FUNCTIONAL MRI [ back to Neuroimaging ]
Functional MRI is a kind of hybrid between regular MRI that depicts brain structure and functional imaging like PET. Like standard MRI it relies on powerful magnets and radio frequency coils (not decay of radioactive isotopes) to create detectable "signals." However, the machines for fMRI have such powerful magnets that the time required to produce signals is reduced from minutes to seconds. This enables the radiologist to visually track blood flow into specific parts of the brain during controlled physical or mental tasks that can include finger tapping, speaking or looking at an object. Although the MRI images are not "real time" images, they are just a few seconds behind the blood flow patterns they capture, and therefore it is legitimate to say they are mapping brain function rather than brain structure. The newest 3 Tesla MRI scanners are being used to map areas of healthy and dead brain tissue following stroke and to map a patient's speech centers before surgery to remove diseased parts of the brain causing seizures. As of the year 2001, the most powerful MRI machine in existence is being built at the West Side Campus of the University of Illinois in Chicago. It is a 9.4 Tesla machine. MRI research director Dr. Keith Thulborn says this scanner is powerful enough to track the flow of chemicals, such as neurotransmitters, into and out of brain cells.