title: Volumetric evaluation of dual-energy perfusion CT by the presence of intrapulmonary clots using a 64-slice dual-source CT.
abstract: BACKGROUND
  Dual-energy perfusion CT (DEpCT) directly represents the iodine distribution in lung parenchyma and low perfusion areas caused by intrapulmonary clots (IPCs) are visualized as low attenuation areas.
  
  
  OBJECTIVE
  To evaluate if volumetric evaluation of DEpCT can be used as a predictor of right heart strain by the presence of IPCs.
  
  
  METHODS
  One hundred and ninety-six patients suspected of having acute pulmonary embolism (PE) underwent DEpCT using a 64-slice dual-source CT. DEpCT images were three-dimensionally reconstructed with four threshold ranges: 1-120 HU (V₁₂₀), 1-15 HU (V₁₅), 1-10 HU (V₁₀), and 1-5 HU (V₅). Each relative ratio per V₁₂₀ was expressed as the %V₁₅, %V₁₀, and %V₅. Volumetric data-sets were compared with D-dimer, pulmonary arterial (PA) pressure, right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio, PA diameter, and PA/aorta (PA/Ao) diameter ratio. The areas under the ROC curves (AUCs) were examined for their relationship to the presence of IPCs. This study was approved by the local ethics committee.
  
  
  RESULTS
  PA pressure and D-dimer were significantly higher in the patients who had IPCs. In the patients with IPCs, V₁₅, V₁₀, V₅, %V₁₅, %V₁₀, and %V₅ were also significantly higher than those without IPC (P ≤ 0.001). %V₅ had a better correlation with D-dimer (r = 0.30, P < 0.001) and RV/LV diameter ratio (r = 0.27, P < 0.001), and showed a higher AUC (0.73) than the other CT measurements.
  
  
  CONCLUSIONS
  The volumetric evaluation by DEpCT had a correlation with D-dimer and RV/LV diameter ratio, and the relative ratio of volumetric CT measurements with a lower attenuation threshold might be recommended for the analysis of acute PE.
authors.affiliation: Department of Radiology, Yamaguchi University Graduate School of Medicine, Yamaguchi.
authors.forename: Munemasa
authors.initials: M
authors.lastname: Okada
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Kunihiro
authors.forename: Sei
authors.initials: S
authors.lastname: Nakao
authors.forename: Noriyasu
authors.initials: N
authors.lastname: Morikage
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sano
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Suga
authors.forename: Naofumi
authors.initials: N
authors.lastname: Matsunaga
mesh_terms: D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D021621:Imaging, Three-Dimensional; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D012372:ROC Curve; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D; D007472:Iohexol
keywords: Acute pulmonary embolism; D-dimer; dual-energy perfusion CT; intrapulmonary clots; right ventricular to left ventricular diameter ratio