Three-dimensional assessment of myocardial oxidative metabolism: a new approach for regional determination of PET-derived carbon-11-acetate kinetics.

We have developed a new analysis algorithm which generates polar coordinate maps of myocardial carbon-11-(11C) acetate kinetics. In 10 normal subjects (n = 20 studies), myocardial 11C clearance rate constants (k) averaged 0.057 +/- 0.009 (per minute). Regional k-values varied only 10.6 +/- 2.4% in the normal left ventricle. However, there was a small but significant segmental variation with increased 11C clearance in the septal, anterior, and basal regions (p less than 0.05). Since 11C clearance rates reflect tri-carboxylic acid cycle flux, these results suggest that myocardial oxidative metabolism is relatively homogeneous in the normal human heart at rest with minor regional variations, which possibly reflect varying regional wall stresses or substrate utilization. The proposed approach provides three-dimensional evaluation of regional oxidative metabolism which will permit characterization of the location, extent, and severity of myocardial disease.