Mirror-Integrated Ultrasound Image-Guided Needle Intervention

Percutaneous Nephrolithotomy (PCNL), otherwise known as kidney stone removal, requires needle insertion through the patient’s skin towards stones in the kidney. Existing ultrasound (US) image-guided needle insertion employed in PCNL faces the challenge in terms of keeping the needle tip visible during the insertion process. We propose a needle insertion device with mirror-integrated US imaging, which provides an intuitive and simple solution to monitor the needle insertion path. This is achieved by using acoustic mirror to change the direction of ultrasound image plane while the needle goes through the spacing between two pieces of acoustic mirror, so that the needle path overlaps with the US image plane. Both the needle and the acoustic mirror are designed to be rotatable to provide the clinician with the flexibility to search for the optimal needle insertion orientation. According to the law of acoustic wave reflection, the needle should rotate two times the amount of the mirror to keep aligned with the US image plane. A synchronization mechanism consisting of belts and pulleys were designed to achieve this 2:1 rotation ratio. Needle-mirror synchronized rotation is tested using an imageprocessing-based method. In terms of imaging functionality, US images display the point target inside the gelatin phantom as well as the needle tip clearly. In the needle insertion experiment, a needle is inserted into the gelatin phantom to reach point targets, and results show a millimeter level insertion error. Overall, our results demonstrate the potential of using the proposed US image-guided needle intervention mechanism in clinical scenarios.