Kachelriess M, Kalender W A
Institute of Medical Physics, University of Erlangen-Nürnberg, Germany.
Med Phys. 1998 Dec;25(12):2417-31. doi: 10.1118/1.598453.
Subsecond computed tomography (CT) scanning offers potential for improved heart imaging. We therefore developed and validated dedicated reconstruction algorithms for imaging the heart with subsecond spiral CT utilizing electrocardiogram (ECG) information. We modified spiral CT z-interpolation algorithms on a subsecond spiral CT scanner. Two new classes of algorithms were investigated: (a) 180 degrees CI (cardio interpolation), a piecewise linear interpolation between adjacent spiral data segments belonging to the same heart phase where segments are selected by correlation with the simultaneously recorded ECG signal and (b) 180 degrees CD (cardio delta), a partial scan reconstruction of 180 degrees + delta with delta < fan angle, resulting in reduced effective scan times of less than 0.5 s. Computer simulations as well as processing of clinical data collected with 0.75 s scan time were carried out to evaluate these new approaches. Both 180 degrees CI and 180 degrees CD provided significant improvements in image quality. Motion artifacts in the reconstructed images were largely reduced as compared to standard spiral reconstructions; in particular, coronary calcifications were delineated more sharply and multiplanar reformations showed improved contiguity. However, new artifacts in the image plane are introduced, mostly due to the combination of different data segments. ECG-oriented image reconstructions improve the quality of heart imaging with spiral CT significantly. Image quality and the display of coronary calcification appear adequate to assess coronary calcium measurements with conventional subsecond spiral CT.
亚秒级计算机断层扫描（CT）为改善心脏成像提供了可能。因此，我们开发并验证了利用心电图（ECG）信息通过亚秒级螺旋CT对心脏进行成像的专用重建算法。我们在亚秒级螺旋CT扫描仪上修改了螺旋CT的z轴插值算法。研究了两类新算法：（a）180度CI（心脏插值），即在属于同一心脏相位的相邻螺旋数据段之间进行分段线性插值，其中数据段通过与同时记录的ECG信号的相关性来选择；（b）180度CD（心脏增量），一种180度 + 增量的部分扫描重建，增量 < 扇形角，从而使有效扫描时间缩短至小于0.5秒。进行了计算机模拟以及对以0.75秒扫描时间收集的临床数据的处理，以评估这些新方法。180度CI和180度CD都显著改善了图像质量。与标准螺旋重建相比，重建图像中的运动伪影大幅减少；特别是，冠状动脉钙化的描绘更加清晰，多平面重建显示连续性得到改善。然而，图像平面中引入了新的伪影，主要是由于不同数据段的组合。基于ECG的图像重建显著提高了螺旋CT心脏成像的质量。图像质量和冠状动脉钙化的显示似乎足以用传统的亚秒级螺旋CT评估冠状动脉钙化测量。
