title: Stability of cerebral blood flow measures using a split-dose technique with (99m)Tc-exametazime SPECT.
abstract: OBJECTIVE
  To determine whether there is stability of cerebral blood flow (CBF) measures using single photon emission computed tomography (SPECT) imaging in healthy controls in a test-retest split-dose paradigm. Such a paradigm is frequently used in the clinical and research setting to assess various brain states.
  
  
  METHODS
  Five healthy volunteers underwent two brain SPECT scans after the administration of low and high doses of (99m)Tc-exametazime. The first SPECT scan was acquired approximately 30 min after the intravenous injection of approximately 259 MBq of (99m)Tc-exametazime. The second SPECT scan was acquired approximately 30 min after the intravenous injection of 925 MBq of (99m)Tc-exametazime. Both scans were acquired over approximately 30-45 min and the images were reconstructed using filtered backprojection, a low-pass filter and Chang's first-order attenuation correction. Values were obtained for regions of interest (ROIs) in major brain structures and normalized to whole brain activity. Counts on the second SPECT scan were also decay corrected for activity from the first scan.
  
  
  RESULTS
  The results demonstrated a strong correlation between the low-dose and high-dose scans for all regions (r = 0.86, P<0.0001). Symmetries were preserved with a strong correlation between low-dose and high-dose scans (r = 0.70, P<0.0001). Finally, most regions demonstrated less than a 5% difference between the low-dose and high-dose scans.
  
  
  CONCLUSIONS
  The results of this study demonstrate that the split-dose technique can be employed for clinical and research applications to measure CBF in different brain states using two SPECT scans on the same day.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA. newberg@rad.upenn.edu
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Newberg
authors.forename: Janet
authors.initials: J
authors.lastname: Saffer
authors.forename: John
authors.initials: J
authors.lastname: Farrar
authors.forename: Michael
authors.initials: M
authors.lastname: Pourdehnad
authors.forename: Abass
authors.initials: A
authors.lastname: Alavi
mesh_terms: D000328:Adult; D001776:Blood Circulation Time; D001921:Brain / Q000473:pathology; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D019690:Technetium Tc 99m Exametazime; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D019690:Technetium Tc 99m Exametazime