Department of Cardiology, Aarhus University Hospital, Aarhus N, Denmark.
Invest Radiol. 2011 Dec;46(12):790-5. doi: 10.1097/RLI.0b013e31822b122e.
Noninvasive contrast-enhanced coronary computed tomography (CT) angiography enables distinction between calcified and noncalcified atherosclerotic plaques. However, separation of noncalcified plaques into rupture prone lipid-rich and stable fibrous subtypes is challenging because CT density of the plaque, characterized by Hounsfield Units (HU), varies with intraluminal contrast density and acquisition protocol. This study aims at testing the influence of intraluminal contrast densities and kV-settings on coronary plaque density values in vitro.
We scanned 16 coronary arteries with 3 different contrast solutions (no contrast, 1:70, and 1:23 Iomeron, 350 mgI/mL) and 3 different kV-settings (80, 120, and 140 kV). The arteries were sectioned into 5-mm segments. Every segment was evaluated with CT and histopathology for suitability of analysis, presence, and subtype of plaque.
Sixty-four segments were analyzed and classified with CT. Agreement between plaques classified with CT angiography in vitro and histopathology was poor-to-moderate, with no kappa-values above 0.21. The kV-settings affected the CT density in all plaque types. The CT density decreased 0.25 (0.07) HU, P=0.013 in noncalcified plaques, and 5.5 (0.7) HU, P<0.0001, in calcified plaques for every kV increase. CT densities in noncalcified plaques changed when the contrast concentration was changed. From no to high contrast concentration resulted in a 21.7 (8.3) HU increase, P=0.041, and from low to high contrast concentration resulted in a 21.5 (6) HU increase, P=0.011, causing several plaques to change in subtype from lipid-rich (low contrast concentration) to fibrotic (high contrast concentration).
Agreement between CT angiography in vitro and histopathology for classification of coronary plaque subtype is poor to moderate. However, no specific combination seems superior to the most commonly used protocols for distinction between lipid-rich and fibrotic plaque subtypes in current clinical practice.
非侵入性对比增强冠状动脉计算机断层扫描（CT）血管造影能够区分钙化和非钙化的动脉粥样硬化斑块。然而，将非钙化斑块分为易破裂的富含脂质和稳定的纤维亚型具有挑战性，因为斑块的 CT 密度（以亨氏单位[HU]表示）随管腔对比度密度和采集方案而变化。本研究旨在测试管腔内对比度密度和 kV 设置对体外冠状动脉斑块密度值的影响。
我们使用 3 种不同的对比剂溶液（无对比剂、1:70 和 1:23 Iomeron，350mgI/mL）和 3 种不同的 kV 设置（80、120 和 140kV）扫描了 16 条冠状动脉。将动脉切成 5mm 段。对每段进行 CT 和组织病理学评估，以确定是否适合分析、斑块的存在和类型。
共分析了 64 个节段，并通过 CT 进行分类。体外 CT 血管造影和组织病理学分类的斑块之间的一致性为差到中等，kappa 值均不超过 0.21。kV 设置影响所有斑块类型的 CT 密度。每增加 1kV，非钙化斑块的 CT 密度降低 0.25（0.07）HU，P=0.013，钙化斑块降低 5.5（0.7）HU，P<0.0001。当对比浓度改变时，非钙化斑块的 CT 密度也会发生变化。从无对比到高对比浓度导致增加 21.7（8.3）HU，P=0.041，从低对比到高对比浓度导致增加 21.5（6）HU，P=0.011，导致一些斑块的亚型从富含脂质（低对比浓度）转变为纤维（高对比浓度）。
体外 CT 血管造影与组织病理学对冠状动脉斑块亚型的分类之间的一致性为差到中等。然而，在目前的临床实践中，没有特定的组合似乎优于最常用的区分富含脂质和纤维斑块亚型的方案。
