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）从业者一直采用二维（2D）术中透视成像（intraoperative fluoroscopic imaging）联合血管内造影显像（intra-vascular contrast opacification）的方式，治疗复杂的三维（3D）血管病变。近年来，术中成像领域的重大技术进展使影像融合技术成为可能：即基于术前影像构建与术中透视影像配准的患者特异性三维血管路径图，该技术具备诸多潜在优势。首先，从术前影像（通常为计算机断层扫描（CT））中分割得到三维血管模型，以此规划手术流程，包括放置特定标记点并记录用于术中导航的C形臂（C-arm）角度参数。手术实施阶段，先完成术中锥形束CT（cone-beam CT）扫描，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影像之上。影像融合技术在血管内手术中拥有广泛应用场景，我们的实践证实，其在血管内动脉瘤修复术（endovascular aneurysm repair, EVAR）、复杂型EVAR、胸主动脉腔内修复术（thoracic endovascular aneurysm repair, TEVAR）、颈动脉支架置入术以及2型内漏（type 2 endoleaks）的治疗中尤为实用。多项临床研究已表明，影像融合技术可在多种场景下降低辐射暴露剂量、减少碘对比剂使用量并缩短手术时长。未来，融合模型或可补偿硬导丝及手术器械置入引发的血管变形，且部分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，影像融合技术已被证实是复杂血管内手术规划与成功实施的核心必备环节。