4D‐Flow MRI intracardiac flow analysis considering different subtypes of pulmonary hypertension

Figure 1. The post‐processing workflow of the right ventricular diastolic vorticity. (a) From the 4‐chamber view and short‐axis view perspectives, vector glyph represented velocity ( v ) and vorticity (ω) vector fields for both left and right ventricles are visualized during early filling phase. (b) Calculated right ventricular vorticity throughout the cardiac cycle, with the corresponding tricuspid valve Doppler pattern. Individual color‐coded data points represent a specific cardiac cycle phase: yellow = systole, green = rapid early filling phase, blue = diastasis, red = atrial systole. (c) From the short‐axis view perspective, vorticity vector field segmented within the right ventricle during diastole with the time steps corresponding to the cardiac phases depicted in the above vorticity waveform.

Figure 2. Comparison of the right ventricular diastolic dysfunction imaging biomarkers between pulmonary arterial hypertension (PAH) and pulmonary hypertension due to chronic lung disease (PH‐CLD) and control groups. (a) 4D‐Flow MRI derived E‐vorticity was the only discriminating biomarker differentiating all groups with the lowest E‐vorticity values noted in PAH patients. (b) Atrial phase A‐vorticity was no different between the PAH and PH‐CLD groups yet both PH groups has increased A‐vorticity when compared to control group. (c) Similar findings were observed for the E/A vorticity ratio. (d) There were no differences in Doppler E‐wave velocity between the considered group. (e) Tissue Doppler e' velocity was decreased in both PH groups when compared to controls with no differences between the specific PH groups. (f) Similarly, E/e' ratio was increased in both PH groups but there were no differences between specific PH groups.

Figure 3. Comparison of the right ventricular (RV) velocity and vorticity vector fields in representative patients with pulmonary arterial hypertension (PAH), pulmonary hypertension due to chronic lung disease (PH‐CLD), and control subject. The most left column depicts velocity vector field with the superimposed vorticity field oriented from the right long axis ‐ RV outflow tract view. Other columns depicts intracardiac vorticity from the short‐axis view perspective during early diastolic filling phase. Vorticity is in each subject generated primarily along the endocardial surfaces. One can appreciate higher density and magnitude of vorticity vector glyphs in the control subject with additional source of vorticity generated within the RV outflow tract (**) and inside the RV cavity (*). Representative RV vorticity waveforms through the cardiac cycle are depicted at the bottom of the figure.

Figure 4. Graphical representation of the most significant correlations showing the relationship between the 4D‐Flow MRI vorticity and (a) right ventricular ejection fraction (RVEF) and (b) RV end‐systolic volume (RV‐ESV).