Comparison of Four-Dimensional Magnetic Resonance Imaging Analysis of Left Ventricular Fluid Dynamics and Energetics in Ischemic and Restrictive Cardiomyopathies.

Riva A, Sturla F, Pica S, Camporeale A, Tondi L, Saitta S, Caimi A, Giese D, Palladini G, Milani P, Castelvecchio S, Menicanti L, Redaelli A, Lombardi M, Votta E. Comparison of Four-Dimensional Magnetic Resonance Imaging Analysis of Left Ventricular Fluid Dynamics and Energetics in Ischemic and Restrictive Cardiomyopathies. J Magn Reson Imaging. 2022 Oct;56(4):1157-1170. doi: 10.1002/jmri.28076. Epub 2022 Jan 24. PMID: 35075711; PMCID: PMC9541919. Abstract <strong>Background: </strong>Time-resolved three-directional velocity-encoded (4D flow) magnetic resonance imaging (MRI) enables the quantification of left ventricular (LV) intracavitary fluid dynamics and energetics, providing mechanistic insight into LV dysfunctions. Before becoming a support to diagnosis and patient stratification, this analysis should prove capable of discriminating between clearly different LV derangements. <strong>Purpose: </strong>To investigate the potential of 4D flow in identifying fluid dynamic and energetics derangements in ischemic and restrictive LV cardiomyopathies. <strong>Study type: </strong>Prospective observational study. <strong>Population: </strong>Ten patients with post-ischemic cardiomyopathy (ICM), 10 patients with cardiac light-chain cardiac amyloidosis (AL-CA), and 10 healthy controls were included. <strong>Field strength/sequence: </strong>1.5 T/balanced steady-state free precession cine and 4D flow sequences. <strong>Assessment: </strong>Flow was divided into four components: direct flow (DF), retained inflow, delayed ejection flow, and residual volume (RV). Demographics, LV morphology, flow components, global and regional energetics (volume-normalized kinetic energy [KE_V ] and viscous energy loss [EL_V ]), and pressure-derived hemodynamic force (HDF) were compared between the three groups. <strong>Statistical tests: </strong>Intergroup differences in flow components were tested by one-way analysis of variance (ANOVA); differences in energetic variables and peak HDF were tested by two-way ANOVA. A P-value of &lt;0.05 was considered significant. <strong>Results: </strong>ICM patients exhibited the following statistically significant alterations vs. controls: reduced KE_V , mostly in the basal region, in systole (-44%) and in diastole (-37%); altered flow components, with reduced DF (-33%) and increased RV (+26%); and reduced basal-apical HDF component on average by 63% at peak systole. AL-CA patients exhibited the following alterations vs. controls: significantly reduced KE_V at the E-wave peak in the basal segment (-34%); albeit nonstatistically significant, increased peaks and altered time-course of the HDF basal-apical component in diastole and slightly reduced HDF components in systole. <strong>Data conclusion: </strong>The analysis of multiple 4D flow-derived parameters highlighted fluid dynamic alterations associated with systolic and diastolic dysfunctions in ICM and AL-CA patients, respectively.Riva A、Sturla F、Pica S、Camporeale A、Tondi L、Saitta S、Caimi A、Giese D、Palladini G、Milani P、Castelvecchio S、Menicanti L、Redaelli A、Lombardi M、Votta E开展的这项研究题为《缺血性与限制性心肌病左心室流体动力学及能量学的四维磁共振成像分析》，发表于《磁共振成像杂志（J Magn Reson Imaging）》2022年10月第56卷第4期，页码范围1157-1170，DOI：10.1002/jmri.28076，2022年1月24日在线发表，PMID：35075711；PMCID：PMC9541919。**背景：** 时间分辨三向流速编码（4D flow）磁共振成像（magnetic resonance imaging, MRI）可量化左心室（left ventricular, LV）腔内流体动力学与能量学特征，为左心室功能障碍提供机制层面的阐释。在该方法用于辅助临床诊断与患者分层前，需先验证其能够区分差异显著的左心室异常状态。**目的：** 探讨四维流速编码MRI在鉴别缺血性与限制性左心室心肌病患者流体动力学及能量学异常的应用潜力。**研究类型：** 前瞻性观察性研究。**研究人群：** 纳入10例缺血性心肌病（ischemic cardiomyopathy, ICM）患者、10例心脏轻链型淀粉样变性（cardiac light-chain cardiac amyloidosis, AL-CA）患者及10名健康对照者。**场强与序列：** 1.5T场强下的平衡稳态自由进动cine序列及四维流速编码序列。**评估指标：** 将血流分为4个组分：直接血流（direct flow, DF）、滞留流入血流、延迟射流血流及残余容积（residual volume, RV）。比较三组受试者的人口学资料、左心室形态学特征、血流组分、全局及局部能量学指标[单位体积动能（volume-normalized kinetic energy, KE_V）与黏性能量损失（viscous energy loss, EL_V）]及压力源性血流动力学力（hemodynamic force, HDF）。**统计学检验：** 采用单因素方差分析（one-way analysis of variance, ANOVA）比较各组间血流组分的差异；采用双因素方差分析（two-way ANOVA）比较能量学指标及峰值血流动力学力的差异。以P<0.05为差异具有统计学意义。**结果：** 与健康对照相比，缺血性心肌病患者出现以下具有统计学意义的异常：收缩期与舒张期的单位体积动能显著降低，其中基底部区域降幅最为明显（收缩期降低44%，舒张期降低37%）；血流组分异常，直接血流减少33%、残余容积增加26%；收缩期峰值时基底部-心尖部血流动力学力组分平均降低63%。心脏轻链型淀粉样变性患者与健康对照相比，出现以下异常：舒张早期E波峰值时基底部节段的单位体积动能显著降低34%；虽无统计学显著性，但舒张期基底部-心尖部血流动力学力组分的峰值升高且时间进程出现异常，收缩期血流动力学力组分轻度降低。**数据结论：** 对多种四维流速编码衍生参数的分析结果显示，缺血性心肌病与心脏轻链型淀粉样变性患者分别存在与收缩及舒张功能障碍相关的流体动力学异常。