title: Absolute SPECT/CT quantification of cerebral uptake of 99mTc-HMPAO for patients with neurocognitive disorders.
abstract: It was reported from planar imaging studies that the cerebral uptake of injected 99mTc-HMPAO activity is about 4-7% in humans. Recent work has shown that modern SPECT/CT devices are able to quantify the tissue concentration of radioactivity in vivo in absolute units (Bq/ml), while avoiding the limitations of planar techniques. The aims of this study were (a) to determine the cerebral uptake of 99mTc-HMPAO in absolute units in SPECT/CT, (b) to investigate potential differences in absolute tracer uptake for patients suspected of dementia.
  
  
  METHODS
  We performed 99mTc-HMPAO SPECT/CT in 65 patients with suspected dementia. 99mTc-HMPAO uptake was determined using a previously published quantitative SPECT/CT protocol. The absolute HMPAO uptake and the results of a regionalized analysis were compared for MMSE and NINCDS-ADRDA based patient groups.
  
  
  RESULTS
  The mean absolute uptake of 99mTc-HMPAO for our patient population was 4.3 ± 0.8% of the injected dose. The uptake, as well as the regionalized analysis yielded significantly different results for low (≤23) and high (>23) MMSE groups and also for some of the NINCDS-ADRDA groups.
  
  
  CONCLUSIONS
  Our results show that the absolute cerebral uptake of 99mTc-HMPAO is in the range of previously reported results, obtained by planar techniques. Absolute uptake is significantly different between the patient groups.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Welz
authors.forename: James C
authors.initials: JC
authors.lastname: Sanders
authors.forename: Torsten
authors.initials: T
authors.lastname: Kuwert
authors.forename: Juan
authors.initials: J
authors.lastname: Maler
authors.forename: Johannes
authors.initials: J
authors.lastname: Kornhuber
authors.affiliation: Philipp Ritt, PhD, Clinic of Nuclear Medicine, Ulmenweg 18, 91054 Erlangen, Germany, Tel. +49/(0)91 31/853-34 11, Fax -92 62, philipp.ritt@uk-erlangen.de.
authors.forename: Philipp
authors.initials: P
authors.lastname: Ritt
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D003198:Computer Simulation; D003704:Dementia / Q000175:diagnosis* / Q000378:metabolism*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D008959:Models, Neurological; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000072098:Single Photon Emission Computed Tomography Computed Tomography / Q000379:methods*; D019690:Technetium Tc 99m Exametazime / Q000493:pharmacokinetics*
chemical_list: D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime
keywords: Absolute quantification; HMPAO; SPECT/CT; brain perfusion