title: Quality Improvement of Dual-Energy Lung Perfusion Image by Reduction of Low-Energy X-Ray Spectrum: An Evaluation on Clinical Images.
abstract: BACKGROUND
  The effects of the reduction of low-energy X-ray spectrum on lung perfusion images created by dual-energy CT have not been well evaluated. The aim of this study is to investigate the reliability of lung perfusion blood volume (PBV) images created by dual-energy CT (DECT) equipped with or without a tin filter, focusing on its accuracy adjacent to high-attenuation areas.
  
  
  METHODS
  Among 176 patients who underwent DECT for suspicion of pulmonary embolism, 38 patients (mean age, 64; range, 16 to 83 years) without apparent evidence of pulmonary embolism were evaluated in this study. They underwent DECT at 100/140 kVp with a tin filter on 140 kVp tube (Group A; n=18) or at 80/140 kVp without the filter (Group B; n=20). On the lung PBV images, the degrees of artifacts - pulmonary enhancement defect (PED) and pseudo-enhancement in the trachea (PTE) adjacent to the vena cava were evaluated using a four-point scale (0=minimal to 3=prominent).
  
  
  RESULTS
  The mean degrees of artifact in Group A were significantly lower than those in Group B (0.8vs.1.9; P<0.0001 for PED, respectively, and 1.1vs.2.2; P<0.0001 for TPE, respectively). The mean CTDIvols were 4.90±1.14 and 12.98±3.15 mGy (P<0.0001) for Group A and Group B, respectively.
  
  
  CONCLUSIONS
  The quality and accuracy of dual-energy lung perfusion image will be improved by using the tin filter technique.
authors.affiliation: Department of Radiology, Nagoya City University, Nagoya, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kawai
authors.affiliation: Department of Radiology, Nagoya City University, Nagoya, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ozawa
authors.affiliation: Department of Radiology, Nagoya City University, Nagoya, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Ogawa
authors.affiliation: Central Division of Radiology, Nagoya City University Hospital, Nagoya, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ohashi
authors.affiliation: Department of Radiology, Nagoya City University, Nagoya, Japan.
authors.forename: Kazushi
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Department of Radiology, Nagoya City University, Nagoya, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Shibamoto
keywords: Perfusion Imaging; Radiography, Dual-Energy Scanned Projection; Tomography Scanners, X-Ray Computed