title: Usefulness of dual-energy CT scanning at 80 kVp for identifying hilar and mediastinal structures: evaluation of contrast enhancement of the pulmonary vessels and lymph nodes.
abstract: OBJECTIVE
  We examined whether the 80-kVp CT images scanned at 100 s after contrast material injection using a dual-source scanner could be substituted for the conventional 120-kVp images obtained at an earlier timing of 30 s.
  
  
  METHODS
  Seventy-eight patients with suspected lung cancer were examined with a 120-kVp mode at 30 s after contrast material injection (early phase) and a dual-energy (80 and 140 kVp) mode at 100 s (late phase). CT numbers of the pulmonary artery (PA), pulmonary vein (PV) and hilar zone lymph nodes (LN) were measured. Contrast between the PA/PV and LN was visually evaluated using a 5-point scale. Beam-hardening artifacts were also visually assessed.
  
  
  RESULTS
  The mean difference in attenuation between the PA/PV and LN on the early phase 120-kVp, late phase 80-kVp and late phase weighted-average 120-kVp images was 171.3/160.8, 100.5/106.8 and 67.5/67.5, respectively (p < 0.001). The mean contrast score of these three images for the hilar/mediastinal LN was 4.5/4.7, 3.4/3.8 and 2.9/3.3, respectively (all p < 0.05). The mean artifact score of the three images was 2.6, 4.0 and 4.0, respectively; on most early phase images, the beam-hardening artifacts influenced the diagnosis (p < 0.001).
  
  
  CONCLUSIONS
  The late phase 80-kVp images showing few artifacts may be an alternative to early phase 120-kVp images.
authors.affiliation: Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8601, Japan. ayanokushita@hotmail.com
authors.forename: Ayano
authors.initials: A
authors.lastname: Imafuji
authors.forename: Masaki
authors.initials: M
authors.lastname: Hara
authors.forename: Shigeru
authors.initials: S
authors.lastname: Sasaki
authors.forename: Toshinao
authors.initials: T
authors.lastname: Arakawa
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ozawa
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shibamoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008198:Lymph Nodes / Q000000981:diagnostic imaging*; D008297:Male; D008482:Mediastinum / Q000000981:diagnostic imaging; D008875:Middle Aged; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011667:Pulmonary Veins / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol