Shape-recovery of implanted shape-memory devices remotely triggered via image-guided ultrasound heating
Yang Zhu, Kaicheng Deng, Jianwei Zhou, Chong Lai, Zuwei Ma, Hua Zhang, Jiazhen Pan, Liyin Shen, Matthew D. Bucknor, Eugene Ozhinsky, Seungil Kim, Guangjie Chen, Sang‐Ho Ye, Yue Zhang, Donghong Liu, Changyou Gao, Yonghua Xu, Huanan Wang, William R. Wagner
Abstract
Shape-memory materials hold great potential to impart medical devices with functionalities useful during implantation, locomotion, drug delivery, and removal. However, their clinical translation is limited by a lack of non-invasive and precise methods to trigger and control the shape recovery, especially for devices implanted in deep tissues. In this study, the application of image-guided high-intensity focused ultrasound (HIFU) heating is tested. Magnetic resonance-guided HIFU triggered shape-recovery of a device made of polyurethane urea while monitoring its temperature by magnetic resonance thermometry. Deformation of the polyurethane urea in a live canine bladder (5 cm deep) is achieved with 8 seconds of ultrasound-guided HIFU with millimeter resolution energy focus. Tissue sections show no hyperthermic tissue injury. A conceptual application in ureteral stent shape-recovery reduces removal resistance. In conclusion, image-guided HIFU demonstrates deep energy penetration, safety and speed.