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Dr. Okun

Post of the Week: DBS in the MRI Suite

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Dear forum members,


We have been following the evolving story on a new system for doing DBS in the MRI suite (not the OR). Below are the results of an experiment showing it could be pretty accurate. We will keep you posted on testing.



Neurosurgery. 2011 Jul 25. [Epub ahead of print]

An Optimized System for Interventional MRI Guided Stereotactic Surgery: Preliminary Evaluation of Targeting Accuracy.

Larson PS, Starr PA, Bates G, Tansey L, Richardson RM, Martin AJ.


1 Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, USA; 2SurgiVision, Inc, Irvine, CA, USA; 3Department of Radiology, University of California, San Francisco, San Francisco, CA, USA.



Deep brain stimulation (DBS) electrode placement using interventional MRI has been previously reported using a commercially available skull mounted aiming device (Medtronic Nexframe MR) and native MRI scanner software. This first-generation method has technical limitations that are inherent to the hardware and software used. A novel system (SurgiVision ClearPoint) consisting of an aiming device (SMARTFrame) and software has been developed specifically for iMRI interventions including DBS.



A series of phantom and cadaver tests were performed to determine the system's capability, preliminary accuracy and workflow.



18 experiments using a water phantom were used to determine predictive accuracy of the software. 16 experiments using a gelatin-filled skull phantom were used to determine targeting accuracy of the aiming device. 6 procedures in three cadaver heads were performed to compare workflow and accuracy of ClearPoint with Nexframe MR.



Software prediction experiments showed an average error of 0.9±0.5 mm in magnitude in pitch and roll (mean pitch error -0.2±0.7 mm, mean roll error +0.2±0.7 mm) and an average error of 0.7±0.3 mm in X-Y translation with a slight anterior (0.5±0.3 mm) and lateral (0.4±0.3mm) bias. Targeting accuracy experiments showed average radial error of 0.5±0.3 mm. Cadaver experiments showed a radial error of 0.2±0.1 mm with the ClearPoint system (average procedure time 88±14 minutes) vs 0.6±0.2 mm with the Nexframe MR (average procedure time 92±12 minutes).



This novel system provides the submillimetric accuracy required for stereotactic interventions including DBS placement. It also overcomes technical limitations inherent in the first-generation iMRI system.

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