Multimodal localization of electrodes in deep brain stimulation: comparison of stereotactic CT and MRI with teleradiography.

Objective: In cross-sectional imaging, like CT or MRI, electrodes for deep brain stimulation are visualized by an artifact, which can differ from the real physical size of the electrode and even have an asymmetric appearance on MRI. The accuracy of such artifact-based estimation of the real position of the electrode using CT or MRI is investigated here. Stereotactic teleradiography was used as the gold standard.

Methods: Twenty-three patients with implanted electrodes in the subthalamic nucleus (DBS type 3389; Medtronic, Minneapolis, Minn., USA) were included in a retrospective study on multimodal estimation of electrode position by 2 raters. Short spoiled gradient echo MRI (n = 10) and multi-row CT (n = 13) data were compared with teleradiography.

Results: Mean radial differences between CT and X-ray for both raters were 0.6 +/- 0.2 and 0.7 +/- 0.3 mm, with maximum values of 1.0 and 1.2 mm, respectively. Both raters showed quite similar assessments in their ratings. Mean radial differences between MRI and X-ray were 1.2 +/- 0.4 and 1.1 +/- 0.4 mm, with maximum values of 1.7 and 2.2 mm. Concordance of the assessment was lower compared to CT.

Conclusion: Spoiled gradient echo MR imaging cannot be recommended for visual localization of the quadripolar macroelectrode type 3389 from Medtronic. In contrast, CT imaging in absolute terms and with quite similar assessments by both raters is intra- and postoperatively a satisfactory alternative to teleradiography.