Search results for "gadolinium"
showing 10 items of 303 documents
Fragmenting gadolinium: Mononuclear polyoxometalate-based magnetic coolers for ultra-low temperatures
2012
The polyoxometalate clusters with formula [Gd(W 5O 18) 2] 9- and [Gd(P 5W 30O 110)] 12- each carry a single magnetic ion of gadolinium, which is the most widespread element among magnetic refrigerant materials. In an adiabatic demagnetization, the lowest attainable temperature is limited by the presence of magnetic interactions that bring about magnetic order below a critical temperature. We demonstrate that this limitation can be overcome by chemically engineering the molecules in such a way to effectively screen all magnetic interactions, suggesting their use as ultra-low-temperature coolers. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Texture analysis of cardiac cine magnetic resonance imaging to detect nonviable segments in patients with chronic myocardial infarction.
2017
[EN] Purpose: To investigate the ability of texture analysis to differentiate between infarcted nonviable, viable, and remote segments on cardiac cine magnetic resonance imaging (MRI). Methods: This retrospective study included 50 patients suffering chronic myocardial infarction. The data were randomly split into training (30 patients) and testing (20 patients) sets. The left ventricular myocardium was segmented according to the 17-segment model in both cine and late gadolinium enhancement (LGE) MRI. Infarcted myocardium regions were identified on LGE in short-axis views. Nonviable segments were identified as those showing LGE 50%, and viable segments those showing 0 < LGE < 50% transmural …
All-cis-1,2,3,4,5,6-cyclohexanehexacarboxylate two-dimensional gadolinium(III) complexes: Synthesis, X-ray crystal structure and magnetic properties
2010
Abstract The first gadolinium(III) complexes with the trideprotonated form of the 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H3clhex3−) of formulae [Gd(H3clhex)(H2O)4]n·3nH2O (1) and [Gd(H3clhex)(H2O)4]n·6nH2O (2) have been prepared through the gel technique and their structures determined by single crystal X-ray diffraction. The structure of 1 is made up of 63 honey-comb layers which are generated by [Gd(H2O)4]3+ cations and H3clhex3− anions acting as three-fold nodes and three-fold connectors, respectively. The structure of 2 consists of a [44,62] two-dimensional network extended in the ac plane where the H3clhex−3 groups act as four-fold connectors and the [Gd(H2O)4]3+ units as four-fol…
Distribution of REEs in box-core sediments offshore an industrial area in SE Sicily, Ionian Sea: Evidence of anomalous sedimentary inputs
2009
The distribution of rare earth elements and yttrium (REEs+Y) has been investigated in box-core sediments recovered from four stations in the Sicilian coastal zone seawards of Augusta, one of the most industrialized and contaminated areas in the Mediterranean region. Shale-like REE patterns and low Y/Ho ratios (close to the chondritic ratio) suggest a dominant terrigenous (geogenic) source for REE. Slight enrichment of LREE over the HREE is interpreted as due to preferential adsorptive transfer of LREE from seawater to sediment particles. Samples from offshore cores exhibit slightly positive Gd and negative Ce anomalies. It is here hypothesized that main drivers of anthropogenic Gd flux towa…
Characterization and biodistribution of Au nanoparticles loaded in PLGA nanocarriers using an original encapsulation process
2021
Due to their imaging and radiosensitizing properties, ultrasmall gadolinium chelate-coated gold nanoparticles (AuNP) represent a promising approach in the diagnosis and the treatment of tumors. However, their poor pharmacokinetic profile, especially their rapid renal clearance prevents from an efficient exploitation of their potential for medical applications. The present study focuses on a strategy which resides in the encapsulation of AuNP in large polymeric NP to avoid the glomerular filtration and then to prolong the vascular residence time. An original encapsulation procedure using the polyethyleneimine (PEI) was set up to electrostatically entrap AuNP in biodegradable poly(lactic-co-g…
Terbium Medical Radioisotope Production: Laser Resonance Ionization Scheme Development
2021
Terbium (Tb) is a promising element for the theranostic approach in nuclear medicine. The new CERN-MEDICIS facility aims for production of its medical radioisotopes to support related R&D projects in biomedicine. The use of laser resonance ionization is essential to provide radioisotopic yields of highest quantity and quality, specifically regarding purity. This paper presents the results of preparation and characterization of a suitable two-step laser resonance ionization process for Tb. By resonance excitation via an auto-ionizing level, the high ionization efficiency of 53% was achieved. To simulate realistic production conditions for Tb radioisotopes, the influence of a surplus of Gd at…
Gadolinium toxicity on sea urchin embryos of geographically and phylogenetically distant species
2016
Pharmaceuticals are a class of emerging environmental contaminants. Gadolinium (Gd) is a metal of the lanthanide series of the elements whose chelates are commonly employed as contrast agents for magnetic resonance imaging, and subsequently released into the aquatic environment. We investigated the consequences of sea urchin embryo exposure to sublethal Gd concentrations, comparing the effects on the development of four phylogenetically and geographically distant species: two Mediterranean species, Paracentrotus lividus and Arbacia lixula, and two species living in the East coast of Australia, Heliocidaris tuberculata and Centrostephanus rodgersii. Measures of the Gd and Ca content inside e…
Perfusion MRI in normal and abnormal pituitary gland. A preliminary study.
1997
Perfusion MRI (magnetic resonance imaging) of the pituitary gland was performed in 20 healthy volunteers and 63 patients with various lesions involving the pituitary gland. All patients underwent sequential contrast-enhanced MRI using spoiled gradient recalled sequences with high temporal resolution (7 seconds). Four pituitary areas (pituitary stalk, posterior lobe, postero-superior, and antero-inferior adenohypophysis) were tested with a selected region of interest. Maximal contrast percentual variation was calculated. The timing of enhancement in normal patients matched perfectly with normal pituitary vascularization. Abnormal timing in pathological condition was investigated.
LI-RADS: Diagnostic Performance of Hepatobiliary Phase Hypointensity and Major Imaging Features of LR-3 and LR-4 Lesions Measuring 10-19 mm With Arte…
2019
OBJECTIVE. The purpose of this study was to determine the diagnostic performance of hepatobiliary phase hypointensity and Liver Imaging Reporting and Data System (LI-RADS) major imaging features in the diagnosis of hepatocellular carcinoma (HCC) in hepatic lesions with arterial phase hyperenhancement (APHE) measuring 10-19 mm in patients at high risk of HCC. MATERIALS AND METHODS. A composite reference standard of pathologic analysis and imaging follow-up was used. The diagnostic performance (sensitivity and specificity) of hepatobiliary phase hypointensity and LI-RADS major imaging features other than APHE for the diagnosis of HCC was assessed and compared by means of a logistic regression…
Enhancing capsule in hepatocellular carcinoma: intra-individual comparison between CT and MRI with extracellular contrast agent
2021
Purpose: The purpose of this study was to compare the value of contrast-enhanced computed tomography (CT) to that of magnetic resonance imaging obtained with extracellular contrast agent (ECA-MRI) for the diagnosis of a tumor capsule in hepatocellular carcinoma (HCC) using histopathologic findings as the standard of reference. Materials and methods: This retrospective study included patients with pathologically-proven resected HCCs with available preoperative contrast-enhanced CT and ECA-MRI examinations. Two blinded radiologists independently reviewed contrast-enhanced CT and ECA-MRI examinations to assess the presence of an enhancing capsule. The histopathological analysis of resected spe…