Correlating Pulmonary Hemodynamics With HP 129Xe Dissolved-Phase MRSI in a Controlled Porcine Intervention Study.

PURPOSE: Pulmonary hypertension is related to a 1-year mortality ranging from < 5% to > 20% in low- and high-risk groups. Right heart catheterization is the diagnostic gold standard, associated with a 1.1% rate of severe adverse events, posing the need for a non-invasive diagnostic tool. This study aims to delineate the effects of controlled changes on pulmonary hemodynamics by quantifying corresponding changes in hyperpolarized 129Xe MRSI dissolved-phase parameters, including RBC oscillations.

METHODS

Seven Danish Landrace pigs underwent hyperpolarized 129Xe dissolved-phase 3D MRSI with interleaved MRS under baseline conditions and three vasoactive interventions, monitored with invasive catheters or phase-contrast MRI. Results were evaluated using one-way ANOVA or mixed-effects analysis followed by Dunnett's multiple comparisons test.

RESULTS

Hypoxia increased mPAP (p = 0.038), reduced RBC:M (-31%, p = 0.007) and RBC:G (-34%, p = 0.009), while increasing RBC chemical shift (0.57%, p = 0.020). Adenosine and dobutamine increased RBC:M (22%, p = 0.003) and RBC:G (30%, p = 0.009), while decreasing RBC chemical shift (-0.38%, p = 0.11). Linear regression revealed an inverse correlation between mPAP and RBC oscillation amplitude (R2 = 0.158, p = 0.04), RBC:M (R2 = 0.25, p = 0.05), and RBC:G (R2 = 0.22, p = 0.01).

CONCLUSION

This study demonstrates that dissolved-phase hyperpolarized 129Xe MRSI parameters are sensitive to hemodynamic changes, exhibiting consistent inverse relationships with invasively measured mPAP. By leveraging concurrent invasive reference measurements, these findings provide physiological validation that dissolved-phase 129Xe metrics reflect pulmonary vascular pressure, supporting their further development as a non-invasive adjunct to right heart catheterization.