Basic Ultrasound interpretation

US Orientation

  • Ultrasound transducers have a marker on one edge

  • By convention, the marker will always point towards the:

    • Transverse view: right side

    • Longitudinal view: patient's head (cranial)

US Terminology

  • Structures are described by their echogenicity, which correlates to how much the wave gets reflected back to the transducer

  • Echogenicity is relative, usually compared to other surrounding structures or the background organ

Anechoic (black)

Waves transmit, no reflection (e.g. water in simple cyst)

Hypoechoic (darker)

Some reflection (e.g. liver metastasis)

Isoechoic (equal to reference)

Some reflection (e.g. liver focal nodular hyperplasia)

Hyperechoic (brighter)

Some reflection (e.g. liver hemangioma)

Very hyperechoic (very bright)

All reflected (e.g. bone cortex, air)

US Artifacts to know

Posterior acoustic enhancement

  • Sound waves normally attenuate as they travel. The US machine will increase the brightness of the deeper tissues to compensate

  • A homogeneous structure (e.g. pure water) does not attenuate the sound as much as expected, so the area posteriorly will artifactually appear brighter as the US machine still applies compensation

Posterior acoustic shadowing

  • Certain structures will absorb or reflect all the sound waves

  • The area posteriorly will artifactually appear dark as the US machine interprets this as the waves had travelled through, when in actuality they had already been accounted for

Try reviewing a normal abdominal US on PACSBIN

  • Click on the capital "A" at the top tools bar to turn on anatomy labels

  • Scrolling with a trackpad may be difficult. A mouse is recommended