Importance of complex blood flow in the assessment of aortic regurgitation severity using phase contrast magnetic resonance imaging

Fig. 1. a Left-ventricular outflow tract viewed in end-diastole, illustrating the image plane position at the sinotubular (ST)-junction (Ao1: red line) and approximately 1 cm above the ST-junction (Ao2: red dashed line), and corresponding PC images (b, c) for the quantification of aortic flow (Ao1: red arrow, Ao2: red dashed arrow). d Right-ventricular outflow tract viewed in end-diastole, illustrating the image plane position for PC imaging at the pulmonary trunk level (white line), and the corresponding PC image (e) for the quantification of pulmonary flow (white arrow). f Delineation of the left ventricular endocardial contour (blue dashed lines) in short-axis view to determine left ventricular volumes

Fig. 2. Examples of net (grey dashed lines), forward (orange), and backward (blue) flow rate curves obtained from PC-MRI measurements in AR patients with non-complex (a) and complex flow (b), including the corresponding velocity profile images (c, d). The curves showed high forward flow during systole for all subjects. In patients with non-complex flow, regurgitant flow was visible as backward flow only during diastole. For patients with complex flow backward flow was also visible during systole. In the velocity profile images the forward flow is indicated in orange and the backward flow in dark blue. In patients with non-complex flow, the velocity profile images showed homogeneous distribution of the velocities over the vessel area. In patients with complex flow, the distribution of velocities was more heterogenic, displaying eccentric outflow jets during systole and sometimes also during diastole, modifying the distribution of the regurgitant flow jet over the diastolic phases. Also, in some patients with complex flow the velocity profile images showed a helical distribution of velocities over the cardiac phases

Fig. 3. Linear regression between backward flow volume (BFV) during systole and the aortic diameter in patients with chronic aortic regurgitation quantified by the direct method

Fig. 4. Bland–Altman plots comparing the regurgitant volume obtained by the internal reference method [RVol = left ventricular stroke volume (LVSV) − pulmonary stroke volume (PuSV)] with the direct method (PC-MRI) at measurement position Ao1 (a, b: top panel; solid lines) and Ao2 (c, d: bottom panel; dashed lines) for patients with non-complex flow (a, c: blue panels to the left), and complex flow (b, d: red panels to the right; NCF: n = 17, CF: n = 26). The colored lines represent the mean relative difference (MD) and 95% limits of agreement (LoA), and the grey line represents zero relative difference. SD, standard deviation

Fig. 5. This figure illustrate the frequency of patients that changed in AR grade from non-severe to severe, and vice versa, based on the RVol and RF. Each pie chart represent the comparison between measurement positions (Ao1: sinotubolar-junction, Ao2: 1 cm above the sinotubolar-junction) for patients with non-complex flow (blue) and complex flow (red), separately. Transparent colors represent the frequency of patients that changed in AR grade (from moderate to severe, or reversed), and saturated color represent the frequency of patients that did not change in AR grade. a RVol, non-complex flow; b RVol, complex flow; c RF, non-complex flow; d RF, complex flow