M-mode has been used primarily to assess which aspect?

• A. Blood flow velocity
• B. Tissue elasticity
• C. Tissue perfusion
• D. The motion of cardiac walls and structures

Answer: (D)

M-mode ultrasound records motion along a single line with very high temporal resolution, so it’s ideal for watching how the heart walls and related structures move over time. Because the display plots depth against time, you can precisely track wall thickening, chamber size changes, and the timing of valve movements throughout the cardiac cycle. That makes it the best tool for assessing the motion patterns of cardiac walls and structures, such as how the ventricles contract and how valves open and close, with accurate measurements of dimensions and timing.

Information like blood flow velocity is obtained with Doppler, tissue stiffness with elastography, and tissue perfusion with perfusion imaging or related techniques—areas that M-mode isn’t designed to measure.