To assess the prognostic value of coronary artery stenosis identification by coronary computed tomographic angiography (CCTA) for the prediction of major adverse cardiac events (MACE) in a multicenter prospective cohort study. We performed a prospective multicenter observational cohort study of symptomatic patients with suspected or known coronary artery disease (CAD) (n = 172; 57% male) undergoing CCTA in accordance to ACC/AHA Appropriateness Criteria from 4 sites in and around Paris, France, and followed for a mean duration of 22.0 +/- 4.5 months (interquartile range 18-26 months). Coronary arteries by CCTA were interpreted by physicians blinded to the patient characteristics for the presence or absence obstructive (>or=70% luminal diameter stenosis), as well as for plaque composition categorized as non-calcified, calcified or "mixed." MACE was defined as death, non-fatal myocardial infarction, unstable angina or target vessel revascularization. MACE event rates were compared between patients with or without obstructive plaque and with differing plaque compositions. MACE event rates were significantly higher in patients with obstructive coronary artery stenosis by CCTA compared to those without (61.1% vs. 3.9%, P < 0.01). In patients with obstructive stenosis, mixed (83.3% vs. 25.3%, P < 0.01) and calcified (94.4% vs. 50.7%, P < 0.01) plaque presence was significantly higher than in patients without obstructive stenosis, with no differences in prevalence of non-calcified plaque (27.8% vs. 20.8%, P = NS). For MACE, the negative predictive value of no observed coronary artery plaque was 100% in the follow-up period. In this prospective multicenter study of symptomatic patients with suspected or known CAD undergoing CCTAs interpreted by imagers blinded to patient characteristics, CCTA presence of plaque severity and composition successfully identifies patients at risk for incident MACE events. Importantly, a negative CCTA portends an extremely low risk for incidence MACE.
Patients with ESRD "End-stage renal disease" require hemodialysis. The most desirable form of vascular access is the arterio-venous fistula (AVF). It is placed surgically joining an artery and a vein together. We propose an investigation protocol to understand the correlation between hemodynamics in this vessel and the associated clinical complications. Realistic 3D reconstruction of the fistula is the result of segmenting CT angiography images for two cases. Then the geometrical model is preprocessed by hybrid meshing and CFD results are confronted with medical image data such as calcifications.
Mechanical properties of cortical human bone have been investigated for more than over three decades. The objectives of the present study were 1) to investigate the influence of multiscale structural characteristics of the bone tissue on its mechanical behavior and 2) to perform a micro-macro numerical modelling based on the experimental data. It should be noted that variations of the osteon lamellae elastic properties are higher (40%) at the microstructural level than those found at the macroscopic level (about 15%) for measurements performed in the same anatomical direction. Physico-chemical analyses found that organic components were found to be higher for femurs exhibiting lower mechanical properties. There is a consistency between changes observed at the different levels. These results contribute to a basic understanding of the multiscale mechanical behavior of human cortical bone.
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