Relationship between coronary arterial ¹⁸F-sodium fluoride uptake and epicardial adipose tissue analyzed using computed tomography.

Abstract

¹⁸F-Sodium fluoride (¹⁸F-NaF) positron emission tomography (PET) has the potential to detect high-risk coronary plaques. Epicardial adipose tissue (EAT) reportedly correlates with coronary atherosclerosis progression. We evaluated the relationship between coronary arterial ¹⁸F-NaF uptake and EAT findings using computed tomography (CT). We studied 40 patients with ≥ 1 coronary plaque detected on cardiac CT who underwent ¹⁸F-NaF PET/CT. EAT volume was measured using CT and indexed to body surface area in each patient. Each plaque was evaluated for CT-based luminal stenosis and high-risk features. The mean EAT density surrounding each plaque was calculated as perilesional EAT density (PLED) using non-contrast CT images. Focal ¹⁸F-NaF uptake in each plaque was quantified using the maximum tissue-to-background ratio (TBR_max). EAT volume index was similar between patients with TBR_max ≥ 1.28 (previously reported optimal cutoff to predict coronary events) and those with lower TBR_max, but patients with TBR_max ≥ 1.28 showed higher maximum PLED per patient (- 86 ± 12 Hounsfield units (HU) versus - 98 ± 11 HU, P = 0.0044). In the lesion-based analysis (n = 92), PLED was positively correlated with TBR_max, and the optimal PLED cutoff to identify TBR_max ≥ 1.28 was - 97 HU. On multivariate analysis adjusted for lesion location, obstructive stenosis, and high-risk plaque on CT, PLED ≥ - 97 HU remained a significant predictor of TBR_max ≥ 1.28. Increased PLED was associated with significant coronary arterial ¹⁸F-NaF uptake. Step-by-step analyses of EAT density on CT and coronary arterial ¹⁸F-NaF uptake on PET may offer novel strategies for risk prediction in coronary artery disease.