Search results for "Positron"
showing 10 items of 1346 documents
Searches for B0 decays to combinations of charmless isoscalar mesons
2004
We search for B meson decays into two-body combinations of eta, eta', omega, and phi mesons from 89 million B B-bar pairs collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find the branching fraction BF(B0 -> eta omega) = (4.0^{+1.3}_{-1.2} +- 0.4) x 10^-6 with a significance of 4.3 sigma. For all the other decay modes we set the following 90% confidence level upper limits on the branching fractions, in units of 10^-6 : BF(B0 -> eta eta)<2.8, BF(B0 -> eta eta')<4.6, BF(B0 -> eta' eta')<10, BF(B0 -> eta'omega)<2.8, BF(B0 -> eta phi)<1.0, BF(B0 -> eta' phi)<4.5, BF(B0 -> phi phi)<1.5.
One-pot, direct incorporation of [11C]CO2 into carbamates.
2009
Why beat about the bush? An operationally simple and mild reaction based on the direct fixation of (11)CO(2) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) has been developed for the synthesis of (11)C-labeled carbamates at 75 degrees C within 10 minutes in radiochemical yields above 70% (see scheme). This strategy should be immediately useful for the construction of new radiotracers for positron emission tomography and other applications.
Search for the Lepton Flavor Violation Process J/ψ→eμ at BESIII
2013
We search for the lepton-flavor-violating decay of the $J/\psi$ into an electron and a muon using $(225.3\pm2.8)\times 10^{6}$ $J/\psi$ events collected with the BESIII detector at the BEPCII collider. Four candidate events are found in the signal region, consistent with background expectations. An upper limit on the branching fraction of $\mathcal{B}(J/\psi \to e\mu)< 1.5 \times 10^{-7}$ (90% C.L.) is obtained.
Predicting the in vivo release from a liposomal formulation by IVIVC and non-invasive positron emission tomography imaging
2010
This study aimed to predict the in vivo performance from the in vitro release of a low-molecular weight model compound, [(18)F]-2-fluoro-2-deoxy-d-glucose ([(18)F]FDG), from liposomes and by means of positron emission tomography (PET). Liposomes composed of hydrogenated phosphatidylcholine (HPC) were prepared by a freeze-thaw method. Particle size distribution was measured by dynamic light scattering (DLS). In vitro release was examined with a dispersion method detecting the radioactivity of [(18)F]FDG. In vivo release of [(18)F]FDG, following i.p. injection of the liposomes in rats, was determined by using a Micro-PET scanner. Convolution was performed to predict the in vivo profiles from …
A smart and operator independent system to delineate tumours in Positron Emission Tomography scans
2018
Abstract Positron Emission Tomography (PET) imaging has an enormous potential to improve radiation therapy treatment planning offering complementary functional information with respect to other anatomical imaging approaches. The aim of this study is to develop an operator independent, reliable, and clinically feasible system for biological tumour volume delineation from PET images. Under this design hypothesis, we combine several known approaches in an original way to deploy a system with a high level of automation. The proposed system automatically identifies the optimal region of interest around the tumour and performs a slice-by-slice marching local active contour segmentation. It automa…
The therapeutic impact of PET-FDG scanning in broncho-pulmonary cancer
2005
Because of the expected high performances of scintigraphic scans with [18F]-fluorodeoxyglucose (FDG) not only in diagnostics and but also in therapeutic impact, especially in thoracic oncology, there are a lot of French nuclear medicine departments which will soon be equipped with a positron emission tomograph (PET).The Nuclear Medicine Department of the Hôpital d'Instructions des Armées du Val-de-Grâce, Paris, led a retrospective study among physicians interested in 338 FDG-PET exams performed between may 2000 and march 2002 in order to compare its own results with international literature concerning four indications for lung cancer: pulmonary nodule or mass malignancy diagnostic, lung car…
Structural Remodeling of the Post‐pneumonectomy Lung is Characterized by Septal Retraction and Alveolar Duct Dilation
2015
Murine pneumonectomy (PNX) is an established model of adult compensatory lung growth, involving structural remodeling of the peripheral parenchyma. Following left PNX, positron emission tomography and computerized tomography have demonstrated heterogeneous growth patterns within the remaining right lung. To characterize the structural changes associated with these observations, we analyzed histological sections of the right lung between 3 and 22 days after PNX. Within 3 days of PNX, alveolar septae were significantly shorter (p<0.05) in a majority of alveolar ducts, while septal angle remained unchanged. Septal retraction resulted in an apparent dilation of the alveolar duct with a signific…
Comparison between whole-body MRI and PET/CT in staging newly diagnosed FDG-avid lymphomas: our experience.
2015
To compare whole body RMI (WB-RMI) and FDG-PET/CT for staging newly diagnosed FDG-avid lymphoma
Functional Plasticity after Unilateral Vestibular Midbrain Infarction in Human Positron Emission Tomography.
2016
The aim of the study was to uncover mechanisms of central compensation of vestibular function at brainstem, cerebellar, and cortical levels in patients with acute unilateral midbrain infarctions presenting with an acute vestibular tone imbalance. Eight out of 17 patients with unilateral midbrain infarctions were selected on the basis of signs of a vestibular tone imbalance, e.g., graviceptive (tilts of perceived verticality) and oculomotor dysfunction (skew deviation, ocular torsion) in F18-fluordeoxyglucose (FDG)-PET at two time points: A) in the acute stage, and B) after recovery 6 months later. Lesion-behavior mapping analyses with MRI verified the exact structural lesion sites. Group su…
Effects of tetrahydrocannabinol on glucose uptake in the rat brain
2017
Δ9-Tetrahydrocannabinol (THC) is the psychoactive component of the plant Cannabis sativa and acts as a partial agonist at cannabinoid type 1 and type 2 receptors in the brain. The goal of this study was to assess the effect of THC on the cerebral glucose uptake in the rat brain. 21 male Sprague Dawley rats (12-13 w) were examined and received five different doses of THC ranging from 0.01 to 1 mg/kg. For data acquisition a Focus 120 small animal PET scanner was used and 24.1-28.0 MBq of [18F]-fluoro-2-deoxy-d-glucose were injected. The data were acquired for 70 min and arterial blood samples were collected throughout the scan. THC, THC-OH and THC-COOH were determined at 55 min p.i. Nine volu…