title: Multiphase CT angiography versus single-phase CT angiography: comparison of image quality and radiation dose.
abstract: OBJECTIVE
  Conventional CT angiography (CTA) is acquired during only a short interval in the arterial phase, which limits its ability to evaluate the cerebral circulation. Our aim was to compare the image quality and radiation dose of conventional single-phase CTA (SP-CTA) with a multiphase CTA (MP-CTA) algorithm reconstructed from a perfusion CT (PCT) dataset.
  
  
  METHODS
  Fifty consecutive patients undergoing head CTA and PCT in 1 examination were enrolled. The PCT dataset was obtained with 40.0-mm-detector coverage, 5.0-mm axial thickness, 80 kilovolt peak (kVp), 180 mA, and 30 mL of contrast medium. MP-CTA was reconstructed from the same PCT dataset with an axial thickness of 0.625 mm by using a new axial reconstruction algorithm. A conventional SP-CTA dataset was obtained with 0.625-mm axial thickness, 120 kVp, 350 mA, and 60 mL of contrast medium. We compared image quality, vascular enhancement, and radiation dose.
  
  
  RESULTS
  SP-CTA and MP-CTA of 50 patients (male/female ratio, 31/19; mean age, 59.25 years) were analyzed. MP-CTA was significantly better than SP-CTA in vascular enhancement (P = .002), in the absence of venous contamination (P = .006), and was significantly higher in image noise (P < .001). MP-CTA used less contrast medium than SP-CTA and could demonstrate hemodynamic information. The effective dose of MP-CTA was 5.73 mSv, which was equal to that in conventional PCT, and it was 3.57 mSv in SP-CTA.
  
  
  CONCLUSIONS
  It is feasible that MP-CTA may provide both CTA and PCT results. Compared with SP-CTA, MP-CTA provides comparable image quality, better vascular enhancement, hemodynamic information, and more noise with less detail visibility with a lower tube voltage. The radiation dose of MP-CTA is higher than that of SP-CTA, but the dose can be reduced by altering the sampling interval.
authors.affiliation: Department of Medical Imaging, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: C-Y
authors.initials: CY
authors.lastname: Yang
authors.forename: Y-F
authors.initials: YF
authors.lastname: Chen
authors.forename: C-W
authors.initials: CW
authors.lastname: Lee
authors.forename: A
authors.initials: A
authors.lastname: Huang
authors.forename: Y
authors.initials: Y
authors.lastname: Shen
authors.forename: C
authors.initials: C
authors.lastname: Wei
authors.forename: H-M
authors.initials: HM
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D016893:Carotid Stenosis / Q000000981:diagnostic imaging; D002533:Cerebral Angiography / Q000592:standards*; D002539:Cerebral Arterial Diseases / Q000000981:diagnostic imaging*; D002544:Cerebral Infarction / Q000000981:diagnostic imaging; D003287:Contrast Media / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000592:standards*; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging*; D002538:Intracranial Arteriovenous Malformations / Q000000981:diagnostic imaging; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D009072:Moyamoya Disease / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed / Q000592:standards*; D014057:Tomography, X-Ray Computed / Q000592:standards*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide