Background: Myocardial viability and quantification of regional myocardial blood flow (MBF) are important for the diagnosis of heart disease. Positron emission tomography is the current gold standard for determining myocardial viability, but most positron-emitting perfusion tracers require an on-site cyclotron. Rubidium-82 (82Rb) is a myocardial perfusion tracer that is produced using an on-site generator. This study investigates 82Rb-measured MBF in canine models of stunned and infarcted myocardium compared with selected measurements obtained concurrently using microspheres.
Methods: Myocardial stunning and infarction were created in canines by occluding the left anterior descending for 15 min and 2 h, respectively. Stunning was produced in all animals; six animals were reperfused after the 2 h occlusion, whereas the other six animals remained occluded permanently. Regional MBF was measured in each group during rest and dobutamine stress at acute and chronic (8 weeks postinsult) time points using dynamic 82Rb perfusion imaging and radioactively labeled microspheres.
Results: Average resting MBF with microspheres and 82Rb was 0.68±0.02 versus 0.73±0.01 (P<0.001) in nonischemic tissue, and 0.53±0.03 versus 0.42±0.02 (P<0.001) in the region-at-risk tissue, respectively. Average MBF during stress with microspheres and 82Rb was 2.78±0.15 versus 3.53±0.16 (P<0.05) in the nonischemic tissue, and 1.90±0.20 versus 2.31±0.26 (P = NS) in the region-at-risk tissue, respectively.
Conclusion: Despite the small significant differences, the dynamic 82Rb measurements provide estimates of MBF in stunned and acutely and chronically infarcted tissue at rest and during hyperemia that correspond with clinical interpretation.
aImaging Program, Lawson Health Research Institute and Nuclear Medicine Department, St. Joseph's Health Care
bDivision of Cardiology, London Health Sciences Centre, London
cNational Cardiac PET Centre, University of Ottawa Heart Institute, Ottawa, Ontario, Canada
Correspondence to Dr Frank S. Prato, PhD, Imaging Program, Lawson Health Research Institute, 268 Grosvenor Street, London, ON N6A 4V2, Canada
Tel: +1 519 646 6000 x64140; fax: +1 519 646 6399;
Received 24 February 2009 Revised 6 July 2009 Accepted 30 August 2009