Suess O, Schönherr S, Schilling A, Kühn B, Mularski S O, Suess S, Brock M, Kombos T
Neurochirurgische Klinik, Charité -- Universitätsmedizin Berlin, Campus Benjamin Franklin.
Rofo. 2005 Jul;177(7):1000-8. doi: 10.1055/s-2005-858205.
Although computer- and image-guided surgical procedures are an improvement of frame-guided stereotaxy, many navigation systems still require rigid fixation of the patient's head throughout the operation. This study describes the clinical application of a technical modification that enables cranial navigation with "free head mobility" using CT and MR images as well as the calculated 3-D reconstruction models.
A sensor-based electromagnetic neuronavigation system was expanded to allow the localization and position monitoring of several sensors within an electromagnetic field. One of these sensors was attached to a dental splint as an additional reference (DRF = dynamic reference frame). Thus, it was possible to determine the position of the sensor-guiding surgical instruments and to record the slightest movement of the cranium as well. This information was then used to continuously adapt the position of the imaging plane and the resultant calculated 3-D reconstructions to the actual position of the cranium.
The clinical application of the DRF was tested for different neurosurgical procedures. They included image-guided biopsies and endoscopic interventions using MRI data, transnasal accesses to the base of the skull using CT data and surgical removal of multilocular metastases using data from both imaging modalities. Intracranial target reference points as well as those on the skull were found with a high accuracy to the initial measurement position after arbitrary movement of the patient's head. Thus, navigation was also possible without rigid fixation of the head because of the continuous adaptation of the imaging data on the change in position of the patient's head.
Based on these first test results, a high clinical potential for DRF application in cranial navigation is to be expected. The aim of DRF is to dispense with the rigid fixation of the patient's head. This increases the application scope of image-guided navigation procedures to include, for example, any bioptic or endoscopic intervention, in which rigid pin fixation of the cranium is not required or desired. For all other procedures, continuous position monitoring by DRF ensures automatic correction of imaging data with mechanical alteration of the head position.
尽管计算机辅助和图像引导的外科手术是框架引导立体定向技术的改进，但许多导航系统在整个手术过程中仍需要对患者头部进行刚性固定。本研究描述了一种技术改进的临床应用，该技术改进能够利用CT和MR图像以及计算出的三维重建模型实现“头部自由移动”的颅骨导航。
对基于传感器的电磁神经导航系统进行扩展，以允许在电磁场中对多个传感器进行定位和位置监测。其中一个传感器附着在牙托上作为额外参考（动态参考框架，DRF）。这样，就能够确定引导传感器的手术器械的位置，并记录颅骨的最轻微移动。然后利用这些信息不断调整成像平面的位置以及由此产生的计算出的三维重建，使其与颅骨的实际位置相匹配。
对DRF在不同神经外科手术中的临床应用进行了测试。这些手术包括使用MRI数据进行图像引导活检和内镜干预、使用CT数据经鼻进入颅底以及使用两种成像方式的数据手术切除多房转移瘤。在患者头部任意移动后，颅内靶点参考点以及颅骨上的参考点与初始测量位置的匹配精度很高。因此，由于成像数据能根据患者头部位置的变化不断调整，即使不进行头部刚性固定也能进行导航。
基于这些初步测试结果，预计DRF在颅骨导航中的临床应用潜力巨大。DRF的目的是无需对患者头部进行刚性固定。这扩大了图像引导导航程序的应用范围，例如包括任何不需要或不希望对颅骨进行刚性针固定的活检或内镜干预。对于所有其他手术，DRF进行的连续位置监测可确保随着头部位置的机械改变自动校正成像数据。
