Editing Gadolinium (section)

===Magnetic contrast agent===
Gadolinium is [[paramagnetic]] at [[room temperature]], with a [[Curie temperature|ferromagnetic Curie point]] of {{convert|20|C}}.<ref name="CRC2">{{RubberBible86th|page=4.122}}</ref> Paramagnetic ions, such as gadolinium, increase [[nuclear spin]] relaxation rates, making gadolinium useful as a [[MRI contrast agent|contrast agent]] for [[magnetic resonance imaging]] (MRI). Solutions of [[organic chemistry|organic]] gadolinium [[coordination complex|complexes]] and gadolinium compounds are used as [[intravenous]] contrast agents to enhance images in medical  and [[magnetic resonance angiography]] (MRA) procedures. [[Magnevist]] is the most widespread example.<ref>{{cite book |pages=13;30|url= https://books.google.com/books?id=xpCffxNrCXYC&pg=PA13 |title= MRI in clinical practice |author=Liney, Gary |publisher=Springer |date= 2006 |isbn= 978-1-84628-161-7}}</ref><ref>{{cite journal |vauthors= Raymond KN, Pierre VC |title= Next generation, high relaxivity gadolinium MRI agents |journal= Bioconjugate Chemistry |volume= 16 |issue= 1 |pages= 3–8 |date= 2005 |pmid= 15656568 |doi= 10.1021/bc049817y }}</ref> Nanotubes packed with gadolinium, called "[[gadonanotube]]s", are 40 times more effective than the usual gadolinium contrast agent.<ref>Wendler, Ronda (1 December 2009) [https://web.archive.org/web/20110728091851/http://www.texasmedicalcenter.org/root/en/TMCServices/News/2009/12-01/Magnets+Guide+Stem+Cells+to+Damaged+Hearts.htm Magnets Guide Stem Cells to Damaged Hearts]. Texas Medical Center.</ref> Traditional gadolinium-based contrast agents are un-targeted, generally distributing throughout the body after injection, but will not readily cross the intact [[blood–brain barrier]].<ref name=pmid32418324>{{cite journal |vauthors=Bagnato F, Gauthier SA, Laule C, Moore G, Bove R, Cai Z, Cohen-Adad J, Harrison DM, Klawiter EC, Morrow SA, Öz G, Rooney WD, Smith SA, Calabresi PA, Henry RG, Oh J, Ontaneda D, Pelletier D, Reich DS, Shinohara RT, Sicotte NL |display-authors=6 |date=May 2020 |title=Imaging mechanisms of disease progression in multiple sclerosis: Beyond brain atrophy |journal=[[Journal of Neuroimaging]] |volume=30 |issue=3 |pages=251–266 |pmid=32418324 |doi=10.1111/jon.12700|s2cid=218677556 }}</ref> [[Brain tumors]], and other disorders that degrade the [[blood-brain]] barrier, allow these agents to penetrate into the brain and facilitate their detection by contrast-enhanced [[MRI]].  Similarly, [[delayed gadolinium-enhanced magnetic resonance imaging of cartilage]] uses an [[ionic compound]] agent, originally [[Magnevist]], that is excluded from healthy [[cartilage]] based on [[electrostatic repulsion]] but will enter [[proteoglycan]]-depleted cartilage in diseases such as [[osteoarthritis]].{{Medical citation needed|date=July 2024}}