Spectral and Ultra High Resolution CT Systems for Non-Invasive Detection of Myocardial Ischemia: Stress CT Perfusion VS. FFR-CT

Coronary artery disease (CAD) is the leading cause of mortality and morbidity worldwide. Coronary Computed Tomography angiography (CCTA) gained a pivotal clinical role for excellent sensitivity in rule-out CAD, but has limited specificity for a tendency to overestimate stenoses and for the lack of information about their hemodynamic impact. Fractional Flow Reserve derived from CT (FFR-CT) and stress CT perfusion (CTP) have been recently proposed to complement CCTA in the non-invasive assessment of myocardial ischemia, increasing the specificity and avoiding unnecessary catheterization. However, on energy-integrating (EID)-CT, FFR-CT has suboptimal performance, while CTP is affected by high radiation exposure. Both these approaches may benefit by the introduction of the new Photon Counting Detector (PCD)-CT technology, but data completely lacks. Aim of the study is to assess the performance of PCD-CT in the identification of significant CAD combining CCTA with FFR-CT and spectral CTP.

Inclusion Criteria: * Patient referred to our hospitals for elective CCTA for ruling out CAD * CCTA evidence of moderate stenosis (50-69%) requiring functional assessment according to ESC guidelines Exclusion Criteria: * hemodynamically unstable conditions, * previous revascularization, * myocardial infarction, * obesity (BMI\>40 kg/m2), * renal insufficiency (GFR\<30 mL/min), * atrial fibrillation or other significant arrhythmias; and * other overt cardiovascular diseases affecting CTP performance (e.g., heart failure, severe valvular regurgitation), * pregnancy and breastfeeding, * contraindications to iodinated contrast agents or regadenoson.