Surface coil

Surface coils are a type of receive-only radiofrequency coil used in MRI to receive the radiofrequency signal (transmitted by the body coil). Surface coils are small and are shaped so that they can be placed near the part of anatomy being imaged. By their nature, surface coils have good signal-to-noise ratio for the tissue adjacent to the coil. They also allow for smaller voxel size which in turn allows for improved image resolution. However, the sensitivity decreases greatly as the distance from the coil is increased. Hence, surface coils have a smaller field of view. Hence, the placement and selection of surface coils is dependent on the type of imaging required, and are particularly useful in localized body regions where relatively superficial anatomy is being studied e.g. temporomandibular joint and spine.

Surface coils have a relatively simple design which consists of a loop of wire. This simple and small structure increases the signal detection as it has a small diameter and increases its proximity to the signal.