Distribution, frequency and clinical implications of napkin-ring sign assessed by multidetector computed tomography

Background: Plaque rupture and secondary thrombus formation play key roles in the onset of acute coronary syndrome (ACS). Plaques showing the napkin-ring sign in multidetector computed tomography (MDCT) have been reported as thin-cap fibroatheroma that is recognized as a precursor lesion for plaque rupture. The purpose of this study was to investigate distribution and frequency of napkin-ring sign and its relationship to features indicating coronary plaque vulnerability on MDCT in patients with coronary artery disease. Methods: We enrolled 273 patients with ACS (n = 61) or stable angina pectoris (SAP, n=212) who were assessed by MDCT. The definition of the napkin-ring sign was the presence of a ring of high attenuation and the CT attenuation of a ring presenting higher than those of the adjacent plaque and no greater than 130 HU. Results: The culprit plaques with the napkin-ring sign show higher remodeling index and lower CT attenuation (1.15 +/- 0.12 vs. 1.02 +/- 0.12, p<0.01 and 39.9 +/- 22.8 vs. 72.7 +/- 26.6, p<0.01, respectively). Napkin-ring sign at culprit lesions was more frequent in patients with ACS than those with SAP (49.0% vs. 11.2%, p<0.01). Moreover, napkin-ring sign at non-culprit lesions was more frequently observed in ACS patients compared with SAP patients (12.7% vs. 2.8%, p<0.01). The distribution of the napkin-ring sign in the right coronary arteries and left circumflex arteries of our population was relatively even, whereas the napkin-ring sign in the left anterior descending artery was common in the proximal sites (p<0.01). Conclusions: The napkin-ring sign assessed by MDCT represents similar clinical features of fibroatheroma. MDCT could contribute to the search for fibroatheroma. (C) 2013 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.