Traditional MRI systems used in hospitals are tuned to the resonant frequency of water, and so are designed to visualize “wet” organs. The cost comes when MRI is used in imaging the lungs which are full of air, leading to low quality images. To address this, Massachusetts researchers from the Harvard-Smithsonian Center for Astrophysics and the Martinos Center for Biomedical Imaging have developed an open access, low magnetic field MRI that focuses on inhaled helium.
From the MIT Technology Review:
Lung function is dependent on the orientation of the body, but it hasn’t been possible to study this before because conventional MRI would require patients to lie on their backs. (PET can be used to look at some aspects of the physiology of the lungs but it gives limited information.) Asthma symptoms can be exacerbated when patients lie down, for example. The Harvard system “allows imaging with the patient in any orientation, something no one has ever been able to do,” says Bastiaan Driehuys, an assistant professor at the Center for In Vivo Microscopy at Duke University.
The open MRI system may also make it possible to monitor the lung function of newborns in intensive care without taking them out of their incubators. The researchers have filed a provisional patent for this application.
Unlike conventional MRI, which images the protons in water molecules, the Harvard MRI system monitors magnetically polarized helium gas inhaled by subjects. Conventional MRI requires a magnet about 150 times stronger than that in the Harvard system to magnetically align protons inside the body. But the helium used in the Harvard system is magnetically aligned before the patient inhales it, making it possible to use a very weak magnet inside the scanner.