Spectral CT Protocol Optimization for Atherosclerotic Plaque CharacterizatION

The SCORPION study (Spectral CT Protocol Optimization for Atherosclerotic Plaque Characterization) is a retrospective and prospective observational research project aimed at improving the diagnostic accuracy of dual-energy CT (DECT) and photon-counting CT (PCCT) in the characterization of atherosclerotic plaques in the coronary and carotid arteries. Given that cardiovascular diseases remain a leading cause of mortality despite advances in prevention and treatment, optimizing non-invasive imaging methods is crucial. CT Angiography (CTA) has become the gold standard for diagnosing coronary artery disease and carotid stenosis, but existing techniques require enhancement to improve plaque characterization, which is vital for risk stratification and patient management. While DECT has demonstrated potential in differentiating tissue types, its clinical adoption has been slow due to a lack of broad validation. This study seeks to establish a standardized imaging protocol that will provide more precise and reproducible plaque characterization.

The primary objective of the study is to develop a standardized method for characterizing atherosclerotic plaques using DECT based on retrospective datasets from Synlab. The first secondary objective is to validate this workflow with photon-counting CT data from an independent cohort at Fondazione Monasterio/CNR, ensuring the reliability of the technique across different imaging modalities. The second secondary objective involves defining an optimized DECT protocol using the energy spectrum of PCCT, ultimately refining imaging parameters for improved plaque assessment.

The study is structured into two phases. In the retrospective phase, data from fifty patients with critical stenosis (greater than 75% narrowing of the artery) who previously underwent DECT scans are analyzed. This step focuses on optimizing imaging parameters, segmentation techniques, and post-processing workflows. In the prospective phase, another cohort of fifty patients undergoes scanning with photon-counting CT to validate the workflow developed in the first phase. The results will inform the refinement of an optimized DECT protocol, translating the benefits of photon-counting technology into more widely available DECT scanners.

Patients included in the study must be at least sixty years old and have undergone DECT for cardiovascular imaging of the coronary or carotid arteries. The imaging process involves a third-generation dual-energy CT scanner (Somatom Force, Siemens) with high-resolution imaging settings, dual-energy tube voltages of 150 and 90 kV, ECG-gated acquisition, and the use of iodine contrast. The collected data is processed using various reconstruction techniques to extract quantitative imaging biomarkers, including total plaque volume, non-calcified and calcified plaque volumes, remodeling index, and degree of luminal stenosis. The study employs PyRadiomics, an open-source platform for radiomic feature extraction, to standardize data analysis and improve reproducibility.

The expected outcome of this research is an improved molecular characterization of atherosclerosis, leading to more accurate risk stratification and predictive models for cardiovascular events. By refining imaging techniques, the study aims to enhance diagnostic precision and minimize unnecessary hospitalizations, ultimately improving patient outcomes. Furthermore, establishing a standardized DECT protocol will allow for broader clinical adoption, making advanced plaque characterization more accessible in routine cardiovascular assessments.