Article
Effect of direct visualization of GPi using MDEFT MR sequence on targeting the GPi and location of the active electrode in the Gpi
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Authors
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Andreas Nowacki
- Department of Neurosurgery, University Hospital Bern, Bern, Switzerland
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Michael Fiechter
- Department of Neurosurgery, University Hospital Bern, Bern, Switzerland
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Jens Fichtner
- Department of Neurosurgery, University Hospital Bern, Bern, Switzerland
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Markus F. Oertel
- Department of Neurosurgery, University Hospital Bern, Bern, Switzerland
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Michael Schüpbach
- Department of Neurology, University Hospital Bern, Bern, Switzerland
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Ines Debove
- Department of Neurology, University Hospital Bern, Bern, Switzerland
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Lenard Lachenmayer
- Department of Neurology, University Hospital Bern, Bern, Switzerland
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Roland Wiest
- Institute for Diagnostic and Interventional Neuroradiology, Inselspital, University of Bern, Bern, Switzerland
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Claudio Pollo
- Department of Neurosurgery, University Hospital Bern, Bern, Switzerland
| Published: | June 2, 2015 |
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Outline
Text
Objective: Deep brain stimulation of the GPi has been shown to be effective in the treatment of dystonia and Parkinson's disease. Recent advances in different MRI sequences have provided direct visualization targeting of the GPi. Whether and how it has changed the way we target and place our electrodes within the GPi compared to standard atlas coordinates is still not clearly documented.The objective of this study is to prospectively study the impact of direct targeting on the final position of the active electrode using a Modified Driven Equilibrium Fourier Transform (MDEFT) sequences for T1-weighted sequence, which shows a good contrast of the basal ganglia and a low distorsion.
Method: 10 consecutive patients considered for bilateral GPi DBS for dystonia or Parkinson's disease were included in this study. Preoperative targeting of the GPi was performed visually on MDEFT sequence, as well as using standard atlas coordinates (Schaltenbrand and Wahren) and fused with stereotactic CT scan. Postoperative CT imaging was performed to calculate the location of the implanted leads as well as the active electrode(s). (iPlan, Brainlab, Germany). The coordinates of both visual and atlas based targets were compared. The stereotasctic coordinates of the lead and active electrode(s) were calculated and projected on the preopsegmented GPi.
Results: We found that the preoperative mean visual target coordinates were LAT = 20.06 ± 1.64, AP = 2,54 ± 0.78, VERT = -2.71 ± 1.30 and there was a significant difference in the LAT coordinate between dystonic (LAT = 19.34 ± 1.05) and parkinsonian (LAT = 20.79 ± 1.85) GPi target. The mean location of the active contact(s) calculated 6 months postoperatively was LAT = 19,97 ± 1,84, AP = 2,76 ± 1,14 and VERT = -4,26 ± 1,16. Projected on the segmented preoperative GPi, they were located in the inferior and posterior part of the structure in both dystonic and parkinsonian patients, which corresponds to the motor part of the GPi.
Conclusions: Compared to atlas based targeting, direct visual targeting using MDEFT shows a significantly higher variability of the laterality of the target coordinates and a significant shift in the posterior direction. Active electrodes were found in the posterior and inferior part of the structure, indicating that visual targeting provides a more precise targeting according to the patient individual anatomy of the GPi.
