British Journal of Radiology (2004) 77, 146-147
© 2004 British Institute of Radiology
doi: 10.1259/bjr/11355045
Gadolinium: named after Finland's most famous chemist
M L Wastie, FRCP, FRCR and
K H Latief, MRCP, FRCR
1 Radiology Department, University Hospital, 59100 Kuala Lumpur, Malaysia and 2 City Hospital, Nottingham, UK
Because MRI gives such excellent tissue contrast with sequences enabling blood flow to be demonstrated, contrast was initially deemed unnecessary. However, just as with CT, the use of contrast was found to be very advantageous in a wide range of clinical settings.
Theoretical considerations pointed to the use of paramagnetic compounds as MR contrast agents, whose effect would be indirect and related to the size of their magnetic moment, and mediated through increase in proton relaxation rates in tissue water by complex molecular interactions. Several metal ions from the transitional and lanthanide series of elements have large magnetic moments derived from the presence of unpaired electrons in their electron shells. Gadolinium, which occupies the central position in the lanthanide series has 7 unpaired electrons in its 4f orbitals giving it a very large magnetic moment. The first intravascular contrast agent to be used was based on this element [1]. The free gadolinium ion is highly toxic and to render it non toxic it is chelated with the ligand diethylene triamine pentacetic acid which does not affect its contrast properties but forms a highly stable complex that does not release the gadolinium ion when injected into the body. After an intravenous injection, gadolinium and the other gadolinium chelates that have been developed, have the same distribution as the iodinated contrast used in CT. They circulate in the vascular system, diffuse into the extracellular space but do not cross the placenta or blood–brain barrier. Gadolinium chelates are filtered unchanged and are rapidly and completely excreted by the kidneys and accumulate in the bladder. These agents increase both the spin–lattice (T1) and spin–spin (T2) relaxation rates in tissues. In the concentrations used in practice the more important effect is on the T1 relaxation time so that changes in tissue signal are best shown on T1 weighted images.
Gadolinium has an atomic number of 64 and, as one of the lanthanides, is one of a series of 17 chemically similar metals. Although the lanthanides are known as rare earths this term is rather a misnomer as they are not particularly rare. Gadolinium is present in 5 parts per million in the Earth's crust [2]. Gadolinium occurs in many minerals along with other rare earths but it is obtained primarily from monazite which is a phosphate mineral found in several countries.
Gadolinium is named after the Finnish chemist Johan Gadolin who was born in 1760 (Figure 1
). Finland was a province of Sweden for 600 years until 1809 when, during the Napoleonic Wars, it became a Grand Duchy of Russia. Independence was gained in 1917.
Gadolin was born in Åbo (Turku), the son of a professor of physics and theology who later became bishop of Åbo. Gadolin first studied chemistry at Åbo and continued his studies for a further 4 years in Uppsala where he produced his doctoral thesis on the analysis of iron. He returned to Åbo but as no professorship was immediately forthcoming he embarked on a tour of Europe from 1786 to 1788. He visited Germany, Holland and Ireland but his longest stay was in England where he was regularly present at meetings of the Royal Society. On his return to Finland Gadolin was appointed Professor in survivance which meant that the professorship would become his after the retirement or death of the incumbent. Gadolin became a full Professor of Chemistry in 1797 and stayed in the chair until his retirement in 1822 [3].
In 1794, at the age of 34, Gadolin analysed a black mineral that had been found a few years earlier at the Ytterby quarry near Stockholm by an amateur mineralogist. Gadolin thought he had discovered an unknown element but what he actually discovered was yttrium oxide — one of the rare earths or lanthanides. The mineral was named gadolinite and subsequently was found to consist of several lanthanides. In 1880 the Swiss chemist de Marginac, using the newly discovered spectroscope, identified spectroscopic lines due to gadolinium in samples of the mineral gadolinite. Gadolinia, the oxide of gadolinium was isolated by the French chemist de Boisbaudran in 1886 and the element was named gadolinium from the mineral gadolinite in which it was found. Pure metallic gadolinium was not isolated until much later in 1935.
Gadolin's discovery of yttrium brought him fame in his lifetime. He amassed a large mineral collection which unfortunately was destroyed, with much of Åbo as well, in the Great Fire of 1827.
Gadolin was innovative as an educator, opening his chemical laboratory to students, where they participated in experiments rather than merely being observers. He wrote an important text book Inledning till Chemien (Introduction to Chemistry) which incorporated the new antiphlogiston doctrines. He published extensively and other contributions included papers on specific heat and analytical chemistry [4].
Gadolin was honoured by his contemporaries with membership of several European scientific societies and granted several honours. He retired to his estate and died 30 years after his retirement in 1852 aged 92. He is buried in the church yard in Wirmo (Mynamäki) with the epitaph on his gravestone mors reparatio vitae — death is the atonement of life (Figure 2).
In 1960 the Finnish Post Office issued a special postage stamp to commemorate the bicentenary of Gadolin's birth.
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Acknowledgments
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I would like to thank my wife and Miss Eeva-Maria Suikkanen for their help with the Finnish translation.
Received for publication March 21, 2003.
Revision received September 8, 2003.
Accepted for publication September 30, 2003.
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References
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- Encyclopaedia Britannica, 15th edition. Chicago: Benton 1974;6:702.
- Kansallisgalleria; Suuret Suomalaiset Sääty-yhteiskunnan Suomi (1150–1850). Johan Gadolin. Porvoo, Weilen & G
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- Dean PB, Dean KI. Sir Johan Gadolin of Turku; the grandfather of gadolinium. Acad Radiol 1996;3:165–8.[CrossRef][Medline]
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