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

Abstract

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 18F-fluorodeoxyglucose (18F-FDG) PET due to non-cardiac reasons. Aortic root and vena cava superior 18F-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 ± 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 18F-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 18F-FDG uptake compared to control patients, which suggests residual inflammatory risk.