Which ultrasound mode samples and displays information along a single line of sight?

• A. A-Mode
• B. B-Mode
• C. M-Mode
• D. Doppler

Answer: (C)

M-Mode is the mode that samples echoes along a single scan line and displays how structures along that line move over time. The transducer repeatedly sends and receives echoes along the same line, creating a plot where depth along that line is shown as time progresses. This lets you track motion of heart walls and valves frame by frame, giving a clear view of dynamic movement along one line of sight.

A-Mode, by contrast, shows echo amplitude along depth on a single axis and isn’t time-based. B-Mode builds a two-dimensional image by scanning many lines to form a picture. Doppler focuses on motion or flow information along a line, typically shown as velocity data, not a time-motion line plot.