Photon-Counting Cardiac CT in Post-PCI Patients

In the long-term management of patients after percutaneous coronary intervention, imaging assessment has become an indispensable tool for detecting in-stent restenosis, progression of native coronary artery disease, myocardial ischemia, and adverse ventricular remodeling. Current guidelines recommend various imaging modalities, including coronary CT angiography for stent and vessel evaluation, stress perfusion imaging for myocardial ischemia, and cardiac magnetic resonance for tissue characterization and ventricular function. However, traditional follow-up strategies require multiple separate examinations, which entail repeated contrast agent administration, cumulative radiation exposure, prolonged diagnostic timelines, and fragmented pathophysiological assessment. How to simultaneously evaluate coronary anatomy, myocardial iodine distribution, extracellular volume, and cardiac function through a single examination is a major clinical need that remains to be addressed.

This study takes patients who have undergone percutaneous coronary intervention as the research subjects and adopts a prospective observational cohort design. The aim is to innovatively develop and validate a "one-stop" photon-counting computed tomography imaging framework. The PCCT ONE-STEP protocol implies that multiple assessments are acquired through a single intravenous contrast injection and a single examination visit, including ultra-high-resolution coronary CT angiography for stent and native artery evaluation, spectral first-pass myocardial iodine distribution imaging, and low-dose delayed myocardial extracellular volume quantification. In a prespecified dose-controlled substudy, cardiac cine imaging and CT-derived strain analysis are additionally obtained.

The PCCT ONE-STEP protocol leverages the intrinsic spectral sensitivity and high spatial resolution of photon-counting detector technology. It can reduce the total volume of iodinated contrast medium and cumulative radiation dose compared with the sum of separate diagnostic examinations, while preserving or expanding the imaging content. By providing integrated coronary, myocardial iodine, extracellular volume, and functional phenotypes at a single visit, it has the potential to shorten the diagnostic work-up, decrease the incidence of contrast-associated adverse events, and improve patient throughput. The acquisition of multiple key imaging indicators enables individualized comprehensive assessment of post-PCI patients, supports the investigation of biological relevance through associations with circulating biomarkers, and facilitates the prediction of clinical ischemic and heart failure-related outcomes. The implementation of this study is expected to optimize the imaging pathway in the long-term care of patients after percutaneous coronary intervention.

Inclusion criteria

• Age 18 years or older;
• History of percutaneous coronary intervention with implantation of at least one coronary stent;
• Ability to undergo iodinated contrast-enhanced CT;
• Ability and willingness to provide written informed consent.

Exclusion criteria

• Estimated glomerular filtration rate below the institutional threshold for contrast-enhanced CT, generally less than 30 mL/min/1.73 m², unless examination is clinically justified and approved according to institutional policy;
• Known severe hypersensitivity to iodinated contrast material that cannot be adequately managed using the institutional premedication protocol; Pregnancy or suspected pregnancy;
• Inability to provide informed consent or comply with study procedures;
• Severe respiratory inability to perform the required breath-hold.