Introduction to Vascular Doppler Ultrasound

Vocabulary flashcards covering core vascular Doppler ultrasound concepts including Doppler angles, beam steering, PRF/scale settings, aliasing rules, and color map conventions.

Doppler Window is the, where what is located

The cleared area on the spectral display where the Doppler waveform is located.

Baseline is the, representing (2)?

The reference line on the Doppler display representing zero ($0$) velocity or frequency shift.

Best Grayscale Imaging Angle I achieved when ultrasound beam is?

Achieved when the ultrasound beam is perpendicular ($90^\bullet$) to the blood vessels.

Best Flow Sampling Angle is achieved when?

Achieved when the beam is parallel ($0^\bullet$) to the direction of blood flow

Diagnostic Doppler Angle Limit, doppler must be, to achieve an angle of incidence of, angles greater than 60 degrees are considered?

The Doppler beam must be steered to achieve an angle of incidence less than $60^\bullet$ ($<60^\bullet$); angles greater than $60^\bullet$ ($>60^\bullet$) are considered non-diagnostic.

Beam Steering the process of firing ultrasound beams from, at different, to improve?

The process of firing ultrasound beams from linear transducers at different angles to improve the Doppler sampling angle.

Curvilinear Probe can’t do what and why (2)

cannot steer the beam due to their fan shape and the physical curvature of the crystals in the probe.

Steering Controls (Cursor Line) indicated the?

indicates the angle at which the ultrasound beam approaches the vessel.

Sample Gate defines the, from which what is gathered?

Defines the specific area within the vessel from which Doppler signal data is gathered.

Angle Correct is the control that inputs the, into the, to accurately?

The control that inputs the measured angle into the Doppler equation to accurately calculate flow velocity.

Heel/Toe Technique used to achieve an adequate, or prevent, when beam steering is?

used to achieve an adequate Doppler angle or prevent perpendicular ($90^\bullet$) alignment when beam steering is insufficient.

Unsteered Doppler Beam is a beam that is fired?

A beam that is fired straight down perpendicular ($90^\bullet$) to the transducer face.

Phasing Beam Steering Angles allowing beam to be steered out at what 3 angles?

allowing the beam to be steered out at $15^\bullet$, $20^\bullet$, or $30^\bullet$ angles.

Pulse Repetition Frequency (PRF) is the number of, also known as, which controls the (3)?

The number of pulse-echo cycles per second, also known as Scale, which controls the sensitivity and display of spectral and color Doppler.

High Flow State Scale Adjustment requires an increased, to display, without?

Requires an increased PRF/scale to display high-velocity Doppler shifts properly without signal distortion.

Low Flow State Scale Adjustment requires a decreased, to detect, setting PRF to High results in (2)?

Requires a decreased PRF/scale to detect low-velocity signals; setting PRF too high results in low sensitivity and unfilled spectral windows.

Nyquist Limit calculated as?

calculated as half of the PRF ($\frac{\text{PRF}}{2}$).

Methods to Correct Aliasing (3) increase the, lower the, select a new?

Three actions to resolve aliasing: increase the PRF (scale), lower the transducer frequency, or select a new acoustic view/approach.

Standard Vessel Color Display, arteries appear, veins appear?

The standard display convention where arteries appear red and veins appear blue.

Invert Button is a control that, placing red on, placing blue on?

A control that reverses the visual representation of flow direction, placing red on the bottom and blue on top of the color map bar.

Beam Steering Direction Rules, when steering left observe flow on, when steering down observe flow moving?

When steering left, observe flow on the left side; when steering down, observe flow moving toward the transducer face.