Morris Kevin, O'Brien Terence J, Cook Mark J, Murphy Michael, Bowden Stephen C
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.
AJNR Am J Neuroradiol. 2004 Jan;25(1):77-83.
In selected patients undergoing epilepsy surgery, subdural electrode grids play an important role in localizing the epileptogenic zone and identifying eloquent cortex. Determining the relationship of the electrodes to underlying brain architecture traditionally has been difficult. This report describes and validates the use of an original computer-aided method that displays a representation of the electrode positions, based on postimplantation CT or MR findings, coregistered with a 3D-rendered image of the brain, on an image-guided surgery system.
Seventeen patients underwent the procedure with visual verification of the actual and virtual grids undertaken during the second (postimplantation) surgery. The accuracy of the Virtual Grid electrode positions was further studied in a subgroup of five patients during surgery by plotting the distance from the actual electrode positions by using an infrared stereotactic probe.
The accuracy of the Virtual Grid electrode positions by visual inspection was satisfactory in all 17 cases. In the five cases in which quantitative measurements were performed, the mean error for the CT derived electrode positions was 3.4 mm (range 0.5-5.4) compared with the mean error for the MR-derived electrode positions of 2.5 mm (range 0.5-5.2).
The Virtual Grid electrode positions were highly accurate in localizing the actual position of the subdural electrodes with both CT- and MR-derived images. The MR-derived electrodes demonstrated a trend toward better accuracy, but the CT images were quicker and easier to process. This technology has the potential to minimize both human and technical errors, allowing for a more precise tailoring of the cortical resection in epilepsy surgery.
在部分接受癫痫手术的患者中，硬膜下电极网格在癫痫灶定位及明确功能区皮层方面发挥着重要作用。传统上，确定电极与下方脑结构的关系颇具难度。本报告描述并验证了一种原始的计算机辅助方法，该方法基于植入后CT或MR检查结果，在图像引导手术系统上显示电极位置的示意图，并与大脑的三维渲染图像进行配准。
17例患者接受了该操作，并在第二次（植入后）手术期间对实际网格和虚拟网格进行了视觉验证。在5例患者的亚组中，通过使用红外立体定向探头绘制实际电极位置的距离，进一步研究了虚拟网格电极位置的准确性。
通过视觉检查，17例患者的虚拟网格电极位置准确性均令人满意。在进行定量测量的5例患者中，CT衍生电极位置的平均误差为3.4mm（范围0.5 - 5.4），而MR衍生电极位置的平均误差为2.5mm（范围0.5 - 5.2）。
虚拟网格电极位置在利用CT和MR衍生图像定位硬膜下电极的实际位置方面具有高度准确性。MR衍生电极显示出准确性更高的趋势，但CT图像处理更快、更简便。该技术有可能将人为和技术误差降至最低，使癫痫手术中的皮层切除术更加精确。
