Gadolinium nuclear magnetism

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Rich Feldman
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Gadolinium nuclear magnetism

Post by Rich Feldman »

Here at, I found gadolinium compounds most recently discussed here: viewtopic.php?t=5112

Who can explain what's special about the Gd nuclear magnetism, that makes it useful in MRI contrast agents?
Yesterday I got my head scanned before and after an intravenous infusion of gadobutrol. shows the structure etc. of C18H31GdN4O9 molecule.
330px-Gadobutrol_skeletal.svg.png (10.88 KiB) Viewed 551 times
Says it reduces the T1 relaxation time which is measured by MRI instrument.
All models are wrong; some models are useful. -- George Box
Alex Aitken
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Re: Gadolinium nuclear magnetism

Post by Alex Aitken »

In the Scientific American there is an old demo of NMR, with a coil, a magnetron magnet, a tube oscillator/amplifier and an oscilloscope. It uses US 60Hz as the sweep. Ordinary water is too weak for it to work, so they dissolve a paramagnetic salt, either copper or iron, I forget. This decreases the relaxation time of the proton signal. The same energy being absorbed or emitted in a shorter time is a stronger signal. This also makes the line width of the signal wider and this demo really is only the demo of a signal, it's otherwise useless.

This tells the specifics of Gadolinium but it's really the same. Paramagnetic salts (unpaired electrons) cause shorter brighter signals, and T1 weighted images are short delay echo sequences so the areas the agent is turn out bright. With long delay echo sequences like T2 weighted images, the energy from that area is gone so you would expect darker than normal areas. ... ts?lang=gb
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