4D-FLOW cardiovascular MR in assessment of right ventricular flow in patients with pulmonary hypertension / 中华放射学杂志

ABSTRACT

Objective:To investigatethe relationship between right ventricular blood flow components and right ventricular function in patients with pulmonary hypertension (PH) by 4D-FLOW cardiovascular MR (4D-FLOW CMR).Methods:Thirty patients with PH were prospectively enrolled in this study. All patients underwent right heart catheterization to measure hemodynamics and CMR to measure right ventricular blood flow and right ventricular function within 1 week. The long-axis 4-chamber and contiguous short axis cineslices were acquired with balanced steady-state free precession sequence to calculate RV functional metrics including right ventricular end diastolic volume, end systolic volume, ejection fraction, stroke output and other functional parameters. Ventricular flow was acquired in sagittal direction, using a 3D retrospectively ECG-triggered, navigator-gated prototype sequence to analyze.RV function and flow parameters were correlated with Spearman correlation analysis.Results:Right ventricular percent of direction flow(RVPDF),percent of delayed eject flow (RVPDEF),percent of retained flow (RVPRI) and percent of residual volume(RVPRV) of PH patients measured with 4D-FLOW were 16.4%±9.2%, 16.1%±5.6%, 16.8%±6.1%, and 50.5%±12.3%, respectively. RVPDF negatively correlated with RVPRVo ( r=-0.703, P<0.001) while RVPDEF positively correlated with RVPRI( r=0.955, P<0.001). RVPDF was positively correlated with right ventricular stroke volume index (RVSVI)( r=0.38, P=0.041) and right ventricular eject fraction(RVEF)( r=0.69, P<0.001), and negatively correlated with right ventricular end systolic volume index(RVESVI)( r=-0.65, P<0.001) and right ventricular mass index(RVMI)( r=-0.45, P=0.004). RVPRVo was negatively correlated with RVEF( r=-0.58, P=0.007). The sum of RVPDF and RVPDEF (RVPDF+RVPDEF) was 35.2%±11.4%. RVEF correlated with RVPDF+RVPDEF ( r=0.825, P<0.001) and comparable to RVPDF+RVPDEF ( t=1.427, P=0.164). RVPDF was negatively correlated with pulmonary vascular resistance (PVR) ( r=-0.52, P=0.007) while RVPRVo was positively correlated with PVR ( r=0.54, P=0.004). Conclusions:4D-FLOW CMR can be used to measure right ventricular ejection fraction in PH patients without respiratory control. In PH patients, the right ventricular direct blood flow was significantly decreased, while the residual blood flow was significantly increased. The right ventricular direct blood flow and residual blood flow were related to the right ventricular function and pulmonary vascular resistance, which were important parameters to evaluate the right ventricular function and afterload in PH.