129 Xenon MRI as a Biomarker for Diagnosis and Response to Therapy in Pulmonary Arterial Hypertension (PAH)

This study is exploring whether a special type of MRI that uses inhaled xenon gas (129Xe MRI) can be used to diagnose pulmonary arterial hypertension (PAH) — a condition where blood pressure in the lung arteries is dangerously high — and track how well treatments are working. **You may be eligible if...** - You are 18–75 years old - You have been diagnosed with pulmonary arterial hypertension (PAH), either idiopathic (no known cause) or related to a connective tissue disease (like lupus or scleroderma) - Your disease is classified as WHO functional class 2 or 3 (meaning you have symptoms with moderate or less-than-ordinary activity) - You have had specific measurements confirming elevated lung pressures **You may NOT be eligible if...** - Your pulmonary hypertension has a cause other than idiopathic PAH or connective-tissue-related PAH - You have any condition that prevents you from safely undergoing an MRI scan Talk to your doctor to see if this trial is right for you.