McConnell Brain Imaging Centre, Montreal Neurological Institute, 3801 Rue University, Montreal, Quebec, Canada.
Int J Comput Assist Radiol Surg. 2011 Jul;6(4):523-37. doi: 10.1007/s11548-010-0536-2. Epub 2010 Oct 26.
Accurate registration of patient anatomy and preoperative computed tomography (CT) images is key to successful image-guided spine surgery. Current manual landmark and surface-based techniques are time-consuming and not always accurate. Intraoperative ultrasound imaging of the vertebrae, combined with automated registration, could improve surgery by improving accuracy, reducing operative time, and decreasing invasiveness.
We present a simple ultrasound-CT registration technique that is automated, accurate, and robust. Registration is achieved by aligning the posterior vertebral surface, extracted from both CT and ultrasound images, using a forward and a backward scan line tracing method, respectively. The registration technique is validated using a simple plastic phantom in a water bath and a more realistic porcine cadaver in a simulation of open back surgery.
Clinically relevant accuracy was estimated by comparing automated registrations with gold standard imaging fiducial-based reference transformations, which yielded target registration errors of under 1 mm for the plastic phantom and under 1.6 mm for the porcine cadaver.
Our registration technique demonstrates good accuracy and robustness under clinically realistic conditions and thus warrants further studies on its surgical application.
准确地对患者解剖结构和术前计算机断层扫描（CT）图像进行配准是成功实施图像引导脊柱手术的关键。目前，手动地标和基于表面的技术既耗时又不准确。术中对椎体进行超声成像，并结合自动配准，可通过提高准确性、缩短手术时间和减少侵袭性来改善手术效果。
我们提出了一种简单的自动、准确且鲁棒的超声-CT 配准技术。通过分别使用前向和后向扫描线跟踪方法，将从 CT 和超声图像中提取的后椎体表面对齐来实现配准。使用简单的塑料体模在水浴中和更逼真的猪尸体在开放式背部手术模拟中对配准技术进行了验证。
通过将自动配准与基于金标准成像基准的参考变换进行比较，对临床相关精度进行了估计，对于塑料体模，目标配准误差小于 1mm，对于猪尸体，目标配准误差小于 1.6mm。
在临床现实条件下，我们的配准技术具有良好的准确性和鲁棒性，因此值得进一步研究其在手术中的应用。
