Photon-counting detector computed tomography for the assessment of coronary stents and in-stent restenosis

BACKGROUND: Photon-counting detector computed tomography (PCD-CT) offers enhanced spatial resolution and reduced blooming artefacts, potentially improving the evaluation of stented coronary vessels. AIMS: This study aimed to assess the diagnostic performance of dual-source PCD-CT in detecting obstructive in-stent restenosis (ISR). METHODS: We identified consecutive patients with prior coronary stent implantation who underwent clinically indicated coronary computed tomography angiography (CCTA) with PCD-CT and subsequent invasive coronary angiography within 90 days between 2023 and 2024. Obstructive ISR (≥50% diameter stenosis) was determined by visual assessment of CCTA and invasive quantitative coronary angiography (QCA) in a blinded fashion. The diagnostic performance of CCTA for ISR was compared with that of QCA. RESULTS: A total of 283 stented lesions from 171 patients were included. Of these, only 3 lesions (1.1%) were deemed indeterminate by PCD-CT. Using invasive QCA as the reference standard, PCD-CT demonstrated a lesion-level sensitivity of 80.0%, specificity of 90.4%, positive predictive value (PPV) of 58.2%, negative predictive value (NPV) of 96.4%, and an overall diagnostic accuracy of 88.9% for detecting obstructive ISR. In a subgroup analysis according to the stent diameter (<3.00 mm [n=83] vs ≥3.00 mm [n=108]), there were no significant differences in sensitivity (87.5% vs 86.7%; p=1.00), specificity (93.3% vs 92.5%; p=1.00), PPV (58.3% vs 65.0%; p=1.00), NPV (98.6% vs 97.7%; p=1.00), or overall diagnostic accuracy (92.8% vs 91.7%; p=1.00), respectively. CONCLUSIONS: PCD-CT demonstrated good diagnostic performance for evaluating obstructive ISR using QCA as the reference standard, regardless of stent diameter.