A novel methodology for localizing pallidal deep brain stimulation leads.

Introduction: Positioning of deep brain stimulation (DBS) leads is paramount for optimizing therapeutic efficacy in Parkinson's disease (PD) and dystonia. Quantitative determination of lead position remains essential; however, current atlas-based targeting and stereotactic coordinate methods, while informative, limit patient specificity afforded by high-resolution reconstruction and introduce subjective variability. Methods: We developed a novel pipeline in Unity™ to ingest 7T MRI-based reconstructions of DBS leads within the globus pallidus internus (GPi). Using anatomical landmarks and structure-specific algorithms, the GPi was parcellated into 12 anatomically-based subregions in a semi-automated, reproducible manner. Active contact positions were localized relative to a novel coordinate system developed from a GPi-based bounding box. A novel distance-to-border metric remapped contacts onto a common atlas (PD25) for population comparison against the same contacts mapped onto a common left GPi space using mid-commissural point (MCP) coordinates (Schaltenbrand-Wahren atlas). Results: Fifteen leads from 10 PD subjects were used for ellipsoid fitting of active contact locations, resulting in an elliptical volume of 38.94 mm Conclusion: Our novel software provides a quantifiable lead location with respect to the anatomical target, enhancing patient-specific lead localization by avoiding some of the pitfalls of either structure-to-atlas normalization or traditional stereotactic coordinates.