Magnetic resonance imaging (MRI)

Definition

Magnetic resonance imaging (MRI) is a medical imaging technique that uses powerful magnets and radio waves to create detailed images of the inside of the body. It relies on the principles of nuclear magnetic resonance, where atomic nuclei align with a magnetic field and emit signals when perturbed by radio waves.

5 Must Know Facts For Your Next Test

1. MRI utilizes strong magnetic fields, typically ranging from 1.5 to 3 Tesla.
2. The technique depends on the alignment and realignment of hydrogen nuclei in water molecules within the body.
3. Radiofrequency pulses are used to disturb this alignment, and sensors detect the emitted signals as the nuclei return to their original state.
4. Gradient magnets are used to spatially encode the position of hydrogen atoms, allowing for image formation.
5. MRI does not use ionizing radiation, making it safer compared to X-rays and CT scans.

Review Questions

• What is the primary element in the body that MRI targets for imaging?
• How do gradient magnets contribute to MRI image formation?
• Why is MRI considered safer than some other imaging techniques like X-rays?

Related terms

Tesla (unit): A unit of measurement for magnetic field strength; one Tesla equals one weber per square meter.

Nuclear Magnetic Resonance (NMR): A physical phenomenon in which nuclei in a magnetic field absorb and re-emit electromagnetic radiation; foundational principle behind MRI.

Radiofrequency Pulse: A burst of radio waves used in MRI to disturb the alignment of hydrogen nuclei within a magnetic field.