title: Dual-energy CT based vascular iodine analysis improves sensitivity for peripheral pulmonary artery thrombus detection: an experimental study in canines.
abstract: OBJECTIVE
  To evaluate the performance of dual-energy CT (DECT) based vascular iodine analysis for the detection of acute peripheral pulmonary thrombus (PE) in a canine model with histopathological findings as the reference standard.
  
  
  METHODS
  The study protocol was approved by our institutional animal committee. Thrombi (n = 12) or saline (n = 4) were intravenously injected via right femoral vein in sixteen dogs, respectively. CT pulmonary angiography (CTPA) in DECT mode was performed and conventional CTPA images and DECT based vascular iodine studies using Lung Vessels application were reconstructed. Two radiologists visually evaluated the number and location of PEs using conventional CTPA and DECT series on a per-animal and a per-clot basis. Detailed histopathological examination of lung specimens and catheter angiography served as reference standard. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of DECT and CTPA were calculated on a segmental and subsegmental or more distal pulmonary artery basis. Weighted κ values were computed to evaluate inter-modality and inter-reader agreement.
  
  
  RESULTS
  Thirteen dogs were enrolled for final image analysis (experimental group = 9, control group = 4). Histopathological results revealed 237 emboli in 45 lung lobes in 9 experimental dogs, 11 emboli in segmental pulmonary arteries, 49 in subsegmental pulmonary arteries, 177 in fifth-order or more distal pulmonary arteries. Overall sensitivity, specificity, accuracy, PPV, and NPV for CTPA plus DECT were 93.1%, 76.9%, 87.8%, 89.4%, and 84.2% for the detection of pulmonary emboli. With CTPA versus DECT, sensitivities, specificities, accuracies, PPVs, and NPVs are all 100% for the detection of pulmonary emboli on a segmental pulmonary artery basis, 88.9%, 100%, 96.0%, 100%, and 94.1% for CTPA and 90.4%, 93.0%, 92.0%, 88.7%, and 94.1% for DECT on a subsegmental pulmonary artery basis; 23.8%, 96.4%, 50.4%, 93.5%, and 36.7% for CTPA and 95.9%, 75.5%, 88.2%, 86.5%, and 91.9% on a sub-subsegmental and more distal pulmonary artery basis, respectively. Good inter-modality (κ = 0.65, P<0.001) and inter-reader (κ = 0.70, P<0.001) agreement were observed.
  
  
  CONCLUSIONS
  With histopathological findings as the reference standard, DECT based vascular iodine analysis improves the sensitivity for detecting peripheral PE compared with CTPA, albeit at the price of decreased specificity and PPV.
authors.affiliation: Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu 210002, China.
authors.forename: Chun Xiang
authors.initials: CX
authors.lastname: Tang
authors.forename: Long Jiang
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Zong Hong
authors.initials: ZH
authors.lastname: Han
authors.forename: Chang Sheng
authors.initials: CS
authors.lastname: Zhou
authors.forename: Aleksander W
authors.initials: AW
authors.lastname: Krazinski
authors.forename: Justin R
authors.initials: JR
authors.lastname: Silverman
authors.forename: U Joseph
authors.initials: UJ
authors.lastname: Schoepf
authors.forename: Guang Ming
authors.initials: GM
authors.lastname: Lu
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage; D004285:Dogs; D007275:Injections, Intravenous; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / 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*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide
keywords: Accuracy; Dual energy; Experimental model; Inter-rater reliability; Iodine-selective imaging; Pulmonary embolism