宝石能谱CT显示支架内腔及再狭窄——体模初步实验研究

Evaluation of Coronary Stents by HDCT: An In-vitro Experimental Study

目的：研究宝石能谱CT显示离体支架内腔和不同再狭窄模型的能力。方法：6枚雷帕霉素药物涂层支架（Excel），规格均为2．75mm×18mm，球囊在体外用不同的压力分别扩张成直径2．75mm、3．0mm、3．5mm的支架各两枚，分为A、B、C三组，每枚支架分别建立0％、30％、50％、70％、80％的狭窄模型，置入模拟冠状动脉内，注入含碘对比剂后密封，置入水箱内，利用GSI模式扫描，重建其40-140keVM能量图像、碘基图、水基图和混合能量图像，分析支架内腔显示率和狭窄诊断准确率。结果：140keV单能量图像和水基图显示支架伪影最少，支架内腔显示率高，但水基图支架内腔分辨率低，不适合观察再狭窄。原子序数分析可较清楚分辨支架内斑块和伪影。50～60keV单能量图像对显示支架内腔混合斑块具有较好的图像质量，诊断无、轻度、中度、重度狭窄的准确率较混合能量图像分别提高16．67％、33．33％、16．66％、16．67％。结论：140keV单能量图像和水基图适合显示支架结构，50～60keV单能量图像适合诊断支架内腔再狭窄，能谱物质分析图像有助于区分支架内斑块和伪影，为冠状动脉支架的评估提供了一种新的方法。

Purpose： To assess the ability of HDCT in diagnosing the stenosis of coronary stents and the true lumen. Methods： Six Excel stents （2.75×18mm） were dilated to different size with the diameters of 2,75 mm, 3.0 mm, and 3.5 mm by the balloon dilatation catheters. They were divided into three groups A, B, C and were established stenosis models of 0%, 30%, 50% and 70%-80%, which demonstrated non-stenosis, low-grade stenosis, intermediate stenosis, high-grade stenosis. All stents were filled with iodinated contrast media, placed in a box with water, and scanned by GSI scanning mode. 40-140keV monochromatic energy images, material decomposition images and mixed energy images were reconstructed, and the visibility rate of the stent stenosis was analyze. Results： Water-based material decomposition images and 140- keV monochromatic energy images displayed stents with least artifacts, but the latter had better resolution of the stent lumen, which could help the diagnosis of different stenosis. Effective atomic number images helped to differentiate plaques and artifacts in stents. 50-60keV monochromatic energy images had better image quality in displaying mixed plaques of coronary stents. The diagnostic accuracy of non-, low-grade, intermediate, high-grade stenosis were 16.67%,33.33%,16.66%,16.67% respectively. Conclusion： 40-140keV monochromatic energy images are suitable for displaying stent structure. 50-60keV monochromatic energy images can be used for diagnosing stent restenosis. Spectral substance analysis can be applied to differentiate plaques and artifacts in stents. Spectral CT provides a more accurate measurement of true stent lumen and stenosis of coronary stents.