title: A pilot trial on pulmonary emphysema quantification and perfusion mapping in a single-step using contrast-enhanced dual-energy computed tomography.
abstract: OBJECTIVE
  To know whether contrast-enhanced dual-energy computed tomography angiography (DECTA) can be used for simultaneous assessment of emphysema quantification and regional perfusion evaluation.
  
  
  METHODS
  We assessed 27 patients who had pulmonary emphysema and no pulmonary embolism on visual assessment of CT images, among 584 consecutive patients who underwent DECTA for the evaluation of pulmonary embolism. Virtual noncontrast (VNC) images were generated by modifying the "Liver VNC" application in a dedicated workstation. Using in-house software, the low-attenuation area below 950HU (LAA950), the 15th percentile attenuation (15pctlVNC) and the mean lung attenuation (MeanVNC) were calculated. The "Lung PBV" application was used to assess perfusion, and the low-iodine area below 5HU (LIA5), the 15th percentile iodine (15pctlIodine), and the mean iodine value (MeanIodine) were calculated from iodine map images. The correlation between VNC parameters and pulmonary function test data (available in 22 patients) and the correlation between VNC and iodine map parameters (all included 27 patients) were assessed. Color-coded map of VNC image were compared with iodine map images for the evaluation of regional heterogeneity.
  
  
  RESULTS
  We observed moderate correlations between LAA950 and predicted %FEV1 (rs = -0.47, P < 0.05), and 15pctlVNC and predicted %FEV1 (rs = 0.56, P < 0.05). We also observed significant correlations between LAA950 and LIA5 (rs = 0.48, P < 0.05), 15pctlVNC and 15pctlIodine (rs = 0.59, P = 0.001), and MeanVNC and MeanIodine (rs = 0.47, P < 0.05). On visual assessment of the regional heterogeneity, 82% of patients showed relatively good correlation between the areas of perfusion impairment on iodine map images and areas of emphysema on color-coded VNC images.
  
  
  CONCLUSIONS
  We observed moderate correlations between quantitative parameters on VNC images and pulmonary function test data, and also observed moderate correlations between the severity of parenchymal destruction, as determined from VNC images, and perfusion status, as determined from iodine maps. Therefore, the contrast-enhanced DECTA can be used for the emphysema quantification and regional perfusion evaluation by using the VNC images and iodine map, simultaneously.
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Choong Wook
authors.initials: CW
authors.lastname: Lee
authors.forename: Joon Beom
authors.initials: JB
authors.lastname: Seo
authors.forename: Youngjoo
authors.initials: Y
authors.lastname: Lee
authors.forename: Eun Jin
authors.initials: EJ
authors.lastname: Chae
authors.forename: Namkug
authors.initials: N
authors.lastname: Kim
authors.forename: Hyun Joo
authors.initials: HJ
authors.lastname: Lee
authors.forename: Hye Jeon
authors.initials: HJ
authors.lastname: Hwang
authors.forename: Chae-Hun
authors.initials: CH
authors.lastname: Lim
mesh_terms: D000368:Aged; D000792:Angiography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D006801:Humans; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008297:Male; D010865:Pilot Projects; D011651:Pulmonary Artery / Q000000981:diagnostic imaging*; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement / 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