title: Enhanced visualization of lung vessels for diagnosis of pulmonary embolism using dual energy CT angiography.
abstract: OBJECTIVE
  To evaluate a software algorithm highlighting vascular iodine distribution in dual energy (DE) computed tomography angiography (CTA) for the diagnosis of pulmonary embolism (PE).
  
  
  METHODS
  Pulmonary DE-CTA of 16 patients with PE and 16 patients without PE were analyzed using a software algorithm highlighting vascular iodine distribution. The algorithm color-codes lung vessels depending on their local iodine distribution on a 2-color scale. The diagnostic performance of the software for the detection of PE was assessed on patient and segmental basis by consensus reading of 2 blinded radiologists. The reading of the standard CTA data by an independent third radiologist and clinical follow-up served as the standard of reference for the diagnosis of PE.
  
  
  RESULTS
  Of 576 analyzed segments CTA revealed 88 diseased lung segments with 1 or more emboli. The software correctly highlighted 62 segments as positive. Twenty-six segments with PE were not highlighted. Seventy-five segments were highlighted false positive. All 16 patients with PE were identified as positive, but 1 of these patients had no true positive finding on a segmental basis and was therefore classified as false negative. Twenty-three segments in 8 patients without PE were highlighted as positive. Sensitivity, specificity, positive predictive value, and negative predictive value of the software algorithm were 93.8%, 50%, 65.2%, 88.9% per patient and 70.5%, 84.6%, 45.3%, 94.1% per segment, respectively.
  
  
  CONCLUSIONS
  Additional review of the DE-CTA with a dedicated software algorithm highlighting the vascular iodine distribution has a high negative predictive value important for exclusion of segmental PE.
authors.affiliation: Department of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany. radko.krissak@umm.de
authors.forename: Radko
authors.initials: R
authors.lastname: Krissak
authors.forename: Thomas
authors.initials: T
authors.lastname: Henzler
authors.forename: Miriam
authors.initials: M
authors.lastname: Reichert
authors.forename: Bernhard
authors.initials: B
authors.lastname: Krauss
authors.forename: Stefan O
authors.initials: SO
authors.lastname: Schoenberg
authors.forename: Christian
authors.initials: C
authors.lastname: Fink
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; 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; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*