What error will occur if the angle correct cursor is NOT adjusted parallel to the vessel wall?

What error will occur if the angle correct cursor is NOT adjusted parallel to the vessel wall?

• A. The frequency shift will be underestimated
• B. No Doppler frequency shift will be detected
• C. The velocity estimation will be inaccurate
• D. Aliasing of the Doppler spectrum will occur

Answer: (C)

In Doppler ultrasound, the velocity you calculate depends on the angle between the ultrasound beam and the direction of blood flow. If the angle correction cursor isn’t aligned parallel to the vessel wall (i.e., the angle used in the velocity calculation is wrong), the cosθ term in the Doppler equation is incorrect. Since velocity is derived from the Doppler shift divided by cosθ, using the wrong angle makes the velocity estimate inaccurate. The Doppler frequency shift itself will still be present, but the velocity value derived from it will be off. Aliasing and the presence of a Doppler shift aren’t directly caused by not aligning the angle cursor, so the primary error here is the inaccurate velocity estimation.

In Doppler ultrasound, the velocity you calculate depends on the angle between the ultrasound beam and the direction of blood flow. If the angle correction cursor isn’t aligned parallel to the vessel wall (i.e., the angle used in the velocity calculation is wrong), the cosθ term in the Doppler equation is incorrect. Since velocity is derived from the Doppler shift divided by cosθ, using the wrong angle makes the velocity estimate inaccurate. The Doppler frequency shift itself will still be present, but the velocity value derived from it will be off. Aliasing and the presence of a Doppler shift aren’t directly caused by not aligning the angle cursor, so the primary error here is the inaccurate velocity estimation.