Clinical assessment of aortic valve stenosis: Comparison between 4D flow MRI and transthoracic echocardiography

Abstract

Background The prevalence of valvular aortic stenosis (AS) increases as the population ages. Echocardiographic measurements of peak jet velocity (Vpeak), mean pressure gradient (Pmean), and aortic valve area (AVA) determine AS severity and play a pivotal role in the stratification towards valvular replacement. A multimodality imaging approach might be needed in cases of uncertainty about the actual severity of the stenosis. Purpose To compare four‐dimensional phase‐contrast magnetic resonance (4D PC‐MR), two‐dimensional (2D) PC‐MR, and transthoracic echocardiography (TTE) for quantification of AS. Study Type Prospective. Population Twenty patients with various degrees of AS (69.3 ± 5.0 years). Field Strength/Sequences 4D PC‐MR and 2D PC‐MR at 3T. Assessment We compared Vpeak, Pmean, and AVA between TTE, 4D PC‐MR, and 2D PC‐MR. Flow eccentricity was quantified by means of normalized flow displacement, and its influence on the accuracy of TTE measurements was investigated. Statistical Tests Pearson's correlation, Bland–Altman analysis, paired t‐test, and intraclass correlation coefficient. Results 4D PC‐MR measured higher Vpeak (r = 0.95, mean difference + 16.4 ± 10.7%, P <0.001), and Pmean (r = 0.92, mean difference + 14.9 ± 16.0%, P = 0.013), but a less critical AVA (r = 0.80, mean difference + 19.9 ± 20.6%, P = 0.002) than TTE. In contrast, unidirectional 2D PC‐MR substantially underestimated AS severity when compared with TTE. Differences in Vpeak between 4D PC‐MR and TTE showed to be strongly correlated with the eccentricity of the flow jet (r = 0.89, P <0.001). Use of 4D PC‐MR improved the concordance between Vpeak and AVA (from 0.68 to 0.87), and between PGmean and AVA (from 0.68 to 0.86). Data Conclusion 4D PC‐MR improves the concordance between the different AS parameters and could serve as an additional imaging technique next to TTE. Future studies should address the potential value of 4D PC‐MR in patients with discordant echocardiographic parameters. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:472–480.

Evaluation of Cardiac Shunts With 4D Flow Cardiac Magnetic Resonance: Intra‐ and Interobserver Variability

“…The 4D‐flow technique is particularly useful to assess CHD, as it provides more comprehensive flow data in a wide range of cardiac pathologies through the acquisition of a single 3D volume . Some authors have also compared 4D‐flow MRI to echocardiography to measure flow volumes at the carotid bifurcation and in aortic valve stenosis, reporting good correlation between the two techniques, and demonstrating the potential utility of 4D‐flow MRI to provide greater concordance or flow parameters to the measurements obtained by echocardiography.…”

The impact of 4D flow displacement artifacts on wall shear stress estimation

“…Studies with bicuspid aortic valve patients revealed peak velocities of up to 2.3 m/s, 34 whereas much higher flow velocities of up to 4.7m/s have been reported in aortic valve stenosis patients. 35,36 Furthermore, WSS has been evaluated in the context of these diseases 31,32 because it has a direct impact on cell function and influences aortic wall remodeling. Moreover, some gradient systems today are more performant than the system used here (AS095DS, Siemens Healthineers), which in principle could be used to decrease gradient timings and thus the magnitude of the displacement artifacts.…”

“…However, especially in pathologies, the quantification of hemodynamic parameters is of high interest. Studies with bicuspid aortic valve patients revealed peak velocities of up to 2.3 m/s, 34 whereas much higher flow velocities of up to 4.7m/s have been reported in aortic valve stenosis patients 35,36 . Furthermore, WSS has been evaluated in the context of these diseases 31,32 because it has a direct impact on cell function and influences aortic wall remodeling.…”

Clinical Applications of 4D Flow MR Imaging in Aortic Valvular and Congenital Heart Disease

“…Pronounced flow eccentricity is associated with greater differences in peak jet velocity between transthoracic echocardiography and 4D flow MRI. 30 In healthy volunteers and patients with AS, 4D flow MRI allows for improved flow quantification relative to transthoracic echocardiography. [30][31][32] Research has also demonstrated that helical blood flow, vortical blood flow, and blood eccentricity assessed using 4D flow MRI become stronger as the disease progresses in patients with AS.…”