Consistent tracer administration profile improves test-retest repeatability of myocardial blood flow quantification with82Rb dynamic PET imaging.
OBJECTIVE
Quantification of myocardial blood flow (MBF) and stress/rest flow reserve is used increasingly to diagnose multi-vessel coronary artery disease and micro-vascular disease with PET imaging. However, variability in the measurements may limit physician confidence to direct revascularization therapies based on specific threshold values. This study evaluated the effects of rubidium-82 (82Rb) tracer injection profile using a constant-activity-rate (CA) vs a constant-flow-rate (CF) infusion to improve test-retest repeatability of MBF measurements.


METHODS
22 participants underwent single-session82Rb dynamic PET imaging during rest and dipyridamole stress using one of 2 test-retest infusion protocols: CA-CA (n = 12) or CA-CF (n = 10). MBF was quantified using a single-tissue-compartment model (1TCM) and a simplified retention model (SRM). Non-parametric test-retest repeatability coefficients (RPCnp) were compared between groups. Myocardium-to-blood contrast and signal-to-noise ratios of the late uptake images (2 to 6 minutes) were also compared to evaluate standard myocardial perfusion image (MPI) quality.


RESULTS
MBF values in the CA-CA group were more repeatable (smaller RPCnp) than the CA-CF group using the 1TCM at rest alone, rest and stress combined, and stress/rest reserve (21% vs 36%, 16% vs 19%, and 20% vs 27%, P < 0.05, respectively), and using the SRM at Rest and Stress alone, Rest and Stress combined, and stress/rest reserve (21% vs 38%, 15% vs 25%, 22% vs 38%, and 23% vs 49%, P < 0.05, respectively). In terms of image quality, myocardium-to-blood contrast and signal-to-noise ratios were not significantly different between groups.


CONCLUSIONS
Constant-activity-rate 'square-wave' infusion of82Rb produces more repeatable tracer injection profiles and decreases the test-retest variability of MBF measurements, when compared to a constant-flow-rate 'bolus' administration of82Rb, especially with SRM, and without compromising standard MPI quality.
National Cardiac PET Centre, Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Canada. rklein@toh.on.ca.|Department of Systems and Computer Engineering, Carleton University, Ottawa, Canada. rklein@toh.on.ca.|Division of Nuclear Medicine, Department of Medicine, The Ottawa Hospital and University of Ottawa, Box 232, 1053 Carling Ave, Ottawa, ON, K1Y 4E9, Canada. rklein@toh.on.ca.
Ran
R
Klein
Department of Systems and Computer Engineering, Carleton University, Ottawa, Canada.
Adrian
A
Ocneanu
National Cardiac PET Centre, Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Canada.
Jennifer M
JM
Renaud
National Cardiac PET Centre, Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Canada.|Non Invasive Cardiovascular Imaging Department, Diagnostico Medico Oroño, Rosario, Argentina.
Maria C
MC
Ziadi
National Cardiac PET Centre, Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Canada.|Division of Nuclear Medicine, Department of Medicine, The Ottawa Hospital and University of Ottawa, Box 232, 1053 Carling Ave, Ottawa, ON, K1Y 4E9, Canada.
Rob S B
RSB
Beanlands
National Cardiac PET Centre, Division of Cardiology, Department of Medicine, University of Ottawa Heart Institute, Ottawa, Canada.|Department of Systems and Computer Engineering, Carleton University, Ottawa, Canada.|Division of Nuclear Medicine, Department of Medicine, The Ottawa Hospital and University of Ottawa, Box 232, 1053 Carling Ave, Ottawa, ON, K1Y 4E9, Canada.
Robert A
RA
deKemp
D000368:Aged; D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003326:Coronary Circulation; D004176:Dipyridamole; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000008:administration & dosage*; D015203:Reproducibility of Results; D012414:Rubidium Radioisotopes / Q000008:administration & dosage*; D014665:Vasodilator Agents
D019275:Radiopharmaceuticals; D012414:Rubidium Radioisotopes; D014665:Vasodilator Agents; D004176:Dipyridamole; C000615479:Rubidium-82
Rubidium-82; myocardial blood flow; reproducibility; square-wave infusion profile