Department of Biomedical Engineering, Columbia University, 622 West 168th St., Vanderbilt Clinic, New York, NY 10032, USA.
Phys Med Biol. 2012 Sep 7;57(17):5633-50. doi: 10.1088/0031-9155/57/17/5633. Epub 2012 Aug 14.
Myocardial elastography (ME) is a non-invasive, ultrasound-based strain imaging technique, which can detect and localize abnormalities in myocardial function. By acquiring radio-frequency (RF) frames at high frame rates, the deformation of the myocardium can be estimated, and used to identify regions of abnormal deformation indicative of cardiovascular disease. In this study, the primary objective is to evaluate the effect of torsion on the performance of ME, while the secondary objective is to image inclusions during different motion schemes. Finally, the phantom findings are validated with an in vivo human case. Phantoms of homogeneous stiffness, or containing harder inclusions, were fixed to a pump and motors, and imaged. Incremental displacements were estimated from the RF signals, and accumulated over a motion cycle, and rotation angle, radial strain and circumferential strain were estimated. Phantoms were subjected to four motion schemes: rotation, torsion, deformation, and a combination of torsion and deformation. Sonomicrometry was used as a gold standard during deformation and combined motion schemes. In the rotation scheme, the input and estimated rotation angle agree in both the homogeneous and inclusion phantoms. In the torsion scheme, the estimated rotation angle was found to be highest, closest to the source of torsion and lowest farthest from the source of torsion. In the deformation scheme, if an inclusion was not present, the estimated strain patterns accurately depicted homogeneity, while if an inclusion was present, abnormalities were observed which enabled detection of the inclusion. In addition, no significant rotation was detected. In the combined scheme, if an inclusion was not present, the estimated strain patterns accurately depicted homogeneity, while, if an inclusion was present, abnormalities were observed which enabled detection of the inclusion. Also, torsion was separated from the combined scheme and was found to be similar to the pure torsion findings. This study shows ME to be capable of accurately depicting and distinguishing between different types of motion schemes, and to be sensitive to stiffness changes in localized regions of tissue-mimicking phantoms under physiologic cardiac motion configurations, while strains estimated in the combined motion scheme were noisier than in individual motion schemes. Finally, ME was shown to be capable of distinguishing between deformation and rotation in a normal human heart in vivo.
心肌弹性成像（ME）是一种非侵入性、基于超声的应变成像技术，可检测和定位心肌功能异常。通过以高帧率获取射频（RF）帧，可以估计心肌的变形，并用于识别表明心血管疾病的异常变形区域。在这项研究中，主要目的是评估扭转对 ME 性能的影响，次要目的是在不同运动方案中对内含物进行成像。最后，使用体内人类病例验证了幻影结果。将均匀刚度的幻影或包含较硬内含物的幻影固定在泵和电机上进行成像。从 RF 信号估计递增位移，并在运动周期上累积，估计旋转角度、径向应变和周向应变。幻影经历了四种运动方案：旋转、扭转、变形和扭转和变形的组合。在变形和组合运动方案中，超声声速仪被用作变形和组合运动方案中的黄金标准。在旋转方案中，均匀和内含物幻影的输入和估计旋转角度一致。在扭转方案中，估计的旋转角度最高，最接近扭转源，最低则远离扭转源。在变形方案中，如果不存在内含物，则估计的应变模式准确地描绘了均匀性，如果存在内含物，则会观察到异常，从而能够检测到内含物。此外，没有检测到明显的旋转。在组合方案中，如果不存在内含物，则估计的应变模式准确地描绘了均匀性，如果存在内含物，则会观察到异常，从而能够检测到内含物。此外，还可以将扭转与组合方案分离，并发现其与纯扭转结果相似。这项研究表明，ME 能够准确描绘和区分不同类型的运动方案，并对组织模拟幻影的局部区域的刚度变化在生理心脏运动配置下具有敏感性，而在组合运动方案中估计的应变比在单独运动方案中更嘈杂。最后，ME 能够在体内正常人类心脏中区分变形和旋转。
