Introduction: The STN is the most common target for motor-predominant PD. We are unaware of any comparative studies on a cohort utilizing all of modern modalities, namely intraoperative 32-slice CT, preoperative MR, macrostimulation, and MER-guided DBS implantation. We attempt to describe the contribution of each to clinical outcome, arriving at the surprising conclusion below.

Methods: Preoperative and postoperative clinical results were quantified as shown in Figure 1. Patients had a pre-operative 1.5/3T MRI, were then induced and placed in a stereotactic frame. Neurologica BodyTom was then used to scan the patient. Atlas-derived target was calculated and final targeting was determined by MER/macrostimulation data (Figure 2).

Results: As can be seen in Figure 2, a significant improvement in quality of life was experienced. Figures 3 and 4 show the MER-influenced changes in indirect target coordinates. Given a lead diameter of 1.75 mm, and an inter-microelectrode distance of 2 mm, this brought about the tantalizing question of whether or not we could use this system to directly target the STN. We had a blinded neuroradiologist select an ideal target using our paradigm. Figure 5 shows that in doing so, range from target is only 1.08 to 2.19 mm. Given the robust clinical outcomes we obtained with the ranges outlined above and the deviations listed in Figure 5, this study portends the exciting possibility of directly targeting the STN via high resolution MRI and potentially eliminating the need of MER.

Conclusions: Though we are conducting ongoing studies to verify this hypothesis, the use of our intraoperative scanner has resulted in nearly 90% of patients experiencing symptomatic relief. We encountered no hemorrhages, strokes, or infections, and only 3 lead position changes, all done intraoperatively. This technique is an exciting improvement regardless of targeting implications.

Patient Care: As described above, no comparative studies have been published on the use of a relatively new technological application, intraoperative 32-slice computed tomography, in addition to MR and MER-guided DBS implantation, and their relative contributions to clinical outcomes. Our data not only quantifies many of these variables but portends the exciting possibility of directly targeting the STN with our current paradigm, possibly eliminating MER/macrostimulation modalities. Though we are currently studying this issue, even without direct targeting, intraoperative CT has led to an incredibly safe and efficacious lead placement technique in our cohort as described above. Regardless of its role in direct guidance, which is promising as described above, the use of our 32-slice intraoperative CT scanner is of great benefit in ensuring proper lead placement in patients and thus improving clinical outcomes.

Learning Objectives: Describe the benefits of intraoperative, true 32-slice computed tomography in DBS lead placement while utilizing MRI and MER data, as well as the potential of direct STN targeting with this exciting paradigm as described above.

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