title: Dynamic SPECT measurement of absolute myocardial blood flow in a porcine model.
abstract: Absolute myocardial blood flow (MBF) and myocardial flow reserve (MFR) provide incremental diagnostic and prognostic information over relative perfusion alone. Recent development of dedicated cardiac SPECT cameras with better sensitivity and temporal resolution make dynamic SPECT imaging more practical. In this study, we evaluate the measurement of MBF using a multipinhole dedicated cardiac SPECT camera in a pig model of rest and transient occlusion at stress using 3 common tracers: (201)Tl, (99m)Tc-tetrofosmin, and (99m)Tc-sestamibi.
  
  
  METHODS
  Animals (n = 19) were injected at rest/stress with (99m)Tc radiotracers (370/1,100 MBq) or (201)Tl (37/110 MBq) with a 1-h delay between rest and dipyridamole stress. With each tracer, microspheres were injected simultaneously as the gold standard measurement for MBF. Dynamic images were obtained for 11 min starting with each injection. Residual resting activity was subtracted from stress data and images reconstructed with CT-based attenuation correction and energy window-based scatter correction. Dynamic images were processed with kinetic analysis software using a 1-tissue-compartment model to obtain the uptake rate constant K(1) as a function of microsphere MBF.
  
  
  RESULTS
  Measured extraction fractions agree with those obtained previously using ex vivo techniques. Converting K(1) back to MBF using the measured extraction fractions produced accurate values and good correlations with microsphere MBF: r = 0.75-0.90 (P < 0.01 for all). The correlation in the MFR was between r = 0.57 and 0.94 (P < 0.01).
  
  
  CONCLUSIONS
  Noninvasive measurement of absolute MBF with stationary dedicated cardiac SPECT is feasible using common perfusion tracers.
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and gwells@ottawaheart.ca.
authors.forename: R Glenn
authors.initials: RG
authors.lastname: Wells
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and.
authors.forename: Rachel
authors.initials: R
authors.lastname: Timmins
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and.
authors.forename: Ran
authors.initials: R
authors.lastname: Klein
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and.
authors.forename: Julia
authors.initials: J
authors.lastname: Lockwood
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and.
authors.forename: Brian
authors.initials: B
authors.lastname: Marvin
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and.
authors.forename: Robert A
authors.initials: RA
authors.lastname: deKemp
authors.affiliation: Nordion Inc., Ottawa, Ontario, Canada.
authors.forename: Lihui
authors.initials: L
authors.lastname: Wei
authors.affiliation: Division of Cardiology, University of Ottawa Heart Institute, Ottawa, Ontario, Canada; and.
authors.forename: Terrence D
authors.initials: TD
authors.lastname: Ruddy
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity; D054059:Coronary Occlusion / Q000000981:diagnostic imaging / Q000473:pathology*; D003331:Coronary Vessels / Q000473:pathology; D004195:Disease Models, Animal; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007700:Kinetics; D015233:Models, Statistical; D009206:Myocardium / Q000473:pathology*; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D013552:Swine; D017256:Technetium Tc 99m Sestamibi; D013793:Thallium; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; C078700:technetium tc-99m tetrofosmin; D017256:Technetium Tc 99m Sestamibi; D013793:Thallium
keywords: SPECT; absolute myocardial blood flow; myocardial perfusion imaging; pig model