title: Influence of spatially heterogeneous background activity on "hot object" quantitation in brain emission computed tomography.
abstract: OBJECTIVE
  Our goal was to evaluate the influence of spatially heterogeneous background activity on "hot object" quantitation in brain emission CT.
  
  
  METHODS
  We studied the effects of spatially heterogeneous background activity on hot object quantitative recovery in simulations of both spheres and realistic brain distributions (utilizing human MRI data).
  
  
  RESULTS
  Significant underestimation of object activity concentration was seen for both cortical and subcortical hot objects, with increasing underestimation for increasing hot object/surrounding gray matter contrast. Significant "spill-in" of counts from surrounding activity was present.
  
  
  CONCLUSIONS
  Hot objects are significantly influenced by both "spill-out" and "spill-in." Qualitative and quantitative analyses of such objects must explicitly consider both spill-out and spill-in; this implies a correction scheme that goes beyond simple division of the observed value by a conventional recovery coefficient.
authors.affiliation: Department of Radiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Links
authors.forename: J K
authors.initials: JK
authors.lastname: Zubieta
authors.forename: C C
authors.initials: CC
authors.lastname: Meltzer
authors.forename: M J
authors.initials: MJ
authors.lastname: Stumpf
authors.forename: J J
authors.initials: JJ
authors.lastname: Frost
mesh_terms: D001921:Brain / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D003198:Computer Simulation; D006801:Humans; D008279:Magnetic Resonance Imaging; D014055:Tomography, Emission-Computed