Shorter pulses yield which effect on axial resolution?

Shorter pulses yield which effect on axial resolution?

• A. Improved
• B. Unchanged
• C. Not defined
• D. Deteriorated

Answer: (A)

Shorter pulses improve axial resolution because axial resolution is determined by the spatial pulse length, the distance the pulse occupies in tissue. Spatial pulse length equals the number of cycles in the pulse times the wavelength. When the pulse has fewer cycles (a shorter burst), the spatial pulse length becomes shorter. A shorter pulse means echoes from two closely spaced reflectors along the beam axis are separated in time, allowing them to be distinguished more clearly. Since axial resolution is roughly SPL/2, reducing the spatial pulse length directly enhances the ability to resolve structures that lie along the direction of the beam. So, shorter pulses yield improved axial resolution.

Shorter pulses improve axial resolution because axial resolution is determined by the spatial pulse length, the distance the pulse occupies in tissue. Spatial pulse length equals the number of cycles in the pulse times the wavelength. When the pulse has fewer cycles (a shorter burst), the spatial pulse length becomes shorter. A shorter pulse means echoes from two closely spaced reflectors along the beam axis are separated in time, allowing them to be distinguished more clearly. Since axial resolution is roughly SPL/2, reducing the spatial pulse length directly enhances the ability to resolve structures that lie along the direction of the beam. So, shorter pulses yield improved axial resolution.