## 4 Discussion  
Published data showed that adipose tissue surrounding coronary arteries is present in a larger amount in patients with coronary artery disease than in healthy people [13]. At the same time, several biomarkers associated with inflammation, such as hsCRP, present higher values in patients who exhibit a larger amount of epicardial adipose tissue [14; 15]. This indicates that the interrelation between epicardial adipose tissue and cardiovascular risk is more complex and not strictly limited to the atherosclerotic process. For instance, the amount of epicardial fat has been demonstrated to be associated with the risk of atrial fibrillation and development of ventricular remodeling after myocardial infarction, via a mechanism linked with inflammation [16]. It seems that inflammation plays a crucial role in the process of endothelial dysfunction, altering vascular health on all levels of systemic circulation. It has been demonstrated that in obese patients, perivascular adipose tissue alters the vascular status by producing proinflammatory adipocytes, which decrease endothelial function, increase vascular stiffness and oxidative stress and decrease the production of nitric oxide, all these favoring atherosclerosis progression [17]. Several studies have demonstrated a good correlation between obesity, fat distribution and the presence of aortoiliac peripheral artery disease [18; 19]. The amount of body fat tissue and visceral distribution, the percentage of body fat and the waist-hip ratio are nowadays considered to represent reliable predictors of aortoiliac peripheral artery disease in middle-aged men. A body-mass index higher than 30 kg/m\({}^{2}\), a waist-hip ratio over 1.02, and a quantity of fat tissue higher than 26.5% are strong predictors of aortoiliac disease in middle-aged men [19]. In patients with aortoiliac disease, all these parameters presented a significant correlation with angiographic scores for severity, and with the ankle-bracchial index, a routinely used measure of disease severity. At the same time, several authors studied the effect of intrathoracic fat on the cardiovascular risk. They have demonstrated that the amount of periaortic fat tissue surrounding the thoracic aorta presents a significant association with the presence of peripheral artery disease, as detected by a low ankle-bracchial index in the presence of intermittent claudication [20; 21]. However, the relationship between perivascular adipose tissue at the level of the peripheral arteries, and the severity of peripheral artery disease, has not been studied yet. According to the authors' knowledge, this is the first study to demonstrate that the amount of perivascular fat at the level of iliac arteries is directly linked with both severity and complexity of peripheral atherosclerosis. The present study describes an easy and  
Figure 7: Correlation between mean PIAT volume and (**a**) mean visceral adipose tissue; (**b**) mean subcutaneous adipose tissue. user-friendly technique to quantify this periliac fat via multi-slice computed tomography, a largely used imaging technique. A recent report by [PERSON] et al. demonstrated that endovascular injury indices phenotypic changes in the perivascular adipose tissue, thus indicating that the link between periliac fat and atherosclerosis may be bidirectional, in the sense that perivascular fat may stimulate atherosclerosis progression, but in turn, atherosclerotic lesions may also induce perivascular fat accumulation or changes in the activity of perivascular adipocytes [22]. This could also represent a possible explanation for the good correlation between the complexity of arterial disease and the volume of perivascular fat, recorded in our study. Interestingly, in our study, even if the atherosclerotic lesions were not similar in severity between the two sides of the peripheral circulation, the amount of PIAT was not significantly different between right and left iliac arteries, and the correlation between the left and right PIAT was very good.