MRI-Conditional Eccentric-Tube Injection Needle: Design, Fabrication, and Animal Trial

Effective radiation therapy aims to maximize the radiation dose delivered to the tumor, while minimizing damage to the surrounding healthy tissues, which can be a challenging task when the tissue-tumor space is small. To eliminate the damage to healthy tissue, it is now possible to inject biocompatible hydrogels between cancerous targets and surrounding tissues to create a spacer pocket. Conventional methods have limitations in poor target visualization and device tracking. In this article, we leverage our MR-tracking technique to develop a novel injection needle for hydrogel spacer deployment. Herein, we present the working principle and fabrication method, followed by benchtop validation in an agar phantom, and magnetic resonance imaging (MRI)-guided validation in tissue-mimic prostate phantom and sexually mature female swine. Animal trials indicated that the spacer pockets in the rectovaginal septum can be accurately visualized on T2-weighted MRI. The experimental results showed that the vaginal-rectal spacing was successfully increased by 12 \pm {\bm{\ }}2 mm anterior-posterior.