______ is better than CW for measuring PHT.

______ is better than CW for measuring PHT.

• A. CW
• B. PW
• C. M-mode
• D. 2D Doppler

Answer: (B)

Measuring pressure half-time relies on the velocity-time curve of blood flow across the mitral valve, captured with spectral Doppler. Pulsed-Wave Doppler is preferred because it provides a defined sampling gate, giving range resolution to isolate the flow at the mitral orifice. This lets you accurately track how the velocity (and thus the transmitral gradient) decays after its peak, so you can measure the time from peak to the half-maximum—PHT. Continuous-Wave Doppler samples along the entire ultrasound beam, lacking a specific sampling location. That broad, non-localized signal contaminates the deceleration slope with flow from other parts of the heart, making the PHT measurement unreliable. M-mode and 2D Doppler don’t provide the necessary velocity-time information from a defined gate, so they aren’t suitable for determining PHT.

Measuring pressure half-time relies on the velocity-time curve of blood flow across the mitral valve, captured with spectral Doppler. Pulsed-Wave Doppler is preferred because it provides a defined sampling gate, giving range resolution to isolate the flow at the mitral orifice. This lets you accurately track how the velocity (and thus the transmitral gradient) decays after its peak, so you can measure the time from peak to the half-maximum—PHT.

Continuous-Wave Doppler samples along the entire ultrasound beam, lacking a specific sampling location. That broad, non-localized signal contaminates the deceleration slope with flow from other parts of the heart, making the PHT measurement unreliable. M-mode and 2D Doppler don’t provide the necessary velocity-time information from a defined gate, so they aren’t suitable for determining PHT.