Accuracy evaluation of microTargeting Platforms for deep-brain stimulation using virtual targets.

Deep-brain-stimulation (DBS) surgery requires implanting stimulators at target positions with submillimetric accuracy. Traditional stereotactic frames can provide such accuracy, but a recent innovation called the microTargeting Platform (FHC, Inc.) replaces this large, universal frame with a single-use, miniature, and custom-designed platform. Both single-target and dual-target platforms are available for unilateral and bilateral procedures, respectively. In this paper, their targeting accuracies are evaluated in vitro. Our approach employs "virtual targets," which eliminates the problem of collision of the implant with the target. We implement virtual targets by mounting fiducial markers, which are not used in platform targeting, on an artificial skull and defining targets relative to the skull via that fiducial system. The fiducial system is designed to surround the targets, thereby reducing the overall effect of fiducial localization inaccuracies on the evaluation. It also provides the geometrical transformation from image to physical space. Target selection is based on an atlas of stimulation targets from a set of 31 DBS patients. The measured targeting error is the displacement between the phantom implant and the virtual target. Our results show that the microTargeting Platform exhibits submillimetric in vitro accuracy with a mean of 0.42 mm and a 99.9% level of 0.90 mm.