Cardiac C-Arm CT: A Unified Framework for Motion Estimation and Dynamic CT
Cardiac C-Arm CT: A Unified Framework for Motion Estimation and Dynamic CT
复制标题
DOI：
10.1109/tmi.2009.2025499
复制
发表时间：
2009-11-01
影响因子：
10.6
通讯作者：
Fahrig, Rebecca
中科院分区：
文献类型：
--
作者：
Pruemmer, Marcus;Hornegger, Joachim;Fahrig, Rebecca
在介入手术期间生成心脏的 3D 图像是一项重大挑战。除了实时透视之外，血管造影 C 形臂系统现在还可用于在同一系统上生成 3-D/4-D CT 图像。心脏 CT 的一种方案使用心电图触发的多次扫描。然后，通过将 Feldkamp (FDK) 重建应用于具有回顾性心电图门控的投影图像，重建特定心动时相的心脏 3D 体积。在这项工作中，我们引入了一个统一的框架，用于心脏运动估计和使用运动校正的动态锥束重建。运动校正的好处是 1) 通过消除心电图门控数据集中可能仍然存在的心脏运动来提高时间和空间分辨率，2) 通过使用比标准心电图门控方法中使用的更多的投影数据来提高信噪比 (SNR)。引入了三种信号增强重建方法，这些方法利用所有采集的投影数据来生成所需心脏相位的 3D 重建。第一个平均所有运动校正的反向投影；第二个和第三个根据 1) 强度变化和 2) 相对于时间解析和运动校正参考 FDK 重建的时间距离执行加权平均。在一项比较研究中，对七种方法进行了比较：非门控 FDK、ECG 门控 FDK、ECG 门控和运动校正 FDK、三种信号增强方法以及时间对齐和平均 ECG 门控 FDK 重建。用于比较的质量指标是空间分辨率和信噪比。使用模型数据和动物模型进行评估。我们表明，数据驱动和特定于主题的运动估计与运动校正相结合可以大大减少与运动相关的模糊。此外，SNR 可以提高高达 70%，同时将空间分辨率保持在与 ECG 门控 FDK 提供的相同水平。所提出的框架为心脏 C 形臂 CT 提供了出色的图像质量。
Generating 3-D images of the heart during interventional procedures is a significant challenge. In addition to real time fluoroscopy, angiographic C-arm systems can also now be used to generate 3-D/4-D CT images on the same system. One protocol for cardiac CT uses ECG triggered multisweep scans. A 3-D volume of the heart at a particular cardiac phase is then reconstructed by applying Feldkamp (FDK) reconstruction to the projection images with retrospective ECG gating. In this work we introduce a unified framework for heart motion estimation and dynamic cone-beam reconstruction using motion corrections. The benefits of motion correction are 1) increased temporal and spatial resolution by removing cardiac motion which may still exist in the ECG gated data sets and 2) increased signal-to-noise ratio (SNR) by using more projection data than is used in standard ECG gated methods. Three signal-enhanced reconstruction methods are introduced that make use of all of the acquired projection data to generate a 3-D reconstruction of the desired cardiac phase. The first averages all motion corrected back-projections; the second and third perform a weighted averaging according to 1) intensity variations and 2) temporal distance relative to a time resolved and motion corrected reference FDK reconstruction. In a comparison study seven methods are compared: nongated FDK, ECG-gated FDK, ECG-gated, and motion corrected FDK, the three signal-enhanced approaches, and temporally aligned and averaged ECG-gated FDK reconstructions. The quality measures used for comparison are spatial resolution and SNR. Evaluation is performed using phantom data and animal models. We show that data driven and subject-specific motion estimation combined with motion correction can decrease motion-related blurring substantially. Furthermore, SNR can be increased by up to 70% while maintaining spatial resolution at the same level as is provided by the ECG-gated FDK. The presented framework provides excellent image quality for cardiac C-arm CT.