Preclinical cardiac MR is challenging and time-consuming. A fast and comprehensive acquisition protocol and standardized image post-processing may improve preclinical research, reducing acquisition time, costs and variability of results. In the present study, we evaluated the feasibility of a contrast-enhanced 3D IntraGate steady-state cine sequence (ce-3D-IG-cine) with short acquisition time (11 min) for a single-shot combined characterization of left ventricle (LV) remodeling and infarct size (IS) in a mouse model of acute ischemia-reperfusion injury. Sixteen male C57BL/6N mice underwent 7T cardiac MR (Bruker, BioSpec 70/30) including optimized ce-3D-IG-cine (total scan time 11 min) at day 1, 5 and 28 after surgery. LV end-diastolic volume (EDVMR) and ejection fraction (EFMR) extracted from MR were compared to ones from short-axis (SA-EDVecho, SA-EFecho) and parasternal long-axis (LA-EDVecho, LA-EFecho) echocardiography. IS was manually and semiautomatically segmented from ce-3D-IG-cine using different standard deviation (SD +2, +3, +4, +5, +6 in respect to a reference tissue). Mice were sacrificed at day 28, immediately after imaging. IS at day 28 was compared to injury burden at histology. MR and echocardiographic morpho-functional parameters were compared, as IS from MR and histology. Bland-Altman plots were used to assess the agreement in ischemic burden segmentation. Volumetric and functional parameters measured on ce-3D-IG-cine correlated to the correspondent echocardiographic parameter (EDVMR vs SA-EDVecho: ρ = 0.813; EDVMR vs LA-EDVecho: ρ = 0.845; EFMR vs SA-EFecho ρ = 0.612; EFMR vs LA-EFecho ρ = 0.791; p < 0.001 in all cases). Manually segmented IS strongly correlated with the scar at histology (ρ = 0.904, p < 0.001). A threshold of +3SD showed the highest performance for semiautomatic assessment of IS compared to manual segmentation (ρ = 0.965, p < 0.001), with an overall reproducibility of 73%, and a peak reproducibility of 80% at day 1. The ce-3D-IG-cine sequence, manually or semiautomatically segmented using 3SD threshold, allows fast and comprehensive LV morpho-functional and structural characterization in myocardial ischemia-reperfusion injury model.

中文翻译：

---

在优化的3D IntraGate电影FLASH序列在7T MR的急性缺血/再灌注损伤小鼠模型中，左心室的单次形态功能和结构表征。

临床前心脏MR具有挑战性且耗时。快速而全面的采集协议和标准化的图像后处理可以改善临床前研究，减少采集时间，成本和结果的可变性。在本研究中，我们评估了以增强的3D IntraGate稳态电影序列（ce-3D-IG-cine）和较短的采集时间（11分钟）进行左心室（LV）单次组合表征的可行性）在小鼠急性缺血再灌注损伤模型中的重塑和梗死面积（IS）。十六只雄性C57BL / 6N小鼠在术后第1、5和28天接受了7T心脏MR（Bruker，BioSpec 70/30），包括优化的ce-3D-IG-cine（总扫描时间为11分钟）。将从MR中提取的左室舒张末期容积（EDVMR）和射血分数（EFMR）与短轴（SA-EDVecho，SA-EFecho）和胸骨旁长轴（LA-EDVecho，LA-EFecho）超声心动图。使用不同的标准差（相对于参考组织，SD + 2，+ 3，+ 4，+ 5，+ 6）从ce-3D-IG-cine中手动和半自动分割IS。成像后立即在第28天处死小鼠。将第28天的IS与组织学上的损伤负担进行比较。比较了MR和超声心动图形态功能参数，如MR和组织学的IS。使用Bland-Altman图来评估缺血性负荷分割中的一致性。在ce-3D-IG-cine上测得的体积和功能参数与相应的超声心动图参数相关（EDVMR与SA-EDVecho：ρ= 0.813; EDVMR与LA-EDVecho：ρ= 0.845; EFMR与SA-EFechoρ= 0.612; EFMR与LA-EFechoρ= 0.791；在所有情况下p <0.001）。手工分割的IS与组织学上的瘢痕密切相关（ρ= 0.904，p <0.001）。与手动分割相比，+ 3SD阈值显示的IS半自动评估性能最高（ρ= 0.965，p <0.001），在第1天的总体可重复性为73％，峰值可重复性为80％。使用3SD阈值手动或半自动分割3D-IG-cine序列，可在心肌缺血再灌注损伤模型中快速全面地评估LV形态功能和结构。