Diagnostic Accuracy of Dynamic CT Perfusion in Patients with Coronary Stents

Academic Background

Coronary artery disease (CAD) is one of the leading causes of death worldwide. Percutaneous coronary intervention (PCI) is a common treatment for obstructive CAD. However, after stent implantation, patients may experience in-stent restenosis (ISR) or progression of CAD, which requires effective imaging techniques for diagnosis. Coronary CT angiography (CCTA) is a widely used non-invasive diagnostic tool, but its diagnostic accuracy is limited in stent patients due to artifacts caused by metal stents. In recent years, CT perfusion (CTP) technology has emerged, combining anatomical and functional assessments in a single examination, showing potential in CAD diagnosis. However, there is limited research on dynamic CTP in stent patients, particularly in evaluating regional myocardial blood flow (MBF).

This study aims to explore the diagnostic performance of dynamic CTP in stent patients and compare it with CCTA, using fractional flow reserve (FFR) and the index of microvascular resistance (IMR) as reference standards to assess its accuracy in detecting myocardial ischemia.

Source of the Paper

This study was conducted by Daniele Andreini, Saima Mushtaq, and other researchers from Centro Cardiologico Monzino in Milan, Italy, and the Cardiovascular Center Aalst in Belgium, among other institutions. The paper was published in 2024 in the journal Radiology, titled Diagnostic Accuracy of Dynamic Stress Myocardial CT Perfusion Compared with Invasive Physiology in Patients with Stents: The ADVANTAGE 2 Study.

Research Process

Study Design and Patient Population

This prospective study enrolled 156 patients who were scheduled for invasive coronary angiography due to suspected ISR or CAD progression between January 2021 and June 2022. All patients underwent dynamic CTP and CCTA. A 256-slice CT scanner with a 16 cm Z-axis coverage and a 0.28-second rotation time was used. During invasive coronary angiography, FFR and IMR were used as reference standards.

Imaging Protocol

All CCTA and CTP scans were performed using a 256-slice CT scanner. CCTA was conducted according to the recommendations of the Society of Cardiovascular Computed Tomography. The dynamic CTP protocol included a 12-lead electrocardiogram at rest, followed by intravenous administration of Regadenoson (400 mcg) to induce vasodilation, and then CTP scanning. CTP image analysis used absolute MBF values as the threshold for functional CAD.

Data Analysis

The primary endpoints included the diagnostic rate, sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of CCTA and CTP in a territory-based analysis. Statistical analysis was performed using SPSS software, with continuous variables expressed as mean ± standard deviation and discrete variables as absolute numbers and percentages.

Main Results

Baseline Characteristics and Radiation Exposure

The study included 156 patients with a mean age of 63.1 years, 87% of whom were male. The average number of stents per patient was 3.23, and 54% of the stents had a diameter of less than 3.0 mm. The total effective radiation dose for CTP and CCTA was 10.4 mSv.

Diagnostic Rate

The diagnostic rate of CTP was significantly higher than that of CCTA, with 98.7% vs. 95.6% in the territory-based analysis (p < .001) and 98.7% vs. 87.2% in the patient-based analysis (p < .001).

Diagnostic Accuracy

Compared with FFR as the reference standard, the sensitivity, specificity, and diagnostic accuracy of CTP were significantly higher than those of CCTA (89.0% vs. 60.0%, 82.8% vs. 61.9%, and 84.7% vs. 61.5%, respectively; p < .001). Compared with IMR as the reference standard, the sensitivity, specificity, and diagnostic accuracy of CTP were also significantly higher than those of CCTA (76.5% vs. 48.2%, 85.9% vs. 63.5%, and 82.9% vs. 59.3%, respectively; p < .01).

Conclusion

This study demonstrates that dynamic CTP significantly improves the diagnostic performance of CCTA in detecting myocardial ischemia in patients with coronary stents. CTP shows high diagnostic accuracy in evaluating myocardial blood flow, particularly in patients after stent implantation, providing a more comprehensive anatomical and functional assessment.

Highlights of the Study

1. High Diagnostic Rate: The diagnostic rate of CTP was significantly higher than that of CCTA, indicating its advantage in image interpretability.
2. High Diagnostic Accuracy: Compared with FFR and IMR as reference standards, CTP showed significantly higher diagnostic accuracy than CCTA in detecting myocardial ischemia.
3. Application in Stent Patients: CTP demonstrated significantly higher diagnostic accuracy than CCTA in stent patients, highlighting its clinical value in this population.

Significance of the Study

This is the first prospective study to compare the diagnostic accuracy of dynamic CTP with invasive physiological assessments (FFR and IMR) in stent patients. The results show that dynamic CTP has high diagnostic accuracy in evaluating myocardial blood flow, particularly in patients after stent implantation, providing a more comprehensive anatomical and functional assessment. This finding offers new insights into non-invasive diagnosis for stent patients, and future multicenter studies with larger sample sizes are needed to further validate its clinical application.

Other Valuable Information

The limitations of this study include its single-center design and relatively small sample size. Additionally, the radiation dose of CTP is higher than that of CCTA, which needs to be weighed in practical applications. Nevertheless, the findings of this study provide important evidence supporting the use of dynamic CTP in stent patients.