A Computer-Generated Stereotactic "Virtual Subdural Grid" to Guide Resective Epilepsy Surgery
Kevin Morrisa,
Terence J. O’Briena,
Mark J. Cooka,
Michael Murphya and
Stephen C. Bowdena
a From the Victorian Epilepsy Centre, the Centre for Clinical Neurosciences and Neurological Research, and the Departments of Medicine and Surgery, The University of Melbourne, St. Vincent’s Hospital Melbourne, Victoria, Australia
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FIG 1. Patient 1. Stereotactic IGSS display shows orthogonal MR imaging views, 3D rendering of segmented brain, lesion, and the Virtual Grid prepared by using a coregistered CT scan.
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FIG 2. Development of a Virtual Grid by segmentation and co-registration of a post-implantation CT scan.
A, Axial section from the spiral CT scan of the head acquired following implantation of the subdural grid.
B, Binary image of the subdural electrodes that had been segmented from the spiral CT image.
C and D, Binary image of the subdural electrode positions (C)transformed and combined with the segmented MR image, trileveled image (D) representing, respectively, the brain, the lesion, and the subdural electrodes.
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FIG 3. Patient 2. Image-guided surgery system display shows orthogonal MR views, 3D rendering of segmented brain, and subdural grid (prepared by using segmentation of electrodes from the postgrid-implantation MR image).
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FIG 4. Patient 2. Measuring the displacement of the segmented (MR imaging source) Virtual Grid electrode from the displayed position of the surgeon’s infrared probe centered on the actual subdural grid electrode. The image was captured as a "snapshot" and resized so that nearby electrode centers were close to 1 cm apart. The displacement error has been measured as 0.23 cm.
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