AO Research Institute Davos, AO Foundation, Davos-Platz, Switzerland.
J Digit Imaging. 2011 Aug;24(4):665-71. doi: 10.1007/s10278-010-9327-0.
Sacroiliac (SI) joint dislocations and sacral fractures of the pelvis can be stabilized by SI screws; however, screw insertion into a sacral isthmus region is risky for the adjacent neurovascular structures. Therefore, shape analyses of general SI screw corridors or safety zones are of great surgical interest; however, before such analyses can be conducted, a method for computing 3D models of general SI corridors from routine clinical computed tomography (CT) scans has to be developed. This work describes a method for determining general corridors in pelvic CT data for accurate screw placement into the first sacral body. The method is implemented with the computer language C++. The pelvic CT data are preprocessed before the presented algorithm computes a model of the 3D corridor volume. Additionally, the two most important parameters of the algorithm, the raster step and the virtual SI screw diameter, have been characterized. The result of the work is an algorithm for computing general SI screw corridors and its implementation. Additionally the influences of two important parameters, the raster step and the SI screw diameter, on corridor volume precision and computation time have been quantified for the test sample. We conclude that the method can be used in further corridor shape analyses with a large number of pelvic CT data sets for investigating general SI screw corridors and clinical consequences for the placements of the screws. Implementation of the presented software algorithm could also enhance performance of computer-assisted surgery in the near future.
骶髂（SI）关节脱位和骨盆骶骨骨折可以通过 SI 螺钉固定；然而，将螺钉插入骶骨峡部区域对相邻的神经血管结构有风险。因此，对一般 SI 螺钉通道或安全区域的形状分析具有重要的手术意义；然而，在进行此类分析之前，必须开发一种从常规临床计算机断层扫描（CT）扫描中计算一般 SI 通道的 3D 模型的方法。这项工作描述了一种从骨盆 CT 数据中确定一般通道的方法，以便将螺钉准确地放置到第一骶骨体中。该方法使用 C++编程语言实现。在呈现的算法计算 3D 通道体积模型之前，对骨盆 CT 数据进行预处理。此外，还对算法的两个最重要参数，栅格步长和虚拟 SI 螺钉直径进行了特征描述。工作的结果是一种用于计算一般 SI 螺钉通道的算法及其实现。此外，还针对测试样本量化了两个重要参数，即栅格步长和 SI 螺钉直径对通道体积精度和计算时间的影响。我们得出结论，该方法可用于进一步的通道形状分析，使用大量骨盆 CT 数据集来研究一般 SI 螺钉通道及其对螺钉放置的临床后果。在不久的将来，呈现的软件算法的实现也可以增强计算机辅助手术的性能。
