Quantification of regurgitation in mitral valve prolapse with four-dimensional flow cardiovascular magnetic resonance.
BACKGROUND
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).


METHODS
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).


RESULTS
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%).


CONCLUSIONS
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.
['Spampinato|Ricardo A|RA|', 'Jahnke|Cosima|C|', 'Crelier|Gerard|G|', 'Lindemann|Frank|F|', 'Fahr|Florian|F|', 'Czaja-Ziolkowska|Monika|M|', 'Sieg|Franz|F|', 'Strotdrees|Elfriede|E|', 'Hindricks|Gerhard|G|', 'Borger|Michael A|MA|', 'Paetsch|Ingo|I|']
D006801:Humans D019028:Magnetic Resonance Imaging, Cine D009682:Magnetic Resonance Spectroscopy D008297:Male D008944:Mitral Valve Insufficiency D008945:Mitral Valve Prolapse D011237:Predictive Value of Tests D015203:Reproducibility of Results D012189:Retrospective Studies D012720:Severity of Illness Index
Mitral valve prolapse Four-dimensional Cardiovascular magnetic resonance Echocardiography Degenerative mitral regurgitation Quantification of mitral valve regurgitation