Systems of Biological and Health Systems Engineering, Ira A. Fulton Schools of Engineering, Arizona State University, Tempe, AZ 85287, USA.
J Appl Clin Med Phys. 2013 May 6;14(3):4014. doi: 10.1120/jacmp.v14i3.4014.
The purpose of this study is to evaluate a direct measure of calcium burden by using dual-energy computed tomography (DECT) during contrast-enhanced coronary imaging, potentially eliminating the need for an extra noncontrast X-ray acquisition. The ambiguity of separation of calcium from contrast material on contrast-enhanced images was solved by using virtual noncontrast images obtained by DECT. A new threshold CT number was required to detect the calcium carrying potential risk for adverse coronary events on virtual noncontrast images. Two methods were investigated to determine the 130 HU threshold for DECT scoring. An in vitro anthropomorphic phantom with 29 excised patient calcium plaques inserted was used for both a linear and a logistic regression analysis. An IRB approved in vivo prospective study of six patients was also performed to be used for logistic regression analysis. The threshold found by logistic regression model to define the calcium burden on virtual noncontrast images detects the calcium carrying potential risk for adverse coronary events correctly (2.45% error rate). DECT calcium mass and volume scores obtained by using the threshold correlates with both conventional Agatston and volume scores (r = 0.98, p < 0.001). A conventional CT cardiac exam requires two scans, including a noncontrast scan for calcium quantification and a contrast-enhanced scan for coronary angiography. With the ability to quantify calcium on DECT contrast-enhanced images, a DECT cardiac exam could be accomplished with one contrast-enhanced scan for both calcium quantification and coronary angiography.
本研究旨在通过使用双能计算机断层扫描（DECT）评估钙负荷的直接测量值，从而在对比增强冠状动脉成像期间，可能无需额外进行非对比 X 射线采集。通过 DECT 获得的虚拟非对比图像，解决了对比增强图像中钙与对比材料分离的模糊性问题。为了在虚拟非对比图像上检测出具有不良冠状动脉事件潜在风险的钙携带能力，需要一个新的阈值 CT 数来检测钙携带能力。研究了两种方法来确定 DECT 评分的 130HU 阈值。一个带有 29 个切除的患者钙斑块的体外仿体用于线性和逻辑回归分析。还对六名患者进行了经 IRB 批准的前瞻性体内研究，用于逻辑回归分析。逻辑回归模型确定的用于定义虚拟非对比图像上钙负荷的阈值可以正确检测出具有不良冠状动脉事件潜在风险的钙携带能力（错误率为 2.45%）。使用该阈值获得的 DECT 钙质量和体积评分与传统的 Agatston 和体积评分均相关（r=0.98，p < 0.001）。传统的 CT 心脏检查需要进行两次扫描，包括一次非对比扫描用于钙定量和一次对比增强扫描用于冠状动脉造影。通过在 DECT 对比增强图像上进行定量钙的能力，可以使用一次对比增强扫描同时进行钙定量和冠状动脉造影来完成 DECT 心脏检查。
