Image Fusion and 3D Roadmapping in Endovascular Surgery

Practitioners of endovascular surgery have historically utilized two-dimensional (2D) intraoperative fluoroscopic imaging, with intra-vascular contrast opacification, to treat complex three-dimensional (3D) pathology. Recently, major technical developments in intraoperative imaging have made image fusion techniques possible: the creation of a 3D patient-specific vascular roadmap based on preoperative imaging which aligns with intraoperative fluoroscopy, with many potential benefits. First, a 3D model is segmented from preoperative imaging, typically a CT scan. The model is then used to plan for the procedure, with placement of specific markers and storing of C-arm angles that will be used for intra-operative guidance. At the time of the procedure, an intraoperative cone-beam CT is performed and the 3D model is registered to the patient’s on-table anatomy. Finally, the system is used for live guidance where the 3D model is codisplayed overlying fluoroscopic images. There are many applications for image fusion in endovascular surgery. We have found it to be particularly useful for endovascular aneurysm repair (EVAR), complex EVAR, thoracic endovascular aneurysm repair (TEVAR), carotid stenting and for type 2 endoleaks. Image fusion has been shown in various settings to lead to decreased radiation dose, less iodinated contrast use and shorter procedure times. In the future, fusion models may be able to account for vessel deformation caused by the introduction of stiff wires and devices and the user-dependent steps may become more automated. In its current form, image fusion has already proven itself to be an essential component in the planning and success of complex endovascular procedures.长期以来，血管内手术（endovascular surgery）从业者一直借助结合血管内对比剂造影的二维（2D）术中透视成像，来治疗复杂的三维（3D）病变。近年来，术中成像领域的重大技术突破使图像融合技术成为可能：基于术前影像构建与术中透视对齐的患者特异性血管路线图，该技术具备诸多潜在优势。首先，从术前成像（通常为计算机断层扫描（CT））中分割出三维模型；随后利用该模型规划手术流程，包括放置特定标记物并存储将用于术中导航的C型臂角度参数。手术过程中，先完成术中锥形束计算机断层扫描（cone-beam CT），再将三维模型与患者术中的解剖结构进行配准。最终，系统可用于实时导航，将三维模型叠加显示在透视成像画面之上。 图像融合技术在血管内手术中拥有诸多应用场景。我们发现其在血管内动脉瘤修复术（EVAR）、复杂型血管内动脉瘤修复术、胸主动脉腔内修复术（TEVAR）、颈动脉支架置入术以及II型内漏的治疗中尤为实用。多项研究表明，图像融合技术在多种临床场景中可降低辐射暴露剂量、减少含碘对比剂的使用量，并缩短手术时长。未来，融合模型或许能够抵消硬导丝与器械置入所引发的血管变形问题，且依赖操作者的步骤也将进一步实现自动化。就当前技术形态而言，图像融合技术已被证实是复杂血管内手术的规划与成功实施不可或缺的核心环节。