Relation between myocardial 18F-FDG uptake in the fasting state and coronary angiography in patients with coronary artery disease

The relationship between severity of coronary artery stenosis (CAS) and myocardial 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG) uptake in the fasting state, assessed with positron emission tomography (PET), was examined in a series of 48 patients with CAS undergoing both studies for diagnostic purposes. The data analysis was based on the subdivision of the left ventricular myocardium into four segments defined in relation to ventricular vascularization: the anterior and septal segments, perfused by the left anterior descending artery; the lateral segment, perfused by the left circumflex; and the inferior segment, perfused by the right coronary artery. The 192 segments were grouped according to degree of CAS: I 0-50%, II 51-75%; III 76-90%; IV 91-99%; V and VI occluded coronary artery with good or poor collaterals, respectively. An 18F-FDG index was determined as the tissue blood pool radioactivity ratio in each segment. The statistical analysis was performed by one-way ANOVA, multiple comparison tests and the chi-squared test. The proportion of segments with 18F-FDG uptake was also analysed for a linear trend across the ordered levels of CAS. The 18F-FDG index in groups I to V was significantly higher than in controls, but it was not different among the groups with CAS, except for group V versus I. However, the proportion of segments with enhanced 18F-FDG uptake was correlated to the degree of CAS. In cases of complete occlusion of a major afferent coronary artery, the proportion of segments with 18F-FDG uptake varied in relation to the presence of collaterals. Although the 18F-FDG index is inadequate for estimating the severity of CAS, it provides useful information on the metabolism of segments perfused by collateral circulation.