Permanent magnets, according to this article: https://www.fiercebiotech.com/medtech/fda-clears-world-s-first-portable-bedside-mri https://www.fiercebiotech.com

Permanent magnets, according to this article: https://www.fiercebiotech.com/medtech/fda-clears-world-s-first-portable-bedside-mri https://www.fiercebiotech.com/medtech/fda-clears-world-s-fir... Small permanent magnet NMR spectroscopy units first showed up in chemistry about 10 years ago: https://www.prweb.com/releases/2010/11/prweb4732684.htm https://www.prweb.com/releases/2010/11/prweb4732684.htm