ARDMS Sonography Principles and Instrumentation (SPI) Practice Exam 2025 – Your All-in-One Guide to Exam Success!

Lateral resolution in ultrasound imaging refers to the ability to distinguish separate structures that are oriented side by side, and it is highly dependent on the width of the ultrasound beam. The best lateral resolution occurs where the ultrasound beam is the narrowest, which is typically at the focus of the beam.

At the focus, the beam is tightly constricted, allowing for clearer differentiation between adjacent structures, resulting in improved lateral resolution. This is crucial for accurately visualizing and differentiating anatomical structures in the imaging field.

In contrast, in the near field, although the beam begins to narrow, it is not yet at its most focused point, which can lead to less optimal lateral resolution. In the far field, the beam starts to diverge, causing an increase in beam width and consequently a decrease in lateral resolution. The edges of the beam are the least favorable location for lateral resolution due to the widening of the beam profile.

Therefore, understanding the behavior of the ultrasound beam in relation to its focus is key to maximizing lateral resolution and achieving optimal imaging outcomes.