title: In vivo radionuclide uptake quantification using a multi-pinhole SPECT system to predict renal function in small animals.
abstract: OBJECTIVE
  In vivo quantification of radiopharmaceuticals has great potential as a tool in developing new drugs. We investigated the accuracy of in vivo quantification with multi-pinhole single-photon emission computed tomography (SPECT) in rats.
  
  
  METHODS
  Fifteen male Lewis rats with different stages of renal dysfunction were injected with 50 MBq 99mTc-dimercaptosuccinic acid. Four to six hours after injection, SPECT of the kidneys was acquired with a new four-headed multi-pinhole collimator camera. Immediately after imaging the rats were sacrificed and the kidneys were counted in a gamma-counter to determine the absorbed activity. SPECT data were reconstructed iteratively and regions of interest (ROIs) were drawn manually. The absolute activity in the ROIs was determined.
  
  
  RESULTS
  Uptake values ranging from 0.71% to 21.87% of the injected activity were measured. A very strong linear correlation was found between the determined activity in vivo and ex vivo (r2=0.946; slope m=1.059).
  
  
  CONCLUSIONS
  Quantification in vivo using this multi-pinhole SPECT system is highly accurate.
authors.affiliation: Department of Nuclear Medicine, Erasmus MC Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands. fforrer@uhbs.ch
authors.forename: F
authors.initials: F
authors.lastname: Forrer
authors.forename: R
authors.initials: R
authors.lastname: Valkema
authors.forename: B
authors.initials: B
authors.lastname: Bernard
authors.forename: N U
authors.initials: NU
authors.lastname: Schramm
authors.forename: J W
authors.initials: JW
authors.lastname: Hoppin
authors.forename: E
authors.initials: E
authors.lastname: Rolleman
authors.forename: E P
authors.initials: EP
authors.lastname: Krenning
authors.forename: M
authors.initials: M
authors.lastname: de Jong
mesh_terms: D000818:Animals; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation / Q000379:methods; D007677:Kidney Function Tests / Q000295:instrumentation / Q000379:methods / Q000662:veterinary; D008297:Male; D011866:Radioisotope Renography / Q000295:instrumentation* / Q000379:methods / Q000662:veterinary*; D019275:Radiopharmaceuticals / Q000032:analysis / Q000493:pharmacokinetics; D051381:Rats; D011917:Rats, Inbred Lew; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019783:Technetium Tc 99m Dimercaptosuccinic Acid / Q000032:analysis / Q000493:pharmacokinetics*; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation* / Q000379:methods / Q000662:veterinary*
chemical_list: D019275:Radiopharmaceuticals; D019783:Technetium Tc 99m Dimercaptosuccinic Acid