Use of [C-11]acetate and [O-15]O-2 PET for the assessment of myocardial oxygen utilization in patients with chronic myocardial infarction

Carbon-11 acetate positron emission tomography (PET) has been widely used t o assess regional oxidative metabolism of the heart. However, the accuracy of [C-11]acetate PET in assessing oxidative metabolism in infarcted myocard ium remains controversial. Thirteen patients with stable coronary artery di sease and old myocardial infarction were studied. The O-15-based PET studie s yielded regional blood flow (rMBF, ml/min/g) and oxygen consumption (rMMR O(2), ml/min/g), which was compared with the myocardial clearance rate cons tant (k(mono)) of [C-11]acetate in segments with rMBF greater than or equal to 75% (group A), 50%-74% (group B) or <50% (group C) of the normal refere nce segment. Mean MBF was 0.96<plus/minus>0.08 ml/g/min in group A, 0.67 +/ -0.06 ml/g/min in group B and 0.42 +/-0.07 ml/g/min in group C segments. Th e segmental rMMRO(2) correlated linearly with k(mono) (r=0.89, P<0.001, y=0 .61x+0.026). The k(mono)/rMMRO(2) ratio was comparable in the group A and B segments (0.99<plus/minus>0.19 vs 1.07 +/-0.21, P=NS). However, the ratio was significantly higher in the group C segments (1.28 +/-0.35, P=0.037). I t is concluded that k(mono) of [C-11]acetate correlates linearly with rMMRO (2) determined by [O-15]O-2 inhalation. However, k(mono) appears to yield h igher rMMRO(2) estimates than the [O-15]O-2 method in low-flow areas.