Direct targeting of globus pallidus internus for deep brain stimulation using susceptibility-weighted magnetic resonance imaging

BACKGROUND: Deep brain stimulation (DBS) is a commonly used surgical treatment for various neurological disorders. Globus pallidus internus (GPi) is one of the main targets for DBS. Indirect targeting entails the use of atlas-based coordinates to establish anterior commissure - posterior commissure line and targets. T2-weighted (T2W) MRI is used for targeting GPi. In this radio-morphological study, we explored the compatibility of susceptibility-weighted imaging (SWI) for visualizing and targeting GPi.METHODS: Cranial MRI scans including SWI acquisitions of patients with generalized dystonia (GD) were reviewed. One patient received bilateral GPi electrodes using SWI scans as the baseline framework for targeting and electrode localizations were investigated. The preoperative and postoperative SWI-T2 MRI scans were fused to determine the target zone visibility.RESULTS: Twenty GD patients were included in the study, one of whom underwent DBS surgery. Intensity contrast values of the borders of GPi were compared using the Wilcoxon Test and P values <0.05 are considered significant. There was no significant difference between T2W and SWI sequences regarding CNR ventral and lateral scores, CNR medial scores were significantly different and favored SWI acquisition over T2W (P<0.001).CONCLUSIONS: SWI acquisition provides better visualization of the deep nuclei and helps detect and localize microvasculature along the trajectory. It provides similar target localization if not superior, compared to conventional planning acquisitions. SWI is a potentially safe and reliable preoperative planning image modality.