“…US images tend to be noisy, due to reflections, reverberations, shadows, air pockets, and biological speckle, which makes needle localization challenging. Some needle localization methods use 2D images [15,20,53], while others compound a 3D volume from a tracked sweep of 2D images [2,21]. For completeness, we note that, due to current limitations on voxel resolution and transfer speed, 3D US probes have not been practical for image-based needle guidance.…”