Lapinskas Tomas, Grune Jana, Zamani Seyedeh Mahsa, Jeuthe Sarah, Messroghli Daniel, Gebker Rolf, Meyborg Heike, Kintscher Ulrich, Zaliunas Remigijus, Pieske Burkert, Stawowy Philipp, Kelle Sebastian
Department of Cardiology, Medical Academy, Lithuanian University of Health Sciences, Eiveniu Street 2, LT-50161, Kaunas, Lithuania.
Department of Internal Medicine / Cardiology, Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
BMC Med Imaging. 2017 Aug 23;17(1):51. doi: 10.1186/s12880-017-0223-7.
Cardiovascular magnetic resonance feature tracking (CMR-FT) is a novel tissue tracking technique developed for noninvasive assessment of myocardial motion and deformation. This preliminary study aimed to evaluate the observer's reproducibility of CMR-FT in a small animal (mouse) model and define sample size calculation for future trials.
Six C57BL/6 J mice were selected from the ongoing experimental mouse model onsite and underwent CMR with a 3 Tesla small animal MRI scanner. Myocardial deformation was analyzed using dedicated software (TomTec, Germany) by two observers. Left ventricular (LV) longitudinal, circumferential and radial strain (Ell, Ecc and Err) were calculated. To assess intra-observer agreement data analysis was repeated after 4 weeks. The sample size required to detect a relative change in strain was calculated.
In general, Ecc and Ell demonstrated highest inter-observer reproducibility (ICC 0.79 (0.46-0.91) and 0.73 (0.56-0.83) Ecc and Ell respectively). In contrast, at the intra-observer level Ell was more reproducible than Ecc (ICC 0.83 (0.73-0.90) and 0.74 (0.49-0.87) Ell and Ecc respectively). The reproducibility of Err was weak at both observer levels. Preliminary sample size calculation showed that a small study sample (e.g. ten animals to detect a relative 10% change in Ecc) could be sufficient to detect changes if parameter variability is low.
This pilot study demonstrates good to excellent inter- and intra-observer reproducibility of CMR-FT technique in small animal model. The most reproducible measures are global circumferential and global longitudinal strain, whereas reproducibility of radial strain is weak. Furthermore, sample size calculation demonstrates that a small number of animals could be sufficient for future trials.
心血管磁共振特征追踪（CMR-FT）是一种用于无创评估心肌运动和变形的新型组织追踪技术。这项初步研究旨在评估CMR-FT在小动物（小鼠）模型中观察者的可重复性，并为未来试验确定样本量计算方法。
从现场正在进行的实验小鼠模型中选取6只C57BL/6 J小鼠，使用3特斯拉小动物MRI扫描仪进行CMR检查。由两名观察者使用专用软件（德国TomTec）分析心肌变形情况。计算左心室（LV）的纵向、圆周和径向应变（Ell、Ecc和Err）。为评估观察者内部的一致性，4周后重复进行数据分析。计算检测应变相对变化所需的样本量。
总体而言，Ecc和Ell表现出最高的观察者间可重复性（Ecc和Ell的组内相关系数分别为0.79（范围0.46 - 0.91）和0.73（范围0.56 - 0.83））。相比之下，在观察者内部水平，Ell比Ecc的可重复性更高（Ell和Ecc的组内相关系数分别为0.83（范围0.73 - 0.90）和0.74（范围0.49 - 0.87））。Err在两个观察者水平上的可重复性都较弱。初步样本量计算表明，如果参数变异性较低，一个小的研究样本（例如10只动物以检测Ecc相对10%的变化）就足以检测到变化。
这项初步研究表明CMR-FT技术在小动物模型中具有良好至优秀的观察者间和观察者内部可重复性。最具可重复性的测量指标是整体圆周应变和整体纵向应变，而径向应变的可重复性较弱。此外，样本量计算表明少量动物可能足以用于未来试验。
