Acoustic enhancement, also called posterior enhancement or enhanced through transmission, refers to the increased echoes deep to structures that transmit sound exceptionally well.
This is characteristic of fluid filled structures such as cysts, the urinary bladder and the gallbladder. The fluid only attenuates the sound less than the surrounding tissue. The time gain compensation (TGC) overcompensates through the fluid-filled structure causing deeper tissues to be brighter. Simply it is seen as increased echogenicity (whiteness) posterior to cystic area. The presence of acoustic enhancement aids in the identification of cystic masses but some solid masses, especially lymphoma, may also show acoustic enhancement posteriorly.