King's College London British Heart Foundation Centre of Excellence, London, UK.
J Cardiovasc Magn Reson. 2011 Oct 12;13(1):58. doi: 10.1186/1532-429X-13-58.
Dobutamine stress cardiovascular magnetic resonance (DS-CMR) is an established tool to assess hibernating myocardium and ischemia. Analysis is typically based on visual assessment with considerable operator dependency. CMR myocardial feature tracking (CMR-FT) is a recently introduced technique for tissue voxel motion tracking on standard steady-state free precession (SSFP) images to derive circumferential and radial myocardial mechanics.We sought to determine the feasibility and reproducibility of CMR-FT for quantitative wall motion assessment during intermediate dose DS-CMR.
10 healthy subjects were studied at 1.5 Tesla. Myocardial strain parameters were derived from SSFP cine images using dedicated CMR-FT software (Diogenes MRI prototype; Tomtec; Germany). Right ventricular (RV) and left ventricular (LV) longitudinal strain (EllRV and EllLV) and LV long-axis radial strain (ErrLAX) were derived from a 4-chamber view at rest. LV short-axis circumferential strain (EccSAX) and ErrSAX; LV ejection fraction (EF) and volumes were analyzed at rest and during dobutamine stress (10 and 20 μg · kg⁻¹· min⁻¹).
In all volunteers strain parameters could be derived from the SSFP images at rest and stress. EccSAX values showed significantly increased contraction with DSMR (rest: -24.1 ± 6.7; 10 μg: -32.7 ± 11.4; 20 μg: -39.2 ± 15.2; p < 0.05). ErrSAX increased significantly with dobutamine (rest: 19.6 ± 14.6; 10 μg: 31.8 ± 20.9; 20 μg: 42.4 ± 25.5; p < 0.05). In parallel with these changes; EF increased significantly with dobutamine (rest: 56.9 ± 4.4%; 10 μg: 70.7 ± 8.1; 20 μg: 76.8 ± 4.6; p < 0.05). Observer variability was best for LV circumferential strain (EccSAX ) and worst for RV longitudinal strain (EllRV) as determined by 95% confidence intervals of the difference.
CMR-FT reliably detects quantitative wall motion and strain derived from SSFP cine imaging that corresponds to inotropic stimulation. The current implementation may need improvement to reduce observer-induced variance. Within a given CMR lab; this novel technique holds promise of easy and fast quantification of wall mechanics and strain.
多巴酚丁胺负荷心脏磁共振（DS-CMR）是评估冬眠心肌和缺血的一种成熟的工具。分析通常基于具有相当大的操作者依赖性的视觉评估。CMR 心肌特征追踪（CMR-FT）是一种最近引入的技术，用于在标准稳态自由进动（SSFP）图像上对组织体素运动进行跟踪，以得出圆周和径向心肌力学。我们旨在确定 CMR-FT 在中等剂量 DS-CMR 期间进行定量壁运动评估的可行性和可重复性。
在 1.5T 下对 10 名健康受试者进行研究。使用专用的 CMR-FT 软件（Diogenes MRI 原型；Tomtec；德国）从 SSFP 电影图像中获得心肌应变参数。从 4 腔视图在休息时获得右心室（RV）和左心室（LV）纵向应变（EllRV 和 EllLV）和 LV 长轴径向应变（ErrLAX）。在休息和多巴酚丁胺应激时（10 和 20μg·kg⁻¹·min⁻¹）分析 LV 短轴圆周应变（EccSAX）和 ErrSAX；LV 射血分数（EF）和容量。
在所有志愿者中，都可以从 SSFP 图像在休息和应激时得出应变参数。EccSAX 值显示收缩与 DSMR 明显增加（休息：-24.1±6.7；10μg：-32.7±11.4；20μg：-39.2±15.2；p<0.05）。ErrSAX 随着多巴酚丁胺的增加而显著增加（休息：19.6±14.6；10μg：31.8±20.9；20μg：42.4±25.5；p<0.05）。与这些变化平行，EF 随着多巴酚丁胺的增加而显著增加（休息：56.9±4.4%；10μg：70.7±8.1；20μg：76.8±4.6；p<0.05）。通过差异的 95%置信区间确定，观察者变异性最好为 LV 圆周应变（EccSAX），最差为 RV 纵向应变（EllRV）。
CMR-FT 可靠地检测出从 SSFP 电影成像得出的定量壁运动和应变，这与变力刺激相对应。当前的实现可能需要改进，以减少观察者引起的方差。在给定的 CMR 实验室中；这项新技术有望实现壁力学和应变的快速、简便的定量。
