Objective: In this phantom study we created an overview of the accuracy of four different modalities frequently used in DBS surgery and investigated the influence of non-linear distortion due to interaction between the radiation field and the stereotactic Leksell G-frame.

Background: The clinical response to Deep Brain Stimulation (DBS) surgery is highly dependent on accurate electrode placement. Various CT and MRI modalities, each with specific characteristics, are used for planning and verification in DBS surgery. However, the comparative accuracy of the different modalities for lead verification and the influence of a stereotactic frame application is unclear, and ideally investigated in a fixed investigational setting.

Method: A phantom containing 27 balls was scanned in four different modalities (3T MRI, 1.5T MRI, intraoperative CT (ioCT) and post-operative CT (poCT)) with and without the Leksell G-frame using a 3D-printed connecting construction. The primary outcome was defined as the Euclidean Distance (ED) measured between the actual phantom coordinates and the scan-coordinates and the ED between the localization of the balls on the scan with and without the stereotactic frame. Secondary outcomes were the deviation in individual x-, y- and z-coordinates, ED changes relative to the distance towards the stereotactic frame and frameless inter-scan variation.

Results: The median ED was 4.11 mm, 2.43 mm, 1.10 mm and 1.29 mm for respectively 3T MRI, 1.5T MRI, ioCT and poCT compared to actual coordinates. The ED between the frameless and frame-based scans was found clinically relevant only for 1.5T MRI (median 1.80 mm) with the largest difference in the z-axis. There was an association between the ED and the distance to the stereotactic frame from the center of the phantom downwards. The mean inter-scan variation for both MRI modalities were larger (mean 0.77 and 0.91 mm) with a wider spread compared to both CT modalities (mean 0.10 mm and 0.22 mm).

Conclusion: IoCT has a high and consistent accuracy for lead verification and can safely be used with or without stereotactic frame. Either frame-based ioCT or poCT can be used as a more accurate alternative to the frame-based 1.5T MRI to translate anatomical coordinates into stereotactical coordinates.

« Back to 2022 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/verifying-imaging-accuracy-for-targeting-and-lead-positioning-in-dbs-a-phantom-study/