Pericoronary adipose tissue attenuation and effective atomic number as novel imaging biomarkers for severe coronary artery stenosis

Abstract Objectives Conventional CT has limitations in material component differentiation. Our study aims to assess pericoronary adipose tissue (PCAT) attenuation using gemstone spectral imaging (GSI)-dual-energy computed tomography (DECT) and to define any possible association with severe atherosclerotic coronary artery disease (CAD). Methods Consecutive patients with significant CAD (60% narrowing of the lumen) were enrolled. All undergone GSI-DECT cardiac computed tomography imaging. The mean PCAT attenuation (in HU) was assessed by polychromatic images using GSI viewer using threshold between −190 HU and 0 HU on 40 keV (CT40 keV) and 70 keV (CT70 keV) as well as the mean effective atomic number of PCAT (Zeff). Mean PCAT attenuation values were assessed starting 10 mm from the ostium, in multiple segments of 40-mm in length along the coronary arteries and within a radial distance from the outer vessel wall equal to the diameter of the vessel in segments with severe stenosis from atherosclerotic plaques and in distal segments without atherosclerotic measurements Measurements were performed by 2 radiologists with 12 and 10 years of experience in cardiac imaging, respectively. Results We include 22 males and 4 females, aged 42-76 years (mean age 64+6 years). Twenty-one (81%) had stable angina, while 5 (19%) were asymptomatic. PCAT attenuation of coronary artery segments with severe stenosis ranged between -88 and -64 HU (mean value of – 72 ΗU), while PCAT attenuation surrounding distal segments without atherosclerotic lesions ranged between -124 and -92 HU (mean value of - 96 HU). In addition, the mean effective atomic number of PCAT (Zeff) at the level of significantly stenosed segments ranged between 6.6 and 7.7 (mean value 7.2) A statistically significant association was found between segments with severe CAD and higher mean PCAT values (−72 HU) (p=0.022) as well as with higher PCAT (Zeff) values (mean 7.2, p=0.024) while in distal non atherosclerotic coronary segments ranged between 5.8 and 6.6 (mean value 6.4) Conclusions: PCAT surrounding significantly stenosed coronary segments from atherosclerotic plaques showed higher attenuation values as well as higher mean effective atomic number (Zeff), than PCAT surrounding distal coronary segments without atherosclerotic lesions. Higher mean PCAT attenuation values as well as higher Z effective number may be attributed to chronic pericoronary fat inflammation accompanying segments of higher atherosclerotic burdenFor image description, please refer to the figure legend and surrounding text.