The Presence of Residual Vascular and Adipose Tissue Inflammation on 18F-FDG PET in Patients with Chronic Coronary Artery Disease

Purpose We evaluated the residual vascular and adipose tissue inflammation in patients with chronic coronary artery disease (CAD) using positron emission tomography (PET). Methods Our study population consisted of 98 patients with known CAD and 94 control subjects who had undergone F-18-fluorodeoxyglucose (F-18-FDG) PET due to non-cardiac reasons. Aortic root and vena cava superior F-18-FDG uptake were measured to obtain the aortic root target-to-background ratio (TBR). In addition, adipose tissue PET measurements were done in pericoronary, epicardial, subcutaneous, and thoracic adipose tissue. Adipose tissue TBR was calculated using the left atrium as a reference region. Data are presented as mean & PLUSMN; standard deviation or as median (interquartile range). Results The aortic root TBR was higher in CAD patients compared to control subjects, 1.68 (1.55-1.81) vs. 1.53 (1.43-1.64), p < 0.001. Subcutaneous adipose tissue uptake was elevated in CAD patients 0.30 (0.24-0.35) vs. 0.27 (0.23-0.31), p < 0.001. Metabolic activity of CAD patients and control subjects was comparable in the pericoronary (0.81 +/- 0.18 vs. 0.80 +/- 0.16, p = 0.59), epicardial (0.53 +/- 0.21 vs. 0.51 +/- 0.18, p = 0.38) and thoracic (0.31 +/- 0.12 vs. 0.28 +/- 0.12, p = 0.21) adipose tissue regions. Aortic root or adipose tissue F-18-FDG uptake was not associated with the common CAD risk factors, coronary calcium score, or aortic calcium score (p value > 0.05). Conclusion Patients with a chronic CAD had a higher aortic root and subcutaneous adipose tissue F-18-FDG uptake compared to control patients, which suggests residual inflammatory risk.