FIGURE 1.

Fidelity of phantom targets is demonstrated by side-by-side comparison to human neurovascular sonoanatomy. A and B, Image and diagram of typical human neurovascular ultrasound showing characteristic diffuse hyperechoic neuroanatomy and hypoechoic vasculature with hyperechoic regions in the margins and deep acoustic shadow. C, Targets for target-proximity tasks were constructed of oil-filled capsules resembling human hypoechogenic arterial sonoanatomy (C, top right: similar sonoanatomic characteristics of defined circular boundaries and inner hypoechoic regions in representative human median nerve). D, Accuracy for target-proximity tasks was assessed by distance in millimeters (displacement distance, i) of a guidewire extended from the needle tip into contact with the target. E, Targets for target-contact tasks were constructed of metallic “nail head” anchors resembling small regions of diffuse hyperechoic nervous sonoanatomy (E, top right: similar sonoanatomic characteristics of diffuse hyperechoic regions in representative human median nerve). F, Accuracy for target-contact tasks was assessed by distance in millimeters (r) from target center to the needle puncture in the adjacent membrane.