index; D016009:Chi-Square Distribution; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol