Epicardial Adipose Tissue: A Multimodal Imaging Diagnostic Perspective

Abstract

Epicardial adipose tissue (EAT), strategically located between the myocardium and the visceral pericardial layer, is increasingly recognized as an active player in cardiovascular health rather than a passive fat depot. EAT secretes a notable array of bioactive molecules known as adipokines, which exert critical exocrine and paracrine effects. Recent research has focused on pericoronary adipose tissue (PCAT)-the EAT surrounding coronary arteries-demonstrating its intricate bidirectional relationship with the vascular wall. Under normal physiological conditions, this interaction promotes vascular homeostasis; however, dysfunctional PCAT can release pro-inflammatory adipokines implicated in the pathogenesis of atherogenesis. Notably, PCAT inflammation has emerged as a significant factor associated with the development of coronary artery disease (CAD) and major cardiovascular events. This review seeks to elucidate the imaging methodologies employed to evaluate EAT, emphasizing cardiac computed tomography (CCT) as the preeminent imaging modality. Unlike echocardiography and cardiac magnetic resonance imaging, CCT not only visualizes and quantifies EAT but also concurrently assesses coronary arteries and PCAT. Recent findings have established the potential of CCT-derived PCAT attenuation as a noninvasive biomarker for coronary inflammation, offering prospects for monitoring therapeutic responses to innovative anti-inflammatory interventions in CAD management.

Keywords: echocardiography; epicardial adipose tissue; multimodality imaging; pericoronary adipose tissue.

Figure 1

Echocardiographic parasternal long-axis view showing measurement of epicardial fat thickness. AO: aortic root; LA: left atrium; LV: left ventricle; RV: right ventricle.

Figure 2

Epicardial adipose tissue visualization (red arrow) at cardiac magnetic resonance in four-chamber (left) and short-axis (right) steady-state free precession cine sequences.

Figure 3

Pericoronary fat attenuation index (pFAI) measurement: Example of how to measure the pericoronary adipose tissue in a male patient with ACS using Aquarius Workstation version 4.4.13.P4 (TeraRecon Inc., Foster City, CA, USA). (A) Three-dimensional (3D) coronary CT reconstruction focused on right coronary artery. (B) Selection of the right coronary artery (RCA) and its region of interest. (C) Pericoronary tissue analysis is performed starting 10 mm from the ostium then the proximal 40 mm segment of the RCA is traced. The adipose tissue within a radial distance from the outer vessel wall equal to the diameter of the vessel is defined perivascular fat. (D) Histogram showing the distribution of pericoronary tissue values in the range of −190 and −30 HU. In Table 1, the main advantages and disadvantages of imaging methods are presented.