How is it done?
To determine the exact location of speech or memory or motor functions, a patient has a normal MRI scan of his or her brain, but at the end of these scans, specialized fMRI protocols are added. These special protocols make apparent differences in tiny amounts of increased blood flow in the venioles and capillary beds, and they record its location. Each scan takes about 3 minutes, and it is usually necessary to scan differing brain areas, so functional scans normally take about a half to three-quarters of an hour. No contrast agent is injected into the patient, so these scans are completely non-invasive and are safe. Each fMRI patient has to be able to follow very simple instructions while he or she is being scanned, such as listen to a sentence and squeeze a rubber bulb, or follow motor commands, such as wiggle your fingers. Each has to lie very still. Children younger than 13 years old present more challenge as they usually have much greater difficulty lying still for the fMRI sequences. These tiny differences require that the patient lie virtually still during the scan.
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