Doppler Echocardiography & Spectral Analysis Flashcards

Which Doppler modality is best suited for measuring high-velocity jets such as severe aortic stenosis?

Answer: Continuous-wave Doppler

Continuous-wave Doppler has no aliasing limit and can accurately measure high-velocity jets exceeding the Nyquist limit.

The Nyquist limit in pulsed-wave Doppler is equal to:

Answer: One-half the pulse repetition frequency (PRF/2)

Aliasing occurs when the sampled velocity exceeds half the PRF (Nyquist limit), causing velocity wrap-around on the spectral display.

On a pulsed-wave Doppler spectral display, flow moving toward the transducer is displayed:

Answer: Above the baseline

By convention, flow directed toward the transducer produces a positive Doppler shift and is displayed above the baseline.

Which of the following best describes the term 'angle of incidence' in Doppler echocardiography?

Answer: The angle between the ultrasound beam and the direction of blood flow

The angle of incidence is the angle between the ultrasound beam and the direction of blood flow; accuracy is greatest when this angle is less than 20 degrees.

The modified Bernoulli equation used in echocardiography is expressed as:

Answer: ΔP = 4V²

The simplified Bernoulli equation ΔP = 4V² converts peak Doppler velocity (m/s) to pressure gradient (mmHg), widely used to estimate stenotic and regurgitant jet gradients.

In color flow Doppler imaging, aliasing is indicated by:

Answer: A mosaic or variance map pattern where colors reverse at high velocities

Aliasing in color flow Doppler appears as a mosaic of colors, particularly where flow velocities exceed the Nyquist limit and colors wrap from red to blue or vice versa.

Tissue Doppler imaging (TDI) differs from conventional Doppler primarily because it measures:

Answer: Low-velocity myocardial wall motion

TDI uses a low-velocity, high-amplitude filter to display myocardial motion rather than blood flow, making it useful for diastolic function assessment.