What does an MR scanner use to produce an image, and what does the image show?
It uses magnetic fields and radio-frequency (RF) signals to image a cross-section of a patient.
AQA A-level Physics (7408) · 3.10.4.3
Revise AQA A-level Physics (7408) specification point 3.10.4.3, Magnetic resonance (MR) scanner (A-level only), with free active-recall flashcards. Flip through the set or review every question and answer below.
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What does an MR scanner use to produce an image, and what does the image show?
It uses magnetic fields and radio-frequency (RF) signals to image a cross-section of a patient.
How are proton spins preferentially aligned in the strong field of an MR scanner’s superconducting magnet?
Parallel to the magnetic field.
How do proton spins move relative to the magnetic field lines in an MR scanner?
They precess about the field lines.
How do gradient field coils enable spatial selection and signal localisation in MRI?
They vary the magnetic field with position, allowing regions to be selected and signal positions identified.
What do short RF pulses do to protons during an MR scan?
They excite protons, changing their spin states, in successive small regions.
What do excited protons emit as they de-excite during an MR scan?
Radio-frequency (RF) signals.
How are the emitted RF signals used to form an MR image?
They are detected and processed by a computer to form the image.