title: Single-acquisition dual-energy multidetector computed tomography: analysis of vascular enhancement and postprocessing techniques for evaluating the thoracic aorta.
abstract: OBJECTIVE
  The objectives of this study were (1) to evaluate the potential of low-peak kilovoltage (kVp) images acquired with dual-energy computed tomography (DECT) to improve aortic attenuation and reduce contrast agent utilization and (2) to evaluate the feasibility of material-specific DECT imaging for evaluating aortic disease.
  
  
  METHODS
  Aortic imaging characteristics of 2 groups of patients examined with DECT were compared. In the first group, CT angiography (CTA) was performed in patients with known or suspected aortic disease (CTA group: n = 20, 100-150 mL of contrast at 4.5 mL/s). In the second group, reduced contrast volume CTA was performed in patients with "routine" indications (RC group: n = 20, 50-60 mL at 3 mL/s followed by a saline chaser). In both groups, aortic attenuation and SD were measured at 80 and 140 kVp, and the image quality was analyzed using a 5-point scale. The use of DECT postprocessing techniques for assessing aortic pathology was also evaluated.
  
  
  RESULTS
  For all patients, the aortic attenuation was significantly higher at 80 kVp than at 140 kVp (P < 0.001). Image noise measured quantitatively was higher at 80 kVp (P < 0.001) but did not affect the perceived image quality (P = 0.3). Using low-peak kilovoltage allowed aortic CTA to be performed with a markedly reduced contrast volume and flow rate, with image quality similar to standard CTA (P = 0.2). In a series of cases with proved aortic disease, comparison of true precontrast and subtraction "virtual noncontrast" images showed the potential to eliminate aortic precontrast imaging, reducing radiation exposure.
  
  
  CONCLUSIONS
  Single-acquisition DECT combines (1) the benefits of low-kVp vascular imaging (increased iodine conspicuity coupled with a contrast volume/rate reduction) and (2) the use of material-specific imaging techniques to uniquely characterize the aortic pathology.
authors.affiliation: Division of Thoracic Imaging, Department of Radiology, New York University Langone Medical Center, New York, NY, USA. mgodoy@mdanderson.org
authors.forename: Myrna C B
authors.initials: MC
authors.lastname: Godoy
authors.forename: David P
authors.initials: DP
authors.lastname: Naidich
authors.forename: Edson
authors.initials: E
authors.lastname: Marchiori
authors.forename: Christianne
authors.initials: C
authors.lastname: Leidecker
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmidt
authors.forename: Bernard
authors.initials: B
authors.lastname: Assadourian
authors.forename: Ioannis
authors.initials: I
authors.lastname: Vlahos
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001018:Aortic Diseases / Q000000981:diagnostic imaging*; D001027:Aortography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D017023:Coronary Angiography / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007472:Iohexol / 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; D007472:Iohexol; C038192:iopromide