7-Tesla Magnetic Resonance Imaging Scanning in Deep Brain Stimulation for Parkinson's Disease: Improving Visualization of the Dorsolateral Subthalamic Nucleus.

BACKGROUND: Identifying the dorsolateral subthalamic nucleus (STN) for deep brain stimulation (DBS) in Parkinson's disease (PD) can be challenging due to the size and double-oblique orientation. Since 2015 we implemented 7-Tesla T2 weighted magnetic resonance imaging (7 T T2) for improving visualization and targeting of the dorsolateral STN. We describe the changes in surgical planning and outcome since implementation of 7 T T2 for DBS in PD. METHODS: By comparing two cohorts of STN DBS patients in different time periods we evaluated the influence of 7 T T2 on STN target planning, the number of microelectrode recording (MER) trajectories, length of STN activity and the postoperative motor (UPDRS) improvement. RESULTS: From February 2007 to January 2014, 1.5 and 3-Tesla T2 guided STN DBS with 3 MER channels was performed in 76 PD patients. Average length of recorded STN activity in the definite electrode trajectory was 3.9 ± 1.5 mm. From January 2015 to January 2022 7 T T2 and MER-guided STN DBS was performed in 182 PD patients. Average length of recorded STN activity in the definite electrode trajectory was 5.1 ± 1.3 mm and used MER channels decreased from 3 to 1. Average UPDRS improvement was comparable. CONCLUSION: Implementation of 7 T T2 for STN DBS enabled a refinement in targeting. Combining classical DBS targeting with dorsolateral STN alignment may be used to determine the optimal trajectory. The improvement in dorsolateral STN visualization can be used for further target refinements, for example adding probabilistic subthalamic connectivity, to enhance clinical outcome of STN DBS.

Dorsal subthalamic nucleus targeting in deep brain stimulation: microelectrode recording versus 7-Tesla connectivity.

Connectivity-derived 7-Tesla MRI segmentation and intraoperative microelectrode recording can both assist subthalamic nucleus targeting for deep brain stimulation in Parkinson's disease. It remains unclear whether deep brain stimulation electrodes placed in the 7-Tesla MRI segmented subdivision with predominant projections to cortical motor areas (hyperdirect pathway) achieve superior motor improvement and whether microelectrode recording can accurately distinguish the motor subdivision. In 25 patients with Parkinson's disease, deep brain stimulation electrodes were evaluated for being inside or outside the predominantly motor-connected subthalamic nucleus (motor-connected subthalamic nucleus or non-motor-connected subthalamic nucleus, respectively) based on 7-Tesla MRI connectivity segmentation. Hemi-body motor improvement (Movement Disorder Society Unified Parkinson's Disease Rating Scale, Part III) and microelectrode recording characteristics of multi- and single-unit activities were compared between groups. Deep brain stimulation electrodes placed in the motor-connected subthalamic nucleus resulted in higher hemi-body motor improvement, compared with electrodes placed in the non-motor-connected subthalamic nucleus (80% versus 52%, P < 0.0001). Multi-unit activity was found slightly higher in the motor-connected subthalamic nucleus versus the non-motor-connected subthalamic nucleus (P < 0.001, receiver operating characteristic 0.63); single-unit activity did not differ between groups. Deep brain stimulation in the connectivity-derived 7-Tesla MRI subthalamic nucleus motor segment produced a superior clinical outcome; however, microelectrode recording did not accurately distinguish this subdivision within the subthalamic nucleus.

Utilizing 7-Tesla Subthalamic Nucleus Connectivity in Deep Brain Stimulation for Parkinson Disease.

BACKGROUND: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a highly effective surgical treatment for patients with advanced Parkinson disease (PD). Combining 7.0-Tesla (7T) T2- and diffusion-weighted imaging (DWI) sequences allows for selective segmenting of the motor part of the STN and, thus, for possible optimization of DBS. MATERIALS AND METHODS: 7T T2 and DWI sequences were obtained, and probabilistic segmentation of motor, associative, and limbic STN segments was performed. Left- and right-sided motor outcome (Movement Disorders Society Unified Parkinson's Disease Rating Scale) scores were used for evaluating the correspondence between the active electrode contacts in selectively segmented STN and the clinical DBS effect. The Bejjani line was reviewed for crossing of segments. RESULTS: A total of 50 STNs were segmented in 25 patients and proved highly feasible. Although the highest density of motor connections was situated in the dorsolateral STN for all patients, the exact partitioning of segments differed considerably. For all the active electrode contacts situated within the predominantly motor-connected segment of the STN, the average hemi-body Unified Parkinson's Disease Rating Scale motor improvement was 80%; outside this segment, it was 52% (p < 0.01). The Bejjani line was situated in the motor segment for 32 STNs. CONCLUSION: The implementation of 7T T2 and DWI segmentation of the STN in DBS for PD is feasible and offers insight into the location of the motor segment. Segmentation-guided electrode placement is likely to further improve motor response in DBS for PD. However, commercially available DBS software for postprocessing imaging would greatly facilitate widespread implementation.