title: The effect of the section thickness used for 2- and 3-dimensional quantification of dual-energy perfusion computed tomography.
abstract: OBJECTIVE
  To retrospectively investigate the effect of the section thickness used for quantifying dual-energy perfusion computed tomography (DEpCT) during 2- and 3-dimensional evaluation.
  
  
  METHODS
  Sixty-six patients (22 males and 44 females; mean age, 59.3 years) suspected of having an acute pulmonary embolism underwent DEpCT, and 15patients were diagnosed to have intrapulmonary clots (IPCs). Two-dimensional DEpCT images were reconstructed into various section thicknesses from 1 to 10 mm at the main pulmonary artery, and the ratios of the low attenuation area (LAA) ranging from 1 to 5 HU (%LAA5) and 10 HU (%LAA10) on DEpCT were compared with the relative areas of the lung with attenuation coefficients lower than -950 HU (RA-950) using the lung CT images of each section thickness. Three-dimensional values of DEpCT were reconstructed with 3 different section thicknesses (1, 3, and 10 mm) and were analyzed for the presence of IPC burden using the factors suggesting IPC burden, including the right/left ventricular diameter ratio and CT obstruction index.
  
  
  RESULTS
  The mean attenuation and image noise were decreased as the section thickness increased. In the 2-dimensional analysis, the %LAA5 and %LAA10 had the smallest value at 1-mm section, and DEpCT with thinner sections had a correlation with the RA-950 (r = 0.22-0.23, P < 0.05). The 3-dimensional values of DEpCT reconstructed with a 1- or 3-mm section thickness had a correlation with the CT obstruction index (r = 0.52-0.59, P < 0.05) and right/left ventricular diameter ratio (r = 0.60-0.68, P < 0.01).
  
  
  CONCLUSIONS
  The thinner images should be used for 2- and 3-dimensional quantification of DEpCT.
authors.affiliation: From the *Department of Radiology, Yamaguchi University Graduate School of Medicine; †Department of Radiology, Yamaguchi Grand Medical Center; ‡Department of Radiology, Yamaguchi University Hospital; and §Computer-aided Diagnosis and Biomedical Imaging Research Biomedical Engineering, Applied Medical Engineering Science Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Nomura
authors.forename: Munemasa
authors.initials: M
authors.lastname: Okada
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Teppei
authors.initials: T
authors.lastname: Yonezawa
authors.forename: Shohei
authors.initials: S
authors.lastname: Kudomi
authors.forename: Shoji
authors.initials: S
authors.lastname: Kido
authors.forename: Naofumi
authors.initials: N
authors.lastname: Matsunaga
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008171:Lung Diseases / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D013927:Thrombosis / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult