Image quality is improved by:

The improvement of image quality in ultrasound is closely related to the characteristics of the ultrasound beam and the manner in which images are generated. Shortening the pulse length enhances image quality due to its direct impact on spatial resolution.

Shorter pulse lengths correspond to higher frequency ultrasound waves, which result in better axial resolution. Axial resolution is the ability to distinguish two structures that are close together along the direction of the beam. When the pulse length is reduced, the system can more accurately differentiate between closely spaced structures, leading to sharper and clearer images. This increased resolution is fundamental for identifying and diagnosing various conditions accurately.

In contrast, decreasing the output (which relates to the strength of the ultrasound signal) could lead to a weaker signal returning to the transducer, thereby reducing image clarity and diagnostic capability. Decreasing the frame rate may result in a smoother image motion but can potentially lower the temporal resolution, especially important when imaging moving structures. Increasing beam width generally spreads the ultrasound energy over a larger area, which can lead to lower resolution and poorer image quality, particularly in differentiating between adjacent structures.

Thus, shortening the pulse length is a key factor in enhancing image resolution and overall image quality in sonography.