Abstract: Abstract：Objective To compare the displayed inner diameter of coronary stent by high definition（HD）and gem⁃ stone spectral imaging（GSI）using dynamic cardiac and coronary artery phantom. Methods Five different types of coro⁃ nary stents（internal diameter, 3.10 mm±0.55 mm; strut thickness, 0.12 mm±0.04 mm）were placed into a pulsating cardiac phantom（ALPHA 1-VT PC, Fuyo Corporation, Japan）. The stent phantom was scanned by 3 systems, gemstone spectral im⁃ aging（GSI）, spiral scan（S）and HD. All the spectral imaging data were analyzed using GSI viewer to reconstruct the VMS (monochromic spectral) images（60-140 keV）. Image noise（N）, signal-to-noise ratio（SNR）, contrast-to-noise ratio（CNR） and inner diameter were compared between images acquired through these 3 systems. Results SNRs in images of S and HD were higher than that of GSI（P < 0.05），while there were no significant differences in CNRs among images of GSI, S and HD（P > 0.05）. The visible diameter（%）measurements of HD（0.85±0.06）was significant higher than that of the other 2 scan systems and most close to the width of those stent’s actual size.（GSI:0.40±0.16, 0.48±0.13, 0.50±0.14, 0.51±0.13, 0.45±0.05,0.52±0.13, 0.53±0.13, 0.53±0.13, 0.53±0.13, S:0.53±0.14, P < 0.05）. Conclusion There was no significant dif⁃ ferences in image quality among the images acquired by these 3 systems when the heart rate was set to 60 beats per min. Comparing to GSI and S, HD can produce best represent images to the known inner diameter of coronary stent.

Key words: stents, coronary computed tomography angiography, HDCT, gemstone spectral imaging, blooming effect, beam-hardening