title: Dual energy CTA of the supraaortic arteries: technical improvements with a novel dual source CT system.
abstract: OBJECTIVE
  Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts.
  
  
  METHODS
  Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1=poor; 3=excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n=26) with a 5-point scale (1=poor; 5=excellent), CTA source data served as the reference.
  
  
  RESULTS
  Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations <10%, 27 segments (3.1%) lumen alterations >10% resulting in a total luminal reduction <50%, 17 segments (2%) lumen alterations of more than 10% resulting in a total luminal reduction >50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries.
  
  
  CONCLUSIONS
  Excellent bone suppression could be achieved, DE imaging with 100 and 140kV lead to improved image quality and vessel integrity in the shoulder region than previously reported. The ophthalmic artery still cannot be adequately visualized.
authors.affiliation: Department of Radiology, University Erlangen, Maximiliansplatz 1, Erlangen, Germany. Michael.lell@uk-erlangen.de
authors.forename: Michael M
authors.initials: MM
authors.lastname: Lell
authors.forename: Fabian
authors.initials: F
authors.lastname: Hinkmann
authors.forename: Emeka
authors.initials: E
authors.lastname: Nkenke
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmidt
authors.forename: Peter
authors.initials: P
authors.lastname: Seidensticker
authors.forename: Willi A
authors.initials: WA
authors.lastname: Kalender
authors.forename: Michael
authors.initials: M
authors.lastname: Uder
authors.forename: Stephan
authors.initials: S
authors.lastname: Achenbach
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D001027:Aortography / Q000379:methods*; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*