Appear as a line of dots of varying brightness.

• A. A-mode
• B. B-mode
• C. C-mode
• D. D-mode

Answer: (B)

In ultrasound, how echoes are turned into a picture depends on the display mode. The line-of-dots, with brightness varying from moment to moment, comes from brightness mode. In this mode, each echo along the scan line is converted into a dot, and the dot’s brightness mirrors the strength of the echo. As the beam sweeps across tissue, you get a row of these dots forming a two-dimensional grayscale image, with darker and lighter spots indicating different tissue boundaries and densities. This is why you see a line of dots of varying brightness when the image is being formed.

The other modes don’t produce that dot-based line image. A-mode displays echoes as spikes along depth, not a dotted line. M-mode shows motion over time along a single line, useful for observing movement like heart wall motion. Doppler modes convey flow or velocity information rather than a static brightness dot array.