Diagnostic accuracy of photon-counting detector CT for detection of coronary in-stent restenosis.

Background

Photon-counting detector computed tomography (PCD-CT) offers improved spatial resolution and reduced blooming artifacts compared with conventional CT, potentially improving visualization of coronary stents. We evaluated the diagnostic performance of PCD-CT for detecting significant coronary in-stent restenosis (ISR) using invasive coronary angiography (ICA) as the reference standard.

Methods

This retrospective, single-center diagnostic-accuracy study included consecutive adults with prior coronary stenting who underwent clinically indicated PCD-CT followed by ICA between February 2025 and January 2026. The primary outcome was the diagnostic performance of PCD-CT for detecting significant ISR, defined as >50% luminal diameter stenosis, on a per-stent basis. Secondary analyses evaluated patient-level performance and exploratory differences according to stent diameter, length, and location.

Results

The study included 52 patients (mean age, 70.5 ± 9.7 years; 83% male) with 69 evaluated stents. Significant ISR was present on ICA in 16 stents. PCD-CT correctly identified 12 of 16 stents with ISR and excluded ISR in 44 of 53 stents without ISR, corresponding to a sensitivity of 75.0%, specificity of 83.0%, positive predictive value of 57.1%, negative predictive value of 91.7%, and area under the curve (AUC) of 0.79 (95% CI, 0.67-0.91). Patient-level sensitivity was 86.7%, specificity was 85.7%, and AUC was 0.86 (95% CI, 0.76-0.97). Diagnostic performance was numerically higher in stents ≥3 mm than in stents <3 mm (AUC, 0.82 versus 0.71), although the difference was not statistically significant (P = 0.42).

Conclusion

PCD-CT demonstrated promising diagnostic performance and a high negative predictive value for detecting significant coronary ISR. Its potential utility for excluding ISR, including in smaller stents, warrants validation in larger prospective multicenter studies using standardized acquisition protocols.