Which ultrasound display modes are described in standard practice?

• A. A-mode, B-mode, and M-mode
• B. A-mode and B-mode only
• C. B-mode and M-mode only
• D. A-mode and M-mode only

Answer: (A)

In standard ultrasound practice, three display modes are described: A-mode, B-mode, and M-mode. A-mode shows echoes as individual spikes along a depth axis, with the position of each spike indicating depth and the height reflecting echo strength. This mode is the simplest and is mainly used for distance measurements and in certain specialized applications, such as ophthalmology. B-mode provides the classic two-dimensional grayscale image; brightness at each point corresponds to the strength of the reflected signal, giving a cross-sectional view of anatomy. This is the workhorse display for most clinical imaging. M-mode records motion along a single line over time, producing a time-based trace that shows how structures move, which is especially valuable for assessing cardiac motion and valve dynamics. Together, these three modes are the standard ways ultrasound can present data, with B-mode acting as the primary imaging mode in routine practice, while A-mode and M-mode remain important in specific contexts and historical descriptions.