Right Ventricular to Left Ventricular (RV/LV) Blood Pool T2 Ratio Is Associated With Invasive Hemodynamics Across...

Pulmonary hypertension (PH) is defined by elevated mean pulmonary arterial pressure (mPAP). Pulmonary vascular resistance (PVR) and SvO₂ (mixed venous oxygenation), measured by right heart catheterization (RHC), are key determinants of disease severity and prognosis. The right-to-left ventricular (RV/LV) blood-pool T2 ratio (T2_RV/LV) by MRI has been proposed as a surrogate of RV-LV blood oxygenation differences and SvO₂. Therefore, we analyzed 31 consecutive patients with PH (precapillary = 13, postcapillary = 6, combined = 12) compared to data from four patients with no PH and 21 healthy subjects. All subjects underwent 1.5 T MRI with cine for RV/LV and atrial volumes and T2 mapping. Blood T2_RV/LV was measured on mid-ventricular short-axis images. Hemodynamic data (including mPAP, PVR, pulmonary arterial wedge pressure (PAWP) and oxygen saturations) were obtained from recent (within 1.5 months) RHC. We found that the T2_RV/LV was significantly lower in PH patients than in healthy controls (0.76 ± 0.09 vs. 0.91 ± 0.05; p < 0.001) and correlated with pulmonary artery oxygen saturations (SvO₂) (r = 0.77; p < 0.001). It also correlated with PVR (ρ = -0.74; p < 0.001), mPAP (r = -0.54; p < 0.001), RVEF (r = -0.61; p < 0.001). In multivariable analysis, T2_RV/LV independently predicted mPAP (p < 0.001; R ²= 0.64 with LA volume index and RVEF) and PVR (p < 0.001; R ²= 0.63 with RVEF). Inter- and intra-observer variability for T2_RV/LV was excellent (R = 0.96-0.97). In conclusion, blood T2_RV/LV independently predicts invasive hemodynamic indices and is a non-invasive biomarker of SvO₂, which might enable noninvasive risk stratification and treatment monitoring in PH.