What is the difference between B-mode and M-mode ultrasound?

B-mode (Brightness mode) and M-mode (Motion mode) ultrasound serve different purposes in imaging and display characteristics. B-mode is primarily known for generating two-dimensional cross-sectional images of tissues by displaying a two-dimensional grayscale image where the brightness of each pixel corresponds to the strength of the reflected ultrasound signal. This mode provides detailed structural information and is widely used in various diagnostic applications.

In contrast, M-mode is particularly useful for capturing motion over time, making it beneficial in cardiology for assessing cardiac structures, such as valves and chambers, as they move with the heartbeat. M-mode presents the data as a series of vertical lines or waveforms on the screen, allowing for the observation of real-time motion. The horizontal axis represents time, while the vertical axis represents the depth of the structures being observed.

The correct understanding of these two modes highlights the use of B-mode for 2D imaging and M-mode for visualizing motion, particularly in a temporal context. Thus, the distinction and functionality of each mode are critical for clinicians to make informed decisions based on the types of images and information they provide.