• Echogenic: the ability of a structure to produce echoes. Echoes are created when emitted sound waves encounter tissues with an acoustic mismatch. This causes some sound waves to continue traveling and others to be reflected back to the transducer. These reflected echoes are then converted into an image that is displayed on a monitor.

  • Anechoic: no echoes and sonolucent—appears black on ultrasound

  • Hypoechoic: less reflective and low amount of echoes when compared with neighboring structures, appears as varying shades of darker gray

  • Hyperechoic: highly reflective and echo rich when compared with neighboring structures, appears as varying shades of lighter gray; the term echogenic is often used interchangeably

  • Isoechoic: having similar echogenicity to a neighboring structure


  • Homogeneous: organ parenchyma is uniform in echogenicity

  • Inhomogeneous or heterogeneous: organ parenchyma is not uniform in echogenicity


  • Completely anechoic, smooth walled, with posterior enhancement

  • Reverberation may be seen on the anterior wall of the cyst


  • Anechoic, smooth walled, with posterior enhancement

  • Septations that appear as echogenic hair-like strands within mass

  • Multilocular compartments (cluster of cysts)

  • Internal low-level echoes that may indicate hemorrhage or infection

  • Fluid-fluid layers that may represent blood, fluid, or fat layers

  • Calcification that appears as highly reflective echoes (hyperechoic) with posterior shadowing


  • Homogeneous or inhomogeneous

  • Hypoechoic to hyperechoic

  • May attenuate sound partially or completely


  • Reverberation (ring down): This occurs when sound travels with minimal to no attenuation through a fluid-filled structure. It is displayed as multiple parallel echogenic lines equidistant from each other. They become fainter as sound travels deeper into the structure (such as the anterior region of a filled urinary bladder or large cystic mass). Reverberation can mimic solid elements in an otherwise cystic organ or a mass. Changing the scanning angle of approach may resolve this artifact.

  • Comet tail: This is a type of reverberation artifact. It appears as a dense, tapering trail of echoes distal to a strongly reflecting structure. Metallic objects (such as surgical clips and bullet fragments) and adenomyomatosis of the gallbladder may produce comet-tail artefacts.

  • Acoustic enhancement (posterior enhancement, good through transmission): This is seen as a hyperechoic pattern posterior to a poorly or nonattenuating structure or mass (e.g., a cyst).

  • Attenuation: This is the lack of sound transmission through a mass. It generally indicates a solid internal consistency.

  • Shadowing: This appears as a hypo echoic pattern posterior to highly attenuating structures (e.g., calcifications such as gallstones or plaque, bone, and air). Echoes posterior to these structures look “darker” (a reduction in the amplitude of the echoes) than adjacent echoes. Shadowing is described as “clean” or “dirty.” “Clean” shadows present posterior to calcifications, bone, plaque, and dense structures such as intrauterine contraceptive devices. Shadows from these structures are sharply demarcated. Shadows posterior to air or bowel are referred to as “dirty” shadows, and they lack the clean, sharp side edges. Air-filled bowel loops near the gallbladder can mimic gallstones.

  • Slice thickness artifact: This occurs when a fluid structure lies adjacent to a soft-tissue structure. The ultrasound beam strikes both simultaneously, producing low-level echoes in the fluid structure. These low-level echoes can be mistaken for pathology. Changing the scanning angle of approach can resolve this problem.


Emergency Medicine Sonography, Dunstan Abraham Cynthia Silkowski Charles Odwin

#ultrasound #imaging