نتایج جستجو برای: attenuation correction
تعداد نتایج: 212408 فیلتر نتایج به سال:
Introduction: Metallic artifacts due to pacemaker/ implantable cardioverter defibrillator (ICD) leads in CT images can produce artifactual uptake in cardiac SPECT/CT images. The aim of this study was to determine the influence of the metallic artifacts due to pacemaker and ICD leads on myocardial SPECT/CT imaging. Methods: The study included 9 patients wh...
In this paper we describe and evaluate an image-based spectral CT method. Its central formula expresses measured CT data as a spectral integration of the spectral attenuation coefficient multiplied by a Local Weighting Function (LWF). The LWF represents the local energy weighting in the image domain, taking into account the system and reconstruction properties and the object self attenuation. A...
There is a renewed interest in the use of X-band weather radars, due to specific advantages such as applications to rainfall estimation in light rain, monitoring of sensitive areas that are inadequately covered by operational radar networks as well as the radar network concept introduced by the Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) (Chandrasekar et al. 2004). The us...
UNLABELLED Cardiac PET combined with CT is rapidly expanding despite artifactual defects and false-positive results due to misregistration of PET and CT attenuation correction data-the frequency, cause, and correction of which remain undetermined. METHODS Two hundred fifty-nine consecutive patients underwent diagnostic rest-dipyridamole myocardial perfusion PET/CT using (82)Rb, a 16-slice PET...
There has been a longstanding interest in fused images of anatomical information, such as that provided by computed tomography (CT) or magnetic resonance imaging (MRI) systems, with biological information obtainable by positron emission tomography (PET). The near-simultaneous data acquisition in a fixed combination of a PET and a CT scanner in a combined PET/CT imaging system minimizes spatial ...
Molecular absorption by the precipitation media is known to reduce values of horizontal reflectivity (ZH) and differential reflectivity (ZDR) for precipitation radars operating at relatively short wavelengths. This attenuation effect is most pronounced behind intense convective echoes. With the advent of polarization diversity, differential propagation phase measurements (ΦDP) offer the advanta...
Behseta S, Berdyyeva T, Olson CR, Kass RE. Bayesian correction for attenuation of correlation in multi-trial spike count data. J Neurophysiol 101: 2186–2193, 2009. First published January 7, 2009; doi:10.1152/jn.90727.2008. When correlation is measured in the presence of noise, its value is decreased. In single-neuron recording experiments, for example, the correlation of selectivity indices in...
Molecular brain imaging using positron emission tomography (PET) has evolved into a vigorous academic field and is progressively gaining importance in the clinical arena. Significant progress has been made in the design of high-resolution three-dimensional (3-D) PET units dedicated to brain research and the development of quantitative imaging protocols incorporating accurate image correction te...
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