MRI For Your Lungs

This is pretty neat:

Led by Matthew Rosen, a visiting scientist at the Harvard-Smithsonian center, and Ronald Walsworth, a senior lecturer in physics at Harvard, the researchers built an MRI scanner that images how gas flows through the lungs and how much oxygen is being absorbed throughout lung tissue. They've used the system to study how lung function differs when lying down and sitting or standing up, and are planning a study of asthma in conjunction with the Martinos Center for Biomedical Imaging in Boston. The system has not yet been used to compare healthy and diseased patients. If it proves its worth in clinical trials, the Harvard researchers believe it would be inexpensive and simple enough to be used in pulmonologists' offices.

They're using magnetically pre-polarized helium, which is inhaled as a marker. The system therefore requires only a modest magnetic field to make the helium emit, which in turn provides excellent lung imaging. Regular MRIs work by magnetically polarizing water molecules in the body, which requires a big magnetic field and also can't image air spaces.