MRI, or Magnetic Resonance Imaging, is the practice of using magnetic fields to create images of the anatomy or physiological processes of the human body. Pulses of radio waves are used to excite the nuclei of hydrogen atoms, affecting their spin polarization. The changes in the spin polarization of these atoms can then be detected and mapped by monitoring changes in a magnetic gradient to effectively create images not just of the structures which exist but also the activity within them. MRI can be used to monitor brain activity or problems with heart function.
MRI machines are enormous, with a roughly human sized tube in the middle. The patient will lie down on a bed which is then moved into the tube. Imaging usually requires a patient to lie still in this confining tube for around 30-45 minutes to get an accurate image of the subject.
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