title: The napkin-ring sign indicates advanced atherosclerotic lesions in coronary CT angiography.
abstract: OBJECTIVE
  This study sought to determine the accuracy of plaque pattern assessment by coronary computed tomography angiography (CCTA) to differentiate between early and advanced atherosclerotic lesions as defined by histology.
  
  
  BACKGROUND
  A ringlike attenuation pattern of coronary atherosclerotic plaques termed as napkin-ring sign (NRS) was described in CCTA of patients who had acute coronary syndrome.
  
  
  METHODS
  All procedures were performed in accordance with local and federal regulations and the Declaration of Helsinki. Approval of the local ethics committees was obtained. We investigated 21 coronary arteries of 7 donor hearts. Overall, 611 histological sections were obtained and coregistered with CCTA images. The CCTA cross sections were read in random order for conventional plaque categories (noncalcified [NCP], mixed [MP], calcified [CP]) and plaque patterns (homogenous, heterogeneous with no napkin-ring sign [non-NRS], and heterogeneous with NRS).
  
  
  RESULTS
  No plaque was detected in 134 (21.9%), NCP in 254 (41.6%), MP in 191 (31.3%), and CP in 32 (5.2%) CCTA cross sections. The NCP and MP were further classified into homogenous plaques (n = 207, 46.5%), non-NRS plaques (n = 200, 44.9%), and NRS plaques (n = 38, 8.6%). The specificities of NCP and MP to identify advanced lesions were moderate (57.9%, 95% confidence interval [CI]: 50.1% to 65.6%, and 72.1%, 95% CI: 64.7% to 79.4%, respectively), which were similar to the homogenous and heterogeneous plaques (62.6%, 95% CI: 54.8% to 70.3%, and 67.3%, 95% CI: 58.6% to 76.1%, respectively). In contrast, the specificity of the NRS to identify advanced lesions was excellent (98.9%, 95% CI: 97.6% to 100%). The diagnostic performance of the pattern-based scheme to identify advanced lesions was significantly better than that of the conventional plaque scheme (area under the curve: 0.761 vs. 0.678, respectively; p = 0.001).
  
  
  CONCLUSIONS
  The assessment of the plaque pattern improves diagnostic accuracy of CCTA to identify advanced atherosclerotic lesions. The CCTA finding of NRS has a high specificity and high positive predictive value for the presence of advanced lesions.
authors.affiliation: Cardiac MR PET CT Program, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Pál
authors.initials: P
authors.lastname: Maurovich-Horvat
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Schlett
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
authors.forename: Masataka
authors.initials: M
authors.lastname: Nakano
authors.forename: Fumiyuki
authors.initials: F
authors.lastname: Otsuka
authors.forename: Paul
authors.initials: P
authors.lastname: Stolzmann
authors.forename: Hans
authors.initials: H
authors.lastname: Scheffel
authors.forename: Maros
authors.initials: M
authors.lastname: Ferencik
authors.forename: Matthias F
authors.initials: MF
authors.lastname: Kriegel
authors.forename: Harald
authors.initials: H
authors.lastname: Seifarth
authors.forename: Renu
authors.initials: R
authors.lastname: Virmani
authors.forename: Udo
authors.initials: U
authors.lastname: Hoffmann
mesh_terms: D000328:Adult; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000473:pathology; D003331:Coronary Vessels / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging* / Q000473:pathology; D012372:ROC Curve; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed