title: Improved reproducibility of simple quantitative indices from ⁹⁹mTc-GSA liver functional imaging.
abstract: OBJECTIVE
  We evaluated intra- and interoperator reproducibilities in calculating the conventional indices HH15 and LHL15 from (99m)Tc-diethylenetriamine pentaacetic acid galactosyl human serum albumin ((99m)Tc-GSA) scintigraphy, and proposed new, simple methods for the calculation of quantitative indices.
  
  
  METHODS
  The results of (99m)Tc-GSA scintigraphy in 33 patients were retrospectively analyzed. Heart and liver ROIs were drawn manually to cover cardiac blood pool and entire liver, respectively, and HH15 and LHL15 were calculated. In addition, square regions of interest (ROIs) of fixed sizes were placed at the highest activity in blood pool and the liver. Using the square heart ROI, sHH15, an equivalent of HH15, was computed. Fractional liver uptake at 15 min (FLU15) was calculated using the square heart and liver ROIs. Intra- and interoperator reproducibilities, as well as correlation with Indocyanine green retention rate at 15 min (ICG R15), were assessed for these four indices by linear regression analysis.
  
  
  RESULTS
  Substantial intra- and interoperator variabilities were found for HH15 and LHL15. The correlation coefficients for intra- and interoperator comparisons were 0.884 and 0.869 for HH15, respectively, and 0.919 and 0.917 for LHL15, respectively. The use of square ROIs instead of hand-drawn ROIs improved reproducibility. The correlation coefficients for intra- and interoperator comparisons were 0.988 and 0.973 for sHH15, respectively, and 0.989 and 0.975 for FLU15, respectively. Correlation with ICG R15 was better for sHH15 (r = 0.619) and FLU15 (r = -0.656) than for HH15 (r = 0.439) and LHL15 (r = -0.490).
  
  
  CONCLUSIONS
  HH15 and LHL15 showed substantial intra- and interoperator variabilities, and the use of square ROIs are indicated to provide better reproducibility.
authors.affiliation: Department of Diagnostic Radiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0374, Japan. r04ogasawa@med.kitasato-u.ac.jp
authors.forename: Gou
authors.initials: G
authors.lastname: Ogasawara
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Inoue
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Itoh
authors.forename: Satomi
authors.initials: S
authors.lastname: Tagami
authors.forename: Keiji
authors.initials: K
authors.lastname: Matsunaga
authors.forename: Kenji
authors.initials: K
authors.lastname: Miki
mesh_terms: D000465:Algorithms; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000000981:diagnostic imaging* / Q000502:physiology*; D008111:Liver Function Tests / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013668:Technetium Tc 99m Aggregated Albumin; D016284:Technetium Tc 99m Pentetate
chemical_list: D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin; C070561:technetium Tc 99m DTPA-galactosyl-human serum albumin; D016284:Technetium Tc 99m Pentetate