MRI interpretation
The MRI scanner

Key points

  • Inside the MRI scanner there is a powerful magnetic field
  • The magnetic field interacts with protons in the body
  • The scanner produces radiofrequency pulses which further interact with protons in the body
  • Protons give off 'signal' which is detected by the scanner

Once an MRI scanner is built, it remains switched on day and night, and produces a powerful magnetic field within the bore of the magnet. When the patient enters the magnet, all the protons (hydrogen ions) within their body become aligned with the magnetic field.

The scanner produces radiofrequency pulses which further interact with protons causing them to give off ‘signal’. This signal is detected by the scanner and transformed into images.

MRI scanner

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MRI scanner

  • The patient lies on the scanner couch (1) which slides into the bore of the scanner (2)
  • Within the bore of the scanner there is a powerful magnetic field
  • The scanner produces radiofrequency pulses to ‘excite’ protons in the body
  • As the excited protons in the body ‘relax’ after each pulse, they give off radiofrequency ‘signal’ which is detected by the receiver (3)
  • The receiver is placed around or near the body part being imaged