4D flow MRI-based grading of left ventricular diastolic dysfunction: a validation study against echocardiography

Abstract Objectives To assess the feasibility and accuracy of 4D flow MRI-based grading of left ventricular diastolic dysfunction, using echocardiography as the reference method. Methods Between October 2016 and February 2022, subjects were prospectively recruited for transthoracic echocardiographic evaluation of left ventricular diastolic function and 4D flow MRI at 3 T. Echocardiographic grading of diastolic dysfunction was performed according to the multiparametric, threshold-based 2016 ASE/EACVI approach. Volumetric and echo-equivalent peak velocity grading parameters were evaluated from 4D flow magnitude and velocity data, respectively. Duration of vortical blood flow along the main pulmonary artery (t vortex) was employed as a surrogate grading parameter for echocardiographic tricuspid regurgitant peak velocity (TR). Correlations between grading parameters were analysed; agreement in grading of diastolic dysfunction between methods was assessed using a 5 × 5 contingency table analysis. Results The study population consisted of 94 participants (mean age, 62 ± 12 years, 50 females, 34 with structural heart disease). All volumetric and echo-equivalent 4D flow grading parameters demonstrated strong to very strong correlations with echocardiography (r = 0.75–0.92). Volumetric parameters showed significant biases between 4D flow and echocardiography. Employing bias-adjusted 4D flow grading cutoffs for volumetric parameter, echo-equivalent cutoffs for diastolic transmitral and myocardial peak velocities, and t vortex > 15% as a surrogate cutoff for TR > 2.8 m/s, nearly perfect agreement in diastolic dysfunction grading between methods was observed (weighted kappa = 0.84). There was no evidence for over- or underestimation of grades by 4D flow (p = 0.53). Conclusion Grading of left ventricular diastolic dysfunction from a single 4D flow measurement is feasible and shows nearly perfect agreement with echocardiography. Key Points Question The lack of comparison studies with echocardiography currently limits cardiac MRI-based grading of diastolic dysfunction. Could 4D flow MRI serve as a viable technique? Findings A single 4D flow MRI measurement allows multiparametric grading of left ventricular diastolic dysfunction in nearly perfect agreement with echocardiography. Clinical relevance Agreement between 4D flow MRI and echocardiographic grading of left ventricular diastolic dysfunction is comparable to that observed in repeated echocardiographic evaluations, suggesting 4D flow as a viable alternative to echocardiography in selected patients, especially when comprehensive MRI is already performed. Graphical Abstract