This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Theory

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

The body should be regarded as a mass of small randomly arranged magnets. These magnets represent the nuclei of hydrogen atoms - protons - which have polarity and thus are able to alter their orientation if they are subjected to a strong magnetic field. MRI utilizes these properties in a 3-stage process.

  • Precession: When a patient is placed in a scanner then some of the protons within the patient become aligned along the axis of the magnetic field. When these protons become magnetized they then rotate and wobble - precess - around the magnetized field axis.
  • Resonance: If there is then application of changes in radiofrequency then the orientation of rotation and wobbling can be altered. Different types of radiofrequency pulse can be used to produce different types of emitted signal with different structures.
  • Emission: Once the radiofrequency pulse is turned off then the protons begin to lose their phase cohesion and this results in the emission of very small radiofrequency signals. The magnitude, phase, amplitude and frequency of these signals are detected by a magnetic resonance imager and used to generate an image.

Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page

The content herein is provided for informational purposes and does not replace the need to apply professional clinical judgement when diagnosing or treating any medical condition. A licensed medical practitioner should be consulted for diagnosis and treatment of any and all medical conditions.

Connect

Copyright 2024 Oxbridge Solutions Limited, a subsidiary of OmniaMed Communications Limited. All rights reserved. Any distribution or duplication of the information contained herein is strictly prohibited. Oxbridge Solutions receives funding from advertising but maintains editorial independence.