Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV and UNIL), Rue du Bugnon 46, Lausanne, 1011, VD, Switzerland.
Center for Biomedical Imaging (CIBM), Lausanne, Switzerland.
J Cardiovasc Magn Reson. 2019 Feb 7;21(1):11. doi: 10.1186/s12968-019-0521-z.
Our objectives were first to determine the optimal coronary computed tomography angiography (CTA) protocol for the quantification and detection of simulated coronary artery cross-sectional area (CSA) differences in vitro, and secondly to quantitatively compare the performance of the optimized CTA protocol with a previously validated radial coronary cardiovascular magnetic resonance (CMR) technique.
256-multidetector CTA and radial coronary CMR were used to obtain images of a custom in vitro resolution phantom simulating a range of physiological responses of coronary arteries to stress. CSAs were automatically quantified and compared with known nominal values to determine the accuracy, precision, signal-to-noise ratio (SNR), and circularity of CSA measurements, as well as the limit of detection (LOD) of CSA differences. Various iodine concentrations, radiation dose levels, tube potentials, and iterative image reconstruction algorithms (ASiR-V) were investigated to determine the optimal CTA protocol. The performance of the optimized CTA protocol was then compared with a radial coronary CMR method previously developed for endothelial function assessment under both static and moving conditions.
The iodine concentration, dose level, tube potential, and reconstruction algorithm all had significant effects (all p < 0.001) on the accuracy, precision, LOD, SNR, and circularity of CSA measurements with CTA. The best precision, LOD, SNR, and circularity with CTA were achieved with 6% iodine, 20 mGy, 100 kVp, and 90% ASiR-V. Compared with the optimized CTA protocol under static conditions, radial coronary CMR was less accurate (- 0.91 ± 0.13 mm vs. -0.35 ± 0.04 mm, p < 0.001), but more precise (0.08 ± 0.02 mm vs. 0.21 ± 0.02 mm, p < 0.001), and enabled the detection of significantly smaller CSA differences (0.16 ± 0.06 mm vs. 0.52 ± 0.04 mm; p < 0.001; corresponding to CSA percentage differences of 2.3 ± 0.8% vs. 7.4 ± 0.6% for a 3-mm baseline diameter). The same results held true under moving conditions as CSA measurements with CMR were less affected by motion.
Radial coronary CMR was more precise and outperformed CTA for the specific task of detecting small CSA differences in vitro, and was able to reliably identify CSA changes an order of magnitude smaller than those reported for healthy physiological vasomotor responses of proximal coronary arteries. However, CTA yielded more accurate CSA measurements, which may prove useful in other clinical scenarios, such as coronary artery stenosis assessment.
我们的目标首先是确定最佳的冠状动脉计算机断层血管造影（CTA）方案，用于体外模拟冠状动脉横截面积（CSA）差异的定量检测，其次是定量比较优化的 CTA 方案与之前验证的径向冠状动脉心血管磁共振（CMR）技术的性能。
使用 256 层多探测器 CTA 和径向冠状动脉 CMR 对定制的体外分辨率体模进行成像，以模拟冠状动脉对压力的生理反应的范围。CSA 自动定量并与已知的标称值进行比较，以确定 CSA 测量的准确性、精密度、信噪比（SNR）和圆度，以及 CSA 差异的检测限（LOD）。研究了各种碘浓度、辐射剂量水平、管电压和迭代图像重建算法（ASiR-V），以确定最佳的 CTA 方案。然后，将优化的 CTA 方案的性能与之前开发的用于静态和动态条件下内皮功能评估的径向冠状动脉 CMR 方法进行比较。
碘浓度、剂量水平、管电压和重建算法均对 CTA 的 CSA 测量的准确性、精密度、LOD、SNR 和圆度有显著影响（均 p<0.001）。CTA 获得的最佳精密度、LOD、SNR 和圆度分别为 6%碘、20 mGy、100 kVp 和 90%ASiR-V。与静态条件下的优化 CTA 方案相比，径向冠状动脉 CMR 的准确性较低（-0.91±0.13mm 与-0.35±0.04mm，p<0.001），但更精确（0.08±0.02mm 与 0.21±0.02mm，p<0.001），并且能够检测到显著较小的 CSA 差异（0.16±0.06mm 与 0.52±0.04mm；p<0.001；对于 3mm 基线直径，相应的 CSA 百分比差异为 2.3%±0.8%与 7.4%±0.6%）。在运动条件下也得出了相同的结果，因为 CMR 的 CSA 测量受运动的影响较小。
径向冠状动脉 CMR 在体外检测小 CSA 差异的特定任务中更精确，并且性能优于 CTA，能够可靠地识别 CSA 变化，其量级小于健康生理冠状动脉近端血管舒缩反应报告的 CSA 变化。然而，CTA 产生的 CSA 测量更准确，这在其他临床情况下可能很有用，例如冠状动脉狭窄评估。
