Ultrasound vocabulary

Sound

A series of pressure waves propagating through a medium.

Acoustic Wave Cycle

One complete positive and negative pressure change of a sound wave.

Wavelength

The distance traveled during one cycle of an acoustic wave.

Frequency

Measured in cycles per second (Hertz, Hz) and indicates the number of cycles per second.

Audible Sound Range

For most humans, it is between 20 Hz and 20,000 Hz (20 kHz).

Ultrasound

Sound waves with frequencies greater than 20 kHz.

Diagnostic Ultrasound Frequency

Typically uses frequencies between 2 and 20 million Hertz (Megahertz - MHz).

Propagation Speed

The speed at which an acoustic wave travels through a medium, determined by the medium's stiffness.

Attenuation

The loss of intensity and amplitude as sound waves travel through a medium.

Absorption

The conversion of acoustic energy into heat, which is a major source of attenuation in soft tissue.

Reflection

When sound waves bounce back towards the source after encountering a boundary between two media.

Refraction

Change in the path of a wave as it travels through different media with varying stiffness.

Scatter

When ultrasound waves encounter a medium with a heterogeneous surface, causing some waves to scatter in random directions.

Pulse-Echo Principle

The methodology used in ultrasound where structures are visualized based on the echoes produced by transmitted sound waves.

Transducer

The device containing piezoelectric crystals which generate and receive ultrasound waves.

Lower Frequencies in Ultrasound

Able to penetrate deeper into tissue but show poorer resolution.

Higher Frequencies in Ultrasound

Display more detail with higher resolution, but have less depth penetration.

B-mode (Brightness mode)

Provides structural information in a two-dimensional image using different shades of gray.

Hypoechoic

Refers to a structure that has very few echoes, appearing darker than surrounding tissue.

Hyperechoic

Refers to a structure with a large amplitude of returning echoes, appearing brighter than surrounding tissue.

Doppler Modes

Used to examine the direction and speed of tissue motion and blood flow, utilizing the Doppler shift.

Color Doppler Ultrasound

Shows blood flow or tissue motion in a selected area, color-coded to indicate direction and velocity.

Power Doppler

Looks at the amplitudes of returning frequency shifts to detect movement in low flow states.

Spectral Doppler

Includes continuous and pulsed-wave forms to measure flow velocities.

Artifacts in Ultrasound

Visual representations that do not exist in reality, which can aid or confuse image interpretation.

Attenuation Artifacts

Artifacts such as shadowing, which are caused by the reflection or absorption of sound energy.

Reverberation Artifact

Occurs when sound encounters two highly reflective layers, causing prolonged travel time.

Comet Tail Artifact

Produced by strong reflectors creating closely spaced reverberations.

Transducers

Devices which include piezoelectric crystals and are used to capture and generate ultrasound images.

Curvilinear Probe

Produces a sector-shaped image with a large footprint, primarily used for transabdominal sonography.

Phased Array Probe

Creates a sector-shaped image with a smaller footprint, ideal for cardiac and transabdominal sonography.

Linear Probe

Produces a rectangular image, typically used in vascular sonography and procedural guidance.

Transverse Plane

Runs perpendicular to the ground, separates superior from inferior in a supine patient.

Sagittal Plane

Runs perpendicular to the ground, separates left from right in a supine patient.

Coronal Plane

Runs parallel to the ground, separates anterior from posterior in a supine patient.

Ultrasound Machine Functions

Basic functionalities that are universal to ultrasound equipment, such as on/off, gain adjustments, and mode changes.