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Magnetic resonance imaging
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Uses nuclear spin in strong fields.
Strong static field (1.5–3 T) aligns hydrogen nuclei; radio pulses tip them, and the emitted signal gives images with contrast from tissue differences. Field gradients encode position.
No ionising radiation.
Metal implants can be hazardous.
In more detail
Magnetic resonance imaging uses strong magnetic fields and radio waves to excite hydrogen nuclei in the body. The signals reveal the density and environment of tissue.
Real-world uses
- MRI scans diagnose brain, joint and soft tissue conditions.
- Researchers use MRI to study brain function.
- Hospitals use magnetic resonance imaging to produce detailed scans of soft tissue without radiation.
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Frequently asked questions
Is MRI safe?
It is generally safe, but metal implants and strong fields require screening.
Why does MRI use radio waves?
Nuclear spins resonate at radio frequencies in a magnetic field.
Is MRI safe for everyone?
No. Metal implants and some devices can be affected by the strong magnetic fields, so patients are screened before scanning.
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