Plaque quantification by coronary computed tomography angiography using intravascular ultrasound as a reference standard: a comparison between standard and last generation computed tomography scanners

Aims
The emerging role of coronary computed tomography angiography (CCTA) as a non-invasive tool for atherosclerosis evaluation is supported by data reporting a good correlation between CCTA and intravascular ultrasound (IVUS) for plaque volume quantification. Aim of the present study was to evaluate whether a last generation CT scanner may improve coronary plaque volume assessment using IVUS as standard-of-reference.

Methods and results
From a registry of 1915 consecutive, all-comers, patients who underwent a clinically indicated IVUS evaluation we
enrolled 59 patients who underwent CCTA with a 64-slice CT (Group 1) and 59 patients who underwent CCTA
with whole-heart coverage CT scanner (Group 2). Patients who underwent CCTA with unfavourable heart rhythm
were not excluded from the analysis. Image quality (4-point Likert scale) focused on plaque analysis was evaluated.
Plaque volume quantification by CCTA was compared to IVUS. No difference in clinical characteristics was found
between Group 1 and Group 2. Plaque volume quantification by CCTA was considered not feasible in 11 plaques
of Group 1 and in 4 plaques of Group 2 (P = 0.09). Higher correlation for plaque volume quantification by CCTA
vs. IVUS was demonstrated in Group 2 when compared with Group 1 (r = 0.9888 vs. 0.9499; P < 0.0001). The
Bland–Altman analysis showed plaque volume overestimation by CCTA of 11.9 mm3 in Group 1 and 4 mm2 in
Group 2 (P < 0.001). Effective radiation dose of CCTA was significantly lower in Group 2 vs. Group 1 (2.7 ± 0.9 vs.
8.1 ± 3.6 mSv, respectively; P < 0.001).
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Conclusions
CCTA using a new scanner generation showed to be an accurate non-invasive tool to assess and quantify coronaryplaque volume.

研究背景与目的
冠状动脉计算机断层血管造影（coronary computed tomography angiography, CCTA）作为一种无创性动脉粥样硬化评估工具的新兴应用价值，已有数据证实其在斑块体积定量方面与血管内超声（intravascular ultrasound, IVUS）具有良好相关性。本研究旨在评估新一代CT扫描仪是否能以IVUS为金标准，改善冠状动脉斑块体积的评估效果。

研究方法与结果
本研究从1915例接受临床指征IVUS评估的连续入组所有就诊患者的登记库中，招募了118例患者，其中59例采用64排CT行CCTA检查（第1组），另外59例采用全心脏覆盖CT扫描仪行CCTA检查（第2组），未排除存在不良心律的CCTA受检者。本研究对针对斑块分析的图像质量采用4级李克特量表进行评估，并将CCTA的斑块体积定量结果与IVUS进行对比。两组患者的临床基线特征无显著差异。第1组中有11处斑块无法通过CCTA完成斑块体积定量，第2组则有4处（P=0.09）。与第1组相比，第2组的CCTA斑块体积定量结果与IVUS的相关性更高（相关系数r分别为0.9888与0.9499；P<0.0001）。布兰德-奥特曼分析显示，CCTA对斑块体积的高估情况在第1组为11.9 mm³，第2组为4 mm²（P<0.001）。第2组的CCTA有效辐射剂量显著低于第1组（分别为2.7±0.9 mSv与8.1±3.6 mSv；P<0.001）。

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结论
采用新一代CT扫描仪的CCTA是一种准确的无创性冠状动脉斑块体积评估与定量工具。