Quantitation of mitral regurgitation with cardiac magnetic resonance imaging: a systematic review

Abstract

In this review discuss the application of cardiac magnetic resonance (CMR) to the evaluation and quantification of mitral regurgitation and provide a systematic literature review for comparisons with echocardiography. Using the 2015 Preferred Reporting Items for Systematic Reviews and Meta-Analyses methodology, we searched Medline and PubMed for original research articles published since 2000 that provided data on the quantification of mitral regurgitation by CMR. We identified 220 articles of which 33 were included. Four main techniques of mitral regurgitation quantification were identified. Reproducibility varied substantially between papers but was high overall for all techniques. However, quantification differed between the techniques studied. When compared with two-dimensional echocardiography, mitral regurgitation fraction and regurgitant volume measured by CMR were comparable but typically lower. CMR has high reproducibility for the quantification of mitral regurgitation in experienced centres, but further technological refinement is needed. An integrated and standardised approach that combines multiple techniques is recommended for optimal reproducibility and precise mitral regurgitation quantification. Definitive outcome studies using CMR as a basis for treatment are lacking but needed.

Secondary mitral regurgitation (part 1): volumetric quantification and analysis

“…This technique is accurate and reproducible, and it appears that MRI provides is more reliable volume data than two-dimensional echocardiography in patients with primary MR 24 38–40. This method should be especially useful in secondary MR because it not only provides the essential volume data (vide supra), but it also allows description of LV structure (including myocardial mass and mass/volume ratio), as well as tissue characterisation and myocardial viability 40. However, the assessment of leaflet structure is best accomplished with echocardiography 34 41.…”

4D flow MRI quantification of mitral and tricuspid regurgitation: Reproducibility and consistency relative to conventional MRI

“…However, multiplanar cardiac MRI is labor‐intensive and requires specialized local expertise, limiting its availability . MRI technologists require additional training to become familiar with cardiac anatomy and how to create cardiac imaging planes using multiple oblique localizers.…”

“…MRI technologists require additional training to become familiar with cardiac anatomy and how to create cardiac imaging planes using multiple oblique localizers. Even if the technologist is able to master the creation of cardiac imaging planes, direct quantification of mitral regurgitation by 2D phase contrast (PC) is challenging, due to dynamic motion of the mitral annulus during systole, and the presence of eccentric regurgitant jets or jets that vary in position throughout systole . Other indirect techniques of quantifying inlet regurgitant volume by multiplanar cardiac MRI are reliant on calculation of ventricular stroke volumes by manually contouring the endocardium in end diastole and end systole, which are prone to error especially at the basal slices …”

Utility of cardiac magnetic resonance for evaluation of mitral regurgitation prior to mitral valve surgery

“…One pitfall of this approach stems from translational valve motion, which can produce under-sampling of flow and produce errors in MR quantification (19). A variant of this approach employs PC-CMR to sample flow through the aortic valve (a region with lesser translational motion than the mitral valve), and cine-CMR to measure LV stroke volume (∆ end-diastole − end-systole); differential stroke volume corresponds to the amount of MR (Figure 1) (24). This method has been shown to correlate well with invasive measurements of MR via cardiac catheterization, as well as non-invasive measurement via echo (25)(26)(27).…”

“…Another potential limitation stems from cine-CMR derived LV stroke volume, which can be challenging in the context of arrhythmias and yield slight variability in the setting of prominent LV trabeculations (28,29). PC data can also be used to calculate MR as differential stroke volume between the left and right ventricle (RV); in the absence of regurgitant valve disease or intracardiac shunts, LV and RV stroke volumes should be near identical (24). Key limitations of this approach include the fact that it is only valid in the setting of isolated MR, and can suffer from pitfalls due to above noted sources of variability with respect to cardiac chamber contouring.…”