PET allows absolute measurements of myocardial blood flow (MBF). The aim of the present study was to evaluate the feasibility and repeatability of supine bicycle exercise stress, compared with standard adenosine stress, in PET.
Methods: In 11 healthy volunteers, MBF was assessed at rest, during adenosine-induced (140 microg/kg/min over 7 min) hyperemia, and immediately after supine bicycle exercise (mean workload, 130 W, which is 70% of the predicted value) using PET and (15)O-H(2)O. The assessment was then repeated after 20 min. Coronary flow reserve (CFR) was calculated as hyperemic/resting MBF for adenosine stress and exercise stress. Repeatability was evaluated according to the method of Bland and Altman.
Results: No significant differences were found between the paired resting MBF (1.22 +/- 0.16 vs. 1.26 +/- 0.21 mL/min/g; mean difference, 3% +/- 11%) and the hyperemic MBF with adenosine stress (5.13 +/- 0.74 vs. 4.97 +/- 1.05; mean difference, -4% +/- 14%) or exercise stress (2.35 +/- 0.66 vs. 2.25 +/- 0.61; mean difference, -4% +/- 19%). CFR was reproducible with adenosine stress (4.23 +/- 0.62 vs. 4.05 +/- 1.06, P = not statistically significant; mean difference, -5% +/- 19%) and exercise stress (1.91 +/- 0.46 vs. 1.80 +/- 0.44, P = not statistically significant; mean difference, -5% +/- 15%). Repeatability coefficients for MBF were 0.26 (rest), 1.34 (adenosine stress), and 0.82 (exercise stress) mL/min/g.
Conclusion: Assessment of CFR with (15)O-H(2)O and PET using bicycle exercise in the PET scanner is feasible and at least as repeatable as using adenosine stress.