What is the primary difference between continuous wave and pulsed wave ultrasound?

The primary distinction between continuous wave and pulsed wave ultrasound lies in the nature of the sound wave transmission. Continuous wave ultrasound emits a constant stream of sound waves. This uninterrupted emission allows for a continuous reception of returning echoes from tissue, which is particularly useful for measuring high-velocity flow, such as in Doppler studies of blood flow. The frequency of the sound waves remains constant, enabling the technique to provide real-time information.

In contrast, pulsed wave ultrasound transmits short bursts of sound waves rather than a continuous signal. After each burst, there is a brief period during which the system listens for returning echoes, allowing for the detection and imaging of structures at varying depths. This pulsing pattern is integral for creating images and obtaining range resolution, helping sonographers distinguish between different layers of tissues based on their depths from the transducer.

The other options address aspects that do not define the fundamental difference between continuous wave and pulsed wave ultrasound. For instance, pulsed wave ultrasound is not limited to deep imaging; rather, it can be used for both superficial and deep structures, depending on the configuration of the transducer and the imaging settings. It's also not inherently true that one wave type operates at a higher frequency than the other, as frequencies can vary