Comparison of intraoperative CT with postoperative MRI for determining DBS electrode coordinates

BACKGROUND: Deep brain stimulation (DBS) is an effective therapy for a variety of refractory movement disorders. Accurate lead placement in the target nucleus is critical to ensure therapeutic effects and to minimize side effects, and intraoperative computed tomography (iCT) scan has been used to target and confirm lead position. The objective of this study is to compare the accuracy of determining the x, y, and z coordinates of final lead placement using iCT scan relative to postoperative magnetic resonance imaging (MRI). METHODS: We conducted a retrospective study on 83 patients who underwent insertion of 145 DBS leads from 2015 to 2017 at a single institution. iCT scan was merged with the preoperative MRI to determine lead coordinates on both magnetic resonance and computed tomography images independently, and the absolute differences between the x, y, and z coordinates between the 2 scans along with the Euclidean vectors were calculated. RESULTS: The mean absolute differences +/- standard error of the mean between iCT scan and postoperative MRI coordinates were as follows: x = 0.01 +/- 0.09 mm (P = 0.89), y = 1.67 +/- 0.14 mm (P < 0.001), and z = 2.75 +/- 0.15 mm (P < 0.001). The average Euclidean vector difference was 3.21 +/- 0.15 mm (P < 0.001). CONCLUSIONS: Significant differences exist between iCT scan and postoperative MRI DBS y and z lead coordinates, but not with x coordinates. Based on this series, iCT scan is more accurate when confirming x coordinates, and less accurate for confirming y and z coordinates during DBS operations.