Coronary CT Angiography and Dual-Energy Computed Tomography in Ischemic Heart Disease Suspected Patients

Advanced computed tomography (CT) scanners enable concurrent assessment of coronary artery anatomy and myocardial perfusion. The purpose of this study was to assess dual-energy CT images in a group of patients suspected for ischemic heart disease and to evaluate agreement of cardiac computed tomography perfusion (CTP) images with CT angiography results in a single dual-energy computed tomography (DECT) acquisition. Thirty patients (mean age: 53.8 ± 12.9 years, 60% male) with angina pectoris or atypical chest pain, suspected for ischemic heart disease, were investigated using a 384-row detector CT scanner in dual-energy mode (DECT). Firstly, resting CTP images were acquired, and then from the same raw data, computed tomography angiography (CTA) studies were reconstructed for stenosis detection. CT-based dipyridamole-stress myocardial perfusion imaging was then performed in patients who exhibited coronary stenosis >50% or had myocardial bridge (MB). A color-coded iodine map was used for evaluation of myocardial perfusion defects using the 17-segment model. Two independent blinded readers analyzed all images for stenosis and myocardial perfusion defects. Different myocardial iodine content (mg/mL) was calculated by parametric tests. The kappa agreement was calculated between results of two methods in cardiac scans. All 30 CT angiograms were evaluated and assessment ability was 100% for combined CTA/CTP. According to the combined CT examination, 17 patients (56.7%) exhibited significant coronary stenosis and/or deep MB (DMB). A total of 510 myocardial segments and 90 vascular territories were analyzed. Coronary CTA demonstrated significant stenosis in 22 vessels (24.4% of all main coronary arteries) among 12 patients (40%), DMB in 6 vessels (6.7% of all main coronary arteries) in 17 out of 30 patients (56.7%). Twenty-eight out of 90 vascular territories (31.1%) and 41 out of 510 segments (8%) showed reversible perfusion defects on stress DECT. Kappa agreement between CTA and CTP results in whole heart was 0.79 (95% confidence interval=0.57–1). There were significant differences in mean iodine concentration between ischemic (0.59 ± 0.07 mg/mL) and normal segments (2.2 ± 0.15) with P < 0.001. Agreement of CTA and CTP in whole heart and in LAD considering DMB and significant CAD together were good to excellent; however, considering sole pathologies, most of the agreements were weak (<0.5). DECT with iodine quantification may provide a valuable method in comparison with previous methods for identifying both coronary stenosis and myocardial ischemia.