细胞外造影剂（钆布醇）对心血管磁共振特征追踪的精度和可重复性的影响。
The effects of extracellular contrast agent (Gadobutrol) on the precision and reproducibility of cardiovascular magnetic resonance feature tracking.
作者信息
Kuetting Daniel L R, Dabir Darius, Homsi Rami, Sprinkart Alois M, Luetkens Julian, Schild Hans H, Thomas Daniel K
机构信息
Department of Radiology, University of Bonn, Sigmund-Freud-Str.25, 53127, Bonn, Germany.
出版信息
J Cardiovasc Magn Reson. 2016 May 21;18(1):30. doi: 10.1186/s12968-016-0249-y.
BACKGROUND
Today feature tracking (FT) is considered to be a robust assessment tool in cardiovascular magnetic resonance (CMR) for strain assessment. The FT algorithm is dependent on a high contrast between blood pool and myocardium. Extracellular contrast agents decrease blood-myocardial contrast in SSFP images and thus might affect FT results. However, in a routine CMR scan, SSFP-cine images including short axis views are partly acquired after contrast agent injection. The aim of this study was to investigate the effect of extracellular contrast agent (Gadobutrol) (CA) on the precision and reproducibility of the feature tracking algorithm.
METHODS
A total of 40 patient volunteers (mean age 51.2 ± 19 years; mean LVEF 61 ± 9 %) were scanned in supine position on a clinical 1.5 T MR scanner (Philips Ingenia). SSFP-cine images in midventricular short axis view (SA) as well as horizontal long axis view (HLA) were acquired before and 10-15 min after injection of a double dose Gadobutrol. FT derived systolic circumferential and longitudinal strain parameters were then calculated for pre- and post-contrast images.
RESULTS
FT derived midventricular peak systolic circumferential strain (PSCS) (-24.8 ± 6.4 % vs. -20.4 ± 6.3 %), apical PSCS (-28.67 ± 6.5 % vs. -24.06 ± 8.5 %), basal PSCS (-24.42 % ± 6.5 vs. -20.68 ± 7.1 %), peak systolic longitudinal strain (-19.57 ± 3.3 % vs. -17.24 ± 4.1 %), midventricular epicardial PSCS (-9.84 ± 3.4 % vs. -8.13 ± 3.4 %) , midventricular PSCS-rate (-1.52 ± 0.4 vs. -1.28 ± 0.5) and peak diastolic circumferential strain rate (1.4 ± 0.5 vs. 1.05 ± 0.5) were significantly reduced after CA application. Post CA strain assessment showed higher intra- and interobserver variability. Pre-CA: intraobserver: mean 0.21, Limits of agreement (LoA) -2.8 and 3.2; interobserver: mean 0.64, LoA -2.8 and 4.1. Post-CA: intraobserver: mean -0.11, LoA -5.1 to 4.9; interobserver: mean 4.93 LoA 2.4 to 12.2.
CONCLUSION
The FT algorithm is dependent on a high contrast between blood and myocardium. Post CA strain results are significantly lower and less reproducible than pre-CA strain results.
背景
如今，特征追踪（FT）被认为是心血管磁共振成像（CMR）中用于应变评估的一种可靠评估工具。FT算法依赖于血池与心肌之间的高对比度。细胞外造影剂会降低稳态自由感应衰减（SSFP）图像中的血-心肌对比度，从而可能影响FT结果。然而，在常规CMR扫描中，包括短轴视图在内的SSFP电影图像部分是在注射造影剂后采集的。本研究的目的是探讨细胞外造影剂（钆布醇）（CA）对特征追踪算法的精度和可重复性的影响。
方法
共有40例患者志愿者（平均年龄51.2±19岁；平均左心室射血分数61±9%）在临床1.5T磁共振扫描仪（飞利浦Ingenia）上仰卧位扫描。在注射双倍剂量钆布醇之前和之后10 - 15分钟采集心室中部短轴视图（SA）以及水平长轴视图（HLA）的SSFP电影图像。然后计算造影剂注射前后图像的FT衍生收缩期圆周应变和纵向应变参数。
结果
应用CA后，FT衍生的心室中部收缩期峰值圆周应变（PSCS）（-24.8±6.4%对-20.4±6.3%）、心尖PSCS（-28.67±6.5%对-24.06±8.5%）、基底PSCS（-24.42%±6.5对-20.68±7.1%）、收缩期峰值纵向应变（-19.57±3.3%对-17.24±4.1%）、心室中部心外膜PSCS（-9.84±3.4%对-8.13±3.4%）、心室中部PSCS速率（-1.52±0.4对-1.28±0.5）和舒张期峰值圆周应变率（1.4±0.5对1.05±0.5）均显著降低。CA应用后的应变评估显示观察者内和观察者间的变异性更高。CA应用前：观察者内：平均值0.21，一致性界限（LoA）-2.8和3.2；观察者间：平均值0.64，LoA -2.8和4.1。CA应用后：观察者内：平均值-0.11，LoA -5.1至4.9；观察者间：平均值4.93，LoA 2.4至12.2。
结论
FT算法依赖于血液与心肌之间的高对比度。CA应用后的应变结果明显低于且不如CA应用前的应变结果可重复。
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