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

Area of Science:

• Cardiovascular Imaging
• Pulmonary Medicine
• Magnetic Resonance Imaging

Background:

• Pulmonary hypertension (PH) has high mortality, and its gold standard diagnosis, right heart catheterization (RHC), carries risks.
• There is a need for non-invasive diagnostic tools to assess PH and monitor hemodynamic changes.
• Hyperpolarized 129Xe MRSI is an emerging technique that can provide functional information about the lungs.

Purpose of the Study:

• To investigate the relationship between controlled hemodynamic changes and dissolved-phase hyperpolarized 129Xe MRSI parameters.
• To quantify the sensitivity of 129Xe MRSI metrics, including red blood cell (RBC) oscillations, to pulmonary vascular pressure.
• To explore the potential of 129Xe MRSI as a non-invasive adjunct to RHC.

Main Methods:

• Seven pigs underwent hyperpolarized 129Xe dissolved-phase 3D MRSI with interleaved MRS.
• Baseline and three vasoactive interventions were performed, with hemodynamics monitored invasively.
• Data were analyzed using ANOVA and Dunnett's multiple comparisons test.

Main Results:

• Hypoxia increased mean pulmonary arterial pressure (mPAP) and altered RBC oscillation parameters (RBC:M, RBC:G, chemical shift).
• Adenosine and dobutamine also affected RBC:M, RBC:G, and RBC chemical shift.
• Linear regression showed inverse correlations between mPAP and RBC oscillation amplitude, RBC:M, and RBC:G.

Conclusions:

• Dissolved-phase hyperpolarized 129Xe MRSI parameters are sensitive to hemodynamic alterations in the pulmonary vasculature.
• The study provides physiological validation for 129Xe MRSI metrics reflecting pulmonary vascular pressure.
• 129Xe MRSI shows promise as a non-invasive tool to complement RHC in PH assessment.