title: Correlation between CT attenuation value and iodine concentration in vitro: discrepancy between gemstone spectral imaging on single-source dual-energy CT and traditional polychromatic X-ray imaging.
abstract: BACKGROUND
  To assess the relation between CT attenuation value and iodine concentration in vitro, using gemstone spectral imaging (GSI) with single-source dual-energy CT and traditional polychromatic X-ray imaging (TPXI), respectively.
  
  
  METHODS
  A polypropylene phantom with eight test tubes in which iodine concentrations of solution were 0.4, 0.7, 2, 5, 10, 20, 30 and 50 mg/mL underwent GSI and traditional polychromatic X-ray scans (80, 100, 120 and 140 kV(p)), using single-source dual-energy spectral CT (Discovery CT750HD; GE Healthcare Technologies, Milwaukee, WI, USA) at the same tube speed of 0.8 s/rotation. All spectral imaging data were analysed with GSI viewer to obtain monochromatic images (50-140 keV, interval of 10 keV). Computed tomography attenuation values of iodine solution were measured with the same size of regions of interest and at the exact same level for both monochromatic and polychromatic images. The relation between CT attenuation value and iodine concentration was examined.
  
  
  RESULTS
  A linear correlation was found between CT attenuation value and iodine concentration for both monochromatic and polychromatic images. Moreover, the fitting coefficients for CT attenuation values and iodine concentrations were closer to one with GSI (r(2) = 0.99824-0.99996) than that with TPXI (r(2) = 0.99640-0.99736).
  
  
  CONCLUSIONS
  Owing to the better correlation coefficients between CT attenuation value and iodine concentration, GSI may be a preferred method for quantitative measurement compared with TPXI.
authors.affiliation: Department of Radiology, the First Affiliated Hospital of AnHui Medical University, Hefei, Japan.
authors.forename: Le
authors.initials: L
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Xing-Wang
authors.initials: XW
authors.lastname: Wu
authors.forename: Jie
authors.initials: J
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Wan-Qin
authors.initials: WQ
authors.lastname: Wang
authors.forename: Xiao-Hong
authors.initials: XH
authors.lastname: Zhu
authors.forename: Yong-Qiang
authors.initials: YQ
authors.lastname: Yu
authors.forename: Xiao-Hu
authors.initials: XH
authors.lastname: Li
authors.forename: Shuai
authors.initials: S
authors.lastname: Zhang
authors.forename: Yun
authors.initials: Y
authors.lastname: Shen
mesh_terms: D000465:Algorithms; D003287:Contrast Media / Q000032:analysis*; D006801:Humans; D007455:Iodine / Q000032:analysis*; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*; D014962:X-Ray Film
chemical_list: D003287:Contrast Media; D007455:Iodine