Abstract
BackgroundFour-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).MethodsSix 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).ResultsThere 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%).ConclusionsIn 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.
Highlights
In past years, considerable advances in surgical treatment options of mitral regurgitation (MR) resulted in improved life expectancy, but prognosis and clinical decision making with regard to timing of surgery strongly depend on the accurate quantification of MR using cardiac imaging techniques [1].Transthoracic multiparametric echocardiography (TTE) is at the forefront and widely recognized as the non-invasive standard of reference for assessment of MR [2] including proximal isovelocity surface area (PISA) determination with its typical methodological limitations (i.e. the reliance on geometric assumptions of a hemispheric flow convergence region (FCR), and Doppler measurement angle dependency)
4D flow cardiovascular magnetic resonance (CMR) analysis was successfully performed in 97% of subjects. 4 DFindirect quantification could be performed in all patients and controls (n = 60), while a 4DFdirect assessment in only 46 patients of the MR group (n = 54)
A 2D-transthoracic echocardiography (TTE) derived PISA method could be obtained in all patients with mitral valve prolapse (MVP)
Summary
Considerable advances in surgical treatment options of mitral regurgitation (MR) resulted in improved life expectancy, but prognosis and clinical decision making with regard to timing of surgery strongly depend on the accurate quantification of MR using cardiac imaging techniques [1].Transthoracic multiparametric echocardiography (TTE) is at the forefront and widely recognized as the non-invasive standard of reference for assessment of MR [2] including proximal isovelocity surface area (PISA) determination with its typical methodological limitations (i.e. the reliance on geometric assumptions of a hemispheric flow convergence region (FCR), and Doppler measurement angle dependency). In borderline cases [3], a multimodality approach employing standard volumetric cardiovascular magnetic resonance (CMR) has been incorporated [4, 5]. Time-resolved, three-dimensional (3D) full anatomic coverage with three-directional velocity-encoded phase contrast CMR, referred to as fourdimensional (4D) flow CMR has further broadened the diagnostic armamentarium [6] and has been proposed for quantification of blood flow volumes across the mitral valve. Four-dimensional cardiovascular magnetic resonance (CMR) flow assessment (4D flow) allows to derive volumetric quantitative parameters in mitral regurgitation (MR) using retrospective valve tracking. 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)
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