BACKGROUND Traditional preclinical echocardiography (ECHO) modalities, including 1-dimensional motion-mode (M-Mode) and 2-dimensional long axis (2D-US), rely on geometric and temporal assumptions about the heart for volumetric measurements. Surgical animal models, such as the mouse coronary artery ligation (CAL) model of myocardial infarction, result in morphologic changes that do not fit these geometric assumptions. New ECHO technology, including 4-dimensional ultrasound (4D-US), improves on these traditional models. This paper aims to compare commercially available 4D-US to M-mode and 2D-US in a mouse model of CAL. METHODS 37 mice underwent CAL surgery, of which 32 survived to a 4 week post-operative time point. ECHO was completed at baseline, 1 week, and 4 weeks after CAL. M-mode, 2D-US, and 4D-US were taken at each time point and evaluated by two separate echocardiographers. At 4 weeks, a subset (n = 12) of mice underwent cardiac magnetic resonance (CMR) imaging to serve as a reference standard. End systolic volume (ESV), end diastolic volume (EDV), and ejection fraction (EF) were compared among imaging modalities. Hearts were also collected for histologic evaluation of scar size (n = 16) and compared to ECHO-derived wall motion severity index (WMSI) and global longitudinal strain as well as gadolinium-enhanced CMR to compare scar assessment modalities. RESULTS 4D-US provides close agreement of ESV (Bias: -2.55%, LOA: - 61.55 to 66.66) and EF (US Bias: 11.23%, LOA - 43.10 to 102.8) 4 weeks after CAL when compared to CMR, outperforming 2D-US and M-mode estimations. 4D-US has lower inter-user variability as measured by intraclass correlation (ICC) in the evaluation of EDV (0.91) and ESV (0.93) when compared to other modalities. 4D-US also allows for rapid assessment of WMSI, which correlates strongly with infarct size by histology (r = 0.77). CONCLUSION 4D-US outperforms M-Mode and 2D-US for volumetric analysis 4 weeks after CAL and has higher inter-user reliability. 4D-US allows for rapid calculation of WMSI, which correlates well with histologic scar size.

中文翻译：

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商业 4 维超声心动图用于心肌梗塞后小鼠心脏容量评估。

背景技术传统的临床前超声心动图（ECHO）模式，包括一维运动模式（M-Mode）和二维长轴（2D-US），依赖于关于心脏的几何和时间假设来进行体积测量。外科动物模型，例如心肌梗塞的小鼠冠状动脉结扎（CAL）模型，会导致不符合这些几何假设的形态变化。新的 ECHO 技术，包括 4 维超声 (4D-US)，对这些传统模型进行了改进。本文旨在在 CAL 小鼠模型中比较市售 4D-US 与 M 模式和 2D-​​US。方法 37 只小鼠接受了 CAL 手术，其中 32 只存活至术后 4 周时间点。ECHO 在基线、CAL 后 1 周和 4 周完成。在每个时间点采集 M 模式、2D-US 和 4D-US，并由两名独立的超声心动图医师进行评估。4 周时，一部分小鼠 (n = 12) 接受了心脏磁共振 (CMR) 成像作为参考标准。比较不同成像方式的收缩末期容积 (ESV)、舒张末期容积 (EDV) 和射血分数 (EF)。还收集心脏用于疤痕大小的组织学评估（n = 16），并与 ECHO 衍生的室壁运动严重性指数（WMSI）和整体纵向应变以及钆增强 CMR 进行比较，以比较疤痕评估方式。结果 与 CMR 相比，CAL 后 4 周，4D-US 的 ESV（偏差：-2.55%，LOA：- 61.55 至 66.66）和 EF（US 偏差：11.23%，LOA - 43.10 至 102.8）非常一致，优于 2D- US 和 M 模式估计。与其他方式相比，4D-US 在 EDV (0.91) 和 ESV (0.93) 评估中通过类内相关性 (ICC) 测量，具有较低的用户间变异性。4D-US 还可以快速评估 WMSI，这与组织学显示的梗死面积密切相关 (r = 0.77)。结论 CAL 后 4 周的体积分析中，4D-US 的性能优于 M 模式和 2D-​​US，并且具有更高的用户间可靠性。4D-US 可以快速计算 WMSI，这与组织学疤痕大小密切相关。