Abstract: Objective To explore the advantages of ultra-high resolution (UHR) mode of photon-counting detector CT (PCCT) over conventional imaging mode of energy-integrating detector CT (EID-CT) in coronary stent CT imaging. Methods The imaging data of 15 patients (32 stents) received coronary stent implantation were prospectively analyzed. All patients underwent coronary CT angiography (CCTA) with PCCT in UHR mode, and had a prior CCTA examination performed with EID-CT. Objective evaluation parameters included the diameter of the inner lumen of the stent, the outer diameter of the stent, the blooming artifact index, the difference in CT values inside versus outside the stent, and the noise within the stent lumen. Subjective evaluation was conducted using Likert’s 5-point method, including the display of the lumen in the stent, delineation of stent structure, visualization of calcified plaques outside the stent,display of peri-stent blood vessels, diagnostic confidence of in-stent restenosist,beam hardening artifacts and blooming artifacts. Results The internal diameter of the stent and the internal lumen noise of the stent measued by PCCT were significantly higher than those measured by EID-CT(P<0.001), while the blooming artifact index and the differences in the internal and external stent CT values of the stent measured by PCCT were significantly lower than those measured by EID-CT (P<0.001). There was no significant difference in the outer diameter of the stents beween the two groups of images (P=0.366). The PCCT images showed significantly higher scores for all subjective indexes than those of the EID-CT images (P<0.001). Conclusions PCCT can obtain better image quality and diagnostic confidence than traditional EID-CT in coronary stent imaging, and it may become a new method for clinical non-invasive evaluation of coronary stent patency in the future.

Key words: photon-counting CT, energy-integrating detector CT, coronary stent, image quality