title: Normal patterns on 99mTc-ECD brain SPECT scans in adults.
abstract: Normative ethyl cysteinate dimer (ECD) SPECT data must be available to successfully apply ECD SPECT to clinical studies. The purpose of this study was to determine ECD SPECT scan patterns of healthy adults.
  
  
  METHODS
  Forty-eight healthy volunteers (22 men, 26 women; age range, 22-95 y; mean age, 47.6 +/- 19.2 y) underwent high-resolution ECD SPECT. For visual analysis of regional brain ECD uptake, we used a scale of +3 to -3, in which +3 and -3 indicated highest ECD uptake and deficit, respectively. For quantitative analysis, we measured the region-to-cerebellum ratio (R/CE) and the region-to-cerebral cortex ratio (R/CO) for 17 regions (13 cortical, 3 subcortical, and 1 cerebellar).
  
  
  RESULTS
  On visual analysis, no subject had a score of -3. All subjects had a score of -2 for the hippocampus and a score of +3 for the medial occipital cortex, except for 2 subjects who had a score of +3 for the striatum and thalamus. A frontal eye field and posterior parieto-occipital junction were identified in 60% of subjects with a score of +1 and 79% of subjects with a score of +2. On quantitative analysis, a significant regional variation (ANOVA, P < 0.0001) was seen in R/CE, ranging from 0.709 (hippocampus) to 1.26 (medial occipital cortex). However, regional right-to-left differences and intersubject variability of R/CE were small (asymmetry index, 3.6% +/- 0.8%; coefficient variation, 6.6% +/- 0.7%). R/CE declined significantly with age in 6 regions, including the anterior and posterior cingulate cortex, superior prefrontal and parietal cortex, striatum, and hippocampus (1.0%-2.0% per decade, P < 0.05), whereas R/CO in the cerebellum increased significantly with age (1.0% per decade, P < 0.05).
  
  
  CONCLUSIONS
  Although regional ECD brain perfusion patterns vary significantly, including variability caused by the age-related effect, intersubject variability is small. Recognition of these normal patterns is important for clinical interpretation of ECD SPECT studies.
authors.affiliation: Department of Medical Imaging, University of Toronto, Ontario, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Tanaka
authors.forename: D
authors.initials: D
authors.lastname: Vines
authors.forename: T
authors.initials: T
authors.lastname: Tsuchida
authors.forename: M
authors.initials: M
authors.lastname: Freedman
authors.forename: M
authors.initials: M
authors.lastname: Ichise
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D001933:Brain Stem / Q000000981:diagnostic imaging; D002531:Cerebellum / Q000000981:diagnostic imaging; D003545:Cysteine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005260:Female; D006624:Hippocampus / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D012016:Reference Values; D012044:Regression Analysis; D013702:Temporal Lobe / Q000000981:diagnostic imaging; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C059659:technetium Tc 99m bicisate; D003545:Cysteine