Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois, USA.
J Neurosurg. 2011 Aug;115(2):301-9. doi: 10.3171/2011.3.JNS101642. Epub 2011 Apr 15.
Correct lead location in the desired target has been proven to be a strong influential factor for good clinical outcome in deep brain stimulation (DBS) surgery. Commonly, a surgeon's first reliable assessment of such location is made on postoperative imaging. While intraoperative CT (iCT) and intraoperative MR imaging have been previously described, the authors present a series of frameless DBS procedures using O-arm iCT.
Twelve consecutive patients with 15 leads underwent frameless DBS placement using electrophysiological testing and O-arm iCT. Initial target coordinates were made using standard indirect and direct assessment. Microelectrode recording (MER) with kinesthetic responses was performed, followed by microstimulation to evaluate the side-effect profile. Intraoperative 3D CT acquisitions obtained between each MER pass and after final lead placement were fused with the preoperative MR image to verify intended MER movements around the target area and to identify the final lead location. Tip coordinates from the initial plan, final intended target, and actual lead location on iCT were later compared with the lead location on postoperative MR imaging, and euclidean distances were calculated. The amount of radiation exposure during each procedure was calculated and compared with the estimated radiation exposure if iCT was not performed.
The mean euclidean distances between the coordinates for the initial plan, final intended target, and actual lead on iCT compared with the lead coordinates on postoperative MR imaging were 3.04 ± 1.45 mm (p = 0.0001), 2.62 ± 1.50 mm (p = 0.0001), and 1.52 ± 1.78 mm (p = 0.0052), respectively. The authors obtained good merging error during image fusion, and postoperative brain shift was minimal. The actual radiation exposure from iCT was invariably less than estimates of exposure using standard lateral fluoroscopy and anteroposterior radiographs (p < 0.0001).
O-arm iCT may be useful in frameless DBS surgery to approximate microelectrode or lead locations intraoperatively. Intraoperative CT, however, may not replace fundamental DBS surgical techniques such as electrophysiological testing in movement disorder surgery. Despite the lack of evidence for brain shift from the procedure, iCT-measured coordinates were statistically different from those obtained postoperatively, probably indicating image merging inaccuracy and the difficulties in accurately denoting lead location. Therefore, electrophysiological testing may truly be the only means of precisely knowing the location in 3D space intraoperatively. While iCT may provide clues to electrode or lead location during the procedure, its true utility may be in DBS procedures targeting areas where electrophysiology is less useful. The use of iCT appears to reduce radiation exposure compared with the authors' traditional frameless technique.
在脑深部刺激（DBS）手术中，正确的目标导联位置已被证明是良好临床效果的重要影响因素。通常，外科医生对这种位置的首次可靠评估是在术后影像学检查中进行的。尽管已经描述了术中 CT（iCT）和术中磁共振成像，但作者介绍了一系列使用 O 臂 iCT 的无框架 DBS 手术。
12 例连续患者共 15 例导联接受了无框架 DBS 放置，使用电生理测试和 O 臂 iCT。初始目标坐标使用标准间接和直接评估方法确定。进行微电极记录（MER）和运动觉反应，然后进行微刺激以评估副作用谱。在每次 MER 通过后和最终导联放置后获得的术中 3D CT 采集与术前 MR 图像融合，以验证目标区域周围的预期 MER 运动，并确定最终导联位置。初始计划、最终目标和 iCT 上实际导联的尖端坐标与术后 MR 成像上的导联位置进行比较，并计算欧几里得距离。计算每次手术的辐射暴露量，并与不进行 iCT 时的估计辐射暴露量进行比较。
初始计划、最终目标和 iCT 上实际导联与术后 MR 成像上导联坐标之间的平均欧几里得距离分别为 3.04 ± 1.45 mm（p = 0.0001）、2.62 ± 1.50 mm（p = 0.0001）和 1.52 ± 1.78 mm（p = 0.0052）。作者在图像融合中获得了良好的融合误差，术后脑移位最小。iCT 的实际辐射暴露始终小于使用标准侧位荧光透视和前后位 X 线摄影的估计暴露量（p < 0.0001）。
O 臂 iCT 可用于无框架 DBS 手术中，以在术中近似微电极或导联位置。然而，术中 CT 可能无法替代运动障碍手术中基本的 DBS 手术技术，如电生理测试。尽管该程序没有脑移位的证据，但 iCT 测量的坐标与术后获得的坐标在统计学上不同，可能表明图像融合不准确，以及准确标记导联位置的困难。因此，电生理测试可能确实是唯一一种在术中精确了解 3D 空间中位置的方法。虽然 iCT 可以在手术过程中提供电极或导联位置的线索，但它的真正用途可能是在电生理作用较小的 DBS 手术部位。与作者传统的无框架技术相比，iCT 的使用似乎降低了辐射暴露量。
