Intra-operative recording of the location of tissue sampling and direct cortical stimulation using a commercial neuro-navigation system.

Correlation of neuro-imaging findings with histopathology is essential to enable diagnostic techniques to be fully evaluated and requires the location from which tissue sample are obtained to be accurately recorded. Commercial neuro-navigation systems present an opportunity to log this data along with other relevant operative information but the mechanism by which it is recorded requires validation.Recording of biopsy locations using the BrainLab VectorVision system was evaluated using the internal point logging system, reconstruction of screenshot images and via a directly interfaced research platform (3D Slicer). Following a phantom study, biopsy locations were recorded for 12 patients using reconstructed screenshots (n=11) and/or the Slicer system (n=2). The Slicer system was further evaluated in tracking the locations at which direct cortical stimulation was performed in 7 patients within a language mapping study.38 tissue samples were obtained for which screenshots were recorded. These could be reconstructed using a custom utility and co-registered with the original 3D image volume in all cases. In no case was a discrepancy of greater than the maximum MRI slice thickness (2 standard deviations of the distance for all 836 points (>83.1mm).The use of commercial neuro-navigation systems to record tissue sampling locations is feasible. Screenshots with an appropriate scale marking can be reconstructed to allow the original location to be recorded with the accuracy constrained partly by the parameters of the structural MRI. Adding a dedicated system enables larger numbers of exact co-ordinates to be recorded with a surgeon triggered interface. However, erroneous points may be recorded, particularly if the tracking system is partially obstructed, making careful error checking essential.