What type of resolution is affected most by pulse duration?

• A. Lateral resolution
• B. Contrast resolution
• C. Temporal resolution
• D. Axial resolution

Answer: (D)

Axial resolution is most affected by pulse duration because it depends on the spatial length of the emitted pulse. Shorter pulse duration means fewer cycles or higher frequency, which shortens the spatial pulse length in tissue. When the pulse is shorter, two reflectors that lie close together along the beam path can be distinguished more clearly, so axial resolution improves. Conversely, a longer pulse duration lengthens the pulse in tissue, causing echoes to blur and axial resolution to worsen.

Lateral resolution depends on beam width and focusing, not pulse duration. Temporal resolution is about how quickly frames are acquired (frame rate), and contrast resolution relates to the ability to differentiate gray levels, driven by signal-to-noise and dynamic range rather than pulse duration.