نتایج جستجو برای: partial volume effect
تعداد نتایج: 2103220 فیلتر نتایج به سال:
Several practical issues must be considered when solid electrical insulation is used in a low pressure environment. While the low pressure environment or partial vacuum (in this context, a region which is almost devoid of any gaseous media) can exhibit good electrical insulating properties, the materials contained within the partial vacuum will effect the insulation integrity over time. Degrada...
Mean diffusivity (MD) measured by diffusion tensor imaging can reflect microstructural alterations of the brain's gray matter (GM). Therefore, GM MD may be a sensitive marker of neurodegeneration related to Alzheimer's Disease (AD). However, due to partial volume effects (PVE), differences in MD may be overestimated because of a higher degree of brain atrophy in AD patients and in cases with mi...
PURPOSE The aim of this study was to clarify the impacts of acquisition parameters on artifacts in four-dimensional computed tomography (4D CT) images, such as the partial volume effect (PVE), partial projection effect (PPE), and mis-matching of initial motion phases between adjacent beds (MMimph) in cine mode scanning. METHODS A thoracic phantom and two cylindrical phantoms (2 cm diameter an...
A partial spatial object is a partial map from space to data. Data types of partial spatial objects are modelled by topological algebras of partial maps and are the foundation for a high level approach to volume graphics called constructive volume geometry (CVG), where space and data are subspaces of n dimensional Euclidean space. We investigate the computability of partial spatial object data ...
the density (d), speed of sound (u) and electrolytic conductivity (λ) for systems containing acetaminophen, ionic liquid {1-octyl-3-methyl imidazolium bromide, [omim] br} and water have been measured at t = 293.15-308.15 k. the measured data have been applied to calculate, standard partial molar volume ( ), hepler’s constant , apparent molar isentropic compressibility (kφ), transfer volume ( ),...
Continuous non-invasive blood pressure (BP) measurement can be realized by using pulse transit time (PTT) based on electrocardiogram (ECG) and pulse wave signal. Modulated magnetic signature of blood (MMSB) is a promising approach to obtain PTT. The origin of MMSB is critical to establish the relationship between MMSB and BP. In this paper, two possible origins of MMSB, blood disturbance mechan...
Several studies using single photon emission tomography (SPECT) have shown changes in cerebral blood flow (CBF) with age, which were associated with partial volume effects by some authors. Some studies have also demonstrated gender-related differences in CBF. The present study aimed to examine age and gender effects on CBF SPECT images obtained using the 99mTc-ethyl cysteinate dimer and a SPECT...
An accurate segmentation is critical, especially when the tumor morphological changes remain subtle, irregular and difficult to assess by clinical examination. This quantitative measurement depends on the accuracy of the segmentation method used. The undesired partial volume effect, which lies on a boundary between a high intensity region and low intensity region, makes unerring boundary determ...
As most local recurrence after breast-conserving treatment occurs within 2 cm around the lumpectomy cavity, wide-volume partial breast rather than whole breast irradiation has been actively investigated with a view to decreasing radiation toxicities. Replacing external beam radiotherapy by wide-volume interstitial brachytherapy offers the advantages of more accurate treatment volume coverage an...
Background: Previous studies have shown that progesterone increases the ventilatory performance in healthy individuals and in patients with chronic obstructive pulmonary disorders. The study was designed to investigate the effect of a single intramuscular administration of progesterone on ventilatory performance in adult trauma patients during partial support mechanical ventilation. Methods: Fo...
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