title: Optimization of keV-settings in abdominal and lower extremity dual-source dual-energy CT angiography determined with virtual monoenergetic imaging.
abstract: OBJECTIVE
  To compare objective image quality indices in dual-energy CT angiography (DE-CTA) studies of the abdomen and lower extremity using conventional polyenergetic images (PEIs) and virtual monoenergetic images (MEIs) at different kiloelectron volt (keV) levels.
  
  
  METHODS
  We retrospectively evaluated 68 dual-source DE-CTA studies. 50 patients (42 men, 71 ± 10 years) underwent abdominal DE-CTA. 18 patients (13 men, 67 ± 10 years) underwent lower extremity DE-CTA. MEIs from 40 to 120 keV were reconstructed. Signal intensity, noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were assessed in infrarenal aorta, superior mesenteric, external iliac, femoral, popliteal, and lower leg arteries. Comparisons between MEIs and PEIs were performed with Dunnett's test.
  
  
  RESULTS
  222 arteries were evaluated. In abdominal arteries 70 keV MEIs showed statistically equal signal intensity, noise and CNR levels (+13%; +31%, -14% on average; all p>0.05) compared to PEIs; SNR was equal or slightly impaired (-7% on average; p<0.001-1.00). In lower extremity arteries 60 keV MEIs resulted in significantly higher signal intensity and CNR (+54%; +54% on average; all p<0.05) compared to PEIs at equal noise levels (+18% on average; all p>0.05) and equal or higher SNR (+49% on average; p<0.01-0.35).
  
  
  CONCLUSIONS
  Low-keV MEIs lead to equal or higher signal intensity and CNR compared to PEIs. In lower extremity DE-CTA, additional reconstruction of low-keV MEIs at 60 keV might increase diagnostic confidence.
authors.affiliation: Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany. sonja_sudarski@gmx.de
authors.forename: Sonja
authors.initials: S
authors.lastname: Sudarski
authors.forename: Paul
authors.initials: P
authors.lastname: Apfaltrer
authors.forename: John W
authors.initials: JW
authors.lastname: Nance
authors.forename: David
authors.initials: D
authors.lastname: Schneider
authors.forename: Mathias
authors.initials: M
authors.lastname: Meyer
authors.forename: Stefan O
authors.initials: SO
authors.lastname: Schoenberg
authors.forename: Christian
authors.initials: C
authors.lastname: Fink
authors.forename: Thomas
authors.initials: T
authors.lastname: Henzler
mesh_terms: D000005:Abdomen / Q000098:blood supply; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000792:Angiography / Q000379:methods*; D001027:Aortography / Q000379:methods*; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000098:blood supply / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods*; D011860:Radiography, Abdominal / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: CT angiography; Dual-energy CT; Dual-source CT; Image quality; Monoenergetic