title: Napkin-ring sign on coronary CT angiography for the prediction of acute coronary syndrome.
abstract: OBJECTIVE
  The aim of this study was to determine the predictive value of the napkin-ring sign on coronary computed tomography angiography (CTA) for future acute coronary syndrome (ACS) events in patients with coronary artery disease.
  
  
  BACKGROUND
  Recent studies have reported a close association between the napkin-ring sign on coronary CTA and thin-cap fibroatheroma.
  
  
  METHODS
  The subjects of this prospective study were 895 consecutive patients who underwent coronary CTA examination and were followed for >1 year. The primary endpoint was an ACS event (cardiac death, nonfatal myocardial infarction, or unstable angina pectoris). The coronary CTA analysis included the presence of obstructive plaque, positive remodeling (PR), low-attenuation plaque (LAP), and the napkin-ring sign. The napkin-ring sign was defined by the following criteria: 1) the presence of a ring of high attenuation around certain coronary artery plaques; and 2) attenuation of the ring presenting higher than those of the adjacent plaque and no >130 Hounsfield units.
  
  
  RESULTS
  Of the 12,727 segments, 1,174 plaques were observed, including plaques with PR in 130 segments (1.0%), LAP in 107 segments (0.8%), and napkin-ring signs in 45 segments (0.4%). Thirty-six of the 45 plaques with napkin-ring signs (80%) overlapped with those showing either PR or LAP. During the follow-up period (2.3 ± 0.8 years), 24 patients (2.6%) experienced ACS events, and plaques developed in 41% with a napkin-ring sign. Segment-based Cox proportional hazards models analysis showed that PR (p < 0.001), LAP (p = 0.007), and the napkin-ring sign (p < 0.0001) were independent predictive factors for future ACS events. Kaplan-Meier analysis demonstrated that plaques with napkin-ring signs showed a higher risk of ACS events compared with those without a napkin-ring sign.
  
  
  CONCLUSIONS
  The present study demonstrated for the first time that the napkin-ring sign demonstrated on coronary CTA was strongly associated with future ACS events, independent of other high-risk coronary CTA features. Detection of the napkin-ring sign could help identify coronary artery disease patients at high risk of future ACS events.
authors.affiliation: Department of Internal Medicine and Cardiology, Osaka City University Graduate School of Medicine, Osaka, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Otsuka
authors.forename: Shota
authors.initials: S
authors.lastname: Fukuda
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tanaka
authors.forename: Koki
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Taguchi
authors.forename: Junichi
authors.initials: J
authors.lastname: Yoshikawa
authors.forename: Kenei
authors.initials: K
authors.lastname: Shimada
authors.forename: Minoru
authors.initials: M
authors.lastname: Yoshiyama
mesh_terms: D054058:Acute Coronary Syndrome / Q000209:etiology* / Q000401:mortality; D000368:Aged; D000789:Angina, Unstable / Q000209:etiology / Q000401:mortality; D016009:Chi-Square Distribution; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000150:complications / Q000000981:diagnostic imaging* / Q000401:mortality; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D018450:Disease Progression; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology / Q000401:mortality; D058226:Plaque, Atherosclerotic; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D061205:Vascular Calcification / Q000150:complications / Q000000981:diagnostic imaging