Left ventricular geometry during unloading and the end-systolic pressure volume relationship: Measurement with a modified real-time MRI-based method in normal sheep
Left ventricular geometry during unloading and the end-systolic pressure volume relationship: Measurement with a modified real-time MRI-based method in normal sheep
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DOI：
10.1371/journal.pone.0234896
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发表时间：
2020-06-22
期刊：
影响因子：
3.7
通讯作者：
Ratcliffe, Mark B.
中科院分区：
文献类型：
--
作者：
Giao, Duc M.;Wang, Yan;Ratcliffe, Mark B.
左心室收缩末期压力容积关系（ESPVR）是分析左心室收缩功能的基础。我们描述了一种基于2D实时（RT）MRI的方法（RTPVR），该方法具有单独的软件工具，用于1）LV的基于半自动水平集的形状先验方法（LSSPM），2）同步压力面积环的生成和3）ESPVR的计算。应用RTPVR方法测量了正常绵羊腔静脉阻塞（VCO）时的心室几何形态、ES压力面积关系（ESPAR）和ESPVR。14只成年绵羊麻醉后行左室收缩功能测定。14只绵羊中有10只接受了RTMRI，14只绵羊中有8只接受了电导导管测量; 4只同时进行了RTMRI和电导测量。在不同的VCO期间，在心尖、中心室和基底水平进行2D横截面RTMRI。Dice相似系数用于比较LSSPM和手动图像分割，从而确定LSSPM的准确性。在每个LV水平测量LV横截面积、长轴和短轴长度、轴比、长轴方向角和ESPAR。采用梯形法则计算ESPVR。LSSPM和两名读者手动分割之间的Dice相似系数分别为87.31 +/- 2.51%和88.13 +/-3.43%。在VCO期间，所有横截面变得更加椭圆。在VCO期间主轴取向发生了变化，但仍保持在隔-侧方向。在接受RTMRI的10只绵羊中，有7只在VCO期间发生心尖水平的LV腔闭塞。ESPAR在所有水平上都是非线性的。最后，由于心尖塌陷，ESPVR呈非线性。电导导管测量的ESPVR（E-ES，E-Index= 2.23 +/- 0.66 mmHg/ml/m2）和RT（E-ES，E-Index= 2.31 +/- 0.31 mmHg/ml/m2）无显著差异。2D RT MRI图像的LSSPM分割是准确的，并且允许在VCO期间计算LV几何结构、ESPAR和ESPVR。在未来，RTPVR将有助于确定ESPVR基础上的区域收缩材料参数。
The left ventricular (LV) end-systolic (ES) pressure volume relationship (ESPVR) is the cornerstone of systolic LV function analysis. We describe a 2D real-time (RT) MRI-based method (RTPVR) with separate software tools for 1) semi-automatic level set-based shape prior method (LSSPM) of the LV, 2) generation of synchronized pressure area loops and 3) calculation of the ESPVR. We used the RTPVR method to measure ventricular geometry, ES pressure area relationship (ESPAR) and ESPVR during vena cava occlusion (VCO) in normal sheep. 14 adult sheep were anesthetized and underwent measurement of LV systolic function. Ten of the 14 sheep underwent RTMRI and eight of the 14 underwent measurement with conductance catheter; 4 had both RTMRI and conductance measurements. 2D cross sectional RTMRI were performed at apex, mid-ventricle and base levels during separate VCOs. The Dice similarity coefficient was used to compare LSSPM and manual image segmentation and thus determine LSSPM accuracy. LV cross-sectional area, major and minor axis length, axis ratio, major axis orientation angle and ESPAR were measured at each LV level. ESPVR was calculated with a trapezoidal rule. The Dice similarity coefficient between LSSPM and manual segmentation by two readers was 87.31 +/- 2.51% and 88.13 +/- 3.43%. All cross sections became more elliptical during VCO. The major axis orientation shifted during VCO but remained in the septo-lateral direction. LV chamber obliteration at the apical level occurred during VCO in 7 of 10 sheep that underwent RTMRI. ESPAR was non-linear at all levels. Finally, ESPVR was non-linear because of apical collapse. ESPVR measured by conductance catheter (E-ES,E-Index= 2.23 +/- 0.66 mmHg/ml/m(2)) and RT (E-ES,E-Index= 2.31 +/- 0.31 mmHg/ml/m(2)) was not significantly different. LSSPM segmentation of 2D RT MRI images is accurate and allows calculation of LV geometry, ESPAR and ESPVR during VCO. In the future, RTPVR will facilitate determination of regional systolic material parameters underlying ESPVR.