Optimize Xe-MRI Oscillation Imaging for PAH. Regional mapping of oscillations in the xenon RBC signal is a new technique that may provide new insights into microvascular function in PH. Recent innovations in Xe-MRI have enabled improvements to this methodology, but these have yet to be explored and optimized.~Quantify the short- and long-term repeatability of Xe-MRI oscillation imaging in patients with PAH. Hyperpolarized 129Xe oscillation imaging is a novel technique that may provide regional quantification of pulmonary microvascular function. However, the repeatability of this technique has not been measured, which limits its use as an outcome measure.~Determine the minimum time-point at which Xe-MRI shows a clinically meaningful change following treatment. Current standards in the PAH community are to assess treatment efficacy in PAH patients at 3-6 months using 6MWTs, REVEAL Lite scores, echocardiograms, and possibly RHCs. However, Xe-MRI may be more sensitive to functional improvements. We hypothesize that Xe-MRI biomarkers will show a clinically meaningful change within 12 weeks of initiation of pulmonary vasodilators.
In this study, hyperpolarized 129Xe MRI will be used to evaluate treatment efficacy in patients with pulmonary arterial hypertension (PAH). Participants will be imaged at 4 timepoints (baseline, 6 weeks post-therapy initiation, 12 weeks, and 18 weeks). Images will be analyzed to develop new biomarkers and to understand treatment effects.