Objective: To establish a pipeline for reliable determination of lead rotation in directional DBS.

Background: New directional leads with segmented electrodes are now widely used in DBS for movement disorders. Consecutively, lead rotation is now a new degree of freedom which has to be accounted for when investigating directional DBS.

Methods: We created a Matlab-based algorithm which determines lead rotation by analysing the artefacts generated by the leads in postoperative CT imaging. The algorithm first tries to automatically detect rotation angles. If results are not satisfactory, the user is then able to fine-tune certain parameters of the algorithm. For this study the algorithm was employed in 85 consecutive patients which had been implanted with directional leads in different targets, by different surgeons, using different stereotactic frames, and different intraoperative imaging. All leads had been implanted with the stereotactic marker facing anteriorly. To validate our algorithm we first compared its results against those of a previously well validated and published algorithm (Sitz et al., (1)) using both the fully automatic and the user supervised workflow. We also investigated the amount of rotatory deviation from the patients’ anterior/posterior axis.

Results: In about 80 % of the cases rotation angles showed a deviation of less than 5 ° from the Sitz et al. algorithm when using the fully automatic workflow. Most of the remaining cases needed further fine-tuning by the user but then also produced accurate results. Mean rotatory deviation from the patients’ anterior/posterior axis was about 30 ° and in some cases deviations of more than 90 ° could be observed. No differences were observed when comparing different surgeons, stereotactic systems, or intraoperative imaging modalities.

Conclusions: The results confirm, that our algorithm can be used to determine the rotation of directional DBS leads. While the automatic version of the algorithm often provides very good results, user supervision is still needed to detect those cases where further fine-tuning is needed. We also demonstrated, that relevant rotatory deviation can be seen in many patients and that this occurs independent of intraoperative factors. In Conclusion we suggest that lead rotation should be controlled for in all studies investigating directional DBS. This is why the algorithm described in this study has now been made publicly available as part of the LEAD-DBS toolbox (www.lead-dbs.org, (2)).

References: 1. Sitz A, Hoevels M, Hellerbach A, et al. Determining the orientation angle of directional leads for deep brain stimulation using computed tomography and digital x-ray imaging: A phantom study. Med Phys. 2017;44:4463–4473. 2. Horn A, Kühn AA. Lead-DBS: a toolbox for deep brain stimulation electrode localizations and visualizations. NeuroImage. 2015;107:127–135.

« Back to 2018 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/directional-dbs-a-new-algorithm-to-determine-lead-rotation/