skip to main content

Speed of Sound Soft Tissue 1540 m/s — FRCA Primary MCQ

Instant feedback + full explanation. One question, done properly.

HardPhysics & Clinical MeasurementSpeed of Sound Soft Tissue 1540 m/sFRCA Primary

Pulsed-wave Doppler of a high-velocity jet shows wrap-around aliasing. Which single adjustment most directly raises the Nyquist limit while preserving pulsed-wave range resolution?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Increase the pulse-repetition frequency

The best answer is “Increase the pulse-repetition frequency”. The Nyquist limit is one half of the pulse-repetition frequency, so increasing pulse-repetition frequency permits a larger Doppler shift before aliasing. Gain, output power, persistence and dynamic range alter display or signal strength but do not raise the sampling limit. Continuous-wave Doppler avoids aliasing but loses range resolution.

Reference: Magee, Essential notes on the physics of Doppler ultrasound: https://pmc.ncbi.nlm.nih.gov/articles/PMC7807840/