title: Equivalence of arterial and venous blood for [11C]CO2-metabolite analysis following intravenous administration of 1-[11C]acetate and 1-[11C]palmitate.
abstract: OBJECTIVE
  Sampling of arterial blood for metabolite correction is often required to define a true radiotracer input function in quantitative modeling of PET data. However, arterial puncture for blood sampling is often undesirable. To establish whether venous blood could substitute for arterial blood in metabolite analysis for quantitative PET studies with 1-[(11)C]acetate and 1-[(11)C]palmitate, we compared the results of [(11)C]CO2-metabolite analyses performed on simultaneously collected arterial and venous blood samples.
  
  
  METHODS
  Paired arterial and venous blood samples were drawn from anesthetized pigs at 1, 3, 6, 8, 10, 15, 20, 25 and 30min after i.v. administration of 1-[(11)C]acetate and 1-[(11)C]palmitate. Blood radioactivity present as [(11)C]CO2 was determined employing a validated 10-min gas-purge method. Briefly, total blood (11)C radioactivity was counted in base-treated [(11)C]-blood samples, and non-[(11)C]CO2 radioactivity was counted after the [(11)C]-blood was acidified using 6N HCl and bubbled with air for 10min to quantitatively remove [(11)C]CO2.
  
  
  RESULTS
  An excellent correlation was found between concurrent arterial and venous [(11)C]CO2 levels. For the [(11)C]acetate study, the regression equation derived to estimate the venous [(11)C]CO2 from the arterial values was: y=0.994x+0.004 (r(2)=0.97), and for the [(11)C]palmitate: y=0.964x-0.001 (r(2)=0.9). Over the 1-30min period, the fraction of total blood (11)C present as [(11)C]CO2 rose from 4% to 64% for acetate, and 0% to 24% for palmitate. The rate of [(11)C]CO2 appearance in venous blood appears similar for the pig model and humans following i.v. [(11)C]-acetate administration.
  
  
  CONCLUSIONS
  Venous blood [(11)C]CO2 values appear suitable as substitutes for arterial blood samples in [(11)C]CO2 metabolite analysis after administration of [(11)C]acetate or [(11)C]palmitate
  
  
  CONCLUSIONS
  Quantitative PET studies employing 1-[(11)C]acetate and 1-[(11)C]palmitate can employ venous blood samples for metabolite correction of an image-derived tracer arterial input function, thereby avoiding the risks of direct arterial blood sampling.
authors.affiliation: Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Yen
authors.initials: Y
authors.lastname: Ng
authors.forename: Steven P
authors.initials: SP
authors.lastname: Moberly
authors.forename: Kieren J
authors.initials: KJ
authors.lastname: Mather
authors.forename: Clive
authors.initials: C
authors.lastname: Brown-Proctor
authors.forename: Gary D
authors.initials: GD
authors.lastname: Hutchins
authors.forename: Mark A
authors.initials: MA
authors.lastname: Green
mesh_terms: D000085:Acetates / Q000008:administration & dosage* / Q000097:blood* / Q000378:metabolism; D061605:Administration, Intravenous; D000818:Animals; D001158:Arteries / Q000000981:diagnostic imaging / Q000378:metabolism*; D002244:Carbon / Q000008:administration & dosage* / Q000097:blood* / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D002250:Carbon Radioisotopes; D008297:Male; D010168:Palmitates / Q000008:administration & dosage* / Q000097:blood* / Q000378:metabolism; D011877:Radionuclide Imaging; D013552:Swine; D014680:Veins / Q000378:metabolism*
chemical_list: D000085:Acetates; D002250:Carbon Radioisotopes; D010168:Palmitates; C438206:carbon-11 acetate; D002245:Carbon Dioxide; D002244:Carbon