425 research outputs found

    MITRAL ANNULAR AREA: ACCURACY OF SINGLE AND BIPLANE LINEAR MEASUREMENTS COMPARED TO 3D PLANIMETRY

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    Real-Time Segmentation of 4D Ultrasound by Active Geometric Functions

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    Four-dimensional ultrasound based on matrix phased array transducers can capture the complex 4D cardiac motion in a complete and real-time fashion. However, the large amount of information residing in 4D ultrasound scans and novel applications under interventional settings pose a big challenge in efficiency for workflow and computer-aided diagnostic algorithms such as segmentation. In this context, a novel formulation framework of the minimal surface problem, called active geometric functions (AGF), is proposed to reach truly real-time performance in segmenting 4D ultrasound data. A specific instance of AGF based on finite element modeling and Hermite surface descriptors was implemented and evaluated on 35 4D ultrasound data sets with a total of 425 time frames. Quantitative comparison to manual tracing showed that the proposed method provides LV contours close to manual segmentation and that the discrepancy was comparable to inter-observer tracing variability. The ability of such realtime segmentation will not only facilitate the diagnoses and workflow, but also enables novel applications such as interventional guidance and interactive image acquisition with online segmentation

    Segmentation of RT3D Ultrasound with Implicit Deformable Models Without Gradients

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    This paper presents the implementation and validation of a new 3D deformable model method, based on the Mumford-Shah functional for segmentation of three-dimensional real-time ultrasound. An experiment on 10 patients with primary hypertension was carried out to compare three segmentation methods for quantification of right and left ventricular ejection fraction: (1) manual tracing by an expert cardiologist, (2) 2D parametric deformable model, and (3) 3D implicit deformable model implemented with a level set framework. Deformable model segmentations were performed on denoised data using a (3D+Time) brushlet expansion. The clinical study showed superior performance of the deformable model in assessing ejection fraction when compared to MRI measures. It also showed that the three-dimensional deformable model improved EF measures, which is explained by a more accurate segmentation of small and convoluted ventricular shapes when integrating the third spatial dimension

    Quantitative Three-Dimensional Wall Motion Analysis Predicts Ischemic Region Size and Location

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    Stress echocardiography is an important screening test for coronary artery disease. Currently, cardiologists rely on visual analysis of left ventricular (LV) wall motion abnormalities, which is subjective and qualitative. We previously used finite-element models of the regionally ischemic left ventricle to develop a wall motion measure, 3DFS, for predicting ischemic region size and location from real-time 3D echocardiography (RT3DE). The purpose of this study was to validate these methods against regional blood flow measurements during regional ischemia and to compare the accuracy of our methods to the current state of the art, visual scoring by trained cardiologists. We acquired RT3DE images during 20 brief (<2min) coronary occlusions in dogs and determined ischemic region size and location by microsphere-based measurement of regional perfusion. We identified regions of abnormal wall motion using 3DFS and by blinded visual scoring. 3DFS predicted ischemic region size well (correlation r 2=0.64 against microspheres, p<0.0001), reducing error by more than half compared to visual scoring (8±9% vs. 19±14%, p<0.05), while localizing the ischemic region with equal accuracy. We conclude that 3DFS is an objective, quantitative measure of wall motion that localizes acutely ischemic regions as accurately as wall motion scoring while providing superior quantification of ischemic region siz

    Effect of Anger Provocation on Endothelium-Dependent and -Independent Vasodilation

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    Anger is an independent predictor of coronary heart disease events, although the mechanisms for this relation are unclear. The effects of an anger-provoking interview compared with a neutral interview on endothelium-dependent and -independent vasodilation assessed by brachial artery ultrasound were examined in 14 healthy subjects without coronary heart disease risk factors. The anger provocation condition, but not the neutral condition, caused a significant impairment in endothelium-dependent vasodilation at 90 minutes compared with baseline (p = 0.004) and 30 minutes (p = 0.013). Similarly, endothelium-independent vasodilation was significantly impaired at 90 minutes after the angry interview compared with baseline (p = 0.003) and 30 minutes (p = 0.001). The decreases in endothelium-dependent and -independent vasodilation were greater after the anger-provoking interview than after the neutral interview, especially between 30 and 90 minutes. In conclusion, preliminary results suggest that an episode of anger is associated with a dysregulation in endothelium-dependent and -independent pathways, suggesting that these mechanisms might contribute to the link between anger and coronary heart disease events. Although anger is associated with increased short- and long-term risk for coronary heart disease (CHD) events, independent of traditional CHD risk factors,1, 2, 3, 4, 5 and 6 the mechanisms that underlie this relation are unknown. Endothelial dysfunction plays a major role in the development of atherosclerosis.7 Traditional CHD risk factors are associated with endothelial dysfunction8 and may also impair arterial vasodilation in response to exogenous nitric oxide (NO), suggesting concomitant vascular smooth muscle dysfunction.8 and 9 Thus, the higher risk for CHD events associated with anger may be similarly mediated through an impairment in endothelium-dependent vasodilation (EDV) with or without an impairment in endothelium-independent vasodilation (EIV). To our knowledge, the effects of anger on EDV and EIV have never previously been examined. To test this hypothesis, we examined the effects of anger induction in humans on EDV and EIV assessed by brachial artery ultrasonography
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