Single-Element Needle-Based Ultrasound Imaging of the Spine: An In Vivo Feasibility Study

Spinal interventional procedures, such as lumbar puncture, require insertion of an epidural needle through the spine without touching the surrounding bone structures. To minimize the number of insertion trials and navigate to a desired target, an image-guidance technique is necessary. We developed a single-element needle-based ultrasound system that is composed of a needle-shaped ultrasound transducer that reconstructs B-mode images from lateral movement with synthetic aperture focusing. The objective of this study is to test the feasibility of needle-based single-element ultrasound imaging on spine in vivo. Experimental validation was performed on a metal wire phantom, ex vivo porcine bone in both water tank and porcine tissue, and spine on living swine model. The needle-based ultrasound system could visualize the structure, although reverberation and multiple reflections associated with the needle shaft were observed. These results show the potential of the system to be used for in vivo environment.