Four-dimensional cardiovascular magnetic resonance (CMR) flow assessment (4D flow) allows to derive volumetric quantitative parameters in mitral regurgitation (MR) using retrospective valve tracking. However, prior studies have been conducted in functional MR or in patients with congenital heart disease, thus, data regarding the usefulness of 4D flow CMR in case of a valve pathology like mitral valve prolapse (MVP) are scarce. This study aimed to evaluate the clinical utility of cine-guided valve segmentation of 4D flow CMR in assessment of MR in MVP when compared to standardized routine CMR and transthoracic echocardiography (TTE). Six healthy subjects and 54 patients (55 ± 16 years; 47 men) with MVP were studied. TTE severity grading used a multiparametric approach resulting in mild/mild-moderate (n = 12), moderate-severe (n = 12), and severe MR (n = 30). Regurgitant volume (RVol) and regurgitant fraction (RF) were also derived using standard volumetric CMR and 4D flow CMR datasets with direct measurement of regurgitant flow (4DFdirect) and indirect calculation using the formula: mitral valve forward flow - left ventricular outflow tract stroke volume (4DFindirect). There was moderate to strong correlation between methods (r = 0.59–0.84, p < 0.001), but TTE proximal isovelocity surface area (PISA) method showed higher RVol as compared with CMR techniques (PISA vs. CMR, mean difference of 15.8 ml [95% CI 9.9–21.6]; PISA vs. 4DFindirect, 17.2 ml [8.4–25.9]; PISA vs. 4DFdirect, 27.9 ml [19.1–36.8]; p < 0.001). Only indirect CMR methods (CMR vs. 4DFindirect) showed moderate to substantial agreement (Lin’s coefficient 0.92–0.97) without significant bias (mean bias 1.05 ± 26 ml [− 50 to 52], p = 0.757). Intra- and inter-observer reliability were good to excellent for all methods (ICC 0.87–0.99), but with numerically lower coefficient of variation for indirect CMR methods (2.5 to 12%). In the assessment of patients with MR and MVP, cine-guided valve segmentation 4D flow CMR is feasible and comparable to standard CMR, but with lower RVol when TTE is used as reference. 4DFindirect quantification has higher intra- and inter-technique agreement than 4DFdirect quantification and might be used as an adjunctive technique for cross-checking MR quantification in MVP.

中文翻译：

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四维血流心血管磁共振对二尖瓣脱垂的反流进行量化


四维心血管磁共振 (CMR) 流量评估（4D 流量）允许使用回顾性瓣膜跟踪得出二尖瓣反流 (MR) 的体积定量参数。然而，之前的研究是在功能性 MR 或先天性心脏病患者中进行的，因此，关于 4D 流 CMR 在二尖瓣脱垂 (MVP) 等瓣膜病理情况下的有效性的数据很少。本研究旨在与标准化常规 CMR 和经胸超声心动图 (TTE) 相比，评估 4D 流 CMR 电影引导瓣膜分割在 MVP MR 评估中的临床效用。对 6 名健康受试者和 54 名 MVP 患者（55 ± 16 岁；47 名男性）进行了研究。 TTE 严重程度分级采用多参数方法，分为轻度/轻度-中度 (n = 12)、中度-重度 (n = 12) 和重度 MR (n = 30)。还使用标准体积 CMR 和 4D 流量 CMR 数据集导出返流体积 (RVol) 和返流分数 (RF)，直接测量返流流量 (4DFdirect) 并使用以下公式间接计算：二尖瓣前向流量 - 左心室流出道每搏输出量（4D间接）。方法之间存在中度至强相关性（r = 0.59–0.84，p < 0.001），但与 CMR 技术相比，TTE 近端等速表面积 (PISA) 方法显示出更高的 RVol（PISA 与 CMR，平均差异为 15.8 ml） [95% CI 9.9–21.6]；PISA 与 4DFindirect，17.2 ml [8.4–25.9]；PISA 与 4DFdirect，27.9 ml [19.1–36.8]；p < 0.001）。只有间接 CMR 方法（CMR 与 4DFindirect）显示出中等至显着的一致性（Lin 系数 0.92–0.97），没有显着偏差（平均偏差 1.05 ± 26 ml [− 50 至 52]，p = 0.757）。 所有方法的观察者内和观察者间可靠性均从良好到优秀（ICC 0.87-0.99），但间接 CMR 方法的变异系数在数值上较低（2.5% 至 12%）。在评估 MR 和 MVP 患者时，电影引导瓣膜分割 4D 流 CMR 是可行的，并且与标准 CMR 相当，但当使用 TTE 作为参考时，RVol 较低。 4DF 间接量化比 4DF 直接量化具有更高的技术内和技术间一致性，并且可以用作 MVP 中交叉检查 MR 量化的辅助技术。