Which statement correctly describes continuous-wave Doppler?

Which statement correctly describes continuous-wave Doppler?

• A. It uses two elements, one to transmit and one to receive
• B. It uses a single transducer element
• C. It cannot measure high velocities
• D. It is the same as color Doppler

Answer: (B)

Continuous-wave Doppler is defined by transmitting a continuous ultrasound wave and simultaneously receiving echoes to measure the Doppler frequency shift. This is achieved by using two transducer elements: one dedicated to transmitting the continuous wave and another dedicated to receiving the reflected signal. Separating the transmit and receive paths lets the system continuously sample motion along the beam, which enables accurate velocity measurements at high speeds without the aliasing that can occur with pulsed techniques. Because there’s no depth-gating, CW Doppler doesn’t provide range information. The idea that it uses a single transducer element isn’t how CW Doppler is typically arranged; a single element is associated with pulsed-wave Doppler, where short pulses and time-gated reception target specific depths. Color Doppler is a different modality that maps Doppler information onto a gray-scale image, often using pulsed Doppler data for each pixel.

Continuous-wave Doppler is defined by transmitting a continuous ultrasound wave and simultaneously receiving echoes to measure the Doppler frequency shift. This is achieved by using two transducer elements: one dedicated to transmitting the continuous wave and another dedicated to receiving the reflected signal. Separating the transmit and receive paths lets the system continuously sample motion along the beam, which enables accurate velocity measurements at high speeds without the aliasing that can occur with pulsed techniques. Because there’s no depth-gating, CW Doppler doesn’t provide range information.

The idea that it uses a single transducer element isn’t how CW Doppler is typically arranged; a single element is associated with pulsed-wave Doppler, where short pulses and time-gated reception target specific depths. Color Doppler is a different modality that maps Doppler information onto a gray-scale image, often using pulsed Doppler data for each pixel.