Objectives: The goal of this study was to validate right ventricular outflow tract systolic flow acceleration (RVOTacc; peak flow velocity/time to peak velocity) estimated by phase contrast cardiovascular magnetic resonance (PC-CMR) imaging in patients with pulmonary arterial hypertension (PAH). Background: Invasively measured maximum dP/dt has been utilized to evaluate right ventricular (RV) function as contractility index. Previous study demonstrated left ventricle outflow tract systolic acceleration (LVOTacc: peak flow velocity/time to peak velocity) derived by Doppler echocardiography was linearly related to the LV contractility. However, its use in evaluating RV function has been not applied yet. Recent investigations showed RV outflow parameters measured by PC-CMR are more accurate and compatible to those by right heart catheterization (RHC). Results: 30 PAH patients (38% male, 43짹15 years, 63% idiopathic), underwent baseline CMR and RHC within the 3 days. PC-CMR derived RVOTACC were compared with parameters acquired by RHC. PC-CMR derived RVOTACC showed strong linear correlation compared to RHC-derived maximum dp/dt determined by RHC (R2=0.81, p<0.001). Conclusions: PC-CMR derived RVOTacc significantly correlates with RHC-derived maximum dP/dt in patients with PAH. This proposed index might be a promising tool for non-invasively measured RV function.