MRI Flashcards
1
Q
How would you describe MRI to a non scientist?
A
- MRI makes use of a quantum effect called spin. This property affects all protons in the body, and protons are in every type of tissue
- A strong magnetic field is applied across the patient, and protons align parallel or anti-parallel to the direction of the field
- If the field is sufficiently strong, a small excess will be in the parallel, or lower energy spin up state
- Pulses of radio waves cause protons to flip into higher energy parallel states
- When the pulses are stopped, the protons slowly return to their original lower energy state, at a rate which is dependent on the type of tissue they are in (be it water or fat for example)
- The protons emit radio frequency photons as they do so, which is detected by the same coil that was used to emit the radio photons. This is measured as an electric signal which can be used to generate an image
