In vivo coronary stent evaluation using photon-counting computed tomography: diagnostic performance

To assess the diagnostic performance of photon-counting computed tomography (PCCT) coronary angiography for the detection of in-stent restenosis (ISR) ≥ 50%, and image quality.

141 consecutive patients with coronary stents referred to coronary computed tomography angiography (CTA) were enrolled in this retrospective single-center study, using either PCCT or energy-integrating detector (EID)-CT. Image quality of the in-stent lumen (ISL) was graded using a 3-point scale as 2 = "excellent diagnostic", 1 = "limited diagnostic", or 0 = nondiagnostic. Coronary stents were assessed for ISR ≥ 50% compared to invasive coronary angiography (ICA), and quantitative image analysis was performed.

176 stents in 70 patients (age 73.64 ± 12.6, 27.1% women) who underwent PCCT were included and compared to a control group of 71 patients (126 stents) who underwent EID-CT. Subjective image quality scores were higher in stents assessed by PCCT compared with EID-CT (p < 0.001). The rate of nondiagnostic stents was lower (1.1% vs 46.8%, p < 0.001) with PCCT, while the proportion of stents excellent image quality was higher (70.5% vs 23%, p < 0.001). The diagnostic accuracy of PCCT (per-patient) for the detection of ISR ≥ 50% was 90.48% (71.09, 97.35), sensitivity 100% (64.57, 100), specificity 85.71% (60.06, 95.99), PPV 77.78% (45.26, 93.68), NPV 100% (75.75, 100), and per-stent: accuracy 88.52% (78.16, 94.33), sensitivity 100% (70.08, 100), specificity 86.54% (74.73, 93.32), PPV 56.25% (33.18, 76.90) and NPV 100% (92.13, 100). True positive ISR ≥ 50% showed a trend toward lower ISR/ISL ratios than false positives (mean, 0.35 vs 0.87).

Image quality of PCCT for coronary stent evaluation is improved compared to EID-CT, and the accuracy for detection of ISR ≥ 50% is high.

Question Does photon-counting CT improve the diagnostic accuracy for detection of in-stent restenosis (ISR) ≥ 50%, and image quality compared with energy-integrating detector (EID) CT? Findings Photon-counting CT provides higher image quality and a low rate of nondiagnostic stents (0.3%). For detecting ≥ 50% ISR, the diagnostic accuracy is high and the PPV is moderate. Clinical relevance Photon-counting computed tomography (PCCT) has the potential to overcome technical limitations of conventional energy-integrating CT in coronary stent assessment and could improve the reliability of non-invasive follow-up after percutaneous coronary intervention.