Enhancement, more precisely called posterior acoustic enhancement or through-transmission, is an artifact that occurs when the ultrasound beam passes through a structure with low attenuation, such as a fluid-filled cyst, and the tissues behind it appear brighter than surrounding tissue at the same depth. This happens because the sound beam loses less energy traveling through fluid than through solid tissue, so more sound reaches the structures deep to the cyst, producing stronger echoes. Enhancement is one of the most useful artifacts in ultrasound because it helps confirm that a structure is truly cystic or fluid-filled rather than solid. It is an expected finding behind the gallbladder, urinary bladder, cysts, and blood vessels.
Sonography Term