Design and Verification of Novel Low-Cost MR-Guided Small-Animal Stereotactic System

Stereotactic systems have been used for decades to position surgical instruments in important preclinical and clinical studies. We developed and verified a low-cost magnetic-resonance-guided system for accurate preclinical stereotactic operations on small animals. The system consists of both commercially available and custom components, including in-house software written in MATLAB to register coordinate spaces. The software registers target the image-space coordinates from magnetic resonance imaging to the physical space through a rigid-body transform. The transform uses singular value decomposition to determine rotation and translation matrices that are optimal in a least squares sense. Needle positioning and core biopsy studies were performed to verify the accuracy of the system. The needle positioning study demonstrated a sub-millimeter positioning error of 0.294 ± 0.156 mm while using a 26 s gauge Hamilton needle. Biopsy studies demonstrated >94 % success in accessing sub-millimeter stereotactic targets embedded in agarose gel phantoms. These favorable results confirm that despite its relatively low hardware cost (US$18,730) and easy assembly, the system is able to consistently access stereotactic targets on the spatial scale of a small animal.