OBJECTIVES: 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.
