Determining the Rotational Orientation of Directional Deep Brain Stimulation Leads Employing Flat-Panel Computed Tomography.

BACKGROUND: Directional deep brain stimulation (DBS) constitutes an emerging technology that allows selective stimulation of target structures via partitioned electrode contacts. In order to effectively perform target-tailored stimulation, knowledge of the rotational orientation of the segmented leads is imperative. OBJECTIVE: To develop a universally applicable and reliable method for determination of lead orientation angles in DBS using flat-panel computed tomography (fpCT). METHODS: A binary template of directional leads DB-2202-30 (Boston Scientific, Natick, Massachusetts) and 6170 (Abbott, Plano, Texas) was imported into the 2-dimensional raw data set of a conventional fpCT scan. The template was aligned with and manually rotated around the predetermined lead trajectory. The overall orientation of the segmented lead can be deduced by transferring position and orientation of the lead orientation marker into the 3-dimensional volume. Accuracy of the method was investigated by two raters in a phantom study. RESULTS: Accuracy were 5.4° ± 4.1° (range: 0.4°-11.9°) for rater 1 and 5.2° ± 3.0° (range: 0.3°-10.2°) for rater 2, when investigating DB-2202-30. For 6170 observed deviations were 2.5° ± 1.7° (range: 0.2°-5.2°) and 4.3° ± 3.6° (range: 0.2°-11.2°) for raters 1 and 2, respectively. CONCLUSION: fpCT imaging constitutes a precise and accurate means to determine the rotational orientation of directional leads. The approach is universally transferable to different electrode designs as the template can easily be adjusted to the electrodes' specific measures. The approach is independent from polar implantation angles owing to fpCT- and methodological features.

Intensity-based 2D 3D registration for lead localization in robot guided deep brain stimulation.

Intraoperative assessment of lead localization has become a standard procedure during deep brain stimulation surgery in many centers, allowing immediate verification of targeting accuracy and, if necessary, adjustment of the trajectory. The most suitable imaging modality to determine lead positioning, however, remains controversially discussed. Current approaches entail the implementation of computed tomography and magnetic resonance imaging. In the present study, we adopted the technique of intensity-based 2D 3D registration that is commonly employed in stereotactic radiotherapy and spinal surgery. For this purpose, intraoperatively acquired 2D x-ray images were fused with preoperative 3D computed tomography (CT) data to verify lead placement during stereotactic robot assisted surgery. Accuracy of lead localization determined from 2D 3D registration was compared to conventional 3D 3D registration in a subsequent patient study. The mean Euclidian distance of lead coordinates estimated from intensity-based 2D 3D registration versus flat-panel detector CT 3D 3D registration was 0.7 mm ± 0.2 mm. Maximum values of these distances amounted to 1.2 mm. To further investigate 2D 3D registration a simulation study was conducted, challenging two observers to visually assess artificially generated 2D 3D registration errors. 95% of deviation simulations, which were visually assessed as sufficient, had a registration error below 0.7 mm. In conclusion, 2D 3D intensity-based registration revealed high accuracy and reliability during robot guided stereotactic neurosurgery and holds great potential as a low dose, cost effective means for intraoperative lead localization.