Digital Photography and 3D MRI–based Multimodal Imaging for Individualized Planning of Resective Neocortical Epilepsy Surgery

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Abstract
Summary: Purpose: Invasive presurgical work up of pharmacoresistant epilepsies presumes integration of multiple diagnostic modalities into a comprehensive picture of seizure onset and eloquent brain areas. During resection, reliable transfer of evaluation results to the patient's individual anatomy must be made. We investigated the value of digital photography–based grid localization in combination with preoperative three‐dimensional (3D) magnetic resonance imaging (MRI) for clinical routine. Methods: Digital photographs of the exposed cortex were taken before and after grid placement. Location of electrode contacts on the cortex was identified and schematically indicated on native cortex prints. Accordingly, transfer of contact positions to a 3D MRI brain‐surface rendering was carried out manually by using the rendering software. Results of the electrophysiologic evaluation were transferred to either electrode contact reproduction and co‐registered with imaging‐based techniques such as single‐photon emission computed tomography (SPECT), positron emission tomography (PET), and functional MRI (fMRI). Results: Digital photography allows precise and highly realistic documentation of electrode contact positions on the individual neocortical surface. Lesions underneath grids can be highlighted by semitransparent MRI surface rendering, and lobar boundaries can be identified. Because of integrating electrode contact positions into the postprocessed 3D MRI data set, imaging‐based techniques can be codisplayed with the results of the electrophysiologic evaluation. Comparison with CT/MRI co‐registration showed good accuracy of the method. However, grids not sewn to the dura at implantation can become subject to significant displacement. Conclusions: Digital photography in combination with preimplantation 3D MRI allows the generation of reliable tailored resection plans in neocortical epilepsy surgery. The method enhances surgical safety and confidence.