Gadolinium

Gadolinium is a chemical element with symbol Gd and atomic number 64. Gadolinium is a silvery-white, malleable, and ductile rare earth metal. It is found in nature only in oxidized form, and even when separated, it usually has impurities of the other rare earths. Gadolinium was discovered in 1880 by Jean Charles de Marignac, who detected its oxide by using spectroscopy. It is named after the mineral gadolinite, one of the minerals in which gadolinium is found, itself named for the chemist Johan Gadolin. Pure gadolinium was first isolated by the chemist Paul Emile Lecoq de Boisbaudran around 1886.

Gadolinium possesses unusual metallurgical properties, to the extent that as little as 1% of gadolinium can significantly improve the workability and resistance to oxidation at high temperatures of iron, chromium, and related metals. Gadolinium as a metal or a salt absorbs neutrons and is, therefore, used sometimes for shielding in neutron radiography and in nuclear reactors.

Like most of the rare earths, gadolinium forms trivalent ions with fluorescent properties, and salts of gadolinium(III) are used as phosphors in various applications.

The kinds of gadolinium(III) ions occurring in water-soluble salts are toxic to mammals. However, chelated gadolinium(III) compounds are far less toxic because they carry gadolinium(III) through the kidneys and out of the body before the free ion can be released into the tissues. Because of its paramagnetic properties, solutions of chelated organic gadolinium complexes are used as intravenously administered gadolinium-based MRI contrast agents in medical magnetic resonance imaging.

Gadolinium,  64Gd
Gadolinium-4
Gadolinium
Pronunciation/ˌɡædəˈlɪniəm/ (GAD-ə-LIN-ee-əm)
Appearancesilvery white
Standard atomic weight Ar, std(Gd)157.25(3)[1]
Gadolinium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


Gd

Cm
europiumgadoliniumterbium
Atomic number (Z)64
Groupgroup n/a
Periodperiod 6
Blockf-block
Element category  lanthanide
Electron configuration[Xe] 4f7 5d1 6s2
Electrons per shell
2, 8, 18, 25, 9, 2
Physical properties
Phase at STPsolid
Melting point1585 K ​(1312 °C, ​2394 °F)
Boiling point3273 K ​(3000 °C, ​5432 °F)
Density (near r.t.)7.90 g/cm3
when liquid (at m.p.)7.4 g/cm3
Heat of fusion10.05 kJ/mol
Heat of vaporization301.3 kJ/mol
Molar heat capacity37.03 J/(mol·K)
Vapor pressure (calculated)
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1836 2028 2267 2573 2976 3535
Atomic properties
Oxidation states+1, +2, +3 (a mildly basic oxide)
ElectronegativityPauling scale: 1.20
Ionization energies
  • 1st: 593.4 kJ/mol
  • 2nd: 1170 kJ/mol
  • 3rd: 1990 kJ/mol
Atomic radiusempirical: 180 pm
Covalent radius196±6 pm
Color lines in a spectral range
Spectral lines of gadolinium
Other properties
Natural occurrenceprimordial
Crystal structurehexagonal close-packed (hcp)
Hexagonal close packed crystal structure for gadolinium
Speed of sound thin rod2680 m/s (at 20 °C)
Thermal expansionα poly: 9.4 µm/(m·K) (at 100 °C)
Thermal conductivity10.6 W/(m·K)
Electrical resistivityα, poly: 1.310 µΩ·m
Magnetic orderingferromagnetic-paramagnetic transition at 293.4 K
Magnetic susceptibility+755,000.0·10−6 cm3/mol (300.6 K)[2]
Young's modulusα form: 54.8 GPa
Shear modulusα form: 21.8 GPa
Bulk modulusα form: 37.9 GPa
Poisson ratioα form: 0.259
Vickers hardness510–950 MPa
CAS Number7440-54-2
History
Namingafter the mineral Gadolinite (itself named after Johan Gadolin)
DiscoveryJean Charles Galissard de Marignac (1880)
First isolationLecoq de Boisbaudran (1886)
Main isotopes of gadolinium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
148Gd syn 75 y α 144Sm
150Gd syn 1.8×106 y α 146Sm
152Gd 0.20% 1.08×1014 y α 148Sm
154Gd 2.18% stable
155Gd 14.80% stable
156Gd 20.47% stable
157Gd 15.65% stable
158Gd 24.84% stable
160Gd 21.86% stable

Characteristics

Gadolinium-2
A sample of gadolinium metal

Physical properties

Gadolinium is a silvery-white malleable and ductile rare earth metal. It crystallizes in the hexagonal close-packed α-form at room temperature, but, when heated to temperatures above 1235 °C, it transforms into its β-form, which has a body-centered cubic structure.[3]

The isotope gadolinium-157 has the highest thermal-neutron capture cross-section among any stable nuclide: about 259,000 barns. Only xenon-135 has a higher capture cross-section, about 2.0 million barns, but this isotope is radioactive.[4]

Gadolinium is believed to be ferromagnetic at temperatures below 20 °C (68 °F)[5] and is strongly paramagnetic above this temperature. There is evidence that gadolinium is a helical antiferromagnetic, rather than a ferromagnetic, below 20 °C (68 °F).[6] Gadolinium demonstrates a magnetocaloric effect whereby its temperature increases when it enters a magnetic field and decreases when it leaves the magnetic field. The temperature is lowered to 5 °C (41 °F) for the gadolinium alloy Gd85Er15, and this effect is considerably stronger for the alloy Gd5(Si2Ge2), but at a much lower temperature (<85 K (−188.2 °C; −306.7 °F)).[7] A significant magnetocaloric effect is observed at higher temperatures, up to about 300 kelvins, in the compounds Gd5(SixGe1−x)4.[8]

Individual gadolinium atoms can be isolated by encapsulating them into fullerene molecules, where they can be visualized with transmission electron microscope.[9] Individual Gd atoms and small Gd clusters can be incorporated into carbon nanotubes.[10]

Chemical properties

Gadolinium combines with most elements to form Gd(III) derivatives. It also combines with nitrogen, carbon, sulfur, phosphorus, boron, selenium, silicon, and arsenic at elevated temperatures, forming binary compounds.[11]

Unlike the other rare-earth elements, metallic gadolinium is relatively stable in dry air. However, it tarnishes quickly in moist air, forming a loosely-adhering gadolinium(III) oxide (Gd2O3):

4 Gd + 3 O2 → 2 Gd2O3,

which spalls off, exposing more surface to oxidation.

Gadolinium is a strong reducing agent, which reduces oxides of several metals into their elements. Gadolinium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form gadolinium hydroxide:

2 Gd + 6 H2O → 2 Gd(OH)3 + 3 H2.

Gadolinium metal is attacked readily by dilute sulfuric acid to form solutions containing the colorless Gd(III) ions, which exist as [Gd(H2O)9]3+ complexes:[12]

2 Gd + 3 H2SO4 + 18 H2O → 2 [Gd(H2O)9]3+ + 3 SO2−
4
+ 3 H2.

Gadolinium metal reacts with the halogens (X2) at temperature about 200 °C:

2 Gd + 3 X2 → 2 GdX3.

Chemical compounds

In the great majority of its compounds, gadolinium adopts the oxidation state +3. All four trihalides are known. All are white, except for the iodide, which is yellow. Most commonly encountered of the halides is gadolinium(III) chloride (GdCl3). The oxide dissolves in acids to give the salts, such as gadolinium(III) nitrate.

Gadolinium(III), like most lanthanide ions, forms complexes with high coordination numbers. This tendency is illustrated by the use of the chelating agent DOTA, an octadentate ligand. Salts of [Gd(DOTA)] are useful in magnetic resonance imaging. A variety of related chelate complexes have been developed, including gadodiamide.

Reduced gadolinium compounds are known, especially in the solid state. Gadolinium(II) halides are obtained by heating Gd(III) halides in presence of metallic Gd in tantalum containers. Gadolinium also form sesquichloride Gd2Cl3, which can be further reduced to GdCl by annealing at 800 °C. This gadolinium(I) chloride forms platelets with layered graphite-like structure.[13]

Isotopes

Naturally occurring gadolinium is composed of six stable isotopes, 154Gd, 155Gd, 156Gd, 157Gd, 158Gd and 160Gd, and one radioisotope, 152Gd, with the isotope 158Gd being the most abundant (24.84% natural abundance). The predicted double beta decay of 160Gd has never been observed (the only lower limit on its half-life of more than 1.3×1021 years has been set experimentally[14]).

29 radioisotopes of gadolinium have been observed, with the most stable being 152Gd (naturally occurring), with a half-life of about 1.08×1014 years, and 150Gd, with a half-life of 1.79×106 years. All of the remaining radioactive isotopes have half-lives of less than 75 years. The majority of these have half-lives of less than 25 seconds. Gadolinium isotopes have four metastable isomers, with the most stable being 143mGd (t1/2 = 110 seconds), 145mGd (t1/2 = 85 seconds) and 141mGd (t1/2 = 24.5 seconds).

The isotopes with atomic masses lower than the most abundant stable isotope, 158Gd, primarily decay by electron capture to isotopes of europium. At higher atomic masses, the primary decay mode is beta decay, and the primary products are isotopes of terbium.

History

Gadolinium is named after the mineral gadolinite, in turn named after Finnish chemist and geologist Johan Gadolin.[3] In 1880, the Swiss chemist Jean Charles Galissard de Marignac observed the spectroscopic lines from gadolinium in samples of gadolinite (which actually contains relatively little gadolinium, but enough to show a spectrum) and in the separate mineral cerite. The latter mineral proved to contain far more of the element with the new spectral line. De Marignac eventually separated a mineral oxide from cerite, which he realized was the oxide of this new element. He named the oxide "gadolinia". Because he realized that "gadolinia" was the oxide of a new element, he is credited with discovery of gadolinium. The French chemist Paul Émile Lecoq de Boisbaudran carried out the separation of gadolinium metal from gadolinia in 1886.

Occurrence

Gadolinitas
Gadolinite

Gadolinium is a constituent in many minerals such as monazite and bastnäsite, which are oxides. The metal is too reactive to exist naturally. Paradoxically, as noted above, the mineral gadolinite actually contains only traces of this element. The abundance in the Earth's crust is about 6.2 mg/kg.[3] The main mining areas are in China, the US, Brazil, Sri Lanka, India, and Australia with reserves expected to exceed one million tonnes. World production of pure gadolinium is about 400 tonnes per year. The only known mineral with essential gadolinium, lepersonnite-(Gd), is very rare.[15][16]

Production

Gadolinium is produced both from monazite and bastnäsite.

  1. Crushed minerals are extracted with hydrochloric acid or sulfuric acid, which converts the insoluble oxides into soluble chlorides or sulfates.
  2. The acidic filtrates are partially neutralized with caustic soda to pH 3–4. Thorium precipitates as its hydroxide, and is then removed.
  3. The remaining solution is treated with ammonium oxalate to convert rare earths into their insoluble oxalates. The oxalates are converted to oxides by heating.
  4. The oxides are dissolved in nitric acid that excludes one of the main components, cerium, whose oxide is insoluble in HNO3.
  5. The solution is treated with magnesium nitrate to produce a crystallized mixture of double salts of gadolinium, samarium and europium.
  6. The salts are separated by ion exchange chromatography.
  7. The rare earth ions are then selectively washed out by a suitable complexing agent.[3]

Gadolinium metal is obtained from its oxide or salts by heating it with calcium at 1450 °C in an argon atmosphere. Sponge gadolinium can be produced by reducing molten GdCl3 with an appropriate metal at temperatures below 1312 °C (the melting point of Gd) at a reduced pressure.[3]

Applications

Gadolinium has no large-scale applications, but it has a variety of specialized uses.

Because 157Gd has a high neutron cross-section, it is used to target tumors in neutron therapy. This element is effective for use with neutron radiography and in shielding of nuclear reactors. It is used as a secondary, emergency shut-down measure in some nuclear reactors, particularly of the CANDU reactor type.[3] Gadolinium is also used in nuclear marine propulsion systems as a burnable poison.

Gadolinium possesses unusual metallurgic properties, with as little as 1% of gadolinium improving the workability and resistance of iron, chromium, and related alloys to high temperatures and oxidation.

Gadolinium is paramagnetic at room temperature, with a ferromagnetic Curie point of 20 °C.[5] Paramagnetic ions, such as gadolinium, enhance nuclear relaxation rates, making gadolinium useful for magnetic resonance imaging (MRI). Solutions of organic gadolinium complexes and gadolinium compounds are used as intravenous MRI contrast agent to enhance images in medical magnetic resonance imaging and magnetic resonance angiography (MRA) procedures. Magnevist is the most widespread example.[17][18] Nanotubes packed with gadolinium, called "gadonanotubes", are 40 times more effective than the usual gadolinium contrast agent.[19] Once injected, gadolinium-based contrast agents accumulate in abnormal tissues of the brain and body, which provides a greater image contrast between normal and abnormal tissues, facilitating location of abnormal cell growths and tumors.

Gadolinium as a phosphor is also used in other imaging. In X-ray systems gadolinium is contained in the phosphor layer, suspended in a polymer matrix at the detector. Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) at the phosphor layer converts the X-rays released from the source into light. This material emits green light at 540 nm due to the presence of Tb3+, which is very useful for enhancing the imaging quality. The energy conversion of Gd is up to 20%, which means that 1/5 of the X-ray energy striking the phosphor layer can be converted into visible photons. Gadolinium oxyorthosilicate (Gd2SiO5, GSO; usually doped by 0.1–1% of Ce) is a single crystal that is used as a scintillator in medical imaging such as positron emission tomography or for detecting neutrons.[20]

Gadolinium compounds are also used for making green phosphors for color TV tubes.

Gadolinium-153 is produced in a nuclear reactor from elemental europium or enriched gadolinium targets. It has a half-life of 240±10 days and emits gamma radiation with strong peaks at 41 keV and 102 keV. It is used in many quality-assurance applications, such as line sources and calibration phantoms, to ensure that nuclear-medicine imaging systems operate correctly and produce useful images of radioisotope distribution inside the patient.[21] It is also used as a gamma-ray source in X-ray absorption measurements or in bone density gauges for osteoporosis screening, as well as in the Lixiscope portable X-ray imaging system.[22]

Gadolinium is used for making gadolinium yttrium garnet (Gd:Y3Al5O12); it has microwave applications and is used in fabrication of various optical components and as substrate material for magneto-optical films.

Gadolinium gallium garnet (GGG, Gd3Ga5O12) was used for imitation diamonds and for computer bubble memory.[23]

Gadolinium can also serve as an electrolyte in solid oxide fuel cells (SOFCs). Using gadolinium as a dopant for materials like cerium oxide (in the form of gadolinium-doped ceria) creates an electrolyte with both high ionic conductivity and low operating temperatures, which are optimal for cost-effective production of fuel cells.

Research is being conducted on magnetic refrigeration near room temperature, which could provide significant efficiency and environmental advantages over conventional refrigeration methods. Gadolinium-based materials, such as Gd5(SixGe1−x)4, are currently the most promising materials, owing to their high Curie temperature and giant magnetocaloric effect. Pure Gd itself exhibits a large magnetocaloric effect near its Curie temperature of 20 °C, and this has sparked great interest into producing Gd alloys with a larger effect and tunable Curie temperature. In Gd5(SixGe1−x)4, Si and Ge compositions can be varied to adjust the Curie temperature. This technology is still very early in development, and significant material improvements still need to be made before it is commercially viable.[8]

Biological role

Gadolinium has no known native biological role, but its compounds are used as research tools in biomedicine. Gd3+ compounds are components of MRI contrast agents. It is used in various ion channel electrophysiology experiments to block sodium leak channels and stretch activated ion channels.[24] Gadolinium has recently been used to measure the distance between two points in a protein via electron paramagnetic resonance, something that gadolinium is especially amenable to thanks to EPR sensitivity at w-band (95 GHz) frequencies. [25]

Safety

Gadolinium
Hazards
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word Danger
H261
P231+232, P422[26]
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g., sodium chlorideReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calciumSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g., cesium, sodiumNFPA 704 four-colored diamond
0
0
1

As a free ion, gadolinium is reported often to be highly toxic, but MRI contrast agents are chelated compounds and are considered safe enough to be used in most persons. The toxicity of free gadolinium ions in animals is due to interference with a number of calcium-ion channel dependent processes. The 50% lethal dose is about 100–200 mg/kg. Toxicities have not been reported following low dose exposure to gadolinium ions. Toxicity studies in rodents, however show that chelation of gadolinium (which also improves its solubility) decreases its toxicity with regard to the free ion by at least a factor of 100 (i.e., the lethal dose for the Gd-chelate increases by 100 times).[27] It is believed therefore that clinical toxicity of gadolinium-based contrast agents (GBCAs[28]) in humans will depend on the strength of the chelating agent; however this research is still not complete. About a dozen different Gd-chelated agents have been approved as MRI contrast agents around the world.[29][30][31]

GBCAs have proved safer than the iodinated contrast agents used in X-ray radiography or computed tomography. Anaphylactoid reactions are rare, occurring in approximately 0.03–0.1%.[32]

Although gadolinium agents are useful for patients with renal impairment, in patients with severe renal failure requiring dialysis, there is a risk of a rare but serious illness called nephrogenic systemic fibrosis (NSF)[33] or nephrogenic fibrosing dermopathy,[34] that is linked to the use of MRI contrast agents containing gadolinium. The disease resembles scleromyxedema and to some extent scleroderma. It may occur months after a contrast agent has been injected. Its association with gadolinium and not the carrier molecule is confirmed by its occurrence with various contrast materials in which gadolinium is carried by very different carrier molecules. Due to this, it is not recommended to use these agents for any individual with end-stage renal failure as they will require emergent dialysis. Similar but not identical symptoms to NSF may occur in subjects with normal or near normal renal function within hours to 2 months following the administration of GBCAs; the name "gadolinium deposition disease" (GDD) has been proposed for this condition, which occurs in the absence of pre-existent disease or subsequently developed disease of an alternate known process. A 2016 study reported numerous anecdotal cases of GDD.[35] However, in that study, participants were recruited from online support groups for subjects self-identified as having gadolinium toxicity, and no relevant medical history or data were collected. There have yet to be definitive scientific studies proving the existence of the condition. In addition, gadolinium deposition in neural tissues has solely been demonstrated in patients with inflammatory, infective, or malignant disease, and no healthy volunteer studies have assessed the potential of gadolinium deposition within the brain, skin, or bones.[36]

Included in the current guidelines from the Canadian Association of Radiologists[37] are that dialysis patients should only receive gadolinium agents where essential and that they should receive dialysis after the exam. If a contrast-enhanced MRI must be performed on a dialysis patient, it is recommended that certain high-risk contrast agents be avoided but not that a lower dose be considered.[37] The American College of Radiology recommends that contrast-enhanced MRI examinations be performed as closely before dialysis as possible as a precautionary measure, although this has not been proven to reduce the likelihood of developing NSF.[38] The FDA recommends that potential for gadolinium retention be considered when choosing the type of GBCA used in patients requiring multiple lifetime doses, pregnant women, children, and patients with inflammatory conditions.[39]

Long-term environmental impacts of gadolinium contamination due to human usage is a topic of ongoing research.[40][41]

References

  1. ^ Meija, J.; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
  2. ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
  3. ^ a b c d e f Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
  4. ^ "Gadolinium". Neutron News. 3 (3): 29. 1992. Retrieved 2009-06-06.
  5. ^ a b Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. p. 4.122. ISBN 0-8493-0486-5.
  6. ^ Coey JM, Skumryev V, Gallagher K (1999). "Rare-earth metals: Is gadolinium really ferromagnetic?". Nature. 401 (6748): 35–36. Bibcode:1999Natur.401...35C. doi:10.1038/43363. ISSN 0028-0836.
  7. ^ Gschneidner, Karl Jr; Gibson, Kerry (2001-12-07). "Magnetic refrigerator successfully tested". Ames Laboratory. Archived from the original on 2010-03-23. Retrieved 2006-12-17.
  8. ^ a b Gschneidner, K.; Pecharsky, V.; Tsokol, A. (2005). "Recent Developments in Magnetocaloric Materials" (PDF). Reports on Progress in Physics. 68 (6): 1479. Bibcode:2005RPPh...68.1479G. doi:10.1088/0034-4885/68/6/R04. Archived from the original (PDF) on 2014-11-09.
  9. ^ Suenaga, Kazu; Taniguchi, Risa; Shimada, Takashi; Okazaki, Toshiya; Shinohara, Hisanori; Iijima, Sumio (2003). "Evidence for the Intramolecular Motion of Gd Atoms in a Gd2@C92 Nanopeapod". Nano Letters. 3 (10): 1395. Bibcode:2003NanoL...3.1395S. doi:10.1021/nl034621c.
  10. ^ Hashimoto A, Yorimitsu H, Ajima K, Suenaga K, Isobe H, Miyawaki J, Yudasaka M, Iijima S, Nakamura E (June 2004). "Selective deposition of a gadolinium(III) cluster in a hole opening of single-wall carbon nanohorn". Proceedings of the National Academy of Sciences of the United States of America. 101 (23): 8527–30. Bibcode:2004PNAS..101.8527H. doi:10.1073/pnas.0400596101. PMC 423227. PMID 15163794.
  11. ^ Holleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils, ed., Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter, ISBN 0-12-352651-5
  12. ^ "Chemical reactions of Gadolinium". Webelements. The periodic table on the WWW] Copyright 1993-2018 Mark Winter, The University of Sheffield and WebElements Ltd, UK, access-date=2009-06-06.
  13. ^ Cotton (2007). Advanced inorganic chemistry (6th ed.). Wiley-India. p. 1128. ISBN 978-81-265-1338-3.
  14. ^ Danevich, F. A.; et al. (2001). "Quest for double beta decay of 160Gd and Ce isotopes". Nucl. Phys. A. 694 (1): 375–391. arXiv:nucl-ex/0011020. Bibcode:2001NuPhA.694..375D. doi:10.1016/S0375-9474(01)00983-6.
  15. ^ Deliens, M., and Piret, P., 1982. Bijvoetite et lepersonnite, carbonates hydrates d'uranyle et des terres rares de Shinkolobwe, Zaïre. Canadian Mineralogist 20, 231-238
  16. ^ "Lepersonnite-(Gd): Lepersonnite-(Gd) mineral information and data". Mindat.org. Retrieved 2016-03-04.
  17. ^ Liney, Gary (2006). MRI in clinical practice. Springer. pp. 13, 30. ISBN 978-1-84628-161-7.
  18. ^ Raymond KN & Pierre VC (2005). "Next generation, high relaxivity gadolinium MRI agents". Bioconjugate Chemistry. 16 (1): 3–8. doi:10.1021/bc049817y. PMID 15656568.
  19. ^ Wendler, Ronda (December 1, 2009) Magnets Guide Stem Cells to Damaged Hearts. Texas Medical Center.
  20. ^ Ryzhikov VD, Grinev BV, Pirogov EN, Onyshchenko GM, Bondar VG, Katrunov KA, Kostyukevich SA (2005). "Use of gadolinium oxyorthosilicate scintillators in x-ray radiometers". Optical Engineering. 44: 016403. Bibcode:2005OptEn..44a6403R. doi:10.1117/1.1829713.
  21. ^ "Gadolinium-153". Pacific Northwest National Laboratory. Archived from the original on 2009-05-27. Retrieved 2009-06-06.
  22. ^ "Lixi, Inc". Retrieved 2009-06-06.
  23. ^ Hammond, C. R. The Elements, in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
  24. ^ Yeung EW, Allen DG (August 2004). "Stretch-activated channels in stretch-induced muscle damage: role in muscular dystrophy". Clinical and Experimental Pharmacology & Physiology. 31 (8): 551–6. doi:10.1111/j.1440-1681.2004.04027.x. hdl:10397/30099. PMID 15298550.
  25. ^ Yang Y, Yang F, Gong Y, Bahrenberg T, Feintuch A, Su X, Goldfarb, D (October 2018). "High Sensitivity In-Cell EPR Distance Measurements on Proteins using and Optimized Gd(III) Spin Label". 9: 6119–6123. doi:10.1021/acs.jpclett.8b02663.
  26. ^ https://www.sigmaaldrich.com/catalog/product/aldrich/691771?lang=en&region=US
  27. ^ Penfield JG & Reilly RF (December 2007). "What nephrologists need to know about gadolinium". Nature Clinical Practice. Nephrology. 3 (12): 654–68. doi:10.1038/ncpneph0660. PMID 18033225.
  28. ^ "Gadolinium Deposition Disease (GDD) in Patients with Normal Renal Function". Gadolinium Toxicity. 1 November 2015. Retrieved 2016-02-03.
  29. ^ "Questions and Answers on Magnetic resonance imaging" (PDF). International Society for Magnetic Resonance in Medicine. Retrieved 2009-06-06.
  30. ^ "Information on Gadolinium-Containing Contrast Agents". US Food and Drug Administration. Archived from the original on September 6, 2008.
  31. ^ Gray, Theodore (2009) The Elements, Black Dog & Leventhal Publishers, ISBN 1-57912-814-9.
  32. ^ Murphy KJ, Brunberg JA, Cohan RH (October 1996). "Adverse reactions to gadolinium contrast media: a review of 36 cases". AJR. American Journal of Roentgenology. 167 (4): 847–9. doi:10.2214/ajr.167.4.8819369. PMID 8819369.
  33. ^ Thomsen HS, Morcos SK & Dawson P (November 2006). "Is there a causal relation between the administration of gadolinium based contrast media and the development of nephrogenic systemic fibrosis (NSF)?". Clinical Radiology. 61 (11): 905–6. doi:10.1016/j.crad.2006.09.003. PMID 17018301.
  34. ^ Grobner T (April 2006). "Gadolinium--a specific trigger for the development of nephrogenic fibrosing dermopathy and nephrogenic systemic fibrosis?". Nephrology, Dialysis, Transplantation. 21 (4): 1104–8. doi:10.1093/ndt/gfk062. PMID 16431890.
  35. ^ Semelka RC, Ramalho J, Vakharia A, AlObaidy M, Burke LM, Jay M, Ramalho M (December 2016). "Gadolinium deposition disease: Initial description of a disease that has been around for a while". Magnetic Resonance Imaging. 34 (10): 1383–1390. doi:10.1016/j.mri.2016.07.016. hdl:10400.17/2952. PMID 27530966.
  36. ^ Layne KA, Dargan PI, Archer JR, Wood DM (July 2018). "Gadolinium deposition and the potential for toxicological sequelae - A literature review of issues surrounding gadolinium-based contrast agents". British Journal of Clinical Pharmacology. doi:10.1111/bcp.13718. PMID 30032482.
  37. ^ a b Schieda N, Blaichman JI, Costa AF, Glikstein R, Hurrell C, James M, Jabehdar Maralani P, Shabana W, Tang A, Tsampalieros A, van der Pol CB, Hiremath S (2018). "Gadolinium-Based Contrast Agents in Kidney Disease: A Comprehensive Review and Clinical Practice Guideline Issued by the Canadian Association of Radiologists". Canadian Journal of Kidney Health and Disease. 5: 2054358118778573. doi:10.1177/2054358118778573. PMC 6024496. PMID 29977584.
  38. ^ ACR Committee on Drugs; Contrast Media (2010). ACR Manual on Contrast Media Version 7. ISBN 978-1-55903-050-2.
  39. ^ Research, Center for Drug Evaluation and. "Drug Safety and Availability - FDA Drug Safety Communication: FDA warns that gadolinium-based contrast agents (GBCAs) are retained in the body; requires new class warnings". www.fda.gov. Retrieved 2018-09-20.
  40. ^ Gwenzi, Willis; Mangori, Lynda; Danha, Concilia; Chaukura, Nhamo; Dunjana, Nothando; Sanganyado, Edmond (2018-09-15). "Sources, behaviour, and environmental and human health risks of high-technology rare earth elements as emerging contaminants". The Science of the Total Environment. 636: 299–313. doi:10.1016/j.scitotenv.2018.04.235. ISSN 1879-1026. PMID 29709849.
  41. ^ Rogowska J, Olkowska E, Ratajczyk W, Wolska L (June 2018). "Gadolinium as a new emerging contaminant of aquatic environments". Environmental Toxicology and Chemistry. 37 (6): 1523–1534. doi:10.1002/etc.4116. PMID 29473658.

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Arthrogram

An arthrogram is a series of images of a joint after injection of a contrast medium, usually done by fluoroscopy or MRI. The injection is normally done under a local anesthetic.The radiologist or radiographer performs the study using fluoroscopy or ultrasound to guide the placement of the needle into the joint and then injects an appropriate amount of contrast.

Gadobenic acid

Gadobenic acid (INN, trade name MultiHance) is a complex of gadolinium with the ligand BOPTA. In the form of the methylglucamine salt meglumine gadobenate (INNm) or gadobenate dimeglumine (USAN), it is used as a gadolinium-based MRI contrast medium.BOPTA is a derivative of DTPA in which one terminal carboxyl group, –C(O)OH is replaced by -C–O–CH2C6H5. Thus gadobenic acid is closely related to gadopentetic acid. BOPTA itself was first synthesized in 1995.

In the "gadobenate" ion gadolinium ion is 9-coordinate with BOPTA acting as an 8-coordinating ligand. The ninth position is occupied by a water molecule, which exchanges rapidly with water molecules in the immediate vicinity of the strongly paramagnetic complex, providing a mechanism for MRI contrast enhancement. 139La NMR studies on the diamagnetic La-BOPTA2− complex suggest that the Gd complex maintains in solution the same kind of coordination as found, by X-ray crystallography, in the solid state for Gd-BOPTA disodium salt.

Gadodiamide

Gadodiamide is a gadolinium-based MRI contrast agent, used in MR imaging procedures to assist in the visualization of blood vessels. It is commonly marketed under the trade name Omniscan.

Gadofosveset

Gadofosveset (trade names Vasovist, Ablavar) is a gadolinium-based MRI contrast agent. It was used as the trisodium salt monohydrate form. It acts as a blood pool agent by binding to human serum albumin. The manufacturer (Lantheus Medical) discontinued production in 2017 due to poor sales.

Gadolinium(III) bromide

Gadolinium(III) bromide is a crystalline compound of gadolinium atoms and three bromine atoms. Gadolinium bromide is hygroscopic.

Gadolinium(III) chloride

Gadolinium(III) chloride, also known as gadolinium trichloride, is GdCl3. It is a colorless, hygroscopic, water-soluble solid. The hexahydrate GdCl3∙6H2O is commonly encountered and is sometimes also called gadolinium trichloride. Gd3+ species are of special interest because the ion has the maximum number of unpaired spins possible, at least for known elements. With seven valence electrons and seven available f-orbitals, all seven electrons are unpaired and symmetrically arranged around the metal. The high magnetism and high symmetry combine to make Gd3+ a useful component in NMR spectroscopy and MRI.

Gadolinium(III) nitrate

Gadolinium(III) nitrate is an inorganic compound of gadolinium. It is used as a water-soluble neutron poison in nuclear reactors. Gadolinium nitrate, like all nitrates, is an oxidizing agent.

Gadolinium(III) oxide

Gadolinium(III) oxide (archaically gadolinia) is an inorganic compound with the formula Gd2O3. It is one of the most commonly available forms of the rare-earth element gadolinium, derivatives of which are potential contrast agents for magnetic resonance imaging.

Gadolinium gallium garnet

Gadolinium Gallium Garnet (GGG, Gd3Ga5O12) is a synthetic crystalline material of the garnet group, with good mechanical, thermal, and optical properties. It is typically colorless. It has a cubic lattice, a density of 7.08 g/cm3 and its Mohs hardness is variously noted as 6.5 and 7.5. Its crystals are produced with the Czochralski method. During production, various dopants can be added for colour modification. The material is also used in fabrication of various optical components and as a substrate material for magneto–optical films (magnetic bubble memory). It also finds use in jewelry as a diamond simulant. GGG can also be used as a seed substrate for the growth of other garnets such as YIG.

Gadopentetic acid

Gadopentetic acid is one of the trade names for a gadolinium-based MRI contrast agent, usually administered as a salt of a complex of gadolinium with DTPA (diethylenetriaminepentacetate) with the chemical formula A2[Gd(DTPA)(H2O)]; when cation A is the protonated form of the amino sugar meglumine the salt goes under the name "gadopentetate dimeglumine". It was described in 1981 by Hanns-Joachim Weinmann and colleagues and introduced as the first MRI contrast agent in 1987 by the Schering AG. It is used to assist imaging of blood vessels and of inflamed or diseased tissue where the blood vessels become "leaky". It is often used when viewing intracranial lesions with abnormal vascularity or abnormalities in the blood–brain barrier. It is usually injected intravenously. Gd-DTPA is classed as an acyclic, ionic gadolinium contrast medium. Its paramagnetic property reduces the T1 relaxation time (and to some extent the T2 and T2* relaxation times) in NMR, which is the source of its clinical utility.

Marketed as Magnevist by Bayer AG, it was the first intravenous contrast agent to become available for clinical use, and is in widespread use around the world. Similar contrast agents are Magnetol manufactured by Isorad, Dotarem (gadoterate) manufactured by Guerbet, MultiHance (gadobenate dimeglumine) and ProHance (gadoteridol) manufactured by Bracco, Omniscan (gadodiamide) manufactured by GE Healthcare, and OptiMARK (gadoversetamide) manufactured by Mallinckrodt.

Gadolinium based agents may cause a toxic reaction known as nephrogenic systemic fibrosis (NSF) in patients with severe kidney problems.Compared to other gadolinium-based MRI contrast agents, Gadopentetate dimeglumine (Gd-DTPA2-) chelates allow delayed Gadolinium-enhanced Magnetic Resonance of Cartilage (dGEMRIC). The unique charge characteristic of this complex allows researchers to inversely measure spin-lattice relaxation times as they are related to the concentration of proteoglycan aggregates and charged glycosaminoglycan side chains in articular cartilage.

Gadoteric acid

Gadoteric acid (gadoterate meglumine, trade names Artirem, Dotarem and Clariscan) is a macrocycle-structured gadolinium-based MRI contrast agent (GBCA). It consists of the organic acid DOTA as a chelating agent, and gadolinium (Gd3+), and is used in form of the meglumine salt (Gadoterate meglumine). The paramagnetic property of gadoteric acid reduces the T1 relaxation time (and to some extent the T2 and T2* relaxation times) in MRI, which is the source of its clinical utility. Because it has magnetic properties, gadoteric acid develops a magnetic moment when put under a magnetic field, which increases the signal intensity (brightness) of tissues during MRI imaging.

Gadoteridol

Gadoteridol (INN) is a gadolinium-based MRI contrast agent, used particularly in the imaging of the central nervous system. It is sold under the brand name ProHance.

Gadoversetamide

Gadoversetamide is a gadolinium-based MRI contrast agent, particularly for imaging of the brain, spine and liver. It is marketed under the trade name OptiMARK.

Gadoxetic acid

Gadoxetic acid is a gadolinium-based MRI contrast agent. Its salt, gadoxetate disodium, is marketed as Primovist in Europe and Eovist in the United States by Bayer HealthCare Pharmaceuticals.

Isotopes of gadolinium

Naturally occurring gadolinium (64Gd) is composed of 6 stable isotopes, 154Gd, 155Gd, 156Gd, 157Gd, 158Gd and 160Gd, and 1 radioisotope, 152Gd, with 158Gd being the most abundant (24.84% natural abundance). The predicted double beta decay of 160Gd has never been observed; only lower limit on its half-life of more than 1.3×1021 years has been set experimentally.Thirty radioisotopes have been characterized, with the most stable being alpha-decaying 152Gd (naturally occurring) with a half-life of 1.08×1014 years, and 150Gd with a half-life of 1.79×106 years. All of the remaining radioactive isotopes have half-lives less than 74.7 years. The majority of these have half-lives less than 24.6 seconds. Gadolinium isotopes have 10 metastable isomers, with the most stable being 143mGd (t1/2=110 seconds), 145mGd (t1/2=85 seconds) and 141mGd (t1/2=24.5 seconds).

The primary decay mode at atomic weights lower than the most abundant stable isotope, 158Gd, is electron capture, and the primary mode at higher atomic weights is beta decay. The primary decay products for isotopes of weights lower than 158Gd are the element Eu (europium) isotopes and the primary products at higher weights are the element Tb (terbium) isotopes.

Gadolinium-153 has a half-life of 240.4±10 days and emits gamma radiation with strong peaks at 41 keV and 102 keV. It is used as a gamma ray source for X-ray absorptiometry and fluorescence, for bone density gauges for osteoporosis screening, and for radiometric profiling in the Lixiscope portable x-ray imaging system, also known as the Lixi Profiler. In nuclear medicine, it serves to calibrate the equipment needed like single-photon emission computed tomography systems (SPECT) to make x-rays. It ensures that the machines work correctly to produce images of radioisotope distribution inside the patient. This isotope is produced in a nuclear reactor from europium or enriched gadolinium. It can also detect the loss of calcium in the hip and back bones, allowing the ability to diagnose osteoporosis.Gadolinium-148 would be ideal for radioisotope thermoelectric generators due to its 74-year half life, high density, and dominant alpha decay mode. However, Gadolinium-148 cannot be economically synthesized in sufficient quantities to power a RTG.

MRI contrast agent

MRI contrast agents are contrast agents used to improve the visibility of internal body structures in magnetic resonance imaging (MRI). The most commonly used compounds for contrast enhancement are gadolinium-based. Such MRI contrast agents shorten the relaxation times of nuclei within body tissues following oral or intravenous administration. In MRI scanners, sections of the body are exposed to a very strong magnetic field causing primarily the hydrogen nuclei ("spins") of water in tissues to be polarized in the direction of the magnetic field. An intense radiofrequency pulse is applied that tips the magnetization generated by the hydrogen nuclei in the direction of the receiver coil where the spin polarization can be detected. Random molecular rotational oscillations matching the resonance frequency of the nuclear spins provide the "relaxation" mechanisms that bring the net magnetization back to its equilibrium position in alignment with the applied magnetic field. The magnitude of the spin polarization detected by the receiver is used to form the MR image but decays with a characteristic time constant known as the T1 relaxation time. Water protons in different tissues have different T1 values, which is one of the main sources of contrast in MR images. A contrast agent usually shortens, but in some instances increases, the value of T1 of nearby water protons thereby altering the contrast in the image.

Neutron capture therapy of cancer

Neutron capture therapy (NCT) is a noninvasive therapeutic modality for treating locally invasive malignant tumors such as primary brain tumors and recurrent head and neck cancer. Briefly summarized, it is a two-step procedure: first, the patient is injected with a tumor-localizing drug containing the non-radioactive isotope boron-10 (10B) that has a high propensity or cross section (σ) to capture slow neutrons. The cross section of the 10B is many times greater than that of the other elements present in tissues such as hydrogen, oxygen, and nitrogen. In the second step, the patient is radiated with epithermal neutrons, the source of which is either a nuclear reactor or, more recently, an accelerator. After losing energy as they penetrate tissue, the neutrons are absorbed by the capture agent, which subsequently emits high-energy charged particles that can selectively kill tumor cells that have taken up sufficient quantities of 10B.

All of the clinical experience to date with NCT is with the non-radioactive isotope boron-10, and this is known as boron neutron capture therapy (BNCT). At this time, the use of other non-radioactive isotopes, such as gadolinium, has been limited, and to date, it has not been used clinically. BNCT has been evaluated clinically as an alternative to conventional radiation therapy for the treatment of malignant brain tumors (gliomas), and recurrent, locally advanced head and neck cancer and cutaneous and extracutaneous melanomas.

Perfusion MRI

Perfusion MRI or perfusion-weighted imaging (PWI) is perfusion scanning by the use of a particular MRI sequence. The acquired data are then postprocessed to obtain perfusion maps with different parameters, such as BV (blood volume), BF (blood flow), MTT (mean transit time) and TTP (time to peak).

Ribonucleotide reductase inhibitor

Ribonucleotide reductase inhibitors are a family of anti-cancer drugs that interfere with the growth of tumor cells by blocking the formation of deoxyribonucleotides (building blocks of DNA).

Examples include:

motexafin gadolinium.

hydroxyurea

fludarabine, cladribine, gemcitabine, tezacitabine, and triapine

gallium maltolate, gallium nitrate

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