نتایج جستجو برای: لایه واسط mbf 20
تعداد نتایج: 631172 فیلتر نتایج به سال:
AIMS Sympathetic denervation typically occurs in the infarcted myocardium and is associated with sudden cardiac death. Impaired innervation was also demonstrated in non-infarcted myocardium in ischaemic and dilated cardiomyopathy (ICMP and DCMP). Factors affecting sympathetic nerve integrity in remote myocardium are unknown. Perfusion abnormalities, even in the absence of epicardial coronary ar...
BACKGROUND The quantification of myocardial blood flow (MBF) and coronary flow reserve (CFR) are useful approaches for evaluating the functional severity of coronary artery disease (CAD). 15O-water positron emission tomography (PET) is considered the gold standard method for MBF quantification. However, MBF measurements in 15O-water PET with three-dimensional (3D) data acquisition, attenuation ...
UNLABELLED Although a parametric image of myocardial blood flow (MBF) can be obtained from H(2)(15)O PET using factor and cluster analysis, this approach is limited when factor analysis fails to extract each cardiac component. In this study, a linear least-squares (LLS) method for estimating MBF and generating a MBF parametric image was developed to overcome this limitation. The computer simula...
Purpose Endothelial dysfunction is the earliest abnormality in the development of coronary atherosclerosis. Rubidium-82 (82 Rb) is a generator-produced positron emission tomography (PET) myocardial perfusion tracer that is becoming more widely used. We aimed to develop a method for quantitative assessment of coronary endothelial function using the myocardial blood flow (MBF) response during a c...
UNLABELLED Cigarette smoking is one of the risk factors of cardiovascular diseases and is related to abnormal peripheral and coronary vascular vasomotion. Coronary vascular endothelial dysfunction is caused by chronic smoking in smokers without epicardial coronary artery stenosis. The coronary endothelial vasomotion abnormality is restored by interventions such as l-arginine or vitamin C infusi...
Background Several studies have shown the potential of semi-quantitative and fully-quantitative analysis of cardiovascular magnetic resonance (CMR) perfusion images in the diagnosis of coronary artery disease (CAD). However, estimates of myocardial blood flow (MBF) rely on accurate selection of important timing parameters. In this study, we evaluate how the identification of the timing of the S...
Background Diagnostic studies using dynamic contrast enhanced (DCE) MRI perfusion imaging typically evaluate perfusion in terms of the myocardial perfusion reserve (MPR), which is the ratio of stress to rest myocardial blood flow (MBF) measurements. The aim of this study was to establish whether or not, in the case of absolute MBF quantitation, the MPR exhibits a diagnostic advantage over the s...
OBJECTIVE The purpose of this study was to determine how calcitonin gene related peptide (CGRP) via axon reflex participates in increasing local muscle blood flow (MBF) following manual acupuncture (MA). METHODS Male Sprague-Dawley rats (N=56, 270-350 g) were used. We examined (1) the effects of MA on MBF in the tibialis anterior (TA) muscle in normal rats; (2) the effects of MA on MBF in the...
A method for measuring regional myocardial blood flow with a polarographic hydrogen-clearance technique, and its experimental application in dogs, are described. Under pentobarbitone anaesthesia, flow to the superficial (3 mm) and deep (8 mm) layers of the left ventricle was not significantly different. Neither hypocapnia (PaCO2 = 24 mm Hg) nor halothane significantly altered differential distr...
در این پژوهش، فرآیند اتصال فاز مایع گذرا (tlp) در اتصال نامتجانس سوپر آلیاژ پایه نیکلin-738 به سوپر آلیاژ پایه کبالت fsx-414 با استفاده از لایه واسط پایه نیکل mbf-80 با ضخامت μm50 بکار گرفته شده است. اتصال دهی در دمای بهینه ℃1150 و مدت زمان 5 دقیقه در کوره تحت خلا صورت گرفت. در ادامه، عملیات همگن سازی، به منظور بهبود ریزساختار و خواص مکانیکی ناحیه اتصالtlp،در دماهای 1175، 1200 و ℃1225 و به م...
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