Listing 1 - 10 of 103 | << page >> |
Sort by
|
Choose an application
Choose an application
The Alzheimer’s disease (AD) is the most common form of dementia. Because of the ageing of the population, it will become a problem of public health since there is currently no treatment preventing or curing this disease. Although the exact cause of the disease is still unknown, two theories have been put forward : firstly the cholinergic hypothesis, on basis of which the cholinesterase inhibitors were developed – with a limited and only symptomatic effect – and secondly the amyloid hypothesis. It is the latter which is most largely accepted today, so that the attention is currently focused on the development of anti-amyloid therapies. In the context of studying the pathophysiology of AD, PET (Positron Emission Tomography) imaging has proved to be a valuable tool. PET-imaging is indeed a nuclear medical imaging technology which makes it possible both to quantify and to visualize in three dimensions biochemical and functional processes in living humans. This imaging technique uses common radiotracers such as [18F]-FDG (for the measurement of the glucose metabolism in the brain) and [11C]-PIB (for the visualization of amyloid deposits). [18F]-FDG is the only PET radiotracer currently used in clinical evaluations in the context of the differential diagnosis of dementia and for differentiating AD from a mild cognitive impairment, when a traditional evaluation (evaluation of cognition by neuropsychological tests, interview, clinical history…) fails. Thanks to its high diagnostic accuracy level, it allows the right selection of the patients evolving to MA with a view to their enrolment in clinical studies, avoiding erroneous conclusions and wastes of time and money linked with a bad selection of patients. Moreover, it makes it possible to evaluate the effects of new drugs by observing glucose metabolism changes. On the other hand, amyloid imaging is only used in research, but it proves to be a promising tool in the evaluation of drugs targeting amyloid as well as in the early diagnosis of the disease. PET imaging is used at all the research stages, but especially in the early stages because of its capacity to evaluate early the potential effectiveness of drugs. It prevents going on with studies on drugs which will not be appropriate. Moreover, studying the toxicity as well as the pharmacokinetics and pharmacodynamics of a drug can be performed on more restricted numbers of patients than in classical studies since the short radioactive half-life of the tracers used allows the repetition of the studies on the same subject and during the same day, eliminating any variability between the subjects. Lastly, the high sensitivity of PET makes it possible to evaluate with very low dose the distribution of the substances, thus avoiding any risk of toxicity and allowing to save several months or years compared to a traditional drug development schedule. La maladie d’Alzheimer (MA) est la forme la plus courante de démence. En raison du vieillissement de la population, elle est appelée à devenir un problème de santé publique vu qu’il n’existe actuellement aucun traitement permettant de prévenir ou de guérir cette maladie. Bien que la cause exacte de la maladie soit toujours inconnue, deux hypothèses ont été avancées : premièrement, l’hypothèse cholinergique, sur base de laquelle ont été créés les inhibiteurs de cholinestérases – dont l’effet est modeste et seulement symptomatique – et en second lieu l’hypothèse amyloïde. C’est cette dernière qui est la plus largement acceptée aujourd’hui, de sorte que l’attention se focalise actuellement sur la recherche de thérapies anti-amyloïdes. Pour comprendre la physiopathologie de la maladie, l’imagerie PET (Tomographie par Émission de Positrons) s’est avérée être un outil précieux. Le PET est en effet une méthode d’imagerie médicale nucléaire qui permet de visualiser en trois dimensions et de quantifier des processus biochimiques et fonctionnels dans le corps humain. Cette technique d’imagerie utilise des radiotraceurs dont les plus courants sont le [18F]-FDG (pour la mesure du métabolisme cérébral du glucose) et le [11C]-PIB (pour la visualisation des dépôts amyloïdes). Le [18F]-FDG est le seul radiotraceur PET qui soit actuellement utilisé en clinique, dans le cadre du diagnostic différentiel des démences et dans la distinction entre un trouble cognitif léger et la MA, lorsqu’une évaluation classique (évaluation de la cognition par des tests neuropsychologiques, interview, histoire clinique…) n’a pas abouti. Grâce à sa grande précision diagnostique, il permet la sélection judicieuse des patients évoluant vers une MA en vue de leur inclusion dans les études cliniques, évitant ainsi les conclusions erronées et les pertes de temps et d’argent dues à une mauvaise sélection de patients. De plus, il permet d’évaluer l’efficacité de nouveaux médicaments par les changements observés dans le métabolisme glucosé. L’imagerie de l’amyloïde, quant à elle, n’est encore utilisée qu’en recherche, mais elle constitue un outil prometteur dans l’évaluation des médicaments ciblant l’amyloïde ainsi que dans le diagnostic précoce de la maladie. En recherche, le PET est utilisé à toutes les étapes, mais surtout dans les stades précoces en raison de sa capacité à évaluer très tôt l’efficacité potentielle des médicaments. On évite ainsi de poursuivre l’étude de substances qui ne conviendront pas. De plus, l’étude de la toxicité, de la pharmacocinétique et de la pharmacodynamie d’un médicament peut être réalisée sur un nombre plus restreint de patients que dans les études traditionnelles. En effet, en raison de la courte demi-vie radioactive des traceurs, la répétition des études sur le même sujet et durant le même jour est possible, ce qui élimine la variabilité entre les sujets. Enfin, la haute sensibilité du PET permet d’évaluer avec de très faibles doses la distribution des substances, évitant ainsi tout risque de toxicité et faisant gagner plusieurs mois ou années par rapport à un programme classique de développement de médicament
Alzheimer Disease --- Alzheimer Disease --- Positron-Emission Tomography
Choose an application
Positron-Emission Tomography --- Tomography, Emission. --- Tomography, X-Ray Computed --- Methods. --- Methods.
Choose an application
Sustainable development --- Emission control --- Climate change --- Development projects --- European Union
Choose an application
Wind turbines --- Acoustic emission testing. --- Noise pollution. --- Noise --- Measurement.
Choose an application
With the development of medical imaging techniques, care of patients with cancer is likely to be improved. If still the RECIST criteria (Response Evaluation Criteria In Solids Tumors) are used for morphological assessment of response to treatments of solid tumors, the role of functional and molecular imaging will take the extend it is more suitable for monitoring anti-tumors treatments. Indeed, from the beginning of a cytotoxic or cytostatic treatment, physicians will be available to physiological parameters of the tumors that are predictive of the effectiveness of the treatment. Biomarkers to characterize these parameters are among others: metabolic markers (18F-FDG, MRS), markers of proliferation and membrane turnover (18F-FLT, 11C-Choline and 18F-FLT), perfusion markers (DCE-MRI) and diffusion markers (DW-MRI). Moreover, these biomarkers are useful to develop new anti-tumors treatments Avec l'évolution des techniques d'imagerie médicale, la prise en charge des patients souffrant d'un cancer va vraisemblablement être améliorée. Si encore aujourd'hui les critères RECIST (Response Evaluation Criteria In Solids Tumors) sont les critères les plus utilisés pour l'évaluation morphologique de la réponse aux traitements des tumeurs solides, la place de l'imagerie fonctionnelle et moléculaire va prendre de l'ampleur puisqu'elle est bien plus adaptée pour le suivi des traitements anti-tumoraux. En effet, dès le début d'un traitement cytotoxique ou cytostatique, les médecins auront à disposition des paramètres physiologiques de la tumeur qui sont prédictifs de l'efficacité du traitement. Les marqueurs biologiques permettant de caractériser ces paramètres sont entre autres: Les marqueurs métaboliques (18F-FDG, MRS), les marqueurs de prolifération et du turnover membranaire (18F-FLT, 11C-Choline et 18F-FCH), les marqueurs de perfusion (DCE-MRI) et les marqueurs de diffusion (DW-MRI). En outre, ces biomarqueurs sont utiles pour le développement de nouveaux traitements anti-tumoraux
Positron-Emission Tomography --- Biological Markers --- Drug Therapy --- Magnetic Resonance Spectroscopy
Choose an application
Wind turbines --- Acoustic emission testing. --- Noise pollution. --- Noise --- Measurement.
Choose an application
Since its discovery 50 years ago, brain dopamine has been implicated in the control of movement and cognition, and is concerned with diverse brain diseases such as Parkinson's disease, schizophrenia and drug addiction. This book is an illustrated biography of the dopamine molecule, from its synthesis in the brain to its signalling mechanisms and ultimately to its metabolic breakdown. Using colour illustrations of positron emission tomography (PET) scans, each chapter presents a specific stage in the biochemical pathway for dopamine. Writing for researchers and graduate students, Paul Cumming presents a compilation of all that has been learned about dopamine through molecular imaging, a technology which allows the measurement of formerly invisible processes in the living brain. He reviews current technical controversies in the interpretation of dopamine imaging, and presents key results illuminating brain dopamine in illness and health.
Dopamine. --- Molecular radiobiology. --- Single-photon emission computed tomography. --- Tomography, Emission-Computed. --- Tomography, Emission. --- Molecular radiation biology --- Molecular biology --- Radiobiology --- SPECT (Tomography) --- Tomography, Emission --- Computerized emission tomography --- Emission tomography --- PET (Tomography) --- PET-CT (Tomography) --- Positron emission tomography --- Positron emission transaxial tomography --- Radionuclide tomography --- Scintigraphy, Tomographic --- Tomography, Radionuclide --- Diagnosis --- Diagnostic imaging --- Positrons --- Radioisotope scanning --- Biogenic amines --- Bromocriptine --- Catecholamines --- Neurotransmitters --- Data processing --- Emission --- Dopamine --- Single-photon emission computed tomography --- Molecular radiobiology --- Tomography, Emission-Computed --- Computed Tomographic Scintigraphy --- Emission-Computed Tomography --- Radionuclide Computer-Assisted Tomography --- Radionuclide Computerized Tomography --- Radionuclide-Computed Tomography --- Radionuclide-Emission Computed Tomography --- Tomography, Computerized Emission --- CAT Scan, Radionuclide --- CT Scan, Radionuclide --- Computerized Emission Tomography --- Radionuclide Tomography, Computed --- Scintigraphy, Computed Tomographic --- Tomography, Radionuclide-Computed --- CAT Scans, Radionuclide --- CT Scans, Radionuclide --- Computed Radionuclide Tomography --- Computed Tomography, Radionuclide-Emission --- Computer-Assisted Tomographies, Radionuclide --- Computer-Assisted Tomography, Radionuclide --- Computerized Tomography, Radionuclide --- Emission Computed Tomography --- Emission Tomography, Computerized --- Radionuclide CAT Scan --- Radionuclide CAT Scans --- Radionuclide CT Scan --- Radionuclide CT Scans --- Radionuclide Computed Tomography --- Radionuclide Computer Assisted Tomography --- Radionuclide Computer-Assisted Tomographies --- Radionuclide Emission Computed Tomography --- Scan, Radionuclide CAT --- Scan, Radionuclide CT --- Scans, Radionuclide CAT --- Scans, Radionuclide CT --- Tomographic Scintigraphy, Computed --- Tomographies, Radionuclide Computer-Assisted --- Tomography, Computed Radionuclide --- Tomography, Emission Computed --- Tomography, Radionuclide Computed --- Tomography, Radionuclide Computer-Assisted --- Tomography, Radionuclide Computerized --- Tomography, Radionuclide-Emission Computed --- 3,4-Dihydroxyphenethylamine --- 4-(2-Aminoethyl)-1,2-benzenediol --- Dopamine Hydrochloride --- Intropin --- Hydroxytyramine --- 3,4 Dihydroxyphenethylamine --- Hydrochloride, Dopamine --- Dihydroxyphenylalanine --- Levodopa
Choose an application
Photons --- Photon emission --- Scattering (Physics) --- Quantum theory. --- Diffusion (Physique nucléaire) --- Théorie quantique --- Scattering --- Diffusion --- Photon emission. --- Scattering. --- Scattering (Physics). --- Diffusion (Physique nucléaire) --- Théorie quantique
Choose an application
Electromagnetic compatibility techniques and requirements for instruments measuring quasi-peak, peak, rms, and average values for electrical and electronic equipment for various applications are provided. Keywords: electromagnetic compatibility, field strength instrumentation.
Electromagnetic noise --- Electric noise --- Electromagnetic interference --- Noise --- Solar radio emission --- Standards.
Listing 1 - 10 of 103 | << page >> |
Sort by
|