Search results for "positron"
showing 10 items of 1346 documents
Data for: Synthesis and evaluation of 89Zr-labeled and long-lived GLP-1 receptor agonists for PET imaging
2020
Appendix B. PET imaging 3D rendered images. 1. PET 3D of 4-89Zr 2. PET 3D of 5-89Zr
Low in vivo brain glucose consumption and high oxidative stress in accelerated aging
2009
AbstractThe validity of the free radical theory of aging has been recently questioned. Our aim was to test whether there is oxidative stress in tissues critically involved in accelerated aging (senescence-accelerated mice, SAM) and whether this correlates with lower glucose consumption in vivo and behavioural tests. Positron emission tomography shows that brains of old SAM-prone animals consume less glucose than young ones. Behavioural characteristics, mitochondrial peroxide production, and damage in both the central nervous system and bone marrow stem cells also indicate that SAM-prone animals age faster than SAM-resistant ones. Our results support the role of the free radical theory of ag…
Active contour algorithm with discriminant analysis for delineating tumors in positron emission tomography.
2019
Abstract In the context of cancer delineation using positron emission tomography datasets, we present an innovative approach which purpose is to tackle the real-time, three-dimensional segmentation task in a full, or at least nearly full automatized way. The approach comprises a preliminary initialization phase where the user highlights a region of interest around the cancer on just one slice of the tomographic dataset. The algorithm takes care of identifying an optimal and user-independent region of interest around the anomalous tissue and located on the slice containing the highest standardized uptake value so to start the successive segmentation task. The three-dimensional volume is then…
The diagnostic possibilities of Positron Emission Tomography (PET)
2014
Se describen los principios de la tomografía por emisión de positrones (PET) como procedimiento diagnóstico de reciente introducción en el campo de las Ciencias de la Salud. Las aplicaciones clínicas principales se dan en un grupo concreto de especialidades: la cardiología, neurología, psiquiatría y sobre todo la oncología. La tomografía por emisión de positrones es una técnica de diagnóstico por la imagen no invasiva de uso clínico. Se trata de una excelente herramienta para el estudio de la estadificación y la posible malignización de los tumores de cabeza y cuello, la detección de metástasis y linfoadenopatías no valorables clínicamente, así como para el diagnóstico de recidivas tumorale…
Immunohistochemical expression of glucose transporter 1 in keratin-producing odontogenic cysts
2016
Background: Keratin-producing odontogenic cysts (KPOCs) are a group of cystic lesions that are often aggressive, with high rates of recurrence and multifocality. KPOCs included orthokeratinised odontogenic cyst (OOC) and parakeratotic odontogenic cysts, which are now considered true tumours denominated keratocystic odontogenic tumours (KCOTs). GLUT1 is a protein transporter that is involved in the active uptake of glucose across cell membranes and that is overexpressed in tumours in close correlation with the proliferation rate and positron emission tomography (PET) imaging results. Methods: A series of 58 keratin-producing odontogenic cysts was evaluated histologically and immunohistochemi…
An Unusual Presentation of Zollinger-Ellison Syndrome
2013
Abstract Zollinger-Ellison syndrome is an often progressive, persistent and frequently life-threatening disease, described for the first time as characterized by ulceration of the upper jejunum, hypersecretion of gastric acid and non-beta islet cell tumors of the pancreas; this syndrome is due to the hypersecretion of gastrin. We report a case of Zollinger-Ellison syndrome presenting as severe esophagitis evolving in stenosis, which demonstrates how a delayed diagnosis may induce risk of disease spreading. In this setting new diagnostic approaches, such as somatostatin receptor scanning and positron emission tomography with 68 Ga-labeled octreotide, could be particularly useful, as well as …
Image quality analysis of
2019
Background 44Sc has been increasingly investigated as a potential alternative to 68Ga in the development of tracers for positron emission tomography (PET). The lower mean positron energy of 44Sc (0.63 MeV) compared to 68Ga (0.83 MeV) can result in better spatial image resolutions. However, high-energy γ-rays (1157 keV) are emitted at high rates (99.9%) during 44Sc decay, which can reduce image quality. Therefore, we investigated the impact of these physical properties and performed an unbiased performance evaluation of 44Sc and 68Ga with different imaging phantoms (image quality phantom, Derenzo phantom, and three-rod phantom) on two preclinical PET scanners (Mediso nanoScan PET/MRI, Siemen…
Effect of magnetic field on the corrosion of iron and St20 steel as studied by positron annihilation
2010
Lifetime spectra of positron annihilation in iron and St20 steel corroded in the water solution of HCl and in vapour above its surface have been investigated with emphasis on the effect of corrosion time and environment (solution or vapour) as well as of the presence and orientation of the magnetic field on the measured positron annihilation parameters. All the registered positron lifetime spectra consist of two components. For corroded samples the intensities of the two components as well as the corresponding values of the mean positron lifetime, differ from those for uncorroded material. The corrosion-induced changes in the positron annihilation parameters depend on the corrosion environm…
Spectra of Positrons Lifetimes in Choose Gel Drugs
2006
antiphlogistic drugs were investigated. The basic components in them were sodium salts of diclophenac and they difiered from one another with the chemical composition of other components. It was found that in all of the investigated spectra there occurred a component which testifled to the formation of positronium. The difierences in the values of ortho-Ps component lifetimes and their intensity can be attributed to the presence of ingredients modifying the efiects of the drug.
Vacancies and Carbon Impurities in Iron
1981
Point defects in electron-irradiated high-purity α-iron have been studied by positron lifetime measurements. We show that the migration stage of monovacancies occurs already as low as at 220 K, which results in agglomeration of small three-dimensional vacancy clusters. Furthermore, we irradiated carbon-doped iron specimens, where formation of highly asymmetric monovacancycarbon atom pairs was detected during the migration stage of monovacancies at 220 K.