Which coil is specifically designed to improve SNR over the area of interest?

Surface coils are specifically designed to improve the signal-to-noise ratio (SNR) over the area of interest in magnetic resonance imaging (MRI). These coils are placed directly over or adjacent to the body part being imaged, which allows them to collect signals that are more concentrated and therefore have higher quality. By being positioned closer to the anatomical region of interest, surface coils can capture more of the relevant signals while minimizing interference and noise from surrounding structures.

Other coil types serve different purposes. Phased array coils are made up of an array of individual coil elements that work together to enhance imaging of larger areas but may not focus as effectively on a small region as surface coils. Volume coils provide a homogeneous magnetic field across a large volume, which is useful for imaging overall body regions but not optimized for improving SNR in specific areas. Body coils generally encompass larger anatomical regions and are utilized for whole-body imaging; while they allow for broad coverage, they may not deliver the same SNR enhancements as surface coils when focusing on localized areas.