Vembar M, Garcia M J, Heuscher D J, Haberl R, Matthews D, Böhme G E, Greenberg N L
Philips Medical Systems, CT Engineering, Advanced Systems Group, 595 Miner Road, Highland Heights, Ohio 44143, USA.
Med Phys. 2003 Jul;30(7):1683-93. doi: 10.1118/1.1582812.
In this investigation, we describe a quantitative technique to measure coronary motion, which can be correlated with cardiac image quality using multislice computed tomography (MSCT) scanners. MSCT scanners, with subsecond scanning, thin-slice imaging (sub-millimeter) and volume scanning capabilities have paved the way for new clinical applications like noninvasive cardiac imaging. ECG-gated spiral CT using MSCT scanners has made it possible to scan the entire heart in a single breath-hold. The continuous data acquisition makes it possible for multiple phases to be reconstructed from a cardiac cycle. We measure the position and three-dimensional velocities of well-known landmarks along the proximal, mid, and distal regions of the major coronary arteries [left main (LM), left anterior descending (LAD), right coronary artery (RCA), and left circumflex (LCX)] during the cardiac cycle. A dynamic model (called the "delay algorithm") is described which enables us to capture the same physiological phase or "state" of the anatomy during the cardiac cycle as the instantaneous heart rate varies during the spiral scan. The coronary arteries are reconstructed from data obtained during different physiological cardiac phases and we correlate image quality of different parts of the coronary anatomy with phases at which minimum velocities occur. The motion characteristics varied depending on the artery, with the highest motion being observed for RCA. The phases with the lowest mean velocities provided the best visualization. Though more than one phase of relative minimum velocity was observed for each artery, the most consistent image quality was observed during mid-diastole ("diastasis") of the cardiac cycle and was judged to be superior to other reconstructed phases in 92% of the cases. In the process, we also investigated correlation between cardiac arterial states and other measures of motion, such as the left ventricular volume during a cardiac cycle, which earlier has been demonstrated as an example of how anatomic-specific information can be used in a knowledge-based cardiac CT algorithm. Using these estimates in characterizing cardiac motion also provides realistic simulation models for higher heart rates and also in optimizing volume reconstructions for individual segments of the cardiac anatomy.
在本研究中，我们描述了一种测量冠状动脉运动的定量技术，该技术可通过多层螺旋计算机断层扫描（MSCT）扫描仪与心脏图像质量相关联。具有亚秒级扫描、薄层成像（亚毫米级）和容积扫描能力的MSCT扫描仪为无创心脏成像等新的临床应用铺平了道路。使用MSCT扫描仪的心电图门控螺旋CT使得在一次屏气过程中扫描整个心脏成为可能。连续的数据采集使得能够从心动周期中重建多个阶段。我们测量了主要冠状动脉[左主干（LM）、左前降支（LAD）、右冠状动脉（RCA）和左旋支（LCX）]近端、中段和远端区域在心动周期中知名标志点的位置和三维速度。描述了一种动态模型（称为“延迟算法”），该模型使我们能够在螺旋扫描期间随着瞬时心率的变化捕捉心动周期中解剖结构的相同生理阶段或“状态”。从不同生理心动阶段获得的数据重建冠状动脉，并将冠状动脉解剖结构不同部位的图像质量与出现最小速度的阶段相关联。运动特征因动脉而异，RCA的运动最为明显。平均速度最低的阶段提供了最佳的可视化效果。尽管每条动脉都观察到了不止一个相对最小速度阶段，但在心动周期的舒张中期（“舒张期”）观察到了最一致的图像质量，在92%的病例中被判定优于其他重建阶段。在此过程中，我们还研究了心脏动脉状态与其他运动指标之间的相关性，例如心动周期中的左心室容积，此前已证明这是基于知识的心脏CT算法中如何使用解剖特异性信息的一个例子。在表征心脏运动时使用这些估计值还为更高心率提供了逼真的模拟模型，并优化了心脏解剖结构各个节段的容积重建。
