Background-Computed tomography (CT) is increasingly used to detect coronary artery disease, but the evaluation of stenoses is often uncertain. Perfusion imaging has an established role in detecting ischemia and guiding therapy. Hybrid positron emission tomography (PET)/CT allows combination angiography and perfusion imaging in short, quantitative, low-radiation-dose protocols. Methods and Results-We enrolled 107 patients with an intermediate (30% to 70%) pretest likelihood of coronary artery disease. All patients underwent PET/CT (quantitative PET with 15 O-water and CT angiography), and the results were compared with the gold standard, invasive angiography, including measurement of fractional flow reserve when appropriate. Although PET and CT angiography alone both demonstrated 97% negative predictive value, CT angiography alone was suboptimal in assessing the severity of stenosis (positive predictive value, 81%). Perfusion imaging alone could not always separate microvascular disease from epicardial stenoses, but hybrid PET/CT significantly improved this accuracy to 98%. The radiation dose of the combined PET and CT protocols was 9.3 mSv (86 patients) with prospective triggering and 21.8 mSv (21 patients)

Objective-Elevated serum concentration of C-reactive protein (CRP) predicts cardiovascular events in adults. Because atherosclerosis begins in childhood, we undertook a study to determine whether changes in brachial artery endothelial function and the thickness of the carotid intima-media complex, 2 markers of early atherosclerosis, are related to CRP levels in healthy children. Methods and Results-Brachial artery flow-mediated dilatation (FMD) and carotid artery intima-media thickness (IMT) were measured with ultrasound in 79 children (aged 10.5Ϯ1.1 years). Compared with the children with CRP levels under the detection limit (Ͻ0.1 mg/L, nϭ40, group 1), the children with higher CRP (0. 4 -8 Experimental studies have shown that CRP can be found in arterial walls affected by atherosclerosis but not in healthy vessel walls. 9 In a concentrationdependent manner, CRP directly increases endothelial production and the expression of monocyte chemoattractant protein-1 10 and adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1). 11 CRP also influences monocyte chemotaxis during atherogenesis, and the deposition of CRP precedes and mediates the appearance of monocytes in early atherosclerotic lesions. 12 Recently, it has been shown that CRP mediates the uptake of native LDL into macrophages, which is a novel mechanism for foam cell formation without biochemical modification of LDL. 13 Thus, together, these data suggest that CRP may have a direct proatherogenic role by disturbing endothelial function and promoting the formation of early atherosclerotic lesions. Because atherosclerosis begins in childhood, we undertook a study to assess whether changes in brachial artery reactivity and the thickness of the carotid intima-media complex (intima-media thickness [IMT]), 2 markers of early atherosclerosis, are related to serum CRP levels in healthy children. The study of arterial changes in children can provide unique data on early atherosclerosis and its determinants that are not obscured by other chronic diseases or lifestyle habits. Methods SubjectsWe studied 79 children; all were healthy nonsmokers without any regular medication and with no family history of premature vascular disease. None of the children had had symptoms of infection during the 2 weeks before the study. Subjects were children of the hospital staff members (nϭ36) and children participating in a risk factor study (nϭ44). 14 Children's parents were asked about their smoking (smoking/nonsmoking) on a questionnaire. The study protocol was approved by the local Ethics Committee. Legal guardians gave written informed consent. Ultrasound StudiesAll studies were performed in the morning to fasting subjects with the use of a Sequoia 512 mainframe (Acuson) and 13.0-MHz linear array transducer. All ultrasound scans were performed by an expe-