The diagnosis of coronary plaque stability by multi-slice computed tomography coronary angiography.

Background: Coronary computed tomographic angiography is a robust non-invasive method to assess coronary artery disease (CAD) and analyze coronary plaque stability, especially for the non-calcified plaques. The aim of this study was to investigate the differential characteristics between the unstable coronary plaques and the stable coronary plaques using multi-slice computed tomography (MSCT).

Methods: Sixty patients with coronary heart disease (37 unstable plaques and 31 stable plaques) were included. The napkin ring thickness, napkin-ring sign, plaque CT attenuation and degree of lumen stenosis were retrospectively analyzed. The diagnostic performances of MSCT were determined to predict the unstable plaques. The difference was statistically significant if P<0.05.

Results: The napkin ring thickness of the unstable plaques was thinner than that of the stable plaques (P<0.05). The napkin-ring sign was more frequently observed in the unstable group (89.2%) than the stable group (22.6%, P<0.05). The average CT value of the unstable plaques (26.8±17.8 HU) was lower than that of the stable plaques (68.5±25.5 HU, P<0.05). The unstable plaques had more severe lumen stenosis or occlusion (70.3%) than the stable plaques (41.9%, P<0.05). The measurable napkin ring thickness of the plaques with a cutoff value of 0.8 mm and an accuracy of 89.5% was one independent factor to predict unstable plaques. The optimal combined threshold of the napkin-ring sign and/or the plaque CT value of 53 HU with an accuracy of 80.9% was to predict unstable plaques.

Conclusions: The optimal combined threshold of the napkin-ring sign and/or the plaque CT value ≤53 HU may be a good indicator to predict the unstable plaques in patients with CAD. The subgroup of measurable napkin ring thickness of the non-calcified plaques may also be an independent factor to predict the unstable plaques in patients with CAD.