Measurement of myocardial blood flow with PET using 1-11C-acetate.

UNLABELLED

11C-acetate has been used extensively for the noninvasive assessment of myocardial oxygen consumption and viability with PET. The use of early uptake of acetate by the heart to measure myocardial perfusion has been proposed. This study evaluated the application of 11C-acetate for absolute measurement of myocardial blood flow using a simple compartmental model that does not require blood sampling.

METHODS

Eight healthy volunteers and 13 subjects with concentric left ventricular hypertrophy were studied under resting conditions with both 11Cacetate and 15O-water. Myocardial blood flow with 11C-acetate was obtained by fitting the first 3 min of the blood and tissue tracer activity curves to a two-compartment model. Flows obtained were compared with a validated approach using 15O-water.

RESULTS

In healthy volunteers, regional myocardial perfusion at rest estimated with 11C-acetate was comparable with values obtained with 15O-water (1.06 +/- 0.25 and 0.96 +/- 0.12 mL/g/min, respectively). Perfusion in subjects with left ventricular hypertrophy was also comparable if the recovery coefficient (FMM) used was corrected for ventricular mass. If a fixed FMM was used, flow was greatly overestimated. FMM could be estimated from left ventricular mass (FMM = 0.46 + 0.002 x mass, r = 0.86, P < 0.0001).

CONCLUSION

The results of this study suggest that 11C-acetate can be applied to quantitatively estimate myocardial perfusion under resting conditions using a two-compartment model without the need for blood sampling, provided that an appropriate FMM is chosen. This approach should increase the usefulness of this tracer and obviate administration of a separate tracer to independently measure perfusion.