In a typical magnetic resonance imaging (“MRI”) study of the brain, subjects are screened for contraindications before being placed in the bore of a large machine, the MRI scanner, which contains a powerful magnet. The scanner produces cross-sectional images of brain tissue as the subjects undergo a series of brief electromagnetic pulses, perceptible only as noise and vibration. If the protocol involves functional MRI (“fMRI”), a popular research technique for obtaining indirect measurements of brain activity, equipment might be used to present stimuli (sounds or pictures) during the scan, but generally the study involves no invasive procedures, no physical discomfort, and no ionizing radiation. Upon completion of the scan, MRI data is transferred to an investigator's computer for further analysis, often in combination with behavioral test results and clinical information obtained from subjects or their medical records.
This procedure sounds benign, and usually is. But an MRI scanner is a powerful medical device, capable of causing serious injury or death if operated carelessly.