What is the purpose of using a surface coil in MRI?

• A. To decrease patient discomfort
• B. To increase spatial resolution
• C. To improve SNR in specific regions
• D. To reduce scan time

Answer: (C)

The use of a surface coil in MRI primarily enhances the signal-to-noise ratio (SNR) in specific regions of interest. Surface coils are designed to be in closer proximity to the area being imaged, which allows them to collect more signal from that region while minimizing noise from other areas. This direct positioning increases the SNR, leading to clearer and more diagnostic images, particularly in smaller anatomical structures or areas that require high detail.

The other purposes that might be suggested, such as decreasing patient discomfort or reducing scan time, are not the main functions of surface coils. While certain designs might indirectly contribute to patient comfort or efficiency, these are not the primary reasons for their use. Likewise, while increased spatial resolution might be a beneficial effect of improved SNR, the direct contribution to spatial resolution itself is not the primary aim of surface coils; rather, it is the enhancement of the SNR in a targeted region that stands out as their main function.