Which statement describes the primary role of the radiofrequency coil in MRI?

• A. Gradient coil shapes spatial encoding
• B. Body coil provides heating
• C. Surface coil only receives signals
• D. Radiofrequency coil acts as the transmitter and receiver of the MR signal

Answer: (D)

The essential idea is that the radiofrequency coil directly handles both sending and receiving the MR energy. It creates the B1 field that excites the hydrogen nuclei, tipping their net magnetization so detectable transverse magnetization is generated. After excitation, the same coil (or an adjacent one) picks up the faint MR signal as the spins relax and re-emit energy, feeding it into the receiver for amplification and digitization. That dual role—transmitting the RF pulse and receiving the MR signal—defines its primary function. Gradient coils, by contrast, are used to encode spatial information, not to transmit or receive signals. A body coil may act as a transmitter and can contribute to heating, but that isn’t its main purpose, and surface coils are chosen mainly for their high signal in a local area rather than a fundamental change in role.