In MRI, the frequency-encoding gradient (readout gradient) is responsible for:
- A Selecting the imaging slice
- B Making the precessional frequency vary linearly along one in-plane axis to encode spatial position ✓
- C Refocusing dephased spins to form an echo
- D Inverting the net magnetisation vector by 180 degrees
Correct answer: B. Making the precessional frequency vary linearly along one in-plane axis to encode spatial position
Explanation
The frequency-encoding gradient is applied during signal readout and makes the Larmor frequency vary linearly along its direction. Fourier transformation of the received signal then assigns each frequency to a spatial position along that axis. The slice-selection gradient is separate.
Reference: McRobbie, MRI from Picture to Proton, 3rd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.