MRI Magic: Research
In the quarter century since MRI systems were invented, MRI imaging has steadily improved. Better magnets have led to large bore MRI machines with more spacious housings. The machines can accommodate larger patients and are less likely to frighten people who dislike the cramped spaces of conventional MRI machines. Improved electronics and signal processing systems have increased the detail visible in MRI images and even allowed researchers to collect microscopic images of insects and other tiny samples. MRI images also make up a substantial portion of the National Library of Medicine's Visible Human Project, which is a compilation of detailed layer-by-layer images of a pair of complete male and female human bodies.
Recently, MRI machines have been developed to image and track physiological changes in images of humans and animals as they occur from moment to moment. MRI-based functional imaging non-invasively maps subtle increases in blood flow and oxygenation corresponding to changes in brain activity. Functional MRI (fMRI) has revolutionized research in human brain function and is making headway in many clinical applications.
In effect, fMRI provides movies of the brain at work as neurons become more active in response to a stimulus, mental activity, or mental state. Regions associated with basic sensory and motor activity have been studied, as have regions associated with thought processes and changes in mood or attentiveness. Also, specific clinical populations have shown significant differences in fMRI - based brain activation maps, suggesting that the technique can be used towards more accurate diagnoses and assessment of therapy.
Left: A microscopic MRI image shows surprising detail in a Xenopus oocyte (a frog egg cell), including structure in the light gray cell nucleus. (Image courtesy of the Pacific Northwest National Laboratory, Biomolecular Systems Initiative).
Right: This MRI cross section of an abdomen is one of thousands of images in the The Visible Human Project database that provide a highly detailed survey of the human body.
