Aortic Stenosis assessment with a 3-directional phase contrast magnetic resonance technique. Comparison to transthoracic echocardiography

Background Transthoracic Doppler-echocardiography (TTE) is the standard clinical method for diagnosis and staging of aortic stenosis (AS). AS staging is based on measurement of aortic peak velocity, transvalvular gradient, and calculation of aortic valve area. Unidirectional throughplane phase-contrast magnetic resonance imaging (1DPC-MRI) has been widely applied in clinical imaging to quantify aortic peak velocities and flow. Nonetheless, 1DPC-MRI requires accurate positioning of imaging planes perpendicular to flow direction in order to avoid peak velocity underestimation, which can be challenging in patients with multiple or eccentric jets. Therefore PC techniques with multi-directional velocity quantification would likely improve the accuracy of velocity determination, and allow for more accurate grading of AS severity. The aim of this study is to determine whether a rapid technique that is able to capture 3 directions of velocity in a 2D image plane in a single breath-hold (3DPCMRI) provides more accurate estimation of diagnostic parameters compared with the traditional 1DPC-MRI, using TTE as the reference standard.