IADI, INSERM U947 and Université de Lorraine, Nancy, France.
CIC-IT 1433, INSERM, CHRU de Nancy and Université de Lorraine, Nancy, France.
Magn Reson Med. 2018 May;79(5):2665-2675. doi: 10.1002/mrm.26923. Epub 2017 Oct 2.
Segmentation of cardiac cine MRI data is routinely used for the volumetric analysis of cardiac function. Conventionally, 2D contours are drawn on short-axis (SAX) image stacks with relatively thick slices (typically 8 mm). Here, an acquisition/reconstruction strategy is used for obtaining isotropic 3D cine datasets; reformatted slices are then used to optimize the manual segmentation workflow.
Isotropic 3D cine datasets were obtained from multiple 2D cine stacks (acquired during free-breathing in SAX and long-axis (LAX) orientations) using nonrigid motion correction (cine-GRICS method) and super-resolution. Several manual segmentation strategies were then compared, including conventional SAX segmentation, LAX segmentation in three views only, and combinations of SAX and LAX slices. An implicit B-spline surface reconstruction algorithm is proposed to reconstruct the left ventricular cavity surface from the sparse set of 2D contours.
All tested sparse segmentation strategies were in good agreement, with Dice scores above 0.9 despite using fewer slices (3-6 sparse slices instead of 8-10 contiguous SAX slices). When compared to independent phase-contrast flow measurements, stroke volumes computed from four or six sparse slices had slightly higher precision than conventional SAX segmentation (error standard deviation of 5.4 mL against 6.1 mL) at the cost of slightly lower accuracy (bias of -1.2 mL against 0.2 mL). Functional parameters also showed a trend to improved precision, including end-diastolic volumes, end-systolic volumes, and ejection fractions).
The postprocessing workflow of 3D isotropic cardiac imaging strategies can be optimized using sparse segmentation and 3D surface reconstruction. Magn Reson Med 79:2665-2675, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
心脏电影磁共振成像数据的分割通常用于心脏功能的容积分析。传统上,通过在短轴(SAX)图像堆栈上绘制相对较厚的切片(通常为 8mm)来进行 2D 轮廓绘制。在这里,使用获取/重建策略来获得各向同性的 3D 电影数据集;然后使用重新格式化的切片来优化手动分割工作流程。
使用非刚性运动校正(电影-GRICS 方法)和超分辨率从多个 2D 电影堆栈(在 SAX 和长轴(LAX)方向的自由呼吸期间采集)中获得各向同性 3D 电影数据集。然后比较了几种手动分割策略,包括传统的 SAX 分割、仅在三个视图中进行 LAX 分割以及 SAX 和 LAX 切片的组合。提出了一种隐式 B 样条曲面重建算法,用于从稀疏的 2D 轮廓集中重建左心室腔表面。
所有测试的稀疏分割策略都具有很好的一致性,尽管使用的切片较少(3-6 个稀疏切片,而不是 8-10 个连续的 SAX 切片),但 Dice 评分均高于 0.9。与独立的相位对比流量测量相比,从四个或六个稀疏切片计算的搏出量具有比传统 SAX 分割稍高的精度(6.1mL 的标准偏差误差对 5.4mL),代价是稍低的准确性(-1.2mL 的偏差对 0.2mL)。功能参数也显示出提高精度的趋势,包括舒张末期容积、收缩末期容积和射血分数)。
使用稀疏分割和 3D 曲面重建可以优化 3D 各向同性心脏成像策略的后处理工作流程。磁共振医学 79:2665-2675,2018。©2017 年国际磁共振学会。