Our study has demonstrated that P/S and P-S in T2DM patients with carotid plaque, especially with hypoechoic plaque, are lower than those without carotid plaque. After adjusting for covariates, multivariate logistic regression model identifies low P/S and low P-S as independent risk factors for carotid plaque, in particular carotid hypoechoic plaque.
Ct Quantitative Evaluation Of Pancreatic Steatosis
Pancreatic steatosis has been indicated in various diseases [5, 7, 8]. Therefore, a simple and accurate method for evaluating pancreatic fat content is of clinical significance. Ultrasound and magnetic resonance imaging (MRI) have been used to measure pancreatic fat content [15, 16]. However, ultrasound results may be affected by the operator's experience, while MRI is expensive and time-consuming, which limit their clinical application. Histologically, pancreatic CT density index (P/S, P-S) had a good correlation with pancreatic fat content [6]. Therefore, CT, which is widely used in clinical practice, is a reliable tool to evaluate pancreatic fat content. Rather than CT attenuation, P/S and P-S were applied to quantify pancreatic fat content in many studies [17–19], which was also applied in this study.
At present, no uniform CT cutoff value has been applied for the diagnosis of pancreatic steatosis. In this study, cutoff values of P/S (0.72) and P-S (-13.33) were obtained from ROC curves, consistent with previous reports [5, 20]. In this study, there were 117 patients (34.7%) with low P/S and 133 patients (39.5%) with low PS. The incidence of pancreatic steatosis was higher than previously reported in healthy Chinese adults [21], indicating that diabetes patients are more likely to suffer from pancreatic steatosis [22].
Relationship Between Pancreatic Steatosis And Carotid Plaque
Ectopic fat deposition is closely related to atherosclerotic plaque and cardiovascular disease [23]. Pancreatic steatosis is manifestation of ectopic fat deposition, characterized by fat accumulation in the pancreas [5, 24]. Pancreatic steatosis was related to carotid-femoral pulse wave velocity, which might predict carotid atherosclerosis in patients with non-alcoholic fatty liver disease [9]. Pancreatic steatosis was in proportion to aortic intima thickness [25] and systemic arterial calcification [12]. Ectopic fat deposition in the pancreas increased risk for carotid atherosclerosis in non-obese T2DM patients, but not in obese patients [26]. In this study, after adjusting for obesity and other traditional risk factors, low P/S and low P-S remain correlated with carotid plaque. Thus, pancreatic steatosis is an independent risk factor for carotid atherosclerosis.
Hypoechoic plaque is characteristic manifestation of unstable plaque, which is highly enriched in lipids and more prone to cerebrovascular diseases [27]. Previous study reported that hypoechoic plaque was independently related to progression of atherosclerosis [28]. The size of juxtaluminal hypoechoic area in asymptomatic carotid plaque linearly correlated with the risk of stroke [29]. Additionally, carotid hypoechoic plaque predicted adverse cardiovascular events in asymptomatic carotid stenosis [30]. Furthermore, hypoechoic plaque indicated cognitive impairment among patients with acute ischemic stroke [31]. We propose that pancreatic steatosis confers increased risk of hypoechoic carotid plaque. Therefore, for patients with T2DM, pancreatic fat content on CT images can help identify those at high risk of stroke, and guide early clinical intervention to prevent cerebrovascular diseases.
Pathological mechanisms underlying how pancreatic steatosis increases susceptibility to carotid plaque remain unclear. Pancreatic steatosis impairs insulin secretion in patients with T2DM [32], resulting in decreased insulin secretion. Moreover, pancreatic steatosis may contribute to insulin resistance [33], leading to relatively insufficient insulin. Consequently, elevated blood glucose causes damage to blood vessel wall through a variety of molecular pathways [34], and ultimately promotes the formation of atherosclerosis plaque.
There are several limitations in the current study. Firstly, ultrasound, instead of MRI, is applied in this study. Although MRI is superior to ultrasound in evaluating plaque composition, it is not widely used in clinical practice, since most radiologists have insufficient experience in this field. By contrast, ultrasound is easy to operate and widely applied to evaluate carotid plaque. Although ultrasound is not accurate enough to distinguish stable or unstable plaque according to echo features, hypoechoic plaque remains a certain value in predicting cardiovascular events [29, 30]. Secondly, all subjects in this study are patients with T2DM and cannot represent the general population. Thirdly, as a cross-sectional study, cause and effect relationship between pancreatic steatosis and carotid plaque needs to be further explored in future prospective studies with larger sample sizes.