Purpose

The fusion of pre/intraoperative images may improve catheter manipulation during radioembolization (RE) interventions by adding relevant information. The objective of this work is to propose and evaluate the performance of a RE guidance strategy relying on structure-driven intensity-based registration between preoperative CTA and intraoperative X-ray images.

Methods

The navigation strategy is decomposed into three image fusion steps, supporting the catheter navigation from the femoral artery till reaching the injection site (IS). During the pretreatment assessment intervention, the aorta and the origins of its side branches are projected on the intraoperative 2D fluoroscopy following a 3D/2D bone-based registration process, to assist the celiac trunk access. Subsequently, a similar approach consisting in projecting the hepatic vasculature on intraoperative DSA through 3D/2D vessel-based registration is performed to assist the IS location. Lastly, the selected IS is reproduced during the treatment intervention by employing 2D/2D image-based registration between pretreatment and treatment fluoroscopic images.

Results

The three fusion steps were independently evaluated on subsets of 20, 19 and 5 patient cases, respectively. Best results were obtained with gradient difference as similarity measure and with a delimited preoperative vascular structure for vessel-based registration. The approach resulted in qualitatively appropriate anatomical correspondences when projecting the preoperative structures on intraoperative images. With the best configuration, the registration steps showed accuracy and feasibility in aligning data, with global mean landmarks errors of 1.59 mm, 2.32 mm and 2.17 mm, respectively, a computation time that never exceeded 5 s, 25 s and 11 s, respectively, and a user interaction limited to manual initialization of the 3D/2D registration.

Conclusion

An image fusion-based approach has been specifically proposed for RE procedures guidance. The catheter manipulation strategy based on the fusion of pre- and intraoperative images has the potential to support different steps of the RE clinical workflow and to guide the overall procedure.

中文翻译：

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肝脏放射栓塞指导的导管导航支持：基于结构驱动强度的配准的可行性。

目的

通过添加相关信息，术前/术中图像的融合可以改善放射栓塞 (RE) 干预期间的导管操作。这项工作的目的是提出和评估依赖于术前 CTA 和术中 X 射线图像之间基于结构驱动的强度配准的 RE 引导策略的性能。

方法

导航策略分解为三个图像融合步骤，支持从股动脉到注射部位（IS）的导管导航。在预处理评估干预期间，主动脉及其侧支的起源在基于 3D/2D 骨骼的配准过程之后被投影到术中 2D 透视上，以帮助进入腹腔干。随后，通过基于 3D/2D 血管的配准在术中 DSA 上投影肝血管系统，以协助 IS 定位。最后，通过在预处理和治疗透视图像之间采用基于 2D/2D 图像的配准，在治疗干预期间再现选定的 IS。

结果

三个融合步骤分别对 20、19 和 5 个患者病例的子集进行了独立评估。使用梯度差异作为相似性度量并使用用于基于血管的配准的限定术前血管结构获得了最佳结果。当在术中图像上投影术前结构时，该方法产生了质量上适当的解剖对应。使用最佳配置，配准步骤显示对齐数据的准确性和可行性，全局平均地标误差分别为 1.59 mm、2.32 mm 和 2.17 mm，计算时间分别从不超过 5 s、25 s 和 11 s，以及仅限于手动初始化 3D/2D 配准的用户交互。

结论

一种基于图像融合的方法已被专门提出用于 RE 程序指导。基于术前和术中图像融合的导管操作策略有可能支持 RE 临床工作流程的不同步骤并指导整个过程。