The axial resolution can be enhanced by decreasing which of the following parameters?

Axial resolution in ultrasound describes the system's ability to distinguish between two closely spaced reflectors in the direction of the ultrasound beam. This resolution is fundamentally linked to the spatial pulse length, which is determined by the number of cycles in a pulse and the wavelength of the ultrasound.

By decreasing the number of cycles in a pulse, the pulse duration is shortened, which directly affects the spatial pulse length. Since axial resolution improves as the spatial pulse length decreases, reducing the number of cycles in a pulse enhances the ability to differentiate between structures that are close together along the axis of the beam. A shorter pulse corresponds to better axial resolution because it allows the ultrasound system to resolve smaller differences in depth.

While frequency or other parameters like beam width and transducer length can affect resolution, their relationship is more complex and not as directly tied to axial resolution as the number of cycles in a pulse. Thus, by focusing on reducing the number of cycles within the pulse, axial resolution can be effectively improved.