Low-tube-potential ultra-high-resolution coronary CTA with photon-counting detector CT for stent evaluation: a comparative feasibility study

This study aimed to evaluate the feasibility of low-tube-potential ultra-high-resolution (UHR) coronary CT angiography (CCTA) using photon-counting detector CT (PCD-CT) in comparison to low-tube-potential CCTA using energy-integrating detector CT (EID-CT), with a specific focus on the evaluation of coronary stents. This retrospective study included 54 patients (88 stents) who underwent CCTA in UHR mode on PCD-CT at low tube potential (PCDUHR-low; 27 patients [45 stents]) or CCTA with EID-CT at low tube potential (EID-low; 27 patients [43 stents]). The EID-low cohort was selected by propensity score matching to the PCDUHR-low cohort. Image quality of in-stent lumen was assessed using a 4-point Likert scale, with a score of 4 indicating "excellent." Quantitative assessment of stents included stent-induced blooming, edge sharpness, stent full width at half maximum (FWHM) and ΔHUin-stent which quantifies the increase in CT attenuation within the stent lumen. Radiation dose was evaluated using CT dose index volume (CTDIvol) and dose-length product (DLP). PCDUHR-low had higher image quality scores than EID-low (scores of 3 and 4, 82.2% vs. 53.5%; p = 0.02). PCDUHR-low showed reduced stent-induced blooming, superior edge sharpness, smaller stent FWHM and smaller ΔHUin-stent than EID-low (all, p < 0.01). CTDIvol and DLP in PCDUHR-low (9.3 ± 4.4 mGy and 107.1 ± 50.4 mGy・cm) were comparable to those of EID-low (10.5 ± 5.9 mGy and 118.2 ± 74.9 mGy・cm), respectively. (p = 0.26 and 0.47). CCTA using UHR mode in PCD-CT at low tube potential achieved superior image quality for implanted stent visualization as compared to EID-CT at low tube potential, while maintaining comparable radiation doses.