A Testbed for Haptic and Magnetic Resonance Imaging-Guided Percutaneous Needle Biopsy

Magnetic resonance imaging (MRI) is used for soft tissue pathology diagnosis and assistance with targeted lesion procedures. However, limited physician access to patients in the magnetic resonance scanner bore requires iterative positioning and imaging, which extends the procedure time and increases patient risk. We present a teleoperated system and instrumented testbed for robotic MRI-guided needle biopsy, particularly targeting transperineal prostate biopsies. The device has a 1:1 kinematic mapping and uses a low-friction hydrostatic transmission based on antagonistic pairs of rolling diaphragms. It has three degrees of freedom (DOFs) and a passive two-DOF swivel, which holds a biopsy needle at the end-effector. Measured force hysteresis is 0.085 N (single DOF) and 0.44 N (full three-DOF manipulator) at the needle driving point. To quantitatively assess the system's haptic qualities, impulse modal testing for one DOF ( $>$ 300 Hz bandwidth) and three DOFs ( $>$ 40  Hz bandwidth) was conducted. Task performance was also assessed through membrane puncture testing with tissue phantoms; puncture events as low as 0.1 N are reliably detectable from transmission hydraulic pressure sensors.