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Phase-contrast magnetic resonance imaging (PC-MRI) has evolved as a reliable tool for noninvasive flow and velocity measurements and has been validated in vitro and multiple patient groups. 6, 7 In a subgroup of patients, in whom image quality is insufficient or there is discordance between the TTE-derived AS parameters, clinical decision-making may benefit from alternative noninvasive imaging techniques. In fact, the LVOT is elliptical in the majority of patients, and this approach has been reported to result in a considerable underestimation of AVA. This area is typically computed from the LVOT diameter, implicating the outflow tract to have a circular shape. 5 Third, AVA is calculated using the continuity equation, a formula that includes the cross-sectional area of the left ventricular outflow tract (LVOT). Second, Doppler measurements rely on a parallel alignment between the ultrasound beam and the direction of blood flow, and violation of this condition results in underestimation of flow velocities and pressure gradients. 4 First, image quality is operator-dependent and can be hampered by poor acoustic windows. 3 However, certain pitfalls apply to the echocardiographic assessment of AS, which should be avoided in order to ascertain the accuracy of measurements.
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Transthoracic echocardiography (TTE) is the key diagnostic tool for evaluation of stenosis severity, and the main parameters recommended to be recorded include peak jet velocity (V peak), mean transvalvular pressure gradient (P mean), and aortic valve area (AVA). 1, 2 Since the Western population grows progressively older, AS will put an increasing burden on public health and health resources over the coming decades. Future studies should address the potential value of 4D PC-MR in patients with discordant echocardiographic parameters.ĬALCIFIC AORTIC STENOSIS (AS) is the most common valvular heart disease in developed countries, affecting up to 12.4% of elderly patients. Data ConclusionĤD PC-MR improves the concordance between the different AS parameters and could serve as an additional imaging technique next to TTE. Use of 4D PC-MR improved the concordance between V peak and AVA (from 0.68 to 0.87), and between PG mean and AVA (from 0.68 to 0.86). Differences in V peak between 4D PC-MR and TTE showed to be strongly correlated with the eccentricity of the flow jet ( r = 0.89, P <0.001). In contrast, unidirectional 2D PC-MR substantially underestimated AS severity when compared with TTE. Pearson's correlation, Bland–Altman analysis, paired t-test, and intraclass correlation coefficient. Flow eccentricity was quantified by means of normalized flow displacement, and its influence on the accuracy of TTE measurements was investigated. We compared V peak, P mean, and AVA between TTE, 4D PC-MR, and 2D PC-MR. Twenty patients with various degrees of AS (69.3 ± 5.0 years). To compare four-dimensional phase-contrast magnetic resonance (4D PC-MR), two-dimensional (2D) PC-MR, and transthoracic echocardiography (TTE) for quantification of AS. A multimodality imaging approach might be needed in cases of uncertainty about the actual severity of the stenosis. Echocardiographic measurements of peak jet velocity (V peak), mean pressure gradient (P mean), and aortic valve area (AVA) determine AS severity and play a pivotal role in the stratification towards valvular replacement.
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The prevalence of valvular aortic stenosis (AS) increases as the population ages.