Which ultrasound artefact is responsible for the appearance of bright posterior echoes deep to an anechoic structure such as a cyst or fluid-filled viscus?

• A Acoustic shadowing
• B Reverberation artefact
• C Side-lobe artefact
• D Posterior acoustic enhancement (through transmission) ✓

Explanation

Posterior acoustic enhancement (also called through-transmission or back-wall enhancement) occurs because fluid-filled or cystic structures attenuate ultrasound less than surrounding soft tissue. The tissue beyond the fluid receives more energy than expected by the system, which compensates for 'average' attenuation, resulting in erroneously bright (hyperechoic) echoes posterior to the cyst. Acoustic shadowing occurs posterior to highly attenuating structures (calculi, bone). Reverberation produces equidistant parallel lines. Side-lobe artefacts produce false echoes within anechoic structures.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.