High-field MRI-Compatible Needle Placement Robots for Prostate Interventions: Pneumatic and Piezoelectric Approaches

Magnetic resonance imaging (MRI) can be a very effective imaging modality for live guidance during surgical procedures. The rationale of MRI-guided surgery with robot-assistance is to perform surgical interventions utilizing “realtime” image feedback while minimize operation time and improves the surgical outcomes. However, challenges arise from electromagnetic compatibility within the high-field (1.5 Tesla or greater) MRI environment and mechanical constraints due to the confined close-bore space. This chapter presents two distinct MRI-compatible approaches for image-guided transperineal prostate needle placement. It articulates the robotic mechanism, actuator and sensor design, controller design and system integration for a pneumatically actuated robotic needle guide and a piezoelectrically actuated needle placement system. The two degree-of-freedom (DOF) pneumatic robot with manual needle insertion has a signal to noise ratio (SNR) loss limited to 5% with alignment accuracy under servo pneumatic control better than 0.94mm per axis. While the 6-DOF piezoelectrically actuated robot is the first demonstration of a novel multi piezoelectric actuator drive with less than 2% SNR loss for high-field MRI operating at full speed during imaging. Preliminary experiments in phantom studies evaluate system MRI compatibility, workflow, visualization and targeting accuracy.