title: Dual-energy CT for the assessment of contrast material distribution in the pulmonary parenchyma.
abstract: OBJECTIVE
  The purpose of this study was to assess the feasibility and diagnostic value of dual-energy CT iodine mapping at pulmonary CT angiography.
  
  
  METHODS
  Ninety-three patients underwent CT angiography with the dual-energy technique on a dual-source CT scanner. Postprocessing was used to map iodine in the lung parenchyma on the basis of its spectral behavior, and image quality was assessed by two readers. Iodine distribution patterns were rated as homogeneous, patchy, or circumscribed defects. Conventional CT angiographic images reconstructed from the same data sets were reviewed for the presence and localization of pulmonary embolism, whether embolic occlusion was partial or complete, and the presence of changes in the lung parenchyma. Dual-energy perfusion findings were correlated with the CT angiographic and lung-window CT findings in per-patient and per-segment analyses.
  
  
  RESULTS
  Iodine distribution was homogeneous in 49 patients, of whom CT angiography showed no pulmonary embolism in 46 patients and nonocclusive pulmonary emboli in three patients. Images of 29 patients showed a patchy pattern; 24 of these patients had no pulmonary embolism, and five had nonocclusive pulmonary emboli with solely nonocclusive intravascular clots. Images of 15 patients showed segmental or subsegmental defects; four of these patients had evidence of pulmonary embolism, and 11 had occlusive pulmonary emboli with at least one occlusive clot in the pulmonary vasculature.
  
  
  CONCLUSIONS
  Dual-energy CT is reliable in the detection of defects in pulmonary parenchymal iodine distribution that correspond to embolic vessel occlusion.
authors: Department of Clinical Radiology, Klinikum Grosshadern, Ludwig Maximilians University, Marchioninistr. 15, D-81377 München, Germany. sven.thieme@med.lmu.de
authors: Sven F
authors: SF
authors: Thieme
authors: Thorsten R C
authors: TR
authors: Johnson
authors: Christopher
authors: C
authors: Lee
authors: Justin
authors: J
authors: McWilliams
authors: Christoph R
authors: CR
authors: Becker
authors: Maximilian F
authors: MF
authors: Reiser
authors: Konstantin
authors: K
authors: Nikolaou
mesh_terms: D000792:Angiography / Q000379:methods; D003287:Contrast Media / Q000493:pharmacokinetics; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007455:Iodine / Q000493:pharmacokinetics*; D008168:Lung / Q000000981:diagnostic imaging* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007455:Iodine