Objective: Systematic review of literature to verify accuracy of iCT for the anatomical target in DBS surgery.

Background: Accurate lead placement is crucial to maximize efficacy of Deep Brain Stimulation (DBS) and to achieve best clinical results in short and long term. 3D imaging for lead verification consists of intraoperative imaging, including intraoperative CT (ioCT) and intraoperative MRI, and postoperative imaging, including CT (poCT) and MRI (poMRI). ioCT is an established neurosurgical modality to navigate and instantly verify surgical results. In recent years, ioCT has been introduced in verification of the DBS lead position. ioCT could replace routine postoperative imaging and could give the advantage of immediate lead repositioning. Before implementation in the standard care path, a summary of the evidence of validation of (sub)millimetric accuracy of ioCT compared to poCT is required.

Method: Medline, Embase and Web of Science were searched for relevant studies using predefined inclusion and exclusion criteria. The inclusion criteria were comparison of lead coordinates, in patients who underwent surgery for DBS, between ioCT scan and preoperative MRI target; or between ioCT and poCT or poMRI. The studies were assessed for methodological quality with QUADAS-2. Absolute differences in X, Y and Z, vector errors and Euclidian distances (Ed) were compared between the chosen reference points for all comparisons.

Results: 29 articles met the inclusion criteria and were selected. Most studies were of good methodological quality. Studies in which target on MRI was compared to ioCT showed an Ed within a range of 0.886 (sd 0.19)-2.5 (sd 1.2) mm. Direct comparison of ioCT vs poMRI showed an Ed within a range of 0.97 (sd 0.47)-3.2 (sd 1.5) mm. The Ed distance of 3.2 mm was mostly influenced by the dorsoventral (Z-axis) difference of 2.75 (sd 0.15) mm. Direct comparison of ioCT vs poCT showed an Ed within a range of 0.72 (sd 0.38) – 1.43 (sd 0.66) mm.

Conclusion: All Euclidian distances (except for one study comparing ioCT with poMRI) showed accuracy difference of less than 2.5 mm (average 1.57 mm). Accuracy was higher when comparing ioCT with poCT possibly due to the similar modality. This review proves that ioCT for DBS surgery has a reliable accuracy for determining lead position and can be considered as a valid alternative to routine poCT or poMRI with the surplus value of intraoperative guiding.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/review-of-intraoperative-computed-tomography-accuracy-for-deep-brain-stimulation-lead-verification/