BACKGROUND: Right heart catheterization is the gold standard for assessment of pulmonary hemodynamics in patients with chronic thromboembolic pulmonary hypertension. To date, MRI has not been able to produce precise measurements of mean pulmonary arterial pressure (mPAP). The purpose of the study was to create a model for estimating mPAP and pulmonary vascular resistance in patients with chronic thromboembolic pulmonary hypertension by high temporal resolution phase-contrast MRI (PC-MRI) and to correlate the results with simultaneously acquired, invasive catheter-based measurements (simultaneously measured mPAP) and with right heart catheterization measurements. METHODS AND RESULTS: A total of 19 patients with chronic thromboembolic pulmonary hypertension underwent right heart catheterization and-after digital subtraction angiography of the pulmonary arteries-subsequent PC-MRI at 1.5 T with simultaneous recording of mPAP. Velocity- and flow-time curves of PC-MRI were used to calculate absolute acceleration time (Ata), maximum of mean velocities (MV), volume of acceleration (AV), and maximum flow acceleration (dQ/dt). On the basis of these parameters, multiple linear regression analysis revealed maximum achievable model fit (B=0.902) for the following linear combination equation to calculate mPAP (mPAP_cal): mPAP_cal=69.446-(0.521 × Ata)-(0.570 × MV)+(1.507 × AV)+(0.002 × dQ/dt). There was a statistically significant equivalence of mPAP_cal and simultaneously measured mPAP with a goodness of fit of 0.892. Pulmonary vascular resistance was overestimated by calculated pulmonary vascular resistance on the basis of PC-MRI in comparison with right heart catheterization-based measurements by a median of -112 dyn·s·cm(-5), the pairwise regression formula revealed a goodness of fit of 0.792. CONCLUSIONS: PC-MRI-derived parameters enable noninvasive assessment of pulmonary hemodynamics in patients with chronic thromboembolic pulmonary hypertension.