title: Quantification of subendocardial and subepicardial blood flow using 15O-labeled water and PET: experimental validation.
abstract: The purpose of this study was to assess the feasibility and accuracy of quantifying subendocardial and subepicardial myocardial blood flow (MBF) and the relative coronary flow reserves (CFR) using (15)O-labeled water (H(2)(15)O) and 3-dimensional-only PET.
  
  
  METHODS
  Eight pigs were scanned with H(2)(15)O and (15)O-labeled carbon monoxide (C(15)O) after partially occluding the circumflex (n = 3) or the left anterior descending (n = 5) coronary artery, both at rest and during hyperemia induced by intravenous dipyridamole. Radioactive microspheres were injected during each of the H(2)(15)O scans.
  
  
  RESULTS
  In a total of 256 paired measurements of MBF, ranging from 0.30 to 4.46 mL.g(-1).min(-1), microsphere and PET MBF were fairly well correlated. The mean difference between the 2 methods was -0.01 +/- 0.52 mL.g(-1).min(-1) with 95% of the differences lying between the limits of agreement of -1.02 and 1.01 mL.g(-1).min(-1). CFR was significantly reduced (P < 0.05) in the ischemic subendocardium (PET = 1.12 +/- 0.45; microspheres = 1.09 +/- 0.50; P = 0.86) and subepicardium (PET = 1.2 +/- 0.35; microspheres = 1.32 +/- 0.5; P = 0.39) in comparison with remote subendocardium (PET = 1.7 +/- 0.62; microspheres = 1.64 +/- 0.61; P = 0.68) and subepicardium (PET = 1.79 +/- 0.73; microspheres = 2.19 +/- 0.86; P = 0.06).
  
  
  CONCLUSIONS
  Dynamic measurements using H(2)(15)O and a 3-dimensional-only PET tomograph allow regional estimates of the transmural distribution of MBF over a wide flow range, although transmural flow differences were underestimated because of the partial-volume effect. PET subendocardial and subepicardial CFR were in good agreement with the microsphere values.
authors.affiliation: Medical Research Council Clinical Sciences Centre, Faculty of Medicine, Imperial College of Science, Technology and Medicine, Hammersmith Hospital, London, United Kingdom. ornella.rimoldi@csc.mrc.ac.uk
authors.forename: Ornella
authors.initials: O
authors.lastname: Rimoldi
authors.forename: Klaus P
authors.initials: KP
authors.lastname: Schäfers
authors.forename: Ronald
authors.initials: R
authors.lastname: Boellaard
authors.forename: Federico
authors.initials: F
authors.lastname: Turkheimer
authors.forename: Lars
authors.initials: L
authors.lastname: Stegger
authors.forename: Marilyn P
authors.initials: MP
authors.lastname: Law
authors.forename: Adriaan A
authors.initials: AA
authors.lastname: Lammerstma
authors.forename: Paolo G
authors.initials: PG
authors.lastname: Camici
mesh_terms: D000465:Algorithms; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology*; D003326:Coronary Circulation / Q000502:physiology*; D004699:Endocardium / Q000000981:diagnostic imaging*; D005240:Feasibility Studies; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D010104:Oxygen Radioisotopes; D010496:Pericardium / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine; D014867:Water
chemical_list: D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D014867:Water