Mapping the Chemical Shift of 129Xe in Red Blood Cells as a Biomarker for Pulmonary Hypertension

Motivation: Prior work suggests that pre-capillary vascular occlusion in pulmonary hypertension (PH) may lead to paradoxical regions of enhanced blood oxygenation in the distal capillaries. The 129Xe RBC chemical shift is sensitive to such oxygenation variations. Goal(s): We aim to test whether enhanced oxygenation zones in PH could be detected by regional RBC shift mapping via 129Xe CSI. Approach: 129Xe CSI was performed in healthy volunteers and patients with pre-capillary PH. RBC shift maps were computed via spectral fitting and were compared between disease groups. Results: RBC shift maps in PH patients exhibit distinct patterns, consistent with physiological theory. Impact: This work offers a proof-of-concept that mapping the 129Xe RBC chemical shift could be valuable in assessing PH. Compared to current gold standard diagnostic techniques, 129Xe CSI is less invasive and, with further optimization, may permit localization of vascular occlusion.