But now, a new, naturally occurring contrast agent that is used not with PET but with magnetic resonance imaging (MRI) is brightening prospects. Coupled with recently developed high-speed MRI techniques, this new agent is helping researchers create functional brain maps that display detail and sequential processes never before seen.
The newly found contrast agent is hemoglobin, present throughout the body. MRI researchers are taking advantage of the slight difference in magnetic properties between hemoglobin carrying oxygen and hemoglobin from which the oxygen has been stripped to generate their images. Oxygenated hemoglobin is diamagnetic, and deoxygenated hemoglobin is paramagnetic, meaning that oxyhemoglobin is weakly repelled and deoxyhemoglobin weakly attracted by a magnetic field. And, although experimental MRI instruments with high magnetic fields produce the best images based on the hemoglobin contrast, many commercially available clinical MRI machines are also capable of creating such images.
"A lot of what we're trying to ...
