title: Effects of scatter substraction on detection and quantitation in hepatic SPECT.
abstract: The purpose of this investigation was to examine the effects of subtractive scatter compensation methods on lesion detection and quantitation.
  
  
  METHODS
  Receiver operating characteristic (ROC) methodology was used to measure human observer detection accuracy for tumors in the liver using synthetic images. Furthermore, ROC results were compared with mathematical models for detection and activity quantitation to examine (a) the potential for predicting human performance and (b) the relationship between the detection and quantitation tasks. Images with both low and high amounts of scatter were compared with the ideal case of images of primary photons only (i.e., perfect scatter rejection) and with images corrected by subtracting a scatter image estimated by the dual photopeak window method.
  
  
  RESULTS
  With low contrast tumors in a low count background, the results showed that scatter subtraction improved quantitation but did not produce statistically significant increases in detection accuracy. However, primary images did produce some statistically significant improvements in detection accuracy when compared with uncorrected images, particularly for high levels of scatter.
  
  
  CONCLUSIONS
  Although scatter subtraction methods may provide improved activity quantitation, they may not significantly improve detection for liver SPECT. The results imply that significant improvement in detection accuracy for the conditions tested may depend on the development of gamma cameras with better scatter rejection.
authors.affiliation: Department of Nuclear Medicine, University of Massachusetts Medical School, Worcester, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: de Vries
authors.forename: M A
authors.initials: MA
authors.lastname: King
authors.forename: E J
authors.initials: EJ
authors.lastname: Soares
authors.forename: B M
authors.initials: BM
authors.lastname: Tsui
authors.forename: C E
authors.initials: CE
authors.lastname: Metz
mesh_terms: D000704:Analysis of Variance; D016001:Confidence Intervals; D004526:Efficiency; D015902:Gamma Cameras; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D008962:Models, Theoretical; D015588:Observer Variation; D012372:ROC Curve; D012542:Scattering, Radiation; D012984:Software; D013382:Subtraction Technique; D015899:Tomography, Emission-Computed, Single-Photon