Intimal thickness determines the detection of non-calcified plaques by computed tomography angiography

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Coronary atherosclerosis and wall shear stress: Towards application of CT angiography

__Abstract__ Vulnerable plaques are characterized by the presence of a large lipid pool, which is separated from the lumen by a thin fibrous cap, often infiltrated by macro phages [Schaar-04]. Rupture of this fibrous cap is generally regarded as one of the main underlying causes of cardiovascular events [Fa!k-95]. Rupture occurs when the stresses in the cap of the plaque exceed the strength of the cap [Lee-93]. The composition of the plaque plays a crucial role in the rupture process: it determines how blood pressure is translated into stresses in the wall, and composition also determines the strength of the tissue [Loree-94, Holzapfel-05]

3D fusion of intravascular ultrasound and coronary computed tomography for in-vivo wall shear stress analysis: A feasibility study

Wall shear stress, the force per area acting on the lumen wall due to the blood flow, is an important biomechanical parameter in the localization and progression of atherosclerosis. To calculate shear stress and relate it to atherosclerosis, a 3D description of the lumen and vessel wall is required. We present a framework to obtain the 3D reconstruction of human coronary arteries by the fusion of intravascular ultrasound (IVUS) and coronary computed tomography angiography (CT). We imaged 23 patients with IVUS and CT. The images from both modalities were registered for 35 arteries, using bifurcations as landmarks. The IVUS images together with IVUS derived lumen and wall contours were positioned on the 3D centerline, which was derived from CT. The resulting 3D lumen and wall contours were transformed to a surface for calculation of shear stress and plaque thickness. We applied variations in selection of landmarks and investigated whether these variations influenced the relation between shear stress and plaque thickness. Fusion was successfully achieved in 31 of the 35 arteries. The average length of the fused segments was 36.4 ± 15.7 mm. The length in IVUS and CT of the fused parts correlated excellently (R2= 0.98). Both for a mildly diseased and a very diseased coronary artery, shear stress was calculated and related to plaque thickness. Variations in the selection of the landmarks for these two arteries did not affect the relationship between shear stress and plaque thickness. This new framework can therefore successfully be applied for shear stress analysis in human coronary arteries

Plaque and shear stress distribution in human coronary bifurcations: A multislice computed tomography study

Aims: Early atherosclerosis is located in low wall shear-stress (WSS) regions, however plaques are also found in the high WSS sensing flow divider walls of coronary bifurcations. We assessed the plaque distribution and morphology near bifurcations n

Het verloop van tekenpopulaties en de besmetting van teken met Borrelia en Ehrlichia. Resultaten van onderzoek in de periode van 2001-2005

In 2000 is een onderzoek gestart naar de aanwezigheid van teken en de besmetting van teken met Borrelia en Ehrlichia in vier qua vegetatie sterk verschillende recreatieve gebieden: een recreatief duingebied, een recreatief heidegebied, een recreatief bosgebied en een recreatief gebied in het stedelijk groen. Aanleiding voor het onderzoek was het vermoeden dat er tegenwoordig méér teken voorkomen dan vroeger en dat door de aanwezigheid van méér teken risico’s voor het oplopen van de door teken overgebrachte bacterie Borellia veroorzaakte ziekte van Lyme groter zouden zijn voor bezoekers van natuurgebieden. Omdat de omvang van de tekenpopulaties van jaar tot jaar sterk kunnen verschillen (waarbij de weersomstandigheden en daaraan gerelateerde fenomenen vermoedelijk een grote rol spelen) blijft langdurig onderzoek noodzakelijk. In dit verslag worden de tot nu toe verkregen resultaten van de periode 2000-2005 besproke

Head-To-Head Comparison of PET and Perfusion Weighted MRI Techniques to Distinguish Treatment Related Abnormalities from Tumor Progression in Glioma.

The post-treatment imaging surveillance of gliomas is challenged by distinguishing tumor progression (TP) from treatment-related abnormalities (TRA). Sophisticated imaging techniques, such as perfusion-weighted magnetic resonance imaging (MRI PWI) and positron-emission tomography (PET) with a variety of radiotracers, have been suggested as being more reliable than standard imaging for distinguishing TP from TRA. However, it remains unclear if any technique holds diagnostic superiority. This meta-analysis provides a head-to-head comparison of the diagnostic accuracy of the aforementioned imaging techniques. Systematic literature searches on the use of PWI and PET imaging techniques were carried out in PubMed, Embase, the Cochrane Library, ClinicalTrials.gov and the reference lists of relevant papers. After the extraction of data on imaging technique specifications and diagnostic accuracy, a meta-analysis was carried out. The quality of the included papers was assessed using the QUADAS-2 checklist. Nineteen articles, totaling 697 treated patients with glioma (431 males; mean age ± standard deviation 50.5 ± 5.1 years) were included. The investigated PWI techniques included dynamic susceptibility contrast (DSC), dynamic contrast enhancement (DCE) and arterial spin labeling (ASL). The PET-tracers studied concerned [S-methyl-(11)C]methionine, 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG), O-(2-[(18)F]fluoroethyl)-L-tyrosine ([(18)F]FET) and 6-[(18)F]-fluoro-3,4-dihydroxy-L-phenylalanine ([(18)F]FDOPA). The meta-analysis of all data showed no diagnostic superior imaging technique. The included literature showed a low risk of bias. As no technique was found to be diagnostically superior, the local level of expertise is hypothesized to be the most important factor for diagnostically accurate results in post-treatment glioma patients regarding the distinction of TRA from TP