Mitral valve regurgitation assessed by intraventricular CMR 4D-flow: a systematic review on the technological aspects and potential clinical applications

Abstract

Cardiac magnetic resonance (CMR) four-dimensional (4D) flow is a novel method for flow quantification potentially helpful in management of mitral valve regurgitation (MVR). In this systematic review, we aimed to depict the clinical role of intraventricular 4D-flow in MVR. The reproducibility, technical aspects, and comparison against conventional techniques were evaluated. Published studies on SCOPUS, MEDLINE, and EMBASE were included using search terms on 4D-flow CMR in MVR. Out of 420 screened articles, 18 studies fulfilled our inclusion criteria. All studies (n = 18, 100%) assessed MVR using 4D-flow intraventricular annular inflow (4D-flowAIM) method, which calculates the regurgitation by subtracting the aortic forward flow from the mitral forward flow. Thereof, 4D-flow jet quantification (4D-flowjet) was assessed in 5 (28%), standard 2D phase-contrast (2D-PC) flow imaging in 8 (44%) and the volumetric method (the deviation of left ventricle stroke volume and right ventricular stroke volume) in 2 (11%) studies. Inter-method correlations among the 4 MVR quantification methods were heterogeneous across studies, ranging from moderate to excellent correlations. Two studies compared 4D-flowAIM to echocardiography with moderate correlation. In 12 (63%) studies the reproducibility of 4D-flow techniques in quantifying MVR was studied. Thereof, 9 (75%) studies investigated the reproducibility of the 4D-flowAIM method and the majority (n = 7, 78%) reported good to excellent intra- and inter-reader reproducibility. Intraventricular 4D-flowAIM provides high reproducibility with heterogeneous correlations to conventional quantification methods. Due to the absence of a gold standard and unknown accuracies, future longitudinal outcome studies are needed to assess the clinical value of 4D-flow in the clinical setting of MVR.

The Role of Cardiovascular Magnetic Resonance Imaging in the Assessment of Mitral Regurgitation

“…It is suitable for MR assessment also in concomitant valvular pathologies or shunt flows, but has been shown to be less reproducible in primary MR, mainly due to the complex and time-consuming plane reformatting process [ 27 ]. Based on a recent systematic review, more than 80% of recent studies have shown that the 4D flow analysis technique calculating mitral inflow and aortic forward flow for the MR RVol calculation exhibited the best inter- and intra-observer reproducibility [ 33 ]. All standard and novel methods for RVol quantification, summarized in the table below, can be used in routine practice for cross-validating, aiming for a comprehensive and robust assessment of the severity of MR.…”

Parameters of the mitral apparatus in patients with ischemic and nonischemic dilated cardiomyopathy

“… 65 , 66 New advances in 4D flow cardiac magnetic resonance imaging are growing, and potentially will be helpful in the future management of mitral valve regurgitation. 67 …”