This prospective observational study aims to evaluate a high-resolution coronary CT platform (uCT SiriuX Pro) for non-invasive assessment of coronary plaque biomechanics and functional physiology in high-risk patients. The system enables CT-derived radial wall strain (CT-RWS), a novel biomarker reflecting plaque vulnerability, with potential correlation to invasive OCT findings and clinical outcomes.

The study will assess the diagnostic performance and prognostic value of CT-RWS, along with a new CT-based index of systolic flow perfusion (CT-SFPR) for evaluating the hemodynamic relevance of myocardial bridging, compared to nuclear perfusion imaging. Additionally, left ventricular ejection fraction derived from dynamic CTA (CT-EF) will be compared with echocardiography to evaluate its feasibility and accuracy. This is the first study to comprehensively validate CT-RWS, CT-SFPR, and CT-EF using a fully non-invasive, high-temporal-resolution CT platform.

Vulnerable coronary plaques remain a major cause of adverse cardiac events, including myocardial infarction and cardiac death, even in lesions that are not flow-limiting by conventional assessment. Invasive imaging modalities such as optical coherence tomography (OCT) have enabled identification of high-risk plaque features, including thin-cap fibroatheroma (TCFA), large lipid pools, and high lipid-to-cap ratio (LCR), which are linked to plaque rupture and clinical instability. However, the widespread use of OCT is limited by cost, technical demands, and the need for invasive catheterization.

Radial wall strain (RWS) has emerged as a novel imaging biomarker reflecting local plaque biomechanics. Studies based on angiography-derived RWS, such as those by Wang et al. (JACC Cardiovasc Interv 2025) and Hong et al. (EuroIntervention 2023), have shown that high RWS is significantly associated with OCT-defined vulnerable plaque features and predictive of future cardiovascular events, particularly in high-risk populations. Despite this promise, angiographic RWS still requires invasive procedures.

To overcome this limitation, the investigators have developed a non-invasive imaging platform: the uCT SiriuX Pro, an advanced cardiac CT scanner designed by United Imaging Healthcare. With a leading gantry rotation speed of 0.229 seconds, this system enables ultra-high temporal resolution, supporting high-fidelity cardiac cine imaging, spectral imaging, and integrated perfusion-angiography acquisition. These capabilities allow for the first-time derivation of CT-based radial wall strain (CT-RWS) from coronary CT angiography (CTA), offering a novel, fully non-invasive surrogate for assessing plaque biomechanics. This technology has not been previously documented in the literature.

In addition to evaluating plaque vulnerability, the study also aims to assess myocardial bridging (MB), a congenital anomaly often regarded as benign but increasingly linked to ischemia and adverse outcomes. Using high-temporal-resolution CT, the investigators propose to derive a new index-the systolic flow perfusion ratio (CT-SFPR)-to quantify dynamic coronary compression and its hemodynamic impact. The diagnostic relevance of CT-SFPR will be compared with established perfusion deficits identified on nuclear imaging.

Furthermore, the advanced temporal resolution of uCT SiriuX Pro enables dynamic volumetric analysis of left ventricular function. This study will also evaluate CTA-derived ejection fraction (CT-EF) in comparison with echocardiography to validate its feasibility and accuracy for non-invasive cardiac function assessment.

This prospective observational registry will enroll high-risk patients with suspected or known coronary artery disease. It aims to systematically validate CT-RWS, CT-SFPR, and CT-EF against invasive and functional imaging benchmarks and to assess their prognostic significance during clinical follow-up.

Inclusion Criteria:

• Adults ≥18 years with suspected or known CAD or with type 2 diabetes

Exclusion Criteria:

• those can not undergo CTA and angiography

In this study, we consecutively enrolled patients who were either suspected or diagnosed with coronary artery disease (CAD) in the outpatient setting, as well as those with diabetes presenting with atypical symptoms. Patients were eligible for inclusion if they were willing to undergo coronary CT angiography (CTA) followed by invasive coronary angiography. Major exclusion criteria included contrast agent allergy, impaired renal function, a history of coronary artery bypass grafting, and any other condition deemed unsuitable for CTA or invasive coronary angiography.