Validation of time-resolved, automated peak trans-mitral velocity tracking: Two center four-dimensional flow cardiovascular magnetic resonance study

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

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 (tvortex) 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 tvortex > 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.

Dynamic Velocity Tracking in the Left-Ventricular Outflow Track Using Four-Dimensional 4D Flow for the Assessment of Left Ventricular Outflow Track Obstruction

Stress 4D flow CMR is a powerful non-invasive tool for diagnosing and localizing dynamic LVOT obstruction. By quantifying peak velocities and flow patterns under stress, it provides critical insights into hemodynamics, especially when echocardiography is limited, enabling accurate diagnosis and improved clinical decision-making in complex cases.

Cardiovascular magnetic resonance imaging in mitral valve disease

This paper describes the role of cardiovascular magnetic resonance (CMR) imaging in assessing patients with mitral valve disease. Mitral regurgitation (MR) is one of the most prevalent valvular heart diseases. It often progresses without significant symptoms, leading to left ventricular overload, dysfunction, frequent decompensated heart failure episodes, and excess mortality. Cardiovascular magnetic resonance assessment is recommended for MR when routine ultrasound imaging information is insufficient or discordant. A well-planned CMR can provide an in-depth assessment of the mitral valve apparatus, leaflet morphology, and papillary muscles. In addition, it can precisely inform the impact of MR on left atrial and ventricular remodelling. The review aims to highlight established and emerging techniques for morphological assessment, flow assessment (including regurgitation and stenosis), myocardial assessment, and haemodynamic assessment of mitral valve disease by CMR. It also proposes a simplified clinical flow chart for CMR assessment of the mitral valve.

Impact of the evaluation method on 4D flow-derived diastolic transmitral and myocardial peak velocities: Comparison with echocardiography

PURPOSE

To compare agreement of different evaluation methods of magnetic resonance (MR) 4D flow-derived diastolic transmitral and myocardial peak velocities as well as their ratios, using echocardiography as reference.

METHODS

In this prospective study, 60 subjects without symptoms of cardiovascular disease underwent echocardiography and non-contrast 3 T MR 4D flow imaging of the heart. Early- (E) and late-diastolic (A) transmitral peak filling velocities were evaluated from 4D flow data using three different strategies: 1) at the mitral valve tips in short-axis orientation (SA-method), 2) between the mitral valve tips in 4-chamber orientation (4-chamber-method), and 3) as maximal velocities in the transmitral inflow volume (max-velocity-method). Septal, lateral and average early-diastolic myocardial peak velocities (e') were derived from the myocardial tissue in the vicinity of the mitral valve. 4D flow parameters were compared with echocardiography by correlation and Bland-Altman analysis.

RESULTS

All 4D flow-derived E, A and E/A values correlated with echocardiography (r = 0.65-0.73, 0.75-0.83 and 0.74-0.86, respectively). While the SA- and 4-chamber-methods substantially underestimated E and A compared to echocardiography (p < 0.001), the max-velocity-method provided E (p = 0.13) and E/A (p = 0.07) without significant bias. Septal, lateral and average e' from 4D flow as well as the max-velocity-method-derived E/e' correlated with echocardiographic measurements (r = 0.64-0.81) and showed no significant bias (p = 0.26-0.54).

CONCLUSION

MR 4D flow imaging allows precise and accurate evaluation of transmitral and myocardial peak velocities for characterization of LV diastolic function without significant bias to echocardiography, when transmitral velocities are assessed from the transmitral inflow volume. This enables the use of validated echocardiography threshold values.

Automated 4D flow cardiac MRI pipeline to derive peak mitral inflow diastolic velocities using short-axis cine stack: two centre validation study against echocardiographic pulse-wave doppler

BACKGROUND

Measurement of peak velocities is important in the evaluation of heart failure. This study compared the performance of automated 4D flow cardiac MRI (CMR) with traditional transthoracic Doppler echocardiography (TTE) for the measurement of mitral inflow peak diastolic velocities.

METHODS

Patients with Doppler echocardiography and 4D flow cardiac magnetic resonance data were included retrospectively. An established automated technique was used to segment the left ventricular transvalvular flow using short-axis cine stack of images. Peak mitral E-wave and peak mitral A-wave velocities were automatically derived using in-plane velocity maps of transvalvular flow. Additionally, we checked the agreement between peak mitral E-wave velocity derived by 4D flow CMR and Doppler echocardiography in patients with sinus rhythm and atrial fibrillation (AF) separately.

RESULTS

Forty-eight patients were included (median age 69 years, IQR 63 to 76; 46% female). Data were split into three groups according to heart rhythm. The median peak E-wave mitral inflow velocity by automated 4D flow CMR was comparable with Doppler echocardiography in all patients (0.90 ± 0.43 m/s vs 0.94 ± 0.48 m/s, P = 0.132), sinus rhythm-only group (0.88 ± 0.35 m/s vs 0.86 ± 0.38 m/s, P = 0.54) and in AF-only group (1.33 ± 0.56 m/s vs 1.18 ± 0.47 m/s, P = 0.06). Peak A-wave mitral inflow velocity results had no significant difference between Doppler TTE and automated 4D flow CMR (0.81 ± 0.44 m/s vs 0.81 ± 0.53 m/s, P = 0.09) in all patients and sinus rhythm-only groups. Automated 4D flow CMR showed a significant correlation with TTE for measurement of peak E-wave in all patients group (r = 0.73, P < 0.001) and peak A-wave velocities (r = 0.88, P < 0.001). Moreover, there was a significant correlation between automated 4D flow CMR and TTE for peak-E wave velocity in sinus rhythm-only patients (r = 0.68, P < 0.001) and AF-only patients (r = 0.81, P = 0.014). Excellent intra-and inter-observer variability was demonstrated for both parameters.

CONCLUSION

Automated dynamic peak mitral inflow diastolic velocity tracing using 4D flow CMR is comparable to Doppler echocardiography and has excellent repeatability for clinical use. However, 4D flow CMR can potentially underestimate peak velocity in patients with AF.