Non-invasive estimation of pulmonary vascular resistance with cardiac magnetic resonance

Aim To develop a cardiac magnetic resonance (CMR) method for non-invasive estimation of pulmonary vascular resistance (PVR). Methods and results The study comprised 100 consecutive patients with known or suspected pulmonary hypertension (PH; 53 +/- 16 years, 73% women) who underwent same-day right heart catheterization (RHC) and CMR. Increased PVR was defined from RHC as >3 WU (n = 66, 66%). From CMR cine and phase-contrast images, right ventricular (RV) volumes and ejection fraction (RVEF), pulmonary artery (PA) flow velocities and areas, and cardiac output were quantified. The best statistical model to estimate PVR was obtained from a derivation cohort (n = 80) based on physiological plausibility and statistical criteria. Validity of the model was assessed in the remaining 20 patients (validation cohort). The CMR-derived model was: estimated PVR (in WU) = 19.38 - [4.62 x Ln PA average velocity (in cm/s)] - [0.08 x RVEF (in %)]. In the validation cohort, the correlation between invasively quantified and CMR-estimated PVR was 0.84 (P < 0.001). The mean bias between the RHC-derived and CMR-estimated PVR was -0.54 (agreement interval -6.02 to 4.94 WU). The CMR model correctly classified 18 (90%) of patients as having normal or increased PVR (area under the receiver operator characteristics curve 0.97; 95% confidence interval: 0.89-1.00). Conclusions Non-invasive estimation of PVR using CMR is feasible and may be valuable for PH diagnosis and/or follow-up.