title: Two-phase CT pulmonary angiography for detection of hilar pulmonary thromboembolism.
abstract: OBJECTIVE
  To assess the usefulness of two-phase CT pulmonary angiography (CTPA) for patients with suspected pulmonary thromboembolism (PE).
  
  
  METHODS
  Forty-four patients (in 48 studies) underwent two-phase CTPA. Fifteen sec after the injection of contrast material, an entire thorax scan was performed, and in the second phase the hilar territory was rescanned after a 15-sec delay. In the first phase, 25 subjects were scanned cranio-caudally (group A), and 23 caudal-cranially (group B). The mean attenuation values of the main pulmonary artery (MPA) and the ascending aorta (Ao) were measured. Perivenous artifacts in the right pulmonary artery (RPA) were also graded using a 4-point scale.
  
  
  RESULTS
  The mean attenuation values in the MPA and Ao were higher in the first phase than in the second phase. The perivenous artifact scores at the first phase in groups A and B were severe in 12 and 15, moderate in 8 and 7, minimal in 4 and 1, and none in 1 and 0. The scores at the second phase were none in all cases.
  
  
  CONCLUSIONS
  Two-phase CTPA produced good opacification of the RPA without major perivenous artifact and proved useful in the detection of PE in these areas.
authors.affiliation: Division of Radiation Oncology, Department of Molecular Genetics, Course for Molecular and Cellular Medicine, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Hori
authors.forename: Norihiko
authors.initials: N
authors.lastname: Yoshimura
authors.forename: Toshirou
authors.initials: T
authors.lastname: Ozaki
authors.forename: Toru
authors.initials: T
authors.lastname: Takano
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ooi
authors.forename: Motomasa
authors.initials: M
authors.lastname: Kimura
authors.forename: Keisuke
authors.initials: K
authors.lastname: Sasai
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*