fig1
![Advancements in needle visualization enhancement and localization methods in ultrasound: a literature review](https://image.oaes.cc/79a69f4a-333a-43e6-b302-f191c95e0ebf/ais4020.fig.1.jpg)
Figure 1. Needle visibility depends on the insertion technique used and needle insertion angle. (A) For in-plane insertion (top), both the shaft and tip are visible; however, for out-of-plane insertion, (bottom), only the tip is visible (bottom)[15]; (B) For shallow insertion angles, (first column), specular reflection is high and the needle is visible; however, for steeper insertion angles, (second and third column), needle visibility is lost.